RM250 - High RPM problem - SOLVED!

DerickYZ
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DerickYZ
Edited Date/Time 4/14/2019 10:40am
Rebuilt my 2002 RM250 from bottom to top. A buddy of mine rebuilt the carb.

Bike will run in the low to mid rpm's just fine, but in the high RPM's it sounds like its drowning/won't hit the powerband.

I have my old jets from my old set up, should I try to run those and see? The bike will idle and rev in neutral just fine, but it won't hit the powerband.

PV to blame?
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Paul_Pitzonka
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Paul_Pitzonka 4/2/2019 5:22pm
4/2/2019 5:22pm Edited Date/Time 4/2/2019 5:23pm
DerickYZ wrote:
Rebuilt my 2002 RM250 from bottom to top. A buddy of mine rebuilt the carb. Bike will run in the low to mid rpm's just fine...
Rebuilt my 2002 RM250 from bottom to top. A buddy of mine rebuilt the carb.

Bike will run in the low to mid rpm's just fine, but in the high RPM's it sounds like its drowning/won't hit the powerband.

I have my old jets from my old set up, should I try to run those and see? The bike will idle and rev in neutral just fine, but it won't hit the powerband.

PV to blame?
Did He change the jetting? If so why? yes, its possible the power valve isn’t working correctly... Take a look at the spark plug see how that looks... if you want to get really in depth you could do an actual plug chop to see if the plugs lean or rich at the top end... Also did you have this problem prior to your rebuild?
DerickYZ
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DerickYZ 4/2/2019 5:40pm
4/2/2019 5:40pm
Paul_Pitzonka wrote:
Did He change the jetting? If so why? yes, its possible the power valve isn’t working correctly... Take a look at the spark plug see how...
Did He change the jetting? If so why? yes, its possible the power valve isn’t working correctly... Take a look at the spark plug see how that looks... if you want to get really in depth you could do an actual plug chop to see if the plugs lean or rich at the top end... Also did you have this problem prior to your rebuild?
Did not have this problem before the rebuild. I was thinking tomorrow to grab some plugs and put the jetting back to how I had it and go from there
captmoto
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captmoto 4/4/2019 8:52am
4/4/2019 8:52am
I would go back to the power valve. Sounds like it isn't set right. It's a different system but I got the power valve wrong on my 04 CR250 and all it would do is run on the bottom.
DerickYZ
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DerickYZ 4/4/2019 1:19pm
4/4/2019 1:19pm
captmoto wrote:
I would go back to the power valve. Sounds like it isn't set right. It's a different system but I got the power valve wrong on...
I would go back to the power valve. Sounds like it isn't set right. It's a different system but I got the power valve wrong on my 04 CR250 and all it would do is run on the bottom.
I will try tomorrow and see what could be a problem.

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earnestT
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earnestT 4/5/2019 6:24am
4/5/2019 6:24am
Yes. Power valve. Also. Do a leak down. Test, it's something all professional builders do on a two stroke
DerickYZ
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DerickYZ 4/5/2019 9:52am
4/5/2019 9:52am Edited Date/Time 4/5/2019 11:07am
I took the PV cover off and let it run on the stand. The PV arm moves up and down freely when RPM's increasing/decreasing. I can't ride it right now unfortunately due to bad weather, will report back tomorrow with results after the jetting has been set back.
earnestT
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earnestT 4/5/2019 11:13am
4/5/2019 11:13am
U could have the valve that rotate on each side back wagon the wrong side. Pull them out and look at each on. The have a r or l on em. Take top cover off of valve assembly check valve opening by looking into exhaust hole while operating linkage. All three off these exhaust holes must be opened when actuator arm moves. I own a 2 002 rm. 250 for 20 years. Now best rm I have ever owned but a nightmare to keep everything perfedt.
earnestT
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earnestT 4/5/2019 11:13am
4/5/2019 11:13am
earnestT
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earnestT 4/5/2019 11:14am
4/5/2019 11:14am
I meant 10 years
lcgordon711
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lcgordon711 4/8/2019 1:18pm
4/8/2019 1:18pm
Really out there but check the exhaust had the same issue on my rm and my S/A was all plugged up.
DerickYZ
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DerickYZ 4/12/2019 7:01pm
4/12/2019 7:01pm
lcgordon711 wrote:
Really out there but check the exhaust had the same issue on my rm and my S/A was all plugged up.
S/A?
lcgordon711
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lcgordon711 4/12/2019 8:05pm
4/12/2019 8:05pm
Spark Arrestor
DerickYZ
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DerickYZ 4/14/2019 10:43am
4/14/2019 10:43am
I checked everything from the airbox to the carb. Cleaned the jets, set the float again and it still wasn't hitting the powerband 3/4-Full throttle. I went back to the basics. I took my Powervalve cover off, cleaned the powervalves out really good. I took the side cover off of the cylinder and the PV arm was bent inward, which would cause it to hang up and limit the full range of motion desired. I straightened it out. Bike runs like it should! Thank you all for the help!
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