Model Boat Mayhem
The Shipyard ( Dry Dock ): Builds & Questions => Pleasure boats, Sports, Race, Power and Leisure Boats: => Topic started by: Patternmaker on March 02, 2009, 06:49:58 pm
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Dismantled and cylinder machined for water jacket,
Water jacket machined from 70mm aluminium bar
Flywheel housing machined for rear engine mount and flexishaft coupling
Clutch and bearing discarded, bearing housing retained for rear engine mount
Front and rear engine mounts made from 3mm aluminium to fit 5inch rails
Custom made header from stainless steel
Custom made aluminium water cooled flange manifold
Total weight with tune pipe 2.32kg
Original weight with 3.20kg
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More Pictures
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Price ? & power(ish)
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Hello.
Looks like a good job well done. Couple of points. What are you going to put it in?
If you want to Run it in OMRA races there are set sound limits. Your pipe looks as if it has no baffles to keep the noise down. The Cylinder head looks like it only has 2 head bolts. If so when you run the engine make sure you pull them down again after 1/2 hour ruining. I tell you this as it happened to me and did the jug in.
All that said Well done. Where did you get the engine from and How much? A Sick/Zenoha will set you back between £ 175/ £ 195 at todays prices.
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Hi Bill, I might put it in 45" deep vee, because the engine has a larger flywheel than a zen its not really suited for a cat, I got the engine from ebay new for £22.95 I actually bought 2. I am am making a copper head gasket.
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Hi Bill, I might put it in 45" deep vee, because the engine has a larger flywheel than a zen its not really suited for a cat, I got the engine from ebay new for £22.95 I actually bought 2. I am am making a copper head gasket.
Hello
Yes I did see them on e bay. Look like you have done a good jon of converting the engine. I hope you enjoy the boat when you get it running. Good luck.
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You got the time to batch produce them? You could sell them for £80 ish each and make a handsome profit O0
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Hi Bill, I might put it in 45" deep vee, because the engine has a larger flywheel than a zen its not really suited for a cat, I got the engine from ebay new for £22.95 I actually bought 2. I am am making a copper head gasket.
Really nice looking conversion job, are you going to do some porting work to alter the engine timing and wake the motor up a bit? What type of motor is it?
Glenn
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Glenn, The ports have been modified and polished, I will wait and see what the power output is like before I do anything else. I will run the standard one and check RPM angainst the modified one.
Apart from a Sovereign label in the strimmer, which I have never heard of I think the engine is Chinese origin, very well made with the same diameter crankshaft and bearings as a Zenoah but with a larger flywheel and runs very well on idle.
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John, I have just seen your post from June last year (anyone know anything about
These hulls) I recently bought one of these hulls from ebay from a private seller it had obviously been laying about for a few months and the deck and cowl were scratched so I have had to restore by painting.
Quite a nice hull very similar to PMC deep V 2”shorter but with a little more freeboard, not the best quality moulding I have put an extra layer of cloth in the hull and round the stringers to stiffen it up. The hull originates from china and is called Blade.
I am going to fit the 28cc weedwacker engine running a 70mm 110mm 3 bladed prop
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Hi mate that motor is the same one i had in my old vee it actually ran flawlessly as an air cooled motor.I was told by a guy they are made by zenoah which would account for the good quallity and the bearings etc.I installed a walbro 167 carb and she ran very well,def need to ditch the stock carb as its junk.With some porting work id say she would be a very good little motor.Best prop hands down for this low revving motor was a big prather 280 2 blade prop.
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I have run both engines the modified one recorded 11,217rpm at full throttle on the tacho an increase of nearly 4,000rpm on the standard engine with the standard carb, which do not consider low reeving and will stay with my prop choice.
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The stock motor is low revving that was my point,the stock carb doesn't help either which is why i used a walbro 167.That said 11,000 rpm isn't high revving either the stock zenoah puts out almost 14,000 rpm with a pipe.For a stock zen you'd be looking at the prop your using or similar,i ran a 6717/3 on a stock zenoah but for anything lower rpm you would in my opinion be better with a larger prop.The stock sovereign motor with the 167 carb was putting out around 8,500 rpm ,a mate of mine had several of them and fastest speed he measured on the gps was 34 mph and that was with the big prop anda pipe with 90% header.Be interesting to see what speed you get with the mods you have done but i still think the big prop will work best,no harm in trying either.In fact no point just trying one prop on any setup if you want to find the best prop for it.Also your header will be way too long to achieve a good tuned length,you would be best with a 90% header rather than the wtc if your looking for higher rpm.I admire your workmanship though,just not sure its worth the time and effort for this motor.Its a great runner as stock for a play boat not sure how it will be reliability wise with mods done to it but i wish you luck.Its def a better motor than the ones seen on ebay in the cheap china boats.In fact if you get it running well and plan on doing any more id take several off your hands.
Mart
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Also your header will be way too long to achieve a good tuned length,you would be best with a 90% header rather than the wtc if your looking for higher rpm.
Mart
Mart,
what would you recommend for a tuned length on the engine that pattermaker has modified?
I'm thinking that with the sort of timing the motor most likely has at stock, and the fact that it is going to be running lower RPM then it might well be possible to achieve the correct tuned length from that header. What do you reckon?
Patternmaker - have you measured the exhaust timing duration yet?
Glenn
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Well if you look at the header its actually longer than your usual wtc header so my thinking is its too long,granted his tuned length will need to be longer than on a zenoah.I supose without testing it he wont know,im just saying in my opinion it will be too long.Just trying to give him my opinion based on my experience with this engine,even though its slightly modified i still say the prop needs to be bigger too.My old mate Rick actually modified one of these and it was putting out arround 15,000 rpm on a dyno but he never actually got it on the water to do any testing.
Mart
Heres a pic of mine with a tuned pipe,even in this pic the pipe was set too long.
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Just want to say to patternmaker in no way am i critisizing what your doing in fact i like what you have done so far.Just giving you another point of view,if you do intend doing any more i would def be interested .Another possibility to try is one of the ready welded up pipes with wtc header,theyre probably about the correct length for that kind of motor.They tend to work better than the seperate wtc header and pipes as theyre a tad shorter,at least the ones i had were.
Mart
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The reason I water-cooled the head is because so much of the cowling had to be removed air cooling would be not be sufficient, I have left the fins on the flywheel to help cool the crankcase, some of these engine mods the fins are machined of to save drag. I have managed to get a new very cheap carb not a walbro but almost identical with a 13.49 venture.
Because of the type of hull I have had to use a wtc tune pipe therefore I have no choice with the header, yes a compromise but it remains to be seen what performance I will get.
A stock zen 260 PUM produces max power of 2.16kw at 12000rpm and max torque of 1.94 at 9500 rpm, with cylinder displacement of 25.4. The 14000 rpm is obviously not under load
The weedworker has a displacement of 28.2, according to my calculations I will get a torque figure of over 2.00 at 9500rpm
I have been modifying petrol engines for nearly 30 years the first was a 22cc McCullock chainsaw engine which held the spark ignition (as it was known then) record in 1984 of 32.4 mph in a boat I designed and built which I still have
and won many offshore races which incidentally weighs nearly 14 kgs. The problem was they were fitted with points and condenser and not very reliable when they got wet, also the flywheels tended to burst at high RPM. With horrendous results.
My friend Naviga world champion 1988, 1994 & 1998 Dave Marles who has been designing and racing boats for many years suggested the prop size all due respect but I would think he has more experience than yourself and I value his expertises.
As for is it worth the trouble, I do not have a bottomless pit, if I can get the engines performance to equal the stock zen for less than 30 quid, I consider it to be well worth the trouble.
Everyone is entitled to their opinion and suggestions are always welcomed
Incidentally the Mercury Cat I built has been officially timed by his club at
64.3 mph with a stock zen a 257 carb.
Glenn,
the exhaust duration is 164 degrees
When we look today, we see incredible speed records and high standards of competition. We've learned that speed means serious attention to details and that our models require the best materials and demand our very best driving skills. Engines and radios provide nearly flawless performances, and the difference between winning and not boils down to each individual's performance, preparedness and motivation There are two things that I am absolutely certain will remain the same; speed records will continue to be set and broken, and the skills and motivation of the modeller will be the deciding factor as we continue to raise the bar to new heights. I hope we can continue to have fun along the way.
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Never had any problems with running mine air cooled but it wasnt modded in fact its still going 3 yrs later,the guy who has it still runs it with no problems.Of course i ran mine in an open boat but as it wasnt a race boat that was fine for me at the time.As for Daves recomendation on prop all i can say having run that motor for over a year and trying all manner of props as i say the bigger props worked better. Dave himself recomended to me that the x482 is the prop of choice for a weedwacker motor or he did when i was building mine,even the guys running the homies that are suposed to rev higher than these go for the bigger props.I didnt like the price of the octura prop so went for the prather which was cheaper for me at the time.Can i ask what tests have you done to test your motor under load?.As for the mercury cat doing 64 mph with a stock zenoah id like to see that i really would is there any video of it?.Ive seen one up close and personal with a zen 7 and i doubt it was much if any faster than 64 mph at the time.
Mart
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When we look today, we see incredible speed records and high standards of competition. We've learned that speed means serious attention to details and that our models require the best materials and demand our very best driving skills. Engines and radios provide nearly flawless performances, and the difference between winning and not boils down to each individual's performance, preparedness and motivation There are two things that I am absolutely certain will remain the same; speed records will continue to be set and broken, and the skills and motivation of the modeller will be the deciding factor as we continue to raise the bar to new heights. I hope we can continue to have fun along the way.
A very true statement, so many people take for granted what we have available very easily (cheaply) in the current times we live in.
Not that long ago, carbon fibre and kevlar technology was reserved almost exclusively the aerospace and military sector - now it is not uncommon in model boats as well as ever where else.
I look forward to seeing how you get on with the motor - I'm sure Dave will give you some timing figures to work towards and see where you end up. Guess as always it's a case of how far are you going to push it - just a bit more might be the end of it. (Ask me how I know!!)
To quote yourslef - have fun.
Glenn
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Never had any problems with running mine air cooled but it wasnt modded in fact its still going 3 yrs later,the guy who has it still runs it with no problems.Of course i ran mine in an open boat but as it wasnt a race boat that was fine for me at the time.As for Daves recomendation on prop all i can say having run that motor for over a year and trying all manner of props as i say the bigger props worked better. Dave himself recomended to me that the x482 is the prop of choice for a weedwacker motor or he did when i was building mine,even the guys running the homies that are suposed to rev higher than these go for the bigger props.I didnt like the price of the octura prop so went for the prather which was cheaper for me at the time.Can i ask what tests have you done to test your motor under load?.As for the mercury cat doing 64 mph with a stock zenoah id like to see that i really would is there any video of it?.Ive seen one up close and personal with a zen 7 and i doubt it was much if any faster than 64 mph at the time.
Mart
No I have not done any load tests on the engine yet, I would not even consider asking the owner if there is any video for proof, I have no reason to doubt his
word or his club officials
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Look forward to seeing how she works out for you ,as regards the video im genuineley interested in seeing it if there is one as ive never heard of any cat doing that sort of speed with a stock zenoah so maybe i could learn something.
Mart
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My 22cc McCullock Spark ignition Class boat from the early eighties
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Are we sure thats MPH? the mercury looks quite blockish and not incredibly streamlined, it is a big bore crab but on a stock zen??
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You might be interested in the following links
http://www.youtube.chttp://www.youtube.com/watch?v=yIV8ByYhkwYom/watch?v=PwIoboKT8lQe
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Mick the links not working for me and im interested ok2
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Sorry about that, the link does not work, I put it done to my age.
These are all on youtube of the Falcon cat which is also known as Mercury:
FALCON RC BOAT
FALCON 41 GAS BOAT
RC GAS CAT
FALCON CAT WITH ZEN 7
R/C FALCON @ 70+ AND WILD BLACKCAT
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Pictures of my deep vee with moded weedwaker, the carburettor will be changed thanks to a very kind member who has given me one.
The deck and cowl painted in candy gold finished with 2K lacquer
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That looks really nice mate ive got some gold candy paint here waiting to be used on one of my boats ill be doing it over a silver sparkle basecoat.I notice you still have the idle screw in the carb id remove that so you can shut down the motor with the radio.Also you might want to add support to the tube nearer to the collett as i cant see anything withing 3" of it? id also install a shaft saver just in case the collet lets go or you forget to tighten it youd be surprised how many have done that .Apart from that shes looking very nice mate.Heres a sample of the colour i want to end up with,the plan was to do one of the vees i build for my son in this colour but i have been to busy building the moulds for the t boat and getting the first one built for a mate .Check out my build thread,ill be posting new pics in a little while.I wish you luck with yours hope all goes well on your first outing
Mart
http://www.modelboatmayhem.co.uk/forum/index.php?topic=16083.msg159090#new
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There's a T bar 60mm from the end of the tube, I wont put it any closer because even with HD mounts this engine has a lot of torque therefore
movement so its best to let end of shaft tube flex slightly.
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No worries 60 mm isnt far looks more in the pic thats why i asked ,the torque you talk about is why i suggested a big prop by the way ;).You have done a very nice job with the build it looks very nice.Not hard to see you take pride in what you do.What carb is that you have on there now.
Mart
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As Mart said,nice build.
Did you sculpt that intake on the canopy yourself?
Jacks is the same hull,without the 'hole'.
looks the buisness :-))
Brod..
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Brod,
I made a plug and mould for the intake, it serves two purposes, the engine is deeper than the zen the top of the spark plug a cap is higher than
cowl. The cut down intake covers the carb idle screw and choke
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Very nice work on the cowl i forgot that bit :-)),i still say remove that idle scew and throw it away though so you can shut the motor down if needed using the radio.
Mart
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Thanks Mart, I am going to fit a 644 carb kindly given to me by another member, I will have to modify the insulator and the throttle linkage.
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Sounds good mate,i liked the wa 167 carb on the stock one but the 644 should be fine for yours.Keep us posted on how she runs,so whens the big day .One weekness i found on this motor was the recoil starter it seems to ware out pretty quick,did you modify yours at all as id be interested in seeing what you came up with if anything.
Mart
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here you go pattermaker,a quick video of jacks mono,the same as yours,new cheap China pipe and a pals mods to the the Zenoah motor.
Hope yours runs as well,keep us all informed :-)
http://s302.photobucket.com/albums/nn96/brodjack/?action=view¤t=jacksboatmedrivingshrunk.flv
Brod..
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Nice one Brod, goes very well. I have made some more mods to my engine opened up exhaust port even more, fitted 644 carb, now getting over 15000 rpm. one big problem I don't know when I will be able to run my boat. I have a severe back problem, trapped nerve base of the spine
from shattered disc, told I could be laid up for months it may well be the end of my model boating :((
Good luck to all of you, and thanks for all your support.
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Bad luck pattern.Boating does require alot of bending down etc.
I did mine about a yr.and a half ago at the gym,bodybuilding,couldnt walk for a good 4 weeks.
Unbeleivably painful.
Physio told me to start hunting for a good wheelchair.
He was wrong,back at the gym,stronger than ever now,hope yours ends the same...
Good luck...
Brod...
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Thanks for the encouragement Brod, it shows consultants can get it wrong.
Regards Mick
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Mick so sory to hear about your back mate but dont give up hope.A good friend of mine over in the states had a similar prognosis after a botched operation and sold a lot of his boats only to find a different doctor who put his back right for him within a cpl of months and that was after a year or more of pain and thinking he would need a wheelchair etc.He has now just started building and running boats again and in fact has just started up a buisness selling a rtr race ready mono or is in the process as we speak so there is allways hope.Good job on the further mods,sounds similar to what my old pal Rick was getting from the one he modded a cpl of years ago,he too had to give up boating due to all his gear been destroyed in a house fire :o at least it was just the boats that died.His background was in 2 stroke bike racing,he never did get to see his motor run which was a shame.I hope you get well soon and get that boat running :-)).
Mart
ps Brod thats one noisy pipe sounds like that hanson quiet pipe i had ok2,seems to go well.
heres a customers vee i built ,a mate sent a vid of.Another noisy pipe O0.
http://www.youtube.com/watch?v=5qQviWVdD2Q (http://www.youtube.com/watch?v=5qQviWVdD2Q)
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yeh Mart,its no Prestwich pipe :embarrassed:
it was double loud without the silencer in the yard,but we kinda expected that.Dave supplied the pipe and silencer for a song and i had them both tigwelded together.
I've joined the noisy pipe brigade.
your hull on that vid. runs fast,bit of chine walk,but Jacks hull with the extra speed was starting to do it too.
Are you going to build one for yourself?
Sorry Pattern. for the off topic chat.. makes good reading though..
Brod...
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Picture of Walbro 644 fitted with modified insulator, thickness machined 7mm thinner, bore machined to carb venturi and modded throttle linkage.
The recoil starter has been modded plastic ratchet pawls replaced by aluminium and pivot posts made larger.
This boat weighs exactly 7kilos with a full tank of petrol, what does Jacks boat weigh Brod?
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Very nice work Mick good idea changing the recoil starter pawls ,7 kilos isnt a bad weight with a full tank considering this engine is a tad heavier than a zen.Hope yopur well enough soon to run it ok2.
Brod those pies arent bad for the money and produce good power by all accounts.The boat in the vid does look pretty fast but running a little wet,but i think thats the flat water i know mine was better when the chop was on the water.Chinewalk seemed to be a problem with mine running that same prop hes running,when i switched props it stopped doing it.I will build one for me as i miss mine especially when its too choppy for the hydro.Hope we get a good Summer so we can run some boats.
Mart
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Nice work Pattern,do you access to lathes and stuff?
It just shows what a bit of mechanical know-how can do to such almost any motor,without costing the earth.
I have a fishing scale(hook up jobby) somewhere,i'll dig it out later,if i can find it, and weigh Jacks boat later.
I'd like a comparison too.
Think the chine walk is all in the props too,mixed in with the extra speed.Jacks was ok,it seemed to do it as it went back over its own wake,which possibly made the hull run very high on the water for a second.Dont really know.
I like these type of hulls,got a bit bored with the Apache which has been stripped of the bits for another hull.
I would make another for yourself Mart,especially now you have access to cheaper bits.
We are going to go later on, on sundays,it tends to be calmer at that time.Plus not too many spectators. O0
Brod..
by the way the pies are very good for the money!!
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Picture of Walbro 644 fitted with modified insulator, thickness machined 7mm thinner, bore machined to carb venturi and modded throttle linkage.
The recoil starter has been modded plastic ratchet pawls replaced by aluminium and pivot posts made larger.
This boat weighs exactly 7kilos with a full tank of petrol, what does Jacks boat weigh Brod?
Mick,
out of interest, try and give your engine a run with the carb velocity stack off and see if it produces any more revs.
Glenn
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Glenn,
thanks I will try it when my back allows, cannot do much at all at the moment.
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Nice work Pattern,do you access to lathes and stuff?
It just shows what a bit of mechanical know-how can do to such almost any motor,without costing the earth.
I have a fishing scale(hook up jobby) somewhere,i'll dig it out later,if i can find it, and weigh Jacks boat later.
I'd like a comparison to
Brod,
I have a fairy well stocked workshop, lathes, milling machine, all the usual woodworking machines including planer thicknesser. My last scale scratch build was
Thames steam launch Miranda
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Mick now your just showing off :-)),thats a stunning model absoluteley beautifull workmanship.
Mart
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Awesome work! as well as lots of tools,lots of patience needed for models like that,I bet.
Weighed jacks boat and its exactly 14 pounds with an almost full tank.Which is 6.36 KG.
i saved a fair amount of weight with a Maplins clear plastic project box as a Radio box and also used an elderly 3cell 2000mah Lipo pack with a 6v.Sbec regulater.if i remember right,i shaved off 400g from a glass box with a 5cell 3000 nimh.
I originally fitted 1 underwater pickup on Jacks at the rear,but wasnt happy with the water flow,the rudder only having 1 intake hole.
I've since swapped pipes,needing only 1 water inlet source now which feeds both motor and manifolld/flange.
I drilled the single rudder hole larger and water flow is now very good.
I noticed a similar underhull intake on yours.
Brod..
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Brod,
Thanks for letting me no the weight of jacks boat. I originally thought that mine was a bit heavy knowing that the engine was heavier than the zen that's why I moved the engine slightly further forward. I made my own radio box as small as possible to get everything in including fail safe. The pickup from the hull cools the manifold and tune pipe the rudder pickup for the head, I will have to wait see how it works if and when I can ever run the boat.
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Mick,
can you not get hold of someone who will go with you to start and throw the boat into the water for you so you can at least see it running? I know of at least other model boater who lives on Canvey.
It must be killing you not being able to run the model.
The wood boat looks to be a work of art too by the way. And I am not a big fan of wood so there you go. Nice work.
Regards,
Glenn
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Glenn
You're absolutely right, its driving me mad not being able to test the boat, I have a lot of patience building models but not when it comes to this. I cannot even drive at the moment, going to see the consultant tomorrow for scan results so fingers crossed, if all else fails I will have to find a volunteer test pilot.
Regards,
Mick
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hi Mick, sorry to hear about your current predicament. I'm just up the road in Westcliff & would love to help you out if you like. I appreciate your priority is with your health, but would hate to think your sat there wishing there was away of getting to a lake to try out the boat. Let me know if i can be of assistance. good luck with your back
cheers Glenn ( yes another 1)
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Hi Glenn, your offer of assistance is very much appreciated, I will see how I get on tomorrow and keep you informed. Since I joined Modelboatmayhem I have realised what a great bunch of people you all are, thanks again Glenn
Regards Mick
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hi Mick, sorry to hear about your current predicament. I'm just up the road in Westcliff & would love to help you out if you like. I appreciate your priority is with your health, but would hate to think your sat there wishing there was away of getting to a lake to try out the boat. Let me know if i can be of assistance. good luck with your back
cheers Glenn ( yes another 1)
See this is what this hobby (obsession) is all about,people helping one another out when they can nice one Glenn :-)).Good luck today Mick hope its good news.
Mart
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Thanks Mart, you comment is very much appreciated
Regards Mick
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Hi guys, not good news I'm afraid, been told to have complete rest for 2 months and I will be assessed again (keep taking the tablets) being told my age was against me did not help. Been given a back brace which limits your movements, I cant see me wearing this for long its very uncomfortable. The love of my life, my wife is my support even though I have got out of doing the household chores again.
I have had back problems since I was in my early 20s started when I was in the army 3rd battalion parachute regiment, 28 jumps in just in 2 years the base of your spine is stretched with the jerk when the chute opens at about 100mph and compressed when you land at about 14mph depending on how much kit your carrying.
I have found in my case over the years that resting is not the answer, if I keep on the move when possible and it gradually improves and becomes bearable, so only time will tell, one thing I do know it will not stop me building models when possible even if I cant run them. My son who lives in Cornwall will test my boat when he next visits, we used to race together in the 80s and 90 One consolation I will be able to spend more time on MBM forum.
Thanks for all your support, and a special thanks to Glenn from Westcliff.
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Sorry to hear your bad news Mick,just remember doctors don't know everything ok2.Keep your chin up mate and go build some new models for when you can get back out there.I hope your boat runs well when your son gives her a run.Also check out RC Universe theres lots on there to keep you occupied as well as whats on here.
Mart
http://www.rcuniverse.com/forum/default.asp?fh=1&forum=229 (http://www.rcuniverse.com/forum/default.asp?fh=1&forum=229)
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Thank's Mart, you don't have to look very far to see people a lot worse off than yourself.
Mick
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Got my grandson to run the engine without velocity stack slight increase in RPM
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Looks good Mick so come on what mods did you do to the motor how about a few pics of what you did for us dummies ok2.Might even have a bash at doing some minor mods to the one i have here,but i might keep it air cooled for now as i have a boat i can run open top ,this one will be for my son .
Mart
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Hi Mick,
what is the current length from exhaust port flange face to the widest part of your tuned pipe?
Just working out a tuned length for you!
G
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Hi Glenn,
Its 380mm, the most I could gain with the present pipe is by shortening the header to clear the engine cowling is 12mm.
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Looks good Mick so come on what mods did you do to the motor how about a few pics of what you did for us dummies ok2.Might even have a bash at doing some minor mods to the one i have here,but i might keep it air cooled for now as i have a boat i can run open top ,this one will be for my son .
Mart
Mart,
Apart from water-cooling the head if you do not have a lathe anybody could do the mods I have done, porting; inlet open up the port as much as possible but NOT at the top because the port must not be above the piston at BDC, the exhaust port again open up as much as possible and polish both ports. Chamfer the edges of transfer ports, inlet and exhaust inside the cylinder but NOT the top of inlet port, this will prolong the life of the engine when they are not chamfered they act as a scraper ring and take oil from bore.
Open up the carb insulator the same diameter as carb venturi, if you have one fit walbro 257 I think this would be the best for this engine I am running with 644 which I had given to me.
I also rebalanced the flywheel, I notice some vibration when first run, easy to do remove flywheel fit on a shaft the same diameter as crankshaft fairly tight fit, set up 2 parallel bars rotate slowly if the flywheel stops in the same position without rotating its ok, if it moves backwards or forwards before it stops it will rebalancing it will always rotate to bottom, the point of imbalance start with a small drill and remove a little at a time until you achieve correct balance.
I also use NGKCMR7H Spark Plug, hotter than the standard one
You can see what RPM I am getting, so there you go Mart, do you keep the original clutch, I dumped mine and fitted a flexishaft coupling which will screw straight on to crankshaft which also holds the flywheel.
Mick
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Hi Mick thanks for that ill give it a go m8,ive kept the clutch still undecided on that yet as a clutch is a nice feature on a play boat especially for kids.Good to know the threads are the same as the collets we use if i do decide to ditch the clutch though.The clutch is actually decent on these motors,seems to run ok.I never tried a different plug on my old one but might give it a go,you know if you remove the choke from your 644 and plug the holes you will basicly have a carb similar to a 257 and i actually prefer the 644 to the 257.The 644 is a lot cheaper to buy too ;).I will then need to make an adapter for the header to bolt onto to to fit a tuned pipe.
Mart
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Hi Glenn,
Its 380mm, the most I could gain with the present pipe is by shortening the header to clear the engine cowling is 12mm.
I did the calculation, but made an assumption that the pipe is tuned at 15000RPM, which we do not know as you have not run it and found where it is right now, but for arguments sake, if it is set at tuned length @15000RPm, then an increase in exhaust timing to 180 degrees, to aim for power @ 16000RPM would make your pipe tuned length longer @ 15.429". (391mm).
A few assumptions there mind Mick, but increasing the exhaust duration to a bit more might make the pipe easier to get tuned with the longer header you have.
I will email you the calculation if you want it Mick.
Glenn
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Thanks for the info Glenn, very interesting, I will wait until the boat has been run to see what the performance is like, I do not honestly think this engine will take many more revs unloaded. I have been trying to think of a way of loading the engine to simulate, I use a windscreen washer pump for cooling, thanks again for your trouble.
Mick
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Hi Mick thanks for that ill give it a go m8,ive kept the clutch still undecided on that yet as a clutch is a nice feature on a play boat especially for kids.Good to know the threads are the same as the collets we use if i do decide to ditch the clutch though.The clutch is actually decent on these motors,seems to run ok.I never tried a different plug on my old one but might give it a go,you know if you remove the choke from your 644 and plug the holes you will basicly have a carb similar to a 257 and i actually prefer the 644 to the 257.The 644 is a lot cheaper to buy too ;).I will then need to make an adapter for the header to bolt onto to to fit a tuned pipe.
Mart
Mart, The thread on the crankshaft is M8 so its collet would be for a CMB90 for 1/4 flexishaft, the choke has been removed from the 644, its a shame the exhaust port is mounting holes are offset, I had to make a watercooled flange to suit, incedentally I do not use a gasket on the flange and also loctite every bolt on the engine.
Mick
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Thanks for the tip on the collet,yea its strange the bolts are as they are on the exhaust when the bolt spacings are exactly the same as the zens for the carb,very inconsiderate lol.I was going to make a separate flange spacer to fit then tap it to accept the bolts for the header flange i have.Ive seen someone else do a similar thing on this motor and it seemed to work ok,a friend bought this one on ebay the other week.Your lucky you have access to the right machinery to custom make your own items.My expertise is with wood mainly not metal so just have to make do with what tools i have i suppose.
Mart
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Thanks for the info Glenn, very interesting, I will wait until the boat has been run to see what the performance is like, I do not honestly think this engine will take many more revs unloaded. I have been trying to think of a way of loading the engine to simulate, I use a windscreen washer pump for cooling, thanks again for your trouble.
Mick
Probably right on the no load revs, if you can be bothereed make a bench mount and run it with an aero prop (a big one) as a brake.
Then you will be able to see where the power jumps up when the pipe hits a tuned length.
Glenn
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Thats a good idea Glenn, I will try it when I can.
Mick
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Thanks for the tip on the collet,yea its strange the bolts are as they are on the exhaust when the bolt spacings are exactly the same as the zens for the carb,very inconsiderate lol.I was going to make a separate flange spacer to fit then tap it to accept the bolts for the header flange i have.Ive seen someone else do a similar thing on this motor and it seemed to work ok,a friend bought this one on ebay the other week.Your lucky you have access to the right machinery to custom make your own items.My expertise is with wood mainly not metal so just have to make do with what tools i have i suppose.
Mart
Looks good, whats the thickness of the front mount plate? It looks if the 1/4 flexishaft has be has been ground square to fit the original coupling?
Mick
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Hi Mick im not sure as i havent seen the motor in person but i will be asking him,as regards the flex im not sure if its the stock one that came with them as a strimmer like my old one was or not.If i can get some more pics of it ill post them.I just test fitted the motor complete with shroud in one of my stepped vees i had to modify the hatch opening to get it in there but it fits,should be fine air cooled as theres a bit stuck above hatch to catch some air.Ill post a pic later if you like.
Mart
by the way heres my old woody with the stock weedy,only change on it was the carb to the wa 167 carb.
http://www.youtube.com/watch?v=6DkwfMavcqQ&feature=channel_page (http://www.youtube.com/watch?v=6DkwfMavcqQ&feature=channel_page)
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martno1fan do you have the plans for that deep v bud looks like a nice boat for fun
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Hi mate i dont but i can get you some,they print out as tiles so you just print onto A4 and tape the pices together.The hull runs very well,in fact with a zenoah its dam fast but can be a bit flighty so a little weight up front doesnt hurt when its choppy.Ill ask my m8 for a copy of the plans and get back to you.Pm me your email and ill send them.
Mart
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martno1fan do you have the plans for that deep v bud looks like a nice boat for fun
If you want to discuss private business use PMs please.
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lighten up Mick its all boats init give the lad a break hes new ok2
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sorry if i offended anybody and for the slight hijack of the thread no harm meant ill pm you bud thanks
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Hey Mick motors fitted pipes on just need to tune the carb heres a test run.
Mart
http://www.youtube.com/watch?v=Tzf-8O2tRe8 (http://www.youtube.com/watch?v=Tzf-8O2tRe8)
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Jeeeebus you got enough boat with that pipe???
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Yea plenty ;) the silencer is big so pipe looks longer than it is,nice and quiet too should be very quiet on the water.Will be a nice sports boat,testing will be ina cpl of weeks watch this space :-)).
Mart
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Mart I thought the idea of a WTC pipe was to have in the centre of the hull, testing should be interesting!
Mick
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As you know i lengthened the pipe with a sleeve this was the best fit so went with it rather than bend anything where the pipe ended up makes no odds in this situation.Im confident she will be in the 30+ region with this setup stands to reason, i had the stock motor with can muffler in my wooden hull which weighed 16-17 lb and speed was arround 28-30 mph depending on conditions this one weighs only 12.1 lb ok2.
Mart
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If you heat the inside of the bend where it enters the tune pipe to a cherry red you can straighten the bend easily to centre the pipe it will blue the chrome but would polish out.
Mick
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Yup i know i could bend it if i wanted but like i said it doesnt really matter in fact it looks better to me not been in the centre.If id had it bend more central the pipe was too close to the shroud and i didnt want to add too much length to the bend and make the pipe any longer than it need be,id say its quite a bit shorter than yours as i only added a 1 1/2" sleeve and the gap would have been maybe 3/4" at most.I used the wtc pipe because its what i had and i thought a slightly longer pipe would suit the motor better but i didnt want to go any longer than i needed to for obvious reasons.Seems to have good power and quite responsive so cant wait to try it out on the water.The boat should balance better with the pipe on the left anyway as the radio box is going on the oposite side above the stringer ok2.As i say this ones just a play boat but i think some might be a little surprised how well it will run.Next one i do ill maybe go for a hotter setup we shall see.
Mart