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Yamaha 50 fourstroke one cilinder doesn't work

B

bosmari

New member
Hi,
I need your help about Yamaha 50 four stroke (2006). The problem started with loss power. The second cilinder is out of work. We change all sparks with new one - no result! Then we changed the coil for the spark - no result. The second cilinder does not work but the spark has the mark of gasoline. We cleand all carburettors - no results. We changed the gasoline - no result. Finaly we changed electronic box ( black 10x5cm ) - no result!!!!!

Do you have any other ideas?

THX
 
No, I don't becouse I dont have instrument for compression. But in the time I found out problems in both 2. and 3. cilinder. If I pull out spark cable one by one 1. or 4. disconect the engine turns off, if I disconect 2. or 3. the engine still work? If I change the coil I still have the same problem. One more Information when the problem started the engine loss the power slowly not in the moment!

Thanks
 
Having a problem in 2 and 3 may indicate something between the cylinders 2 and 3... maybe even a head gasket...
If you are trying to save a few $$ by not taking it in to a mechanic, id suggest you buy yourself a compression tester... they can be had for quite cheap..
 
Finaly, we found out that the second cilinder has low compresion. I thing we have problem with head gasket, or piston rings, or valve??? What do you thing?
Thanks
 
Not a good thing having low compression, but at least you have sort of found your problem....
It can be any one of those 3 things that you mentioned....
The next step is to remove that cylinder head to see what going on in there.... With any luck it will only be a gasket or valve problem....
 
You can do a cylinder leakage test,if you can stop the motor from turning.you put the piston [any cylinder]at the TDC on the firing stroke,and screw a fitting into the sparkplug hole,and put compressed air in.the motor may kick either way,but if youve got a secure way of holding the flywheel,good.then you can check where your compression is going.listen at the carbie,exhaust,[valves]or take the oil level plug out and listen for air.which means rings are worn.or if you can hear air in another cylinder,then headgasket blown
 
Hi, I have results from servis; The head gasked between 2. and 3. cilinder is broken! Authorized service person changed with the new one and took me 100.-€. Not so expensive for 2 hours work and material?!
The case is closed !!!
Thanks for all your support :)

Bostjan from SLOVEenija
 
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