Can We Talk Carburetors 2000 Yamaha 115 Two Stroke?

[Billybronco]

I recently bought a used Yamaha 115 model# 115TXRY the carbs were pretty dirty barley would run. I pulled them off completely dissembled and cleaned them best I could, carb spray and compressed air. Motor ran better but not so good. Pulled them a second time bought a rebuild kit, new main jets and cleaned again, she ran much better but still not perfect, had idle issues. Third time I bought an ultrasonic cleaner, not sure that did a whole lot but the motor did idle better. I thinking of trying one more time, this time getting a gallon of Gunk carb cleaner let them soak for a week and replacing the other air jets. I have the mixture screws out 5/8 per the manual, not sure how to sinc the four. What do you guys have to say?

[robert graham]

Seems like your carbs should be clean....maybe tuning/synchronizing of carbs is the best way to get then just right....there should be some instructions on- line or in the Yamaha Manual

[Billybronco]

I always assumed the best way to synchronize multiple carbs was with a vacuum gauge, but I'm not 100% sure that is the case on these two strokes, can anyone advise?

[TownsendsFJR1300]

I always assumed the best way to synchronize multiple carbs was with a vacuum gauge, but I'm not 100% sure that is the case on these two strokes, can anyone advise?

Older/most motorcycles (multi-cylinders) have a vacuum port to plug in a manometer, (to adjust), your carbs don't.

Many Yamaha's (OB's, like yours), usually have a long shaft / plate on the side of the carbs-connecting the butterfly linkages.
There's a procedure to adjust(sync), again, usually by initially loosening the adjusters, let butterflys fully close, and then tighten.

The air screw is for fine tuning the idle....

You only have two, two barrel carbs so it should be pretty easy..

Your shop manual should have the exact procedure for your engine, someone here may chime in with it...



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[Billybronco]

I have synced the two carbs in regards to the mechanical aspects (linkage). It idles rough and while *****ing she is like a bobble head, shake rattle and roll. When I boot it from 10 rpm to 5200 she gets there but does not seem to have the response I like out of a two stroke. I was running an older Yamaha 130 that sounded much better, but the salt just ate it up.

[99yam40]

I have synced the two carbs in regards to the mechanical aspects (linkage). It idles rough and while *****ing she is like a bobble head, shake rattle and roll. When I boot it from 10 rpm to 5200 she gets there but does not seem to have the response I like out of a two stroke. I was running an older Yamaha 130 that sounded much better, but the salt just ate it up.

Does it have a lean sneeze ever once and a while?

[Billybronco]

I did before the last carb cleaning. Seemed #2 cyl was skipping I actually thought is was something electrical but it does not do it anymore.

[TownsendsFJR1300]

I did before the last carb cleaning. Seemed #2 cyl was skipping I actually thought is was something electrical but it does not do it anymore.

That "lean sneeze" is from a dirty carb, not enough fuel getting into the engine and it basically sneezes W/O enough fuel..

Have you tried adjusting those air screws slightly to see if you can smooth out the idle?

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[Billybronco]

I did adjust them out to about 3/4 of a turn not sure it made much difference. When there are four to adjust how can you possible sync them by ear?

[TownsendsFJR1300]

I did adjust them out to about 3/4 of a turn not sure it made much difference. When there are four to adjust how can you possible sync them by ear?

Try to get the smoothest idle you can, one at a time..

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[Jason2tpa]

I did adjust them out to about 3/4 of a turn not sure it made much difference. When there are four to adjust how can you possible sync them by ear?

Spec pilot screw turnout for a '98 115HP is 5/8 +/- 1/4. Spec for your '00 carbs are likely same. Spec is a good place to start, then fine tune each carb. The idle will smooth out once you've got it dialed in.