29cc CY Engine problems

Briggs

Member
Messages
16
Location
Gloucester
:helpsmilie: Have recently changed my piston ring and put new gaskets on all round. Engine starts fine and ticks over then as it gets warm the engine starts to increase and decrease revs and then dies. Changed my plug but didnt make any difference. Any suggestions?
 

Timmahh

Bajastafarian Madnes
PLUS member
Messages
3,376
Location
Michigan
ya, air leak somewhere. carb manifold is common place. also check your fuel line for cracks or splits as air can enter there just prior to the carby.

i use wd 40 to spray around and listen for rpm changes. some others use starting fluid.
 

Briggs

Member
Messages
16
Location
Gloucester
Engine Problems remain

I have replaced my fuel line, new gaskets all round start the engine and after a couple of minutes it increases revs and dies. My supplier for the cylinder head gaskets (main supplier for large scale in the UK) have sent me thinner ones than what I had from stock. I contacted them at the time because if I put one of these on and rotate my engine the engine seems to get stuck at the top end. They advised me to put 2 gaskets on which is what I have done. I am wondering if this is the problem and I have an air leak with 2 of them on. Anyone experienced this before only its driving me mad. :helpsmilie:
 

FastEddy

LSF Vendor!
LSF vendor
Messages
432
Location
Sonoma County CA
Leaking...
I just put together an engine using a copper gasket and it was doing the same thing yours is. I took it back apart to find that the cylinder gasket was leaking.

I could see where oil had "Blown By" the gasket and left a black mark on the outside of the case.
 

Bigger the Better

LSF Plus Member
PLUS member
Messages
7,738
Location
Minnesota
Did you install a new crank - 2mm stroker. If so, It sounds like the top end you bought was not machined to accept the 2mm stroker. Or your old motor had the 2mm stroker and the new head does not accept the extra length. Because it was not it will be necessary to stack the gaskets to get the right amount of clearance for the piston not to hit at the top. Stacking has been known to be a difficult problem with blowing out the gaskets or just getting them to seal the 1st time. I think you can buy a thicker gasket but I personally do not know and prefer not to get that type of motor set up. They do sell 29cc heads that have been machined and will accept the 2mm stroker without stacking at DDM. Good luck on it.:) http://www.davesmotors.com/store/product616.html
 

Briggs

Member
Messages
16
Location
Gloucester
Thanks guys that could explain it - as when I had a piston ring go on me I needed to replace the top end and it sounds like its not set for the 2mm stroker etc. Will check it out.
 

Briggs

Member
Messages
16
Location
Gloucester
Sounds like a gasket problem??

It transpires that it wasn't a gasket problem after all, my oil/fuel mix was too high in favour of the oil and it was clogging my fuel filter starving the engine of fuel and thereby increasing the revs. A lesson learned for anyone who is looking for a air leak that doesn't exist. :blush:
 

Bigger the Better

LSF Plus Member
PLUS member
Messages
7,738
Location
Minnesota
It transpires that it wasn't a gasket problem after all, my oil/fuel mix was too high in favour of the oil and it was clogging my fuel filter starving the engine of fuel and thereby increasing the revs. A lesson learned for anyone who is looking for a air leak that doesn't exist. :blush:


What ratio did you use to cause that?
 

veron

Well-Known Member
Messages
190
Location
manchester
well i was just about to advise you to check your needle settings but you boxed it, thats the first thing i do is check the needle settings then trouble shoot every other part. hows the engine performing now?
 
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