The CR made progress, but not there yet

[any sunday]

Hi, first I want to thank you guys for the advice & expertise I have received from this forum. My 01' CR 125 was having real trouble for awhile, but I've been working it out. Adjusted float, exhaust valve, went to 370 & 35pilot for jets(sea level), running 40:1 mix, good compression, took it to a shop & had it checked out. The bike runs great at high rpms but runs rich at idle & off idle conditions, since I ride trails this is not so great. I don't like having to rev it all the time(not to keep it alive, but keep it clear). The shop tweaked my float a bit & said everything was spot on, thats just the way the bike was. The only thing they said to do different was try castor 927 & keep on the throttle. I am sure that there has got to be something else to try. I have heard a different needle might help. My point is I want the bike to be able to idle & ride at lower rpms without a problem. Any & all ideas welcome.
-Thank You

[vintageguy]

U might try a larger rear sprocket that would allow slower speeds more easily.(fly wheel weight?)

[crfjedi393]

I'm not a 2-stroke man by any means. I rode XR's before the CRF. But this sounds like a jetting issue to me. I would be surprised if you can't get it just the way you want it for the trails. When they're tight, you just can't stay on the pipe all the time. One of our more knowledgeable members will offer some advice before long. Sorry I can't help.

[Florida 393]

You can get the CR 125 jetted to a fine edge but it is a mid and up power band scoot. A flywheel weight will add inertia and help a bit with stalling but it won't "move the power band" around. An off-road pipe like the FMF Gnarly will add some bottom bit this is a high strung 125 MX bike.

Bill

[Henry]

i suggest before, getting a pipe, talk to steve at moto814.com, he has a solution to everything two stroke, and porting is way cheaper and more bang for our buck than an exhaust. [Only registered and activated users can see links. ]

[any sunday]

Sorry, I didn't mention I have an FMF SST

[KX02]

What was your original pilot jet size? If you are running rich at low revs and all else is good as you said, it's usually just a matter of going smaller on the pilot jet and possibly leaning the needle. I'm not sure if you done this or not, but if not do a google search for "spanks jetting guide". It explains the best way to determine wether or not you have the right size pilot and the rest of the jetting procedure.

[any sunday]

I went from a 45 stock pilot to a 35 and the bike is still rich. However changing this helped greatly, as did everything else I did & like I said I had it checked out by a very reputable shop. They told me a different sprocket & adjustment to riding style would be of help, but I still want the bike to handle low revs a little better. Different needle?
-Thanks again

[KX02]

I would try experimenting with the needle next. You might just change the clip position leaner.

[wamxp1mp]

I owned this bike from new you can play with the pilot and main till your blue in the face and it's only a minor fix.

The secret to your jetting woes is the needle you need to go leaner on the needle I ran in my '01 45 pilot stock 380 main bike ran like crap put in this needle don't worry bout the first part of the numbering it's that last 4 numbers that count. Change your needle so that it ends with 2170 put it in the 2nd clip re adjust the air screw to 1.5 turns out and you'll be surprized how much better it runs.

[TUK101]

It really doesn't matter how close to stock you are if you changed the pipe. Changing the pipe on some bikes can have a dramatic effect on carburation. Have you tried leaning out the main jet at all yet? If you have went smaller on the pilot and needle with good results and you are still rich, go a tad smaller. You usually want to go to peak crispness on throttle response and then step it back up 1 or 2 jet sizes richer to maintain reliability. You can get your 125 working good for trail riding, but remember that it is still a 125 MX bike and it is never going to lug well or have that down low torque that you really need for trail riding on tight trails. Make sure that your air cleaner is clean and well maintained and make sure that your silencer is packed well before trying to jet for perfection. Also if you have any dings in your head pipe or expansion chamber you wont get peak revs or lugging ability either. That SST pipe is tuned for the track too, not the trail. It is meant to rev to the moon, not run down low.

[any sunday]

Originally Posted by wamxp1mp

I owned this bike from new you can play with the pilot and main till your blue in the face and it's only a minor fix.

The secret to your jetting woes is the needle you need to go leaner on the needle I ran in my '01 45 pilot stock 380 main bike ran like crap put in this needle don't worry bout the first part of the numbering it's that last 4 numbers that count. Change your needle so that it ends with 2170 put it in the 2nd clip re adjust the air screw to 1.5 turns out and you'll be surprized how much better it runs.

Thank you this is something I have not yet tried yet, when I get home next weekend I will see what I have in their stock, and then order a new one.

[OLDMXRACER 393]

It won't change any jetting problems, but I had good luck with a Moose intake spacer on a 125. Moved the power down slightly in the rev range. Cheap too.