89 gsxr 750 slingshot wont fire on third chamber, but theres good spark any ideas?
Answers:
The rule is: There must be three things present in order to make and engine run. 1. Compression 2. Fuel 3. Fire. You are missing one of these. Do a compression test, to check for bent or warped valve, blown head gasket, cracked piston, and broke ring. Compare the reading to a known good cylinder, and it should be within a few pounds of each other. Carb, or injected? Dirt in carb, injector not firing, no fuel pressure on cylinder. If you got fire, then you either have to be missing fuel, or you have a mechanical problem. You should be able to use a pipe to listen to the injectors to hear them clicking when they fire. If no click, replace the injector, after you make sure it is getting power on the pulse rate. A noid light will tell you this. I hope I have been able to help you. Good Luck!
Have you checked fuel is getting into that pot? could be fuel shortage or timing out
If there's a good spark and fuel getting to it, I would suggest a compression check on that cylinder, as it could be a burnt out valve leading to low compression.
Another possibility would be a leaking inlet manifold gasket, but this is unlikely to cause a complete loss of firing.
As an aside the term "Slingshot" was given to the carburettors on the GSX-R's. It won't be injected. Other than that I'd frllow the advice of our mechanic friend if its not too technical.
However, Before going for all the compression testing I'd check electricals thoroughly. I showed good spark on an RD500 but under compression it bailed out.
HTH
there may be a mouse living in there check it out
swop the ht leads between 2 and 3 cylinders, is 2 now the problem? that would make it a lead problem. a plug maybe breaking down under compression( new plugs)
failing that take all plugs out and do a compression test.. they should all be pretty much the same! is number 3 plug wet after a short run? if not then its fuel not getting in. remove float bowl and float and check for blockages in fuel line. you only need a bit off silicon or somthing to block it. shield and blow thro' fuel line in carbs with compressed air. if both 2 and three are a problem then it is either faulty coil, pick ups on end of crank or low tension ciscuit from pick up to coil( check resistance with ohms on multimeter.
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