Jetting 94 Honda CR250R

I recently bought a CR250R that didn't run when I first got it, but soon fired up after a new plug and air filter. The problem I am having is with the idle. It won't idle unless I adjust the choke pretty high up (i.e. needs more fuel).

Here are the specs:

Keihin PJ style carb

55 pilot (stock size)

180 main (175 stock size)

Needle clip on 2nd notch (stock is 3rd)

Air screw 2 turns out (stock setting)

fuel mixture 40:1 Honda HP (stock mixture)

260 cylinder sleeve bored to 270 (what I was told by seller)

FMF exhaust (original)

stock silencer

Purchased 58 & 60 pilot, 170 thru 185 main jets

I tried the 58 pilot first with adjustment of air screw, then moved needle clip down one notch to 3rd (not sure if this has much impact on idle).

None of these changes improved my idling. Any ideas before I install the larger pilot jet?

Before you start changing the jets, I'd take the carb apart and thoroughly clean everything.... Blow compressed air though all openings.

It sounds as though a jet or passage is clogged.

That was the 1st thing I did after getting it running the day I got it running.

Does float level affect idling? Maybe not enough feul getting to the pilot jet? Not sure how that works.

adjusting the choke knob ads fuel and air.

how many clicks out was it adjusted?

go richer on the pilot jet wont solve anything and will just make it run bad.

basically those carbs with that style idle adjustment were never meant to idle like that.

set up correctly it should idle for a few seconds than die off.

Adjusted probably 7 - 8 turns up. Almost halfway to full choke. Doesn't the engine dying off in a couple seconds make it hard to ride? When riding in the woods now, it dies on me when pulling in the clutch to come to a stop. Is that right? Maybe this is just the wrong bike for me.?.?

Adjusted probably 7 - 8 turns up.


Almost halfway to full choke

see above

Doesn't the engine dying off in a couple seconds make it hard to ride?

easier,it wont try to tow yout hru the coraner when the idle fluctuates when its hot.

When riding in the woods now, it dies on me when pulling in the clutch to come to a stop. Is that right?

you need to blip the throttle to keep it running.

Maybe this is just the wrong bike for me

maybe.if you must have it idle just set the knob so it idles and move on.

OK Thanks Eddie. I put the original pilot jet back in and reset the needle clip. While I had the carb off I cleaned it and the reed valves thoroughly. They were dark and gritty with sand. They are now light opaque in color and free of grit. I also put in a 178 main instead of a 180. I'll see how that works tomorrow.

If I can't get over having to blip the throttle all the time, I may have to invest in a newer 4 stroke enduro. I was really happy when I found this 2 stroke enduro, and it may be good for hare scramble races, but not for simple trail riding that I do.


I know this is an old thread, but how did you get things sorted out? Like Eddie said, if you need the bike to idle, set it to idle, but I can't imagine it being that hard to blip the throttle every now and again. If you want a 2 stroke that is specifically built for off road/trail riding, there are other manufacturers that make these. Although, several people on here have successfully set their 2 stroke motocross bikes up for trail riding and prefer the light weight and instant power compared to the heavier 4 strokes.

CRErider...just to pile on..i have a 93 CR250 and 08 CRF 450R. I the 450 is an incredible bike bu i love my 250R too. It took me awhile to get it worked out but once i did it was every bit the bike i needed and i rode it both trails and track. be patient and it will idle for you.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now