Hi all,

I'm trying to help a buddy get his bike going a bit better and I was hoping you guys might be able to offer some insight.

Basically the bike will start with the choke out, and then sits at 2500rpm once the chokes in. You can ride it around just fine, but if you come to a stop and pull the clutch in, the motor struggles and then dies. If the choke is out it's fine, and if I increase the idle speed it's fine, but then idles excessively fast.

The bike Sat for a few years, and I had to clean the carb out to get it to run right, so I don't think it being dirty is the issue, and I also know the clutch is adjusted correctly. Can anyone think of where I should look next? What should this bike idle at?

Many thanks!

Ed

 

I know you said you cleaned the carb, but how did you clean it...method, chemicals, compressed air, etc. It sounds like something is still in the pilot circuit...or...the float/needle segment is sticking because of residue. Carbs sitting that long can be notorious for cleaning out the small pilot circuit. Sometimes you can get them clean enough to run, but not run consistently.

Your description of the choke keeping it running at idle is often indicative of a pilot/idle circuit issue. It could be something else, but this is my first/best guess from the description. It sounds like the bike runs fine everywhere else through the throttle range except idle, correct?

 

Thanks for the reply, I cleaned the carb in an ultrasonic tank, with all needles, Jets and floats removed and cleaned separately - this said it's possible that I didn't get everything, as it was filthy in there. Will pull the carb and give it another going over. Does anyone know a good starting point for the mixture screw? He doesn't have a extender so it's a pain to adjust!

 

Ultrasonic cleaners are pretty good, but I really think you need to add that step of compressed blown through the pilot circuit while having the pilot jet out and the fuel/air screw out. I'm guessing that wasn't carb cleaner in the u-tank, right? Get some Chemtool B12 in the spray can with the small nozzle that you can attach from a local parts store. Be careful not to get it sprayed in your eyes when using to force into the pilot circuit. Make sure to spray into the fuel/air screw hole also.

On the number of turns out, starting around two out will be more than sufficient until you can get it to idle consistently.

 

Shirebikes, Do you have a mini screw driver to adjust the air fuel mixture screw? You need one. When you say "he" do you mean it's not your bike? What jets did you put in your or his bike? What setup is he running ie: lidless ,stock, exhaust? This example was given to me from KLXster who is a great help.

Set idle back down to specs - 1250 to 1300 rpm - Then lets try out the air fuel screw settings. Starting at 4 turns out, and with the bike warmed up and at idle, turn in the air fuel slowly until the idle starts to drop, then back it out 1 turn..

If the engine "acts up" or doesn't like 1250-1300 idle speed, then there is a problem.

 

Yeah it's my buddy's bike, he doesn't really know much about engines, and I ride a rattly old dr350 with no tach, so idle speed was an unknown for me.

I'm going to give the carb a proper going over again, and will look at the mix screw.

Thanks again
Ed

 

Got the carb apart tonight, pilot jet was dirty again, I guess some crap came out of the body. Will hopefully be working nicely soon!

 

Good job. Let us know the results.

 

Drain and clean the tank!

 

Is it stock jets?