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Author Topic: SC 61 break in.  (Read 14419 times)

Biscuit

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SC 61 break in.
« on: December 18, 2006, 09:52:59 PM »

 Hi, New to this Forum, need a bit of help here.
As I was having so much trouble trying to start my SC 61 last time at the lake, infact I gave up and came home, I thought before the next time the lake was booked I would try and run it in at home, got a pump to cool the engine new starter and battery. Got it started but so rich so leaned it out on the top end but then when I shut the throttle it went all lean and started reving its head off! no mater what I did the same thing would happen, been in touch with Dave a Prestwich he said the low running mixture screw should be screwed nearly all the way out and the top end only 1 turn out. Well I was going to try this but noticed today that the motor had lost compression, stripped the motor and found one part of the piston had seized only a small mark but thats all it takes to lose the seal. Could this of happened because the motor was over cooled with the pump, its very powerfull , maybe the piston an liner could not expand so it just nipped up for a second? was thinking of putting it back as its still got a good pop! but will not hold compression at TDC. So lost another Sunday, will I ever get this boat to run? its was all brand new really thinking of throwing in the towel and going back to my helicopters. So can anybody help or give me some advice as I am new to this boating lark.
Thanks.
Steve.
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Martin [Admin]

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Re: SC 61 break in.
« Reply #1 on: December 18, 2006, 10:46:46 PM »

Hi Steve,
Been there, done that!  :-\

1, How old is the engine?
2, Did it run Ok from about 1/3 throttle and up when it was running?

Matrin
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Biscuit

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Re: SC 61 break in.
« Reply #2 on: December 19, 2006, 12:13:24 AM »

Hi, the engine was brand new, the boat and the engine were part of an unfinished project, the engine always seemed a bit rough when you turned it over and there were signs of rust on the plug even though I know the engine had never been run. Since stripping it down I have replaced the rear bearing as it was rough and rusty, it had been kept in a garage for 2 years so rust might of built up then as there was no oil in the motor. Like I said the carburation was just all over the place you opened the throttle it almost stopped so rich, yet even like this it would scream when you closed the throttle, you just looked at this engine carb shut reving its head off, never seen it before only way to stop it finger over the carb. Any Ideas? and have I killed it trying to run it in?
Cheers
Steve.
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BobF

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Re: SC 61 break in.
« Reply #3 on: December 19, 2006, 12:33:49 AM »

Hi Biscuit,

We have a few of these motors at our club, and all of the new ones that belong to new members had this revving or nothing problem. I can't speak from first hand ownership of one of them, but have been using marine IC's since 1963.

The SC engine is very tight when new at the top of the stroke, which they mention in the instructions.
I have heard of people actually skimming the piston sides to remove some of the binding, which is part of the design of an ABC engine. I have an SC21, which feels so tight when turned over by hand with no plug in as if it would tear itself to pieces when running. I don't know how the con rod takes the strain.

I have an OS 32 ABC engine that does not bind at all  (which would suggest clapped out), with the plug removed, so no compression to misslead, and that starts first time every time winter or summer with no problems at any rev range. I would have thought that to have lost enough compression that it is noticeable, the motor would have to be almost minus the piston. It's also strange the the motor would not throttle down. If the air intake is closed, the motor should stop no matter what the mixture setting is. I have a few motors with marks on the piston and bore, and they run with no problems. They may be down on power, I don't know, and they are only used for sport not racing boats, so a slight loss of power does not matter any way. It is also normal now days, to loosen the glow plug about half a turn, and then re tighten it as soon as the engine starts.

I would put it back in the boat, and give it another try. Whats to loose?

Regards Bob

The post above was added while I was typing my reply.
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BobF

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Re: SC 61 break in.
« Reply #4 on: December 19, 2006, 12:37:46 AM »

Hi again, 

Can you actually see the barrel being chocked by the air flap?

Bob
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Biscuit

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Re: SC 61 break in.
« Reply #5 on: December 19, 2006, 09:50:11 AM »

Hi again, 

Can you actually see the barrel being chocked by the air flap?

Bob
Hi Bob, thanks for the reply,
Yeah its shutting down to just leave a cap for tick over, when you start it the tickover is quite fast, but when you open the throttle you can see raw fuel spluttering out of the intake like its too rich on the top end, so you lean it out so it picks up then it wont shut down when the throttle is closed unless you put your finger over the carb intake,had to loosen the plug to turn it over, start it then tighten it again. Did the other lads with the SCs get them sorted?
Thanks
Steve, (biscuit)
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martno1fan

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Re: SC 61 break in.
« Reply #6 on: December 19, 2006, 07:06:47 PM »

hi it sounds like the engine was either damaged or as you say rusted up and youve now probably ruined the piston and  barrel if you say it was grinding?.they are tight engines and you have to loosen the plug all the time to get them to turn over.id strip it and check the piston and barrel and see if its scratched up if so it depends how bad it is as to what you can do.i bought mine off ebay for 25 quid it was quite new ,it was a plane engine and i made a cooling coil for it to put into my boat.she runs well but shes still a devil to turn over.impossible if you dont loosen the plug id say.good luck with it.they are also difficult to tune but once they are they run well .i spent a full day messing with mine to get it to run for more than two minuites now it starts first time and i agree they are powerfull motors .
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Biscuit

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Re: SC 61 break in.
« Reply #7 on: December 19, 2006, 08:21:06 PM »

 
It was the rear bearing that was rough, I think due to storage in a damp garage, might do what Bob says and stick it back in. I have replaced the rear bearing and it is very smooth when you turn it over now, and still got good compression, but not as good as it was, only a little mark on the piston, but like I said before thats all it takes to lose the seal on an ABC engine. You say it took you all day to sort out your engine, did you run it in at home or at the lake? and what settings did you end up with carb wise? and is it reliable now? Any help would be most welcome.
Thanks.
Steve.
Ps trying to upload some pics of my boat but it keeps saying the files to big, always been able to upload on other sites am I doing something wrong here?
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martno1fan

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Re: SC 61 break in.
« Reply #8 on: December 19, 2006, 10:43:50 PM »

hi sorry i cant remember the exact settings it was a guess and see as i had no book for the engine,it runs great but as it was a plane engine i tuned it on the bench ..try the factory settings if you have the book or ask dave marles who sells them for the settings.they are great engines and in my opinion better than os engines at less than half the price,they are copies of the os actually but they are better made apparently.stick with it you will get it going i couldnt fathom it but half a turn of the needles and off she went and hasnt had a problem at all since.i darent touch the needles now lol.forgot to say download microsoft image resizer its free and change pics to medium it works great.sorry i couldnt help more.by the way even with cooling if you test it out of water dont rev it too much or you will over rev the engine with no resistance on the prop and it will seize up.thats why i used the aero prop to tune it before i converted it to marine use.
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RC John

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Re: SC 61 break in.
« Reply #9 on: December 20, 2006, 04:28:57 PM »

http://www.modelboatmayhem.co.uk/forum/index.php?topic=1760.msg17293#msg17293 should be a link back to the thread Basic Setting of SC's started by peewee.
All SC's must run on 20% oil - you did not specify your fuel or oil content. 100ml of extra oil per gallon will increase the oil content by  approx. 2%
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Biscuit

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Re: SC 61 break in.
« Reply #10 on: December 20, 2006, 07:05:19 PM »

http://www.modelboatmayhem.co.uk/forum/index.php?topic=1760.msg17293#msg17293 should be a link back to the thread Basic Setting of SC's started by peewee.
All SC's must run on 20% oil - you did not specify your fuel or oil content. 100ml of extra oil per gallon will increase the oil content by  approx. 2%

Motor Been run on 25% Model Technics Duraglow. Thanks for the link.
Steve.
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Biscuit

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Re: SC 61 break in.
« Reply #11 on: December 20, 2006, 07:13:05 PM »

I have read this link before, no way will my motor run at 2,1/2 turns out on the main needle, more like 1 turn with the idle needle almost out to the stop, or its just too rich on the top end. 30 for new piston and liner, might get one, but going to try it again with the old one first. Made a restrictor for the water pump so that the engine can run a bit hotter.
Thanks
Steve.
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BobF

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Re: SC 61 break in.
« Reply #12 on: December 20, 2006, 10:24:32 PM »

Hi  Biscuit,

Not directly linked to your running problems, but it has always amazed me how people connect some sort of water pick up to a varying length of and bore of pipe. They then run this to a varying range of motors in yes you've guessed it, a varying range of marine craft, from slow to fast. And guess what, everything always seems to work OK.

In the supper sophisticated world of fast I C boats, they do have methods of assessing the running temperature of the motor. But the sport boats just get by with what they are given. A rule of thumb I once read, suggested that after the motor had reached its running temperature, some drops of water should be splashed onto the head. The water should evaporate quickly away, but not boil off.

I use a running tank in the garden made up from a scaffold plank with a heavy duty sheet layed into it, and then filled with water. At the back end of the box, I fold the sheet back towards the front with a board over it, to keep the water in the box. The box has eight angle brackets at the ends, spaced so the sides drop in between, and eight nails just plug into pre drilled holes.

Regards Bob
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RC John

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Re: SC 61 break in.
« Reply #13 on: December 21, 2006, 03:11:17 PM »

http://www.modeltechnics.com/glowfuel/duraglo.html is the link to Model Technics site. Duraglo is 15% oil. You need to be PLUS 5% on Oil.
2 to 2 turns is the starter position for running for a new engine - the final running position will be closed down from there.  1 turns was about the figure that I used. Run the engine HOT especially at this time of the year
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Biscuit

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Re: SC 61 break in.
« Reply #14 on: December 21, 2006, 04:41:52 PM »

 
Yeah I know most engines start at 2.1/2 turns out when new, but the SC was just not going to run at this setting, wether it was because the motor was too cold I don't know. Like I said Dave at Prestwich Models said that the Idle needle is too long so you have to have it right out and then lean the top end down. There must be someone out there who has had this problem and got it sorted, my boat is back together and ready to go, just going to start it and chuck it in and see what happens, got to wait another month to book the lake.
Thanks.
Steve.
Ps managed to get some pics on.
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glennb2006

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Re: SC 61 break in.
« Reply #15 on: December 23, 2006, 04:09:01 PM »

Hi Steve,

I had some set up problems with my SC61 when it was new, one of which was it being really tight, think they all are, made it very hard to start, but experienced some problems with carburration, mine were cured by relocating the fuel tank lower in the model.

Hope this helps.

Glenn
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Biscuit

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Re: SC 61 break in.
« Reply #16 on: December 23, 2006, 04:49:51 PM »

 Thanks Glenn,
Yeah did think about that but the tank is as low as I can get it, might be as Dave said just got to get that carb right.
Thanks.
Steve.
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martno1fan

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Re: SC 61 break in.
« Reply #17 on: December 23, 2006, 07:16:31 PM »

steve as i said these engines just take small adjustments to get it right a slight turn one way or the other on the low end needle and the thing just wont run it will start and probably run at full tilt and then die as mine did till i got it right.can i ask what size the boat is? if its big enough pull the sc out and get a zenoa petrol engine and no problems with starting then lol
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Biscuit

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Re: SC 61 break in.
« Reply #18 on: December 23, 2006, 08:55:18 PM »

 Boat is 42" long, think you can get a Zenoa in not sure about the hight, maybe you can buy a higher hatch for it, I know what you mean got a Zenoa in my FG Buggy, its just so hassle free, and seen a lot of motors on e-bay at a good price. Cheaper than a CMB or Pico, don't know why these engines are so expensive, do you think my boat is big enough for a Zenoa??
Cheers
Biscuit
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martno1fan

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Re: SC 61 break in.
« Reply #19 on: December 23, 2006, 11:40:11 PM »

Boat is 42" long, think you can get a Zenoa in not sure about the hight, maybe you can buy a higher hatch for it, I know what you mean got a Zenoa in my FG Buggy, its just so hassle free, and seen a lot of motors on e-bay at a good price. Cheaper than a CMB or Pico, don't know why these engines are so expensive, do you think my boat is big enough for a Zenoa??
Cheers
Biscuit
Yes i think its big enough its the same boat as this one!! yours is a bit smaller but i think the zen would fit as it fits in this cat which is 41"

http://www.radiocontrol-2005.com/tunami.htm

i think the same company makes the 41" hull too maybe if you ask them they can help you out.
]]http://www.radiocontrol-2005.com/flying%20dragon.htm yours is a bit smaller but i think the zen would fit as it fits in this cat which is 41"




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RC John

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Re: SC 61 break in.
« Reply #20 on: December 27, 2006, 03:28:48 PM »

Biscuit - Have you checked your critical (tuned) length for the engine/pipe set up in your pictures?
Go to http://www.nimrifmodels.co.uk/setup.html for a chart on the critical lengths of engines.
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Biscuit

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Re: SC 61 break in.
« Reply #21 on: December 27, 2006, 09:24:17 PM »

Thanks, but I don't think that is a real tuned pipe, its called a quite pipe just got a baffle in the end with holes in it, will those diagrams and sizes work? wish I had never got this boat spent so much time on it painting and such, its going on e-bay and I will buy a ready to run that I will know will work. Think this boat was supplied with very poor exhaust and engine and hardwear for what it cost, cant see anyone getting this set up to run. Thanks anyway John,
Steve.
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martno1fan

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Re: SC 61 break in.
« Reply #22 on: December 27, 2006, 09:47:08 PM »

where you going to get a decent rtr boat here for good money ,better to buy a hull from usa or china and that zen i showed you then you may get a boat for 400 quid .over here you will be talking 1000 with radio.dont buy one of those crap ebay gas boats unless its that arrow shark one which isnt bad for the money.the other ones you see for 200 to 300 are rubbish.im building my own from plans from ply and ill be using a 28 cc weedy engine i got off ebay for 15 quid and im putting the walbro carb on it as im told it fits.then im using a dave marles strut and a flex cable and ferrule set up to a stub shaft and a prather 275 prop all from china at half uk prices.my boat will be 48 to 54 " long and epoxy coated .with the bigger carb this motor will do over 35 maybe 40 mph with a tuned pipe and some port  mods who knows maybe more.if you fancy building one of these let me know i have free plans of this boat.the yellow ones mine 36" the other one is w3bbys boat from sweden his runs a zen 260.its 48 "
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Biscuit

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Re: SC 61 break in.
« Reply #23 on: December 27, 2006, 10:23:47 PM »

I Know what you are saying, but that boat of mine cost over 450 new, I paid 250 for it as an unfinished project, 80 to have it sprayed, 80 high power servos, plus 75 PCM rx. That is with out the flex drive cable that fell to bits and the rear bearing, and  High power starter and battery, so still looking at a boat that cost me over 550 and never been in the water, and cant ever see it running. Tried again today to run it, put a restrictor in the cooling pipe hoping to keep it warmer, but just getting nowhere, carb settings just all over the place no matter what I do, still revs when you shut down and really rich on the top end oil every where! friend of mine got a proboat miss Lumar pullstart runs really well and no fuss, 300 and its fiberglass. So if you See my boat on e-bay give it a miss, I have had enough.
Thanks for the reply
Biscuit
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martno1fan

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Re: SC 61 break in.
« Reply #24 on: December 27, 2006, 11:54:39 PM »

the miss lumar is a pile of crap!!!!sorry to be so blunt but there you have the truth ,keep trying your engine will run just stick with it .ill tell you what even if you  have to buy another engine it will run better than the miss lumar boat and id say twice if not 3 times as fast.if you cant get the engine running best thing id say is sell it and buy another one maybe a different type ? os are good engines if a little more expensive.is there really noone who you can get to help you out? no clube nearbye?have you emailed dave marles? he knows all there is to know about boats.5 times world champ and he sells the sc range.maybe send the engine to him let him see if he can get it going?.
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