rm wont rev

[125 rider]

While out riding i noticed my RM will not rev past about 7 grand. I want to say this happened all of a sudden but it may be because i was riding other peoples bikes and then hopped back on mine and thats when i really noticed it. It doesn't really bog, it just hits a point where it wont rev further no matter how much throttle is applied. It sounds like its rich. I cleaned the air filter, and it runs the same. Im going to replace the silencer packing and go one step leaner on the main. Does this sound right? What else could cause this? I know reeds would have an effect but i didnt think it would be this drastic unless they're in real bad condition (which they're not) Thanks for any replies.

 

[RM_guy]

Check to make sure that the power valve is opening all the way or at all. Spooge may be making it stick. Make sure the linkage is hooked up too.

 

[Stew312]

What I would check:
1) Sticking power valves
2) Timing

 

[RM_guy]

Another thing, Dont mess with the jetting until you have checked everything else.

 

[IrishEKU]

How many hours on the topend? Have you had it in water? More info please.

Phillip

 

[125 rider]

about 10 hrs on top end, hasnt been in water. Going to check the PV tomorrow and i'll report back.

 

[2001yz250]

I'm also thinking PV but you might want to put a new plug in too and check the wire/cap in case it is misfiring. Your jet may be getting a little clogged so you may want to clean the carb before you mess with the jetting.

 

[marcusgunby]

Check the reeds are sitting flat, look at replacing the plug and silencer packing.Could be a bad coil.PVs and rich jetting sound likely.

 

[125 rider]

The plug is new. The last time i repacked the silencer i used pink home insul. so i know its due for repacking. Last time i had the bike apart i noticed a slight gap between reeds & cage so i flipped them over. The weather hasnt really changed drastically around here yet so im thinking jetting should be last on the list.

 

[125 rider]

2001yz250 just made me remember something.. somewhere around the time it started doing this i changed the plug and and when i put the plug boot on i noticed it didnt "snap" in place like it usualy does. Could the plug/boot connection be the culprit?

 

[IrishEKU]

It can but I doubt it, wear can cause the "snap" that you felt before to reduce over time but I don't think that is your problem due to the young life of your machine. Unless you have been changing plugs every ride. If so.....Turn the fuel off even for short stops, check your float level, remember the hours on the top end, consider the people riding(if it's just you you may be lugging it too much) Don't Grenade your motor by putting it in deep water and wind her out! It sounds like she needs a good carb cleaning and a good hard ride.

My .02
Phillip

 

[DEANSFASTWAY]

125er check those plastic P/V clips top & bottom and sometimes the screws holdind the stuff together in the cyl back out and jam up the linkage under the cover . GOOD LUCK

 

[125 rider]

And by the way the reason why im not exactly sure when this started is because the way this bike is set up it has so much bottom end for a 125 that it should be a crime. The only time i realy hammer around in extreme rpm's is when i drag race or when im in sand pits. I will definatly check the plastic powervalve clip also as dean mentioned because i've seen them break on friends bikes.

 

[DEANSFASTWAY]

If its got killer low end maybe the flywheel key is shearing and advancing the timimg or the stator plate has rotated abit too far clockwise , or the CDI bow is bad and making full advance all the time . I have replaced 2or 3 YZ80 CDI because they lockout and burn a hole in the center of the piston . Usually ruins the topof the rod also . Motor will seem fast but will seem to run flat . check it out .

 

[125 rider]

UPDATE:
Thanks to all that replied. The problem was indeed with the plastic power valve clip. For the mean time i used some wire to hold the PV conecting rod onto the actuator. I rode it today and it rips again! I dont think there is anything wrong causing it to have the great low end. I rode a race prepped 99 rm125 the other day and couldnt wait to get back on my bike. Mine has the killer top end of the 99, but starts making power right off idle. 97 was a good year IMO.

 

[RM_guy]

Glad it was nothing serious. :)

 

[DEANSFASTWAY]

Yeah I have a 96 the year with the extra exhaust boost ports . That bike hauls butt and its for sale fresh crank and all .