I recently bought an 86 250r. I bought it with a broken case. It sat for two years with the motor out of the frame and the carb on a shelf. I had the case repaired and cleaned the jug and carb. I replaced the cylinder base gasket and reasembled the engine. After I got it together, it would run at very high rpms. I cleaned the carb again and made sure the throttle was moving freely. Then, I could not get it to start. I thought I had an electrical problem. After disasembling and testing the wire harness and stator I couldn't find anything bad. When I re-assembled the wire harness I finally got it running again. Now I have to feather the throttle about half open and it still won't run for more than 10-15 seconds before it sputters out and dies. I was wondering what everyone thought. Electrical or carb. I did pull the plug last time and it was a little wet. Any help would be greatly appreciated.

 

thrill,
when you say that you cleaned the carb.did you clean out the pilot and main jet?if it runs with the choke on and sputters with it off your pilot is stoped up.is their any gas coming out of you over flow on your carb?what do you have the air screw set at?[img]i/expressions/face-icon-small-smile.gif[/img]

 

If it's a stock carb you should also look at the float level. Keep in mind most stock 15 year old carbs have the float seal worn out. A leaky float seal will cause the bike to run rich at low RPM and it will be hard to start and foul plugs while starting.

Note: the float seal is not replacable on a stock trx250r carb, you must replace the whole carb.

 

I cleaned the jets, but because it sat so long there might still be stuff in there. The float sticks sometimes causing gas to come out of the overflow, but it stops if I tap on the bowl. I'm not sure what the air screw is set at. I can't keep it running long enough to mess with the choke, but I can start it with it choked. I was told it might be a cracked or worn out reed. Any thoughts on that?

Thanks.

 

If the carb is junk, should I stick with stock or upgrade. Which carb do you recommend.

 

thrill20,
i run the keihin38mm pwk air/stryker.i run great on a moded motor,but is tricky to jet!what mods do you have ?pipe?k&n filter?magic racing carries them for$209.00with the cable.www.magicracing.comor 1- 800-
999-4594.[img]i/expressions/face-icon-small-happy.gif[/img]

 

thrill,
have you choped your plug.if you can get it running and rev it w/o throttle and hit the kill swith and then read you plug by color for correct jetting.CT racing has a good tips for newly built motors for checking the jetting.sounds like you need a new carb,but yes i would check you reeds for cracks.you can get just the reeds for$24.00 carbon fiber.(boesen) @parts direct.or you local shop will carry them.[img]i/expressions/face-icon-small-cool.gif[/img]

 

Thrill20, I would say that you would save yourself alot of heartache by just buying a new carb. I have an Keihin Air Styker 38 and it's worked out great for me. Very easy to tune and it fixed all the carb problems I had. I haven't fouled a plug in 2 years now.

As for which carb to get, the general rules is the smaller the carb the more low-end power you will get. A bigger carb will give you more topend but sacrifices lowend power, even though I didn't loose any noticable low end on mine.

Stock is 34 mm so go figure.

 

Before I spent 200 dollars on a carb I would make sure those jets are clean (it wouldn't hurt to buy new ones) and correct for the mods done. While your wrenching on it check those reeds out. If its stock look at the microfiche for correct jet sizes and air screw adjustments. Go to Macdizzy.com
Dont get carb specs from a clymer manual, I found them very different when compared to Hondas Microfiche.

You might be suprised and find the previous owner has the wrong jets in the carb. When I picked up my R it ran real crappy until at least half throttle. I found the main jet was roughly 5 sizes smaller than spec.(I dont remember exact size, but I know if I continued to run it that way I would of found myself doing the top end over again).

 

I also have an AirStryker 38mm carb, love it!! The best price I've seen is JH Racing, sells them for $179.00. Check out his web site:
http://www.j-hracing.com/