I rebuilt my polaris BST40 carb and when I put it back on it will not slow down to an idle. The lowest I can get the RPMs is around 1300 +- and anything lower than that it dies. I've tried the pilot screw form 1 1/2 to 2 1/2 turns out but still no good idle. Any help would be great. Thanks

 

I'd check the slide diaphragm and spring,plus for any air leaks around the intake manifold.If you installed a carb kit,the float has to be set right or you can have problems. Idle should be around 1080-1100 rpms if I remember correctly.Plus here's a BST40 on a Ktm similar to the one on the Polaris. It may help looking over it.The BST-40 Bible - ADVrider.

 

The float level is good I know, it parallels the float case. It idled find before I took it off to rebuild it, I was smelling a lot of gas from the carb. I looked at the upper diaphragm and I didn't see any daylight through it. Any other thoughts. I am leaving for a meeting now and will check the post later this evening.

 

If you're smelling gas it's either from the float setting,the float needle could be sticking or even the o-ring around the seat could be leaking even though it may be new. BST40 carb is sometimes hard to work on because the float assembly/needle and seat are held in place by pressure from the float bowl only. Dirt Cheap Yamaha, Honda, Arctic Cat & Polaris OEM Parts & Accessories – Cycle Parts Warehouse

 

I think I explained that wrong, the smell of gas was before I rebuilt the carb. That problem has been corrected. Now I can't get the rpm to slow down without dying. It dies around 1300 RPMs.

 

Just another thought is the slack at the throttle lever. Make sure it's only about 1/8" or the etc contacts will touch causing it to die. May or may not be related to your problem. Plus something else that may a problem is the ecm module on this model. Even if it had the recall done,not uncommon for them to have problems again. When one starts to fail it can mimic carb problems,can cause electrical problems. Just something else in case you can't find any problem related to the carb.

 

OK I'll check that play in the cable today. Thanks

 

YAHOOOOOO That was it, I had too much slack in the throttle cable and when I adjusted that it purred like a kitten. Thank you so much for the help.

 

Kinda hoped it was that by the way you described it dying. Glad it was an easy fix and not the carb or anything else.