I have a Keihin PJ 36 for my 87LT250R. I put it on and it started and ran great, but would not idle. When I adjusted the idle screw it did nothing. Could this be caused be an improper needle height, or a pilot or main jet that is not the proper size. It does seem to be much smoother carb then my Michuni, but I need it to idle. As soon as I let off the gas it dies. The carb has been disassembled and cleaned with carb cleaner. The jets all seem clear. I have a 150 main and a 60 pilot. I have heard there could be a problem with throttle valve. I took it out to look at, but don't really see what could be wrong with it. Is there anything I should look for on the throttle valve. I sprayed the carb and boots with starter fluid while running to check for air leaks and it seemed fine. Any ideas would be great. Help.....

 

Please answer some questions first.

1) Is the carb new?
2) Is the air screw turned out approx. 1 1/2 turns?
3) Is the idle screw turned all the way in until it seats against the carb?
4) When you cleaned the carb, did you completely disassemble it and blow out all passages with compressed air?

 

The carb is not new. The air screw is turned 1.5 turns out. I have tried adjusting the screw in and out, which resulted in no changes. I did completely disassemble the carb, soaked it in carb cleaner and sprayed carb cleaner through each hole in the carb. I did not try using a compresser. Does all the fuel for idle go through the pilot jet? I will try cleaning it again and blown out the passages with compressed air. Any other ideas?

 

Welcome to the world of the PJ carb! I've found they are very sensitive and require constant jetting refinements for optimum performance (I change altitude and large temp swings often... that's part of the problem)
The only way i've found to make sure they idle, is to adjust the cable/slide so it can't close all the way...
Then I came to my senses, and tossed the thing in the trash can, and bought a PWK... Now that's a great carb!

 

Did you remove the main and pilot jets and the air screw when you soaked the carbs? An air compressor is a MUST for a complete carb cleaning.

I have a 39mm PWK on my 500 and the idle screw has to be turned all the way in to have even a slow idle. It would be nice to have a larger range of adjustment. The idle screw on that PJ may not have enough range to create a large enough flow area. I've found that trying to adjust the idle with the throttle cable is not very reliable. Doing so means that you no longer have a definate slide stop so the idle level seems to be slightly different every time the throttle is released (since cable tension is holding the slide open).

It may be possible to change the slide out for one with a different cut-out but I could not tell you which one to pick. My suggestion is to buy a new carb set up by a reputable company. You will pay $20 to $40 more for the same carb from say Duncan Racing than from some discount parts outlet but there will be much less fine tuning needed afterward.

 

The Keihen PJ works, I ran a 38 PJ on my modded 92 and it idled great but there is a trick to setting the Idle that alot of so called "experts" don't know about............................

the choke plunger is also the idle fine tune setting, the plunger can be screwed in / out to set the idle mix /idle speed to perfection.......................... Bet that it screwed fully in.......................... cutting rthe circuit of when the plunger is down.

The PJ is a great carb and can be dialed in nicely. The PJ 38 was heaps better than the stocker on my modded LT in every aspect.

Kiwi