yamaha 115

[wvstriper]

I decarbed my yamaha c115. After decarb it has a miss at idle. I replaced all plugs. After running on muffs for a few minutes I checked the new plugs. Three are clean, but one is fouled (wet, with a lot of carbon). I switched ign. coils and the problem stayed with the cylinder. I have good spark. Where should I look next? Thanks.

 

[yamamarinetech40]

Re: yamaha 115

I'd do two things before I paniced on it...first do a compression test on engine, see how that cyl. is....and if it's good(it will be) decarb again....I'm thinking that you only really decarbed that one cyl. only and need to do the rest prperly...
Are you saying you you ran engine first time after decarbing on new plugs?? Or are you saying you decarbed correctly with running of engine after decarb BEFORE you changed the plugs...which would be correct to do? Can't tell......
See you wanna run the crap out of the engine BEFORE you change OLD plugs, cause the decarb/decarb running will ruin(in my opinion) whatever plug is in there....that is if the engine was crudy inside...use more decarb

 

[hasse_2night]

Re: yamaha 115

Hey there

I had the same problem and i can telle you that if it is the lower cylinder nr 4 that has doesnt go CHECK the gas pump membran that was the problem at mine 115 2 stroke yamaha cause it uses the compression from that cylinder to pump up gas, see for yourself if the gaspump is sitting on he same side as the bar igniteted cyllinder
I hope my answer will help you

 

[Ray Neudecker]

Re: yamaha 115

A bad fuel pump can cause a cylinder to run rich is what wv striper is saying.

 

[wvstriper]

Re: yamaha 115

When looking at the motor from behind. Is the #4 cyl the lower one on the left(port) side?