'01 RM250 Power Valve Question

[rm250_rider]

I've read a few threads indicating that this model has an externally adjustable power valve. I've read my Owner's Service Manual and nowhere do I see this issue covered, nor have I found a thread with any further information.

Is the adjuster the spring cap on the gearshift side? Reassembly instuctions have you turn the cap 1/2 turn clockwise after engaging the spring, with the raised ridge down the center of the cap lining up with the 2 retaining screws once the 1/2 turn is made. It appears that the previous owner has turned the cap an additional 1/4 turn. What effect would this have on power delivery, and what effect would it have if I turn it back 1/4 turn?

Thanks much

 

[2-Strokes 4-ever]

Kind of depends on your personal preference.........where you want the "hit" (when powervalve opens.) More tension: will open later, letting the bottom part of powerband last longer. Often times, not enough tension will hurt low-end by opening valve too soon, causing cylinder to not draw fuel from carb. effeciently. (kind of like blocking the intake on a vacuum cleaner) My 03 has a HUGE hit, I also go 3/4 tension........this makes the hit come on at a later rpm. Don't go less than the stock setting, but choose your preference based on 1/2-1 turn tension.

 

[rm250_rider]

That makes sense. I'll experiment with it a bit. The bike has a low-end port job and is pretty decent off idle when woods riding, with a sudden, wicked mid-range hit. It's almost too much at times. Everything peters out quickly and it seems to be lacking a bit on the top-end.

Thanks

 

[RM_guy]

Too much tension on the PV spring will delay when it opens and it can give you quite a flat spot that feels like a lean condition. If you had your engine ported for low end I'd leave it at the miniumn tension. It will let the PV open sooner and reduce the mid range hit. You really need to play with it. They seem to change the setting every year. I thought the '01 setting was 1/4 turn and that is what I run. I had mine set at 3/4 turn when I got it back from porting and it felt very lean. Once I backed it off to 1/4 turn it ran great. It took me a while to realize the PV spring was too tight! I have a nice collection of carb jets now!!

Your lack of top end is typical for a low end port job. The '01 250 has terible top end anyway. I had Erric Gorr give me a Mo Power Everywhere port job and now I have low end as well as plenty of top end.

 

[rm250_rider]

I checked the manual and it does recommend 1/2 turn. I noticed that the model year isn't mentioned anywhere and the manual is copyright 2002 so maybe I have the wrong manual.

I'll try it at 1/4 and 1/2 and see which setting works best.

Thanks for input guys.

 

[rm250_rider]

Thought I'd post an update since today is the first time I've been able to ride after your tips -

I set the powervalve at 1/4 turn and it made a huge difference in the way the bike runs and starts. If I ride everyday it used to take 10-15 kicks to get her going. If I hadn't ridden in a week or so 20-30 kicks was more in order. After 3 weeks of sitting in my trailer it started on the 5th kick yesterday. Today when we unloaded, it started on the 2nd kick. That alone was great news!

Once riding I couldn't believe I was on the same bike. The throttle doesn't operate like a lightswitch now- it was either on or off with not much middle ground. It runs much smoother now, very controllable, without the crap-your-pants hit it had before. The engine responds very well to throttle adjustments too.

My times through the single track stuff was much better, and I always felt like things were under control- not on the verge of going to hell with a shade too much throttle. Very kool!!!

Thanks again for the advice. It was dead-on! :aj:

 

[RM_guy]

BTW, 1/4 turn is the spec for the '01 RM250. I thought I posted it when I checked my manual but I guess I forgot.

Glad to hear it runs so much better!

 

[rm250_rider]

BTW, 1/4 turn is the spec for the '01 RM250. I thought I posted it when I checked my manual but I guess I forgot.

Glad to hear it runs so much better!

You did post it RM_Guy, that's why I tried that setting first. ;)

Yes it does run better! Thanks again man!

 

[RM_guy]

Ooops! I hadn't been on the boards for 3 weeks and that's way past my memory retention ;)