Jump to content
Sign in to follow this  

Power valve trouble

Recommended Posts

What are the most common reasons a power valve would not open until 3/4 of the throttle. I took off the bolt on the left side of my 01 cr250r to check out my PV response. It starts at L when idle. When you give it gas its supposed to turn 90 degrees to H. Well mine barely turns at all in 1rst. I have to really coerse the bike into PV in first! I have to open the throttle 3/4th of the way for it to turn at all in 2nd. After that the response is better, like in 3rd gear, 4th and 5th. But I having a lot of trouble hitting my powerband. Its sucks cuz thats my favorite part of the bike. I feel like im riding a really heavy 80. Suggestions?? Answers maybe.

Share this post


Link to post
Share on other sites

Have you read over your manual? The powervalve isn't supposed to open the minute you start turning the throttle. It is designed to open at a certain rpm at which point is when you hit the "powerband". Does your bike run poorly? Your powervalve may need cleaned.

Share this post


Link to post
Share on other sites

Well i just replaced my piston and rings 2 weeks ago. This problem just came out of the blue. I know that the powerband kicks in at a certain rpm but the bike is running very poorly! It lost maybe half its power. I could hit powerband with no problem before. When i first replaced my piston and rings my bike hit hard! But now it is only half speed. Before my bike would pop up easy and now i feel the loss of power. I cleaned out everything when i did the replacemnet. It starts and kicks fine

Share this post


Link to post
Share on other sites

i will disassemble the engine and clean the whole thing out including the power valve and get back to you!

Share this post


Link to post
Share on other sites

i took the cylinder head off and the piston was good! But the top was discolored. And the power valve is real gunky. I replaced the crank seal on the right side and it is probably lop sided. Probably source of problem but after the clean i will let you know if my problem is solved or not. Thanks

Share this post


Link to post
Share on other sites

http://www.thumpertalk.com/forum/showthread.php?t=974830&highlight=

the governor is rpm related. has nothing to do with the gears, at all. above is a link to a potential problem you may have. i had this issue due to a misadjusted power valve rod, but my issue was that it turned only approximately 50% while yours just takes longer to get there (thats how i understand your post).

your issue sounds very much like a carboned up power valve. if you disassemble the top end again, clean that thing up. i cut open coke cans, clean them, dump in carb cleaner or sea foam or something similar (oven cleaner would work but you wouldnt want to use a coke can for that as it will eat aluminum), let it sit over night, and then take a wire brush to it. you WILL get them pretty spot less. also you need to make sure the center part of the flap valve is clean. on my friends 01 it was neglected and the valve would only move so much until the rod hit the carbon and then it would stop. we ended up using fine sand paper wraped around a screw driver to clean it out until it moved perfectly.

after you get it looking like new i would also make sure the bearings on the left and right sides turn freely. if they do, pop the cylinder back on after making sure the rod orientation is correct, adjust the linkage, pinion AND rod, and tighten and recheck pv operation with engine on. if it STILL does not turn properly you may have a governor problem.

Share this post


Link to post
Share on other sites

@mynewcr250, i took off my pipe and PV case. It looks pretty gunked up! I am kind of putting it off tho. It looks really complicated to disassemble/re-assemble! Any url that would help?

Share this post


Link to post
Share on other sites

its easy. take it apart completely get it soaking and when I get off work I will upload the assembly instructions from the service manual. honestly though if you watch how you took it apart you can put it back k together easy. just remember you gotta adjust it afterwards or you'll think you pit it together wrong.

if you want you can even swing the lever at the bearing clock wise and watch the indicator on the left side and see and feel if ahe moves freely before yanking it apart. just loosen the pinion bolt.

Share this post


Link to post
Share on other sites

also if it is not just carbon build-up it also could be a worn powervalve spring which happens to all older bikes and should be replaced with a new top end even though most people dont.

Share this post


Link to post
Share on other sites

@mynewcr250, that will be a help in the future but i am looking for something to help me take apart the actual PV assembly and re assemble it. I see you had a shop do yours! I like to do everything myself! That's the beauty of the bike!

Share this post


Link to post
Share on other sites
@mynewcr250, that will be a help in the future but i am looking for something to help me take apart the actual PV assembly and re assemble it. I see you had a shop do yours! I like to do everything myself! That's the beauty of the bike!

when did I say I had a shop do it? I do all my own work from cars to bikes. I work on cars for a living...

but either way if you're trying to learn there is no better way than to jump into it and take it apart. 2 bolts, 2 shafts, 1 snap ring and 1 "b clip" and the whole assembly comes apart assuming you have the cylinder off.

Share this post


Link to post
Share on other sites

So I disassembled my entire PV setup and have found the source of my problem. Alhough my pv was a tad gunked up, that most likely was not the problem. One of my rods are bent. Also my little metal flap for the exhaust wasn't moving. It was probably because of the bend linking rod thing. But here is a fiche and the piece is number 14 search%3Fq%3Dpower%2Bvalve%2Bcrows%2Bfoot%26um%3D1%26hl%3Den%26biw%3D1152%26bih%3D683%26tbm%3Disch&um=1&itbs=1&iact=rc&dur=1019&page=1&ndsp=24&ved=1t:429,r:0,s:0&tx=70&ty=26http://www.google.com/imgres?imgurl=http://images.powersportsnetwork.com/fiche/images/Honda/2001/Motorcycles/2296_EXHAUST%2520VALVE.gif&imgrefurl=http://www.allthingsmoto.com/forums/f-31/cr-250-helpppppppppppppppppppppp-43663/&usg=__wtjaFDwGNQl6yUYxEBj88ZFluZs=&h=497&w=1000&sz=15&hl=en&start=0&zoom=1&tbnid=JXu-r0dLQYicFM:&tbnh=77&tbnw=155&ei=L9q5TZb1AsWV0QG_493SDw&prev=/search%3Fq%3Dpower%2Bvalve%2Bcrows%2Bfoot%26um%3D1%26hl%3Den%26biw%3D1152%26bih%3D683%26tbm%3Disch&um=1&itbs=1&iact=rc&dur=1019&page=1&ndsp=24&ved=1t:429,r:0,s:0&tx=70&ty=26

its the bottom of the piece. Kinda looks like a crow foot. And Im sorry mynewcr250! I guess i misread your post. You are right there is no better way than to dig in. I love to do all the work myself also.

****Here is a question, what is that part called so i can order it.****

Edited by Annonymous

Share this post


Link to post
Share on other sites

SHAFT, VALVE DRIVE

http://www.servicehondapsn.com/fiche_section_detail.asp?section=138728&category=MOTORCYCLES&make=HONDA&year=2000&fveh=3271

It's good you pulled the cylinder off and found that but if you were just going to clean the valve in the future you can take it out without pulling the cylinder. Take the subs out the sides and exhaust flap out the exhaust port. you have to let the piston down and slide it out into the cylinder and turn it and take it out the exhaust pipe port.

Share this post


Link to post
Share on other sites

Yeah now I know tidtid. It wasn't as hard as I thought it would be! I went and bought a new one last night @ the shop down the road from me instead of ordering it. Its already all back together and i'll tell you if she has her power back.

Share this post


Link to post
Share on other sites

remember to check to see if it turns from the L all the way to the H.

Share this post


Link to post
Share on other sites

So everything went together just fine! Except that my powerband is not working @ all lol So i know what's wrong just not why. The govenor moves the pinion rod, and that moves the drive shaft. Well my drive shaft is not opening my power valve. (That little set up on the right top side with the spring and levers isn't moving. It's like number 15 (I think its called the lever. If you push it from the left side to the right the valve opens)is spinning on my drive shaft) Since I cleaned my PV my bike is not smoking anymore, thats the only plus "as of now". So I don't know why the PV won't open up. Any ideas?

@tidtid it turns all the way from L to H.

Wow I feel really dumb!! The bolt was loose that goes into the lever on the drive shaft. That's why it wasnt turning. But it really is one thing after the other. Now I think my piston is seized up. I hate Honda man I should have went with Yamaha!!!

Edited by Annonymous

Share this post


Link to post
Share on other sites

*** man I must have done some messed up crap in my last life or something. I was riding it down the road and my piston just seized. I pulled off the cylinder head and there is metal shards everywhere on top of the piston and the piston is shot! So aggravated! This is more of a job than an effing toy!

**** I am going to order a new top/bottom end kit with seals and gaskets. I'm gonna redo this whole thing!****

Edited by Annonymous

Share this post


Link to post
Share on other sites
*** man I must have done some messed up crap in my last life or something. I was riding it down the road and my piston just seized. I pulled off the cylinder head and there is metal shards everywhere on top of the piston and the piston is shot! So aggravated! This is more of a job than an effing toy!

**** I am going to order a new top/bottom end kit with seals and gaskets. I'm gonna redo this whole thing!****

did you make sure the piston rings were hooked properly over the retainers on the intake side? any chance one slipped during install?

weird that it would happen right after reinstallation of the cylinder.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

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

Reply with:

Sign in to follow this  

×