I just installed a 39 mm PWK carb on my pilot. The idle screw is all the way in, but sometimes it idles close to 1600 rpm and other times it idles at 850 rpm or dies. I first adjusted the idle to 1350 rpm, then went for a ride. It stayed there for 15 minutes of stop and go riding, then all of a sudden it idled low, and then finally died. Screwed the idle screw all the way in, and it then idled at 1250 rpm for a 10 minute stop and go ride. I then came to a stop and it was idling at 1850 rpm, so I backed the screw out till it idled at 1350 again. I then rode it into the garage, when it then idled at 850 rpm till it died. I tighten the screw all the way in again, and it would only reach 1050 rpm and barely ran. What could be wrong, and what can I do to start to fix this problem?

The varing idle has the earmark of an air leak some where but contrary to what I hear often and I run a lot of engines and I NEVER have a problem with air leaks on any motor (( Internal Combustion Engine ? )), so i rarely consider that as an option. I would side more with lean jetting, probably the main. too much has been said on jetting for me to add to it

PKW "D slides" are flat out the best carb out there but PWKs can be a pain with idle screw, when you run them rich and even with the idel screw all the way in it they can have a very low idle. I have changed the needle in most of my PWKs except the one i got from pro-flo they set it up almost perfect had to go to a 195 main from a 185 on my KTM 300. i forget the needle i use, sorry.

2 strokes aren't really made to idle excessively, there is no purpose in idleing a 2 storke, driving around at a nice gentle varing throttle for the first few minute until warm is the best way to start a cold motor (( Internal Combustion Engine ? )) or breaking in a new one.

What jets are you running?

??????? The idle screw all the way in???????? That would increase the idle, I hope you don't mean the idle jet screw. If that is the case you just leaned out your lowerend and smoked your pilot's motor (( Internal Combustion Engine ? ))!!!!! Sounds to me that is what you just did. You might want to check which screw you adjusted if you are unfamiliar with air velocity carbs.

I just installed a 39 mm PWK carb on my pilot. At present, the idle adjustment screw( not the air adj. screw)is all the way in, but sometimes it idles close to 1600 rpm and other times it idles at 850 rpm or dies. I first adjusted the idle adj. screw to 1350 rpm, then went for a ride. For 15 minutes of stop and go riding, whenever I came to a stop it would slow to the 1350 rpm idle. Then all of a sudden it started to idle very low, and then even started to die from such a slow idle speed. I then had to screw the idle screw all the way in, and it then idled at an exceptable 1250 rpm for a 10 minute stop and go ride. I later came to a stop and it was idling at 1850 to 1950 rpms, so I backed the screw out till it idled at 1350 again. I then rode it into the building where I store it, when it then started to again idle slow to 850 rpm till it died. I tighten the screw all the way in again, and it would only idle at 1050 rpms and barely continue to run. Let me further say that I just had ATVR port and polish, and shave the head. I also put a delta-force reed valve, rev pipe, no-limit CDI (Capacitor Discharge Ignition) box and a powerbloc clutch, and this thing now runs like a bat out of hell. The only thing wrong is this erratic idling problem. What could be wrong, and what can I do to start to fix this problem?

hey bob, i run the 39pwk on my fl350,here are my thoughts on the situation.I also have my idle screw adjusted all the way in and have left it this way.I believe it is because of a rich slow jet,i like mine a little large on the slow jet side.when coming off of high speed runs or long runs and having to get of the throttle quick it keeps the low end with plenty of fuel in the cylinder for cooling and keeping it from becoming lean.
I also don't get a wide range of adjustment with the air fuel mixture screw this way but it is good enough.
What i do do is leave the adjuster at the wheel somewaht loose so i can adjust it to what ever i want when i start and after it warms up.Once it is warmed i will lock down the set nut a bit by hand and leave it that way for the rest of the day.
It's not a big deal as long as your mid and main jetting are fine.It makes it easy at start up when using the choke too,and you can set wahtever idle you like this way.I like mine a tad high a bit after initial warm up and just before taking it out like hare recommends to finish the warm up.After it's warmed good and thorough you can just reach around and reset by hand and your ready for the day.

Well? Still having a problem or is it cured?

Does the idle RPM change when you adjust the air screw?

What is your current jetting, jet and needle sizes?

You do have a little slack in the throttle cable so the slide is
seated on the idle stop right?


Remove the spark plug cap and inspect, you finding black carbon looking
powder on the porcelain of the spark plug?