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Author Topic: Gannet 4stroke ic marine 15cc engine  (Read 17896 times)

spearfish99

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Re: Gannet 4stroke ic marine 15cc engine
« Reply #25 on: June 17, 2014, 09:37:07 pm »

Hi Dave,
 On my Gannet, the breather on the crankcase is fitted (from the factory) with a brass cap which has a pipe coming out at 90 degrees to the side of the engine. I simply fitted a piece of water cooling tube from this to the catch can.
With the extra balance weight, you have ended up with a pretty hefty boat, but it does look to be sailing well in the photos.  The joy of the Gannet (and I suppose all "sparkies) is the number of variables that you can try to get the best performance. Change one and you have fun trying the rest of the settings to get the best out of it. Do give a bigger prop a try,as I think that you may be surprised how well the Gannet handles it. It also will keep the revs down a bit and preserve the life that the engine has on it.
 
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BrianB6

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Re: Gannet 4stroke ic marine 15cc engine
« Reply #26 on: June 17, 2014, 11:51:20 pm »

Looks terrific.
Nice bit of water as well
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Dave J

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Re: Gannet 4stroke ic marine 15cc engine
« Reply #27 on: June 25, 2014, 09:55:59 pm »

Just when I thought the results were improving, I had fitted a new plug, cap and HT lead, fitted the original 2.5" dia stainless propeller and was giving the boat a test run when I ran hit a semi submerged loose branch in the water. The boat stopped quickly, the engine ran for a few seconds before cutting out. I was lucky that the boat was near to the lake edge and was slowly getting lower in the water. When the boat had been retrieved I found the engine coupling had been forced apart (see photographs) and the shaft and propeller had gone to the lake bed. I tried to trawl the lake bed with a large net but I was not successful. I have now made a new stainless shaft and threaded the end for the 2ba 50mm  xprop I had. The original shaft was 7/32" diam (5.5mm) the stainless shaft I have made is 6mm so I had to bore out the two tube bearings. I also had to make a new leather disc for the coupling. On the first runs the shaft was tight and the engine was dificult to run, now at last I can try to make further adjustments.
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Dave J

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Re: Gannet 4stroke ic marine 15cc engine
« Reply #28 on: July 01, 2014, 07:33:45 pm »

I have now fitted a brass tube from the crankcase breather hole away from the engine, I had noted the amount of oil being dispersed from this breather hole and could this have been one of the problems of oil getting on to the adjacent points and causing the engine to cut out? Initial endurance runs have improved. I have thought about putting the Amal float chamber back on. This float chamber has a outlet hole on the top flange but on the previous photo's of the Screwdriver model the float chamber appears to have a sealed top flange. Should this be a sealed unit?
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spearfish99

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Re: Gannet 4stroke ic marine 15cc engine
« Reply #29 on: July 01, 2014, 08:05:35 pm »

Hi Dave,
I think that my float chamber has a needle size breather hole under the top edge, but not visible in the photos. Will have to dig the boat out of the garage to confirm.
This may also be of interest  http://www.ebay.co.uk/itm/231272179292?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
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Dave J

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Re: Gannet 4stroke ic marine 15cc engine
« Reply #30 on: July 15, 2014, 02:51:40 pm »

I have now repositioned the fuel tank forward of the engine, I had to cut into the forward deck and positioned the tank above the carburetter. I have also replaced Amal float chamber with the valve in line with the low carburetter level as per previous posting diagram. The engine starts quickly and runs on the water alright for about 5 minutes then stops. It is frustrating having to wait for the boat to drift in or have it pushed in by another model. No warning the engine just cuts out, plenty of fuel still in the tank and plenty of oil still evident. I have thought that maybe the points are being shorted out by the oil ? but at the moment the engine does run with the new tank position and I think the float chamber is giving a steady flow of fuel.
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Dave J

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Re: Gannet 4stroke ic marine 15cc engine
« Reply #31 on: July 19, 2014, 04:52:44 pm »

I have now fitted a electric ancillary drive system to improve the recovery when the engine stops away from the lake edge. I had ample room in the hull between the engine and the stern and  it had to clear of the existing drive system and also to be clear of the exhaust pipework. I took the brushed motor and shaft out of a disused Traxxas small motor launch, I then cut a elongated hole parallel to the Gannet shaft 2" off centre. I then obtained a plastic food container 7x7x4"deep and intended to place the motor esc and battery as a contained unit. The battery I decided to use was a sealed lead acid 6volt x 3amp hour, I have now placed this at the stern and took out some of the lead ballast I had previously installed. I have cut a hole in the base of the plastic container and positioned the prop shaft through the hull to give the 32mm dia two bladed metal  propeller suitable clearance from the hull, (the prop shaft tube was reduced in length to 4" and the shaft was also reduced and re threaded) this assembly plus plastic container was positioned with p40 in the hull and the blended with p38 filler. the attached photographs show the final position with the motor esc in the plastic container and also the battery at the stern ( the white material around the exhaust pipe at the stern is Kao-wool to protect the battery) Also shown is a view of the secondary propeller in relationship to the gannet prop.The last view shows the boat under electric power only which is a slow walking pace. Running the gannet engine has not effected the performance and even in blustery conditions the electric power system brings the boat back quickly.
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phillnjack2

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Re: Gannet 4stroke ic marine 15cc engine
« Reply #32 on: July 21, 2014, 08:45:59 pm »

to save all the stripping down of the engine to clean it etc just go to a full size outboard engine shop/marina and get a tin of mercury powertune.
it will clean the head the carb and the exhaust of all the built up carbon in just a few hours of letting it soak.
do it like it says on the can and you will have a engine that is cleaner than doing it by hand.
trust me I use this stuff on full size and its incredible what this stuff does, I have pistons like mirrors oncethis stuff has been through it.
it also works on 2 strokes as well as four strokes and can be used on full size cars as well.
its around £9 a can but youl have a can for years with a gannet that totally clean inside.
and this engine needs a 70mm stainless prop of around 90mm pitch to get it moving properly.
But this hull is not the ideal for it as its not a fast enough hull type.

with the amal carb its better to have gravity feed fuel (tank higher than carb) as that's the whole point in a float bowl of this type.
its very similar to british seagull in the way the carb works.


phill
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Dave J

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Re: Gannet 4stroke ic marine 15cc engine
« Reply #33 on: July 26, 2014, 08:56:35 pm »

Phill,
I managed to get a tin of Mercury Quicksilver power tune £15.25, ran the engine until hot and then tried to spray the foam into the carb. The engine stopped straight away and would not restart. With the engine still hot I also then put the foam into the plug hole and I also took off the exhaust pipe and sprayed down the pipe. I then turned the engine by hand, then left it for a couple of hours, on return the engine would not start even with priming it with petrol it would not fire up. Eventually I put petrol in the carb and down the plug hole and left it to evaporate. Then after a further hour I tried again and with a prime in the carb it started, it does appear to have cleaned the engine OK and I will now have to try the performance of the boat on the water.
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Dave J

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Re: Gannet 4stroke ic marine 15cc engine
« Reply #34 on: January 12, 2015, 08:23:02 pm »

During August 2014 the boat had been sailed on a regular basis when for  suddenly the performace deteriorated the engine started to lose power and started to get difficult to start, eventually stopped running completely. At first I replaced the condenser, changed the plug and checked the points. With the plug out I could get a weak spark but it did not seem to be firing continuously. I also considered that maybe the timing cam had slipped with this adjustment the timing cam can only be completed successfully with the engine out of the hull. The coils appeared to give a Resistance reading but the engine would not fire up and run. I checked the fuel and carburetor but still could not get any results. I was gratefull for suggestions from mayhem member spearfish99, I tried a separate coil, but still retained the existing points system I was getting a spark but the engine would still not run. During a search on the internet I came across a company which specialises coil ignition systems "minimagneto.co.uk" a telephone call and e-mail exchange provided me with a ignition system with a separate coil and replacing the points timing system with a Hall sensor magnetic system. I came to the conclusion that although I was getting a resistance reading that the coil on the engine was breaking down and deteriorated due to old age. Details to follow of results.
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Dave J

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Re: Gannet 4stroke ic marine 15cc engine
« Reply #35 on: January 13, 2015, 07:41:52 pm »

Minimagneto.co.uk supplied the items for the coversion plus reference wiring diagrams and relevent technical information.The attached photographs show the conversion sequence and assembly to my engine. I started by removing the engine and bed plate from the hull. The original coils and magnet were removed from the engine. I might have been able to convertWhen loosened the cam and housing can be withdrawn clear of the timing shaft and engine. I machined a aluminium cylinder with a bore to fit the timing shaft. The hall magnet is 3mm diameter and 2mm deep and fits into a neat hole drilled into the outer circumference of the cylinder and is a press fit to achieve a flush surface. The cylinder is fixed to the timing shaft with two side securing screws. The sensor is fitted on a adjustable aluminium arm, which is supported on a swivel bearing mounted on a steel housing/bracket which is secured to the engine base plate. The sensor arm can be adjusted in a radial movement (advance/retard) and also to adjust clearance above the hall magnet. Once set a knurled sprung screw can be tightened in position. the existing advance/retard housing together with the point system to a more compact hall magnet system, but instead, I decided to retain the original system in storage and develop the new system adjacent to the engine. To remove the cam from the engine timing shaft on the engine you have to rotate the advance/retard housing until the small access hole on the housing is over the grub screw which tightens the cam to the shaft.
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Dave J

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Re: Gannet 4stroke ic marine 15cc engine
« Reply #36 on: January 14, 2015, 11:35:04 am »

To complete the conversion the new separate coil has been situated adjacent to the engine crankcase and is held in place with a spring clip. The electronic control unit has been mounted in a plastic box to keep it dry and clear of any contamination. The 6 volt sealed lead acid 4 amp battery has been positioned at the stern of the hull, together with a fuse holder, on/off switch and charging socket. I have been starting the engine with a belt but now the engine starts very quickly. The engine works very well with the new ignition system and appears to be more powerful than the original set up. The plug gap has been set to 15 thou and the timing has been set to fire at 3/32 inches before top dead centre. The carburetter has the same mixture settings as before. Trials on the water have proved satisfactory, when I thought the problems with the original system had gone beyond further use, this new ignition  system has revitalised this old engine and once again can be used with confidence.
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Martin (Admin)

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Re: Gannet 4stroke ic marine 15cc engine
« Reply #37 on: January 14, 2015, 01:00:44 pm »


And the tenacity award for 2014 goes to.... Dave J
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Bill D203

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Re: Gannet 4stroke ic marine 15cc engine
« Reply #38 on: January 14, 2015, 01:29:07 pm »

Fantastic job well done. may i ask roughly how much was the electronics ? It seems to bring life back to your engine.  :-))
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Dave J

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Re: Gannet 4stroke ic marine 15cc engine
« Reply #39 on: January 14, 2015, 09:00:15 pm »

Hello Bill,
The ingnition items from minimagneto.co.uk in November 2014.
 
           Novus-1 coil                    £41.50
           MFS-1 flanged sensor         £9.80
           MIC-1A ignition controller   £30.00
 
 data sheets are also provided. (the controller has a fail safe power saver, if the engine stops with the sensor in the active position, the coil is switched off after a delay of 0.5 seconds)
 
 Dave.
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Bill D203

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Re: Gannet 4stroke ic marine 15cc engine
« Reply #40 on: January 14, 2015, 09:09:13 pm »

Cheers for that Dave J

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phillnjack3

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Re: Gannet 4stroke ic marine 15cc engine
« Reply #41 on: May 13, 2021, 07:35:30 pm »

to save keep taking the motor to bits to decoke it.. get to a outboard motor shop and buy some MERCURY POWERTUNE, it  will be
quicksilver powertune. if not a mercury dealer...
spray a drop down the plug hole and turn motor over by hand a few times then leave it for an hour.. then clean plug and start it up. this will of cleaned the ring glands out and gone through the valves a bit. now with motor running about 1/2 throttle spray a drop more into air inlet/carb .
The motor will try and stall but will soon pick up and some crap will come out the exhaust. do this a few times and then build rpm up a bit more and spray hard into the carb and it will kill the motor . now let it sit for 2 hours....  clean the plug and start it up and chuck it in the water and watch the performance pick up. will make inside your little motor like brand new.. I use this stuff on big outboards and use it on small 2 stroke strimmer motor and even my ford focus diesel. its brilliant stuff. cost is £17 per 440ml can this will last you years for your model engine as only need to do this ever 25-30 hours of running.. its a proper decoke in a can and get where you cant unless you take pistons out and clean the ring glands manually.
anyone who owns a 2 stroke outboard who knows his stuff will tell you how good this product is. if they dont know of it then they dont know much about outboards...
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