Suzuki 2 Strokes

Hi all,

Looking for some advice on what to do next. I have a T125 that only fires on the left cylinder at idle. When I give it throttle, the right cylinder kicks in but it appears very rich with much more exhaust smoke than the left side. Both carbs are adjusted in a similar manner. Floats have been set many times just to double check and carbs rebuilt. Both plugs are showing spark outside the cylinder. Checked for air leaks with a leak down tester and it held well. Compression in both cylinders around 110psi. Timing is set properly and confirmed with a timing light. I did try to switch the carbs and when i did the right cylinder started running fine and the left cylinder experienced the issues so the problem moves with the carb. Ive tried desperately to clean the carbs. Ultrasonic cleaner and soaking in chem dip. I've also blown everything with compressed air and tried piano wire for any small holes.

I'm hoping someone can explain to me why it wouldnt fire at idle but then fire with throttle but seems rich? I would assume it was overflowing that cylinder and not allowing the plug to fire at idle but somehow overcomes that up at higher rpms but with the float height set properly, i cant understand how that could be the case.

Any advice is greatly appreciated! I want to ride it!

Hi chalcosoma,

It sounds very much like the Pilot jet and/or the Needle Jet are still suffering from a blockage. The fine holes in the Needle Jet can be a PITA to really get clean. When the Right cylinder kicks in with more throttle you are transitioning to Needle Jet/Needle and Main Jet and leaving the Pilot Jet circuit behind, the extra smoke you then see is excess unburnt oil being blown out. Keep cleaning (or source a new Pilot jet)

Cheers Geoff

Like Geoff said. It is most likely a blockage somewhere.
When you ultrasonic cleaned the carbs did your remove all the jets and clean them separately?
To help rule out other possibilities it may be worth asking the following questions:-
Have you checked the end of the pilot/air adjuster screw? Sometimes if they have been screwed in too tight, the tip can snap off and remain embedded in the carb.
Are there any bits missing or jet sizes different when compared to the other carb?
Have you set the float level correctly for your particular carb? This is very important. On many bikes, some models have different carbs with different settings even though they are the same bike.
Is the float valve sealing? (if it has a wear ridge midway up the cone, it most likely is in need of replacing as it may not seal so well)
Is the needle circlip inserted in the same ridge as on the working carb?
Does your main jet have a seating washer installed?
Is your choke plunger stuck on or failing to seat fully?
Do you have a vacuum pipe attached to the faulty carb? (if so, is it leaking or perished)
This isn't an exhaustive diagnostic check list but it may give you a pointer or two in the right direction.
Good luck

You didn't buy a refurb kit and use the jets from that?
If it was a Keyster kit, they are renowned for poor quality jets - only use genuine.