how do i clean a power valve?

[boosten lebaron]

i got an old beaterish 1991 rm125 that im thinking needs to have the pv cleaned. its real boggy down low and power is eratic. is it possible to clean without tearing the whole motor apart or can i just blast something with carb cleaner. I dont mind a little disassembly but im not going to pull the motor apart.

[breakdirt916]

on my '98 RM125, you *can* by removing 3 of the 4 bolts on the exhaust valve cover...the 4th one is blocked by the frame (hey Suzuki: WTF?), but you can get it off enough to swivel the cover down and blow some air or use a rag to clean it out

your motor is a little different, but it may be close

[boosten lebaron]

is it that simple? i see a cover on the clutch side of the motor and the knob for it on the other side. I can get that cover off but i dont know what im looking at in there. Do i just clean crap out of it in there or should i pull the exhaust off too?

[typeone]

it should be pretty basic. i would get a manual and review it, take the PV assembly out and clean everything well. those parts can get real gummy or worn, especially on an older bike. might as well do it right otherwise you may not get the power delivery you're looking for. plus it's just good maint

[breakdirt916]

(btw, I'm a noob)

then I'm not sure...your engine may be laid out differently than mine..got a pic?

but uh...why are you checking for an exhaust valve cover on the side of the motor? it's on the front, towards the upper part of the cylinder...on my bike it's a rectangular cover

off topic: how's the rest of your bike? shooting more broad: top end fresh? jetting correct? spark plug recent?

and yes, it is that simple..,but as type1 said; on an old bike you might as well avoid the shortcut, take apart the exhaust valve parts, and clean everything thoroughly.

edit: no...just take off the cover and clean it. If you take off the cylinder, you may need to spend money on gaskets. do NOT spend a dime on this bike!

[typeone]

edit: no...just take off the cover and clean it. If you take off the cylinder, you may need to spend money on gaskets. do NOT spend a dime on this bike!

see, I don't agree. if people would just care for these things they'd prob last forever! dirt bikes need constant attention, no way around it. and a 125 2T is about as simple as you can get, not to mention pretty damn cheap and easy to keep tight.

[Paul_E_D]

First, I would inspect the reeds.

Next, I would pull the PV cover, start the bike, and rev it, checking to see if the PV operates i.e. opens up at around half throttle, and fully opens by 3/4 or so.

If it looks iffy, I would pull the cylinder off, dismantle the powervalve, soak and brush the dirty parts, replace the worn parts, reassemble and rip. As far as wrenching goes, this is as simple as it gets. Might as well put a new ring in it. plan for a few hours, and possible wait time for parts order. You can reassemble it with worn bits, but it may not operate smoothly and consistently.

I would also clean the jets in the carb.

[boosten lebaron]

(btw, I'm a noob)

then I'm not sure...your engine may be laid out differently than mine..got a pic?

but uh...why are you checking for an exhaust valve cover on the side of the motor? it's on the front, towards the upper part of the cylinder...on my bike it's a rectangular cover

off topic: how's the rest of your bike? shooting more broad: top end fresh? jetting correct? spark plug recent?

and yes, it is that simple..,but as type1 said; on an old bike you might as well avoid the shortcut, take apart the exhaust valve parts, and clean everything thoroughly.

edit: no...just take off the cover and clean it. If you take off the cylinder, you may need to spend money on gaskets. do NOT spend a dime on this bike!

ill look again since it was getting dark when i did but it looks like my pv is accessed on the side of the motor. I have the selector switch on the one side and the cover on the exact opposite. ill have to look again to figure it out.
the reason i think its the pv is the whole front of the motor is covered in soot and grime so i dont think its been cleaned. the power delivery is really bad down low, like i cant even drive up a hill bogging bad and the power delivery is really erratic. sometimes it hits like a 2stroke should and others it just builds. I also believe the carb is out of whack and ill get to that today but i think the pv needs the attention too.
everything else about the bike is fine for the most part. suspension is ruined though. its got a fresh tune up with new uni filter and plug (old plug didnt look bad either) compression is around 120-130. fresh gas to get rid of the old. recent tires and brakes. needs a chain and sprocket but like was posted im not going to put a dime more into if i dont have to and unless it runs great.
right now im into it for just shy of 700. its not bad and i can rid it as is but its a little tough in the woods. the carb is probably my main issue at the moment with it barely idling and im sure the jetting is off. I think once that is done today and the pv is cleaned itll be like a whole new bike.

[boosten lebaron]

so it looks like the pv can be accessed by the front. its pretty dirty up there so im gonna have to clean it up before i even get to it.
I guess on these old rm's its a very real possibility of breaking the pv clips when you remove it so im not going to do it unless i have to. Ill try to start it with the cover off and look at it. I really dont know what im looking for but i guess any movement is a sign.
ill check the reeds when i do the carb, i believe i can see them when its off.
If i plan on keeping the bike i may pull it apart and do it right but for now im looking for a temp short cut.

[Paul_E_D]

Low down power loss is not the PV. That would be top end loss.

Low down is the reeds, or the jets. Likely it's just a plugged pilot jet. This is super easy. drain the carb, remove the bowl, remove jets, spray/sok them, and blow them out really well with compressed air, or use a thin wire to carefully floss them.

[boosten lebaron]

Low down power loss is not the PV. That would be top end loss.

Low down is the reeds, or the jets. Likely it's just a plugged pilot jet. This is super easy. drain the carb, remove the bowl, remove jets, spray/sok them, and blow them out really well with compressed air, or use a thin wire to carefully floss them.

ill give the carbs a go first. after spending the last half hour cleaning the bike i doubt ill be able to get into the pv chamber anyway. the top 2 bolts are covered by the frame and im not sure i can get at them. i should know more about the carbs in an hour or so when i can do it and go for a ride.

[breakdirt916]

oh I agree, db's do need constant maintenance! but it does cost money, and even more money when you're doing corrective maintenance before preventative maintenance.

so if the OP is in $700, I say tinker with it all you want at home, but don't start buying hundreds on parts to "fix that last piece so it'll run right." There is no last piece. It's a black hole, and that's what I got sucked into. You want to do everything Paul and Typeone outlined, go for it. But, if while you're in there, you notice the cylinder could get honed, or that the exhaust valve has permanent damage and needs to be serviced by a machine shop, or that it should really have a new clutch basket, I'd say stop, and sell it for $700.

[gregp]

I'd say stop, and sell it for $700.

On a '91 RM 125 (that doesn't run quite right), I would have to agree.

[typeone]

breakdirt, i kinda meant the guys before him that owned it. if the trail of owners just did basic maintenance, dirt bikes can live a long, useful life. thats all i meant.

in general, i steer clear of basket-cases cheap dirt bike to buy = (more) expensive dirt bike to own. but a beater can still be a good, solid bike.

/OT

[breakdirt916]

agreed

but back on topic...poor guy is now probably debating whether or not to clean his exhaust valve, or sell the bike!

OP - does it idle?

[boosten lebaron]

barely idles but i havent messed with the idle screw. ill probably end up selling the bike but ill give it a go at fixing it. as it sits its totally rideable its just harder to ride than my others because of the running issues. it starts first or second kick and always does so even after beating it for hours.
its real issues come to play when im going slow in the woods. it bogs bad down low, i can rev the shit out of it and dump the clutch and it just bogs then picksup. steep grades are tough if i dont have the rpms to get up it, once i start to really slow down im f'd. If i hit big hills going at a decent clip it climbs them like a 2 stroke should. If im already on the hill and have to stop and go again im in for some trouble.

[Paul_E_D]

If its the same after cleaning...

drop the needle one clip. Adjust the air screw out 2 turns from lightly seated. You likely need a smaller pilot jet.

[boosten lebaron]

the correct answer was the reeds. thanks paul. i did the carbs and they werent too bad. i set the air screw out 1.5 turns, it was previously 1 turn out. bike ran a touch better but still not good. i then moved on to the reeds and boy were they in trouble. one had a gap of .020 and the other wasnt much better. I did the flip trick and closed the gap to a very small amount. it still there but about .003 now. bike runs like it should now. its very fast and powers up nicely. the idle is also good now too.
the only issue i noticed now is the bike like to get stuck in gear on occasion. i dropped the oil and put some rottella t in it and its a bit smoother but can still get stuck. I just have to up shift to the next gear then all is fine for awhile. i dont think its an easy or cheap fix so ill let it be.

[Paul_E_D]

Cool. Get some fresh reeds. They are cheap, and the ones you flipped are gonna break soon leaving you a tough ride out.

Yeah, on the tranny check cable adjustment carefully. Otherwise, just keep the oil fresh and forget about it.

[rbrais]

Your reeds are probably shot, too. They can make a big difference.





Ooops. Too lazy to read all the posts.