cr125 runaway

9/21/2015 9:08am Edited Date/Time 9/29/2015 11:55am
I have a 92 cr 125 that wants to run away only with the choke off. the bike will start first kick with the choke on, after 30 seconds or so turning the choke off the bike acts as its WOT. Choke back on and it quickly goes back to a normal idle. It has power while riding with the choke on (more smoke than usual and felt a little rich obviously) but ran strong.

I used half a can of carb cleaner around the entire engine to check for a leak and there wasnt a single flutter in the idle (choke still on). After that I dropped the needle clip from the middle groove to the bottom. Harder to start with the choke on and wouldnt idle what so ever and smoked like a train. choke off instant run away, same as before.

Is there anything that I missed to check for? Is there another reason that can make it runaway beside being way too lean? ALSO I forgot to mention that I dont think this bike has the stock carb. It has a 38mm Keihin on it which i believe is the cr250 carb? PJ 38dgd111 is on the side of the bowl.
|
9/21/2015 9:10am
Should also mention that I brought this bike home in pieces and this is the first time im hearing it run. engine was complete and according to the guy has a newer top end on it. I havent cracked into the engine at all.
Paw Paw 271
Posts
3640
Joined
4/3/2013
Location
Benton, LA US
9/21/2015 9:15am
Check pilot jet. It may have dirt in it thus creating a lean condition.
I would also check the intake for air leaks as well as the stator side crank seal for an air leak.

Paw Paw
9/21/2015 9:21am
Check pilot jet. It may have dirt in it thus creating a lean condition. I would also check the intake for air leaks as well as...
Check pilot jet. It may have dirt in it thus creating a lean condition.
I would also check the intake for air leaks as well as the stator side crank seal for an air leak.

Paw Paw
does the choke circuit bypass the pilot jet? checked every mating surface for leaks including the left side crank seal with carb cleaner. Visually nothing looks out of place either, I havent pulled the stator to look at the crank seal though.
Paw Paw 271
Posts
3640
Joined
4/3/2013
Location
Benton, LA US
9/21/2015 11:25am
The choke on those bikes is just like a separate small carb. It is not effected by the pilot circuit. You have an air leak, a sticking carb slide or a plugged pilot circuit in the carb.

Paw Paw

The Shop

9/29/2015 9:32am
The choke on those bikes is just like a separate small carb. It is not effected by the pilot circuit. You have an air leak, a...
The choke on those bikes is just like a separate small carb. It is not effected by the pilot circuit. You have an air leak, a sticking carb slide or a plugged pilot circuit in the carb.

Paw Paw
Okay, so I went through the carb again, everything is clean and clear. same problem. i pulled the flywheel/stator but im not sure as what to look for visually? its seated and free of cracks/tears.
Also, I noticed that the coil isn't original. It doesn't span the gap between the mounts, its short about an inch. could this be a problem? I've searched the part number on it and can't find anything. Thanks for your help!
Paw Paw 271
Posts
3640
Joined
4/3/2013
Location
Benton, LA US
9/29/2015 11:55am
The pilot jet can look clear when it really has a dried fuel deposit in it that is as hard as a rock. It takes a wire to clean it out. Have you adjusted the air screw?

Paw Paw

Post a reply to: cr125 runaway

The Latest