Odd problems with a 1995 RMX250

[MX86]

well easy way to test for leaks use a dye and put it in your pipe (while off) and see if it seeps out.... just take the powervalve out and use brake cleaner (if gas doesn't work) to remove all the carbon build-up from it...

I clean mine every 3 weeks... but i ride it and race it a lot! (2 rebuilds a season) it's the easiest way to loose power... and it doesn't take much carbon to hold it up from moving so... that's why on the newer bikes like my YZ they have a vent hose running from the powervalve to allow the carbon to leak out through that hose

[rebelpacket]

Well, its funny you should say that, because my RMX does have vent hose running from the powervalve. Every now and then I'll see some exhaust come out of that.

I'll take it apart tonight and give it a look over. Any special tricks to reinstalling it? I'm usually pretty good about following a Clymers manual, but usually have to find the "tips" out the hard-way.

[diesel-mech]

Luckily the suzuki power valve is pretty self explanitory (not like a kawasaki KIPS system) The only thing that you really have to worry about is the preload on the adjustment spring. I don't remember off hand if you turn it counter clock wise or clock wise.

Something else you might think about is the stator plate being loose. Although I am sticking to the jetting thing because I have been in your shoes and I know what caused it. Think about this, You keep dissmissing the jetting issue because your plug looks good. But it is obvious that the engine is bogging out, If the cylinder was firing perfectly giving the plug a light tan color than your engine would not be bogging out. Even if your powervalve were causing the problem the cylinder would be over fueling, thats why it boggs in order for the plug to stay tan it would have to just flatten out (power wise) and not bog. You can't rely so much on what you are seeing from the plug! remember I have been where you are and I feel your pain. Hell I spent $250 for a new stator because I was sure that it had to be electrical because it couldn't possibly be the jetting. The bike always ran great with the jets that were in it before. I was wrong.

[rebelpacket]

Roger that Diesel-mech. I'm not trying to downplay the wealth of knowledge your bringing here, I'm just trying to go with the simplist fix first. I put it back together late last night with the main jet clipped two settings leaner than it was previously. I figure with a leaner main jet, under full throttle, it'll either work, or it wont.

But considering I recently picked this bike up, and its had this problem since I've owned it, cleaning the powervalve probrobly isnt a bad idea either. When I get home, I'll test it with the new, leaner main jet, and see if it changes performance in the powerband.

Your right about the plug though, and its a very good point. Who's to say that the mixture is perfect when its bogging, but too rich, or too lean everywhere else? Good points. Thanks for your input man.

[diesel-mech]

Remember that your pilot jet works until 1/4 throttle, the needle over laps from just before 1/4 to just after 3/4 throttle and the main jet is 3/4 to full. The taper of the needle and the clip setting both effect the settings. I wish I could tell you what it took to get mine straight but I was so lost because of this problem I took it to the bike shop and they fixed it. I had ruled jetting out but I was wrong and they properly jetted it to solved my problem.

[dchd1130]

that bean oil get real sticky makes a huge mess I used to run it till I stuck the power valve on my CR250 I would look at your power valve

[MX86]

one thing that i have been taught over the years is not to look at the "Color" so much... but look at the arch running to the electrode... optimal is when your burn marks are right on the curve... if the burn mark is toward the thread or on the bottom of the curve as i like to call it your running lean... if it is above or over the electrode it is running rich (don't know about champion but it's 99% right on NGK's)

made this image real quick for reference

[6thWide]

im telling you still dont rule out the reeds. i had an 01 cr80 that had the same problem. off idle it was fine but midrange and up it was breaking up and running crappy. i couldnt tell from inspecting the reeds that it was the problem, but a friend of ours told us to give it a try and after i did the bike ripped. another issue it can be is a headgasket. i had a 97 rm80 that ran fine at idle but when we hit just under the powerband it broke up and stayed there. it had and oring headgasket that blew out, and at the higher engine speeds, the coolant was at enough pressure to force its way into the cylinder. the powervalve could also be your problem. dont rule that out either

[MX86]

i'm having a hard time believeing the reeds... but with two strokes never rule anything out... i would still go with the powervalve.. but check the reeds.. and normally with the head gasket you will see a significant loss in horsepower and would run crappy as soon as you start it.. and would be a real pain in the butt to start (water does not compress). and loose radiator fluid... could be a leaking magnito seal... i mean the possibilities are endless... i'm just trying to cross off the basics before he has to split his case and have to fork out some money.

[diesel-mech]

You could rule out the head gasket do to the design of your engines gasket. I highly doubt its your head gasket, You may want to put a set of reeds in anyway, they do fatique and you can't tell just by looking at them.