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rm 85 runs good then bogs really bad ***

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ok so i went riding and the bike was running good and i was on the throttle and it went good then it bogged after it was revved up. it just almost completely cut out. it did this several times throughout the day but it was not terrible because if it sat for like 2 seconds it was good to go.

What could the problem be?

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what spark plug are you running, because i had similar problems on my Yz85 so i put a NGK BR9EG Spark Plug and it runs perfect now

and try running 32:1 premix ratio with a NGK BR9EG and it should go better

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Sounds like it may be a fuel starvation issue.

Two things to check...fuel cap vent, to make sure it's flowing freely. Take the little hose and blow into it. Should be able to blow air in into the tank (this is how air gets in there to displace the consumed gas).

Second thing to check is there should be a small brass filter at the fuel petcock. Make sure it flows freely also. I've had some luck in "clearing" them by draining the tank, removing the fuel cap, then remove the fuel line, then blowing compressed air back UP through the petcock nipple.

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it is high rpm it really sucked because it did it once when i was about to enter a corner and needed speed to get out of it and it just nearly cut out. I run 32:1 i am not sure on a plug and i thought that it was something in the lie and was planning on cleaning up the bike draining the gas and checking all the gas lines. I will check the petcock

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This will fix it. Run a #45 pilot, #125 to #128 main (no lower or high with the stock carb), slide needle on the 2nd from the top groove, air screw set at 1-1/2 to 1-3/4. I bet your air filter is dirty. The RM85 does not like a dirty air filter.

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This will fix it. Run a #45 pilot, #125 to #128 main (no lower or high with the stock carb), slide needle on the 2nd from the top groove, air screw set at 1-1/2 to 1-3/4. I bet your air filter is dirty. The RM85 does not like a dirty air filter.

padgett, what do you suggest i run for jetting in an 03 rm250?

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This will fix it. Run a #45 pilot, #125 to #128 main (no lower or high with the stock carb), slide needle on the 2nd from the top groove, air screw set at 1-1/2 to 1-3/4. I bet your air filter is dirty. The RM85 does not like a dirty air filter.

I have heard of similar settings so I have to ask before I run to the shop for the parts,what altitude are these set-ups for. I'm @ sea level to maybe 40ft. my sons is doing the same but maybe from lack of clearing the motor runs fine all out on the pipe for me bogs for him

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It will work I'm at about the same altitude as you and that's what I run in my sons bike run the #125 main while it's this hot and bump it up when it cools off. If it ever will:thumbsup:

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padgett, what do you suggest i run for jetting in an 03 rm250?

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:smirk:

Dude, just listen to Padgett on this one, even if you have fixed it with you plug. He as countless hours in jetting an RM85.

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Yes, I have fixed it with the plug many times only to foul it out a week later.:eek: The root of the problem was with the carb and since I used his jetting advise I haven't fouled a plug since:worthy:

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