Bought a 2001 Honda CR 250 - help me work out the bugs

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#1
This is my 2nd 2001 CR 250. I owned one several years back and liked it so much I bought another. This one has a few bugs so here goes:

Exhaust was absolutely shot when I got it - replaced with FMF fatty and Q series silencer

Bike has some issues with either jetting, power valve or reeds - not sure. Runs good and smooth on low end but when it opened up on the pipe it "sputters" and then clears out fine. I can run at low speeds and then open it up again and it does the same thing. As long as I'm on the pipe hard it stays running fine. Don't know if this is the carb, reeds or power valve. The guy I bought it from used cheap 2 cycle oil from a convenience store, so I initially thought it just needed some good stuff ran through it to clean it out. I rode it several hours yesterday and to no avail it never got any better. My buddy rode it and he seemed to think it needed rejetted for the new pipe, since the old one was stock.

Other issue - I noticed after riding yesterday that the front right fork is leaking. Is replacing fork seals a big deal on these bikes. I love this bike and it is a blast to ride, but want to get the bugs worked out first. I need some advice on how to get it right. I appreciate everyone's help. If I can't get it right I'm gonna go 4-stroke :laugh:
 

mx547

Ortho doc's wet dream
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#2
first of all, replace the crappy mikuni with a keihin. it will be the best $160 you'll ever spend. you can thank me later.
 

mx547

Ortho doc's wet dream
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#4
just order one for a 2000 cr250. it goes right in, everything fits, no problems. i bought mine at my local dealer. there is an older thread on here about where to buy one online. maybe someone will search it out for you (i suck at using the search function).

but you still need to check your reeds and powervalve.
 
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#5
Buy the complete carb for a 2000 CR250 from Service Honda for around $200. It is a direct replacement for the Mikuni that you currently have. Your existing airbox, intake boot, and throttle cable will work with the new carb. This is the best modification that I have made to my '01. Bottom end response will be much better and you will not have to play with the jetting nearly as often. You will probably need to lean the jetting out slightly with the new carb. I think I went down 1 or 2 sizes on the main jet and maybe 1 on the pilot jet.
 
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#6
Not to sound stupid, but how do I clean the power valve, where is it located? I know about the reeds. Does it sound like my bike is too lean/too rich?
 
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#7
My '01 250 ran like crap until I found good jetting info online. Check out this thread. It's worth a try after you find out what's in there now. The parts are less than $20.
http://www.dirtrider.net/forums3/showthread.php?t=114595

Sometimes a leaking fork seal can be fixed by swiping camera film under the seal to clean out the dirt.

There is a plug on the side of the powevalve. You can pull it off and start the bike. Rev it up to verify that the valve still swings. If I recall correctly there are lines on the parts and there is a procedure to confirm proper operation without disassembly.
 
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#9
I pulled the carb tonight, the main was 400, pilot was 25. Is this factory? I cleaned it good tonight and reassembled it and it still stumbles ALOT on top end before it clears out. It's like its too rich on top.
 
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#11
jmccown said:
I pulled the carb tonight, the main was 400, pilot was 25. Is this factory? I cleaned it good tonight and reassembled it and it still stumbles ALOT on top end before it clears out. It's like its too rich on top.
No, my owner's manual states 420 main and 35 pilot as standard. It may be rich in the mid range and does not clear out until wot. My bike seems to run great with the factory jetting with only the needle jet (what the main jet screws into) changed to a S-7 (about 450' above sea level). The part # is in the thread link in my post above. Do you know what needle jet is in your bike?
 
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#12
no I couldn't get the top off to check the needle, didn't want to booger the bolt heads. I am in Kentucky. Should I go up to a 420 and 35? My bike smokes alot like it is rich.
 
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#13
jmccown said:
no I couldn't get the top off to check the needle, didn't want to booger the bolt heads. I am in Kentucky. Should I go up to a 420 and 35? My bike smokes alot like it is rich.
Not the needle! the part the main jet screws into. Unscrew the main jet then unscrew the needle jet. If it's stock, it'll read s-9. If it is a S-9, change it to a s-7 and let us know how it rides after that. My bike was soo much better running and with much less spooge. Before the s-7 my jersey would get spattered with black oil spots, after s-7 nothing but a little 2-stroke smell got on me.

If it's already rich I wouldn't richen it up. If you do wind up changing the needle jet, I'd go back to stock jetting to start off with.
 
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#14
I had my bro in law look at my bike, he is a guru on bikes. He said the top end needed rebuilt. We pulled my pipe off and he stuck his fingers back in the cylinder and there was some slack in the piston and the cylinder walls. Could this be what is making my bike run this way? I tore the top end down tonight and am ordering a new top end to replace. I pulled my reeds as well. All of the petals were partially open, shouldn't they be closed? They may need replaced. Thinking of throwing a Vforce on there instead of going back stock. Could a worn piston cause the bike to run this way though?