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anttismo

XR650R side cover drilling

5 posts in this topic

Hey all,

First time psoter, so please be gentle :)

I recently bought myslef an XR650R after not riding a dirt bike in 10 years or more. As a youngen I did a lot of riding on 250 and 500 MX bikes. My inital response was that it really goes quite well. It's been uncorked, but nothing else as far as I can tell.

After reading lots of stuff on the web, I decided to drill some holes (about 100 1/4") in the side cover silimlar to what I'd seen on honda race bikes and other bikes on the web. The result was amazing. It became far more noisy but more importantly, it seems to have some serious jetting shortcomings.

My bike is in australia, and it seems the main jet supplied in the comptetition kit is a 162. so perhaps it's way too lean? Also it it developed a stumble at partial throttle and low rpms. So that soulnds like a needle prob. It runs pretty well as soon as the hole are covered over with tape.

I'm sure there are threads about it on here somewhere but I couldn't eaisly find them. If anyone has some off the bat suggestions, then I'm happy to listen. I'm planning on getting some bigger mains (maybe 170, 175, 180) and trying differnet needle postions. Can't hurt to have a play :)

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I am no expert, but I would imagine it is too lean. I would go to the 175 or 180, and move the clip down on the needle. It's a cheap fix.

Have fun

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Start out with the 175, stock needle in the 4th clip,68s for your pilot jet...

If you really want to wake the beast in your BRP install a Edelbrock carb.... :)

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Thanks folks,

I ended up going up to the forth clip on the needle and put in a 180 main. It's pretty good now with just about everything cured. It is slightly funny right off idle, so I'll try a 68 pilot as mentioned. It's currently a 65 I think.

Anyway, I think there is a bit of a gain in the side cover drilling. Feels super strong at the moment. I have no idea what people do with the piston/cam kitted XRs with another 10 HP, BTW. Must be good for raping and pilaging I reckon :)

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hey I am also in Australia and did exactly what you did and was also impressed with the results. I run a 175 main needleone down from middle and 68 pilot. This does provide pretty good results...... FFS people stop saying get an Edelbrock I know there good but they are also expensive and not everyone has the spare cash. :'(

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