2001 RM250 running rough

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5/31/2018 7:15 PM

Borrowing a buddy’s bike for a 2t shoutout but he told me his last ride it started running rough out of nowhere. No change was made to the bike. At idle it Revs up fine but riding it under a load it spudders/ flutters low to mid until you get into the powerband/top end. I’ve cleaned main/ pilot jet. Carb bowl didn’t have dirt or anything in it and it stills runs poor. I pulled the vforce reeds which seem tight but have slightly chewed up corners. Is this enough to cause it to run poorly? (See photos below) I am no mechanic but going over the basics. I’ve been on 4 strokes most of my racing life and fuel injection for 5-6 years with limited carb knowledge. Thanks for any input.

Photo

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5/31/2018 7:23 PM

yamahaha131 wrote:

Borrowing a buddy’s bike for a 2t shoutout but he told me his last ride it started running rough out of nowhere. No change was ...more

When you pulled the carb apart did you check the needle valve (it’s the little guy that sits by the float usually held up by two little wire like retainers), a lot of times these get scratched up or they aren’t sitting correctly due to the float not being adjusted correctly, which bring me to my next question;

Have you checked the float height? A lot of times the tabs get bent and will cause the float to sit either to low or too high which will drastically change the performance.

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2001 YZ250

5/31/2018 7:38 PM

I have not looked at either. I will check the needle valve. I know you can reference the manual (which I don’t have) for the float height but not 100% how to measure/adjust. I’ve watched a few videos but I don’t have a good instrument to measure with.

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6/1/2018 5:21 AM

yamahaha131 wrote:

I have not looked at either. I will check the needle valve. I know you can reference the manual (which I don’t have) for the ...more

You basically flip the carb upside down, and measure how far the float is protruding from the body of the carb. I'll post a picture of the one I have in my YZ manual, the height may be different for the RM because I don't know what carb it is.

Grab a set of digital calipers, they're good for just about anything from working on motorcycles to measuring stuff around the house. These bad boys are only $17 on Amazon, if you don't have prime, shoot me the $17 via PayPal and I'll buy em and ship em to your house for you.

https://www.amazon.com/Neiko-01407A-Electronic-Millimeter-Conversion/dp/B000GSLKIW/ref=mp_s_a_1_3?ie=UTF8&qid=1527855445&sr=8-3&pi=AC_SX236_SY340_FMwebp_QL65&keywords=digital+caliper&dpPl=1&dpID=41WMvppQQrL&ref=plSrch

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2001 YZ250

6/1/2018 7:15 AM

yamahaha131 wrote:

I have not looked at either. I will check the needle valve. I know you can reference the manual (which I don’t have) for the ...more

Let me know if you have any questions man. Photo

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2001 YZ250