RM125 Sounds bad. No idea why.Please help!

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5/13/2018 12:51 AM
Edited Date/Time: 5/13/2018 12:53 AM

2001 RM125
It sounds like running rich, but the spark plug is nice brown, and i have just replaced my crank seals. My ignition is retarded a bit. Running on 95octane, not better with 100 octane. Premixing with motul710 1:40. The bike pulls great, but sounds bad for me. The bike was rebuilt and I ran 10hours since rebuild. Stock nicasil cylinder, Vertexpiston(C size),new bearings(Prox(ntn)),and seals. Please help me why it doesnt sound well! Heres a video where i pushing it, but its not clear sound.

i cleaned the carb several times. it was running with 460 main jet, the spark was black.I replaced with 430 and its nice brown, and the sound of the bike is better, but still not clear.I dont want to go smaller main jet because it would be too lean, i dont want to seize it. pilot 25(stock 40), Main 430(stock 460), needle in the middle, air screw 0.5 out(if 1,5 out it bogs when i pull the throttle at low rpm.)Spark brown.(at full throttle i cut out the engine and i screw out and check the spark plug.)
Reed seemed OK.(no gap)
Videos:




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5/13/2018 3:01 AM

stock pilot it's 27,5, your pilot is not good if you have only 0,5 at air screw.
Check your reed valves and your valve too, does it really open?
I had a 2001 too, but can't remenber the jetting i had.

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5/13/2018 3:12 AM

Manual says 40pilot is the stock, I bought the bike with 25 pilot. I will check my reed valves once again, but i checked it 2 days ago, and i didnt see any damage, and it was closed well, didnt see any gap. To check my valve is openin wha should i do? Should take off the housing of the valve on the cylinder and check if its moving when i rev it? The power is OK i think. I can easily keep up the speed with my mate with a cr125 '97. Theres a lot of oil on my swingarm, I dont know why, I mix oil 1:40 and crank seal was replaced by me. I Really dont know why is it sound like this sad

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5/13/2018 6:20 AM

If it were me, I'd put it back to stock jetting and re-baseline it. Just make sure you know exactly what it had in it as you put it back to stock.

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5/13/2018 7:01 AM

Are you sure the powervalve is working? Doesnt sound like it opening up to me.

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5/13/2018 7:11 AM

2001 had a problem with the power valve actuating rod breaking. Theb2002 part is updates and fits theb2001

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5/13/2018 7:21 AM

When i rebuilt the engine, i checked the power valve and i could move it, no problem. the rod isnt broken. I just finished the rebuild last week. Its so annoying, i checked everything, it should be running good, every part is in good condition, i replaced every part wich was weared. Mechanically the engine is fine i think. hmmmm.......

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5/13/2018 7:26 AM

martadavid wrote:

When i rebuilt the engine, i checked the power valve and i could move it, no problem. the rod isnt broken. I just finished the rebuild last week. Its so annoying, i checked everything, it should be running good, every part is in good condition, i replaced every part wich was weared. Mechanically the engine is fine i think. hmmmm.......

It was a common problem, the rod actually gets cut by the cmgovenor gear. Just pull off the side cover and check operatio n

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5/13/2018 7:26 AM

Bruce372 wrote:

2001 had a problem with the power valve actuating rod breaking. Theb2002 part is updates and fits theb2001

That was the first thing I thought of, as my 01 had this issue. Bike sounded like shit, and I looked forever till I found the problem. One repaired, life was normal

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5/13/2018 7:34 AM

I will check it again, but if it wouldnt open it would affect the performance? But I can accelerate faster than my mate's 97' CR125, but he is on 45 rear sprocket, and for me its 50.

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5/13/2018 7:42 AM

martadavid wrote:

I will check it again, but if it wouldnt open it would affect the performance? But I can accelerate faster than my mate's 97' CR125, but he is on 45 rear sprocket, and for me its 50.

My mountain bike accelerates faster than a cr125

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5/13/2018 7:47 AM
Edited Date/Time: 5/13/2018 7:48 AM

hahaha lol, i will show it for my friend, he will be mad :D :D
But it sounds shit even lower RPM, when the exhaust valve should be closed. :\

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5/23/2018 12:31 PM

Made a new video this weekend. You can see how it goes next to a 2016 sxf250. Its so annoying. Checked plug several times.Beautiful Brown.



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5/23/2018 12:34 PM
Edited Date/Time: 5/23/2018 12:36 PM

it's a Suszuki, not sure what you expected bro

here's a repair kit, just light and drop in the fuel tank

Photo

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5/23/2018 12:38 PM

thanks, will give it a try :D

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5/23/2018 1:43 PM
Edited Date/Time: 5/23/2018 1:54 PM

almost sounds like the ignition is breaking up. Do you have a buddy with another rm125 that you could swap ignition components with?

Seriously though, your RM125 has probably been infected with '125 Dream Race MEDIA BLACKOUT' virus, and it just won't run right until 125 results are posted.

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5/23/2018 1:57 PM

martadavid wrote:

I will check it again, but if it wouldnt open it would affect the performance? But I can accelerate faster than my mate's 97' CR125, but he is on 45 rear sprocket, and for me its 50.

Bruce372 wrote:

My mountain bike accelerates faster than a cr125

Hahahaha!! Thanks for that laugh!

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2017 RMZ450
2005 YZ250-sold :,(
1998 YZ250
2005 KX250F

80% of the time it works every time
IG @hammerfamily_4 & @2HRacing
Thanks to : Factory Effex, N2Dirt, Acerbis, DT1, Fasthouse, Matix, FMF, ASV, 100% & Mika Metals

5/23/2018 2:42 PM

My old piston wich replaced 15hours ago looked like this:
Photo
Maybe detonation??

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5/23/2018 3:43 PM

When an odd situation comes up and seems everything has been ruled out...I always mention something odd that caused my YZ250 to break up in the mid to top. My spark plug cap had gone bad...swapped out the rubber spark plug boot and it ran good again. Good luck!

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6/4/2018 11:44 AM

UPDATE!UPDATE!UPDATE!
I figured out that my powervalve doesnt open. I was riding to home and i started to pull the throtle crazy, ganged up to 6 gear, and revved it to the point where i felt it started to weak like it does everytime, then i went in a bump and the bike started to pull like hell.I reallyzed my powervalve opened in the bump. So i started to riding wide open in my village with my gopro on, and after 10minutes crazy ride i finally caught on camera when its opening. Heres a video, its opening in the 27th sec.Full throttle in 1st gear then i go in neutral, then second and in second its open, but when i shift in 3rd its not open.

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6/4/2018 11:50 AM

I'm 100% sure the powervalve in the cylinder is good.I could move it easy when i took off the cylinder when i rebuilt the top end. The bottom end part should be ok too, but i know the 2001 RM had problems with the valve rod.But i dont know Its not openning when i rev the shit out of it. What could be the problem?

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6/4/2018 11:53 AM

peelout wrote:

it's a Suszuki, not sure what you expected bro

here's a repair kit, just light and drop in the fuel tank

Photo

Ha

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6/4/2018 12:22 PM

martadavid wrote:

I'm 100% sure the powervalve in the cylinder is good.I could move it easy when i took off the cylinder when i rebuilt the top end. The bottom end part should be ok too, but i know the 2001 RM had problems with the valve rod.But i dont know Its not openning when i rev the shit out of it. What could be the problem?

Simple way to find out:
1) Remove the exhaust pipe.
2) Remove the powervalve cover
3) Put the exhaust pipe back on
4) Start the engine and rev it. Watch the powervalve arm move up and down. If it doesn't move, you have a problem.

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6/4/2018 1:46 PM
Edited Date/Time: 6/4/2018 1:47 PM

martadavid wrote:

I'm 100% sure the powervalve in the cylinder is good.I could move it easy when i took off the cylinder when i rebuilt the top end. The bottom end part should be ok too, but i know the 2001 RM had problems with the valve rod.But i dont know Its not openning when i rev the shit out of it. What could be the problem?

mxrose3 wrote:

Simple way to find out:
1) Remove the exhaust pipe.
2) Remove the powervalve cover
3) Put the exhaust pipe back on
4) Start the engine and rev it. Watch the powervalve arm move up and down. If it doesn't move, you have a problem.

X2.... I would suspect there is something going on with the PV. Even if it felt good on the bench and everything went back together normal it may not be functioning properly. This test won’t take very long and at least it will either confirm or deny that it is good to go.

I would also try a new spark plug cap or verify that your cap is fully snapped down on the plug, or that the little metal end isn’t loose on top of the spark plug if is the kind you can remove. I have a feeling this issue will end up being simple and stupid that is being overlooked and That it will make you laugh (or cry) in the end.

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