XR650R main jet size

Joined
Jun 16, 1999
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#1
When I got my 650 home yesterday, I installed the following Power Up parts and mods:

-Intake manifold
-Carb needle (clip in middle position)
-Removed snorkel and restrictor plate in air box

Instead of getting the Power Up exhaust insert, I used a 2" hole saw and drilled out the baffle from the stock spark arrestor. Got that idea from here.

http://members.nbci.com/bhoth/nonepa.html

The Power Up kit came with a 175 main jet. So I put that in. Rode the bike, and it was running way rich. It would really lurch and blubber when you'd back off the throttle. So, I went down to a 165.....a little better, but still quite rich. So now I'm down a 160, and its still acting rich.

Any ideas? I wouldn't think I'd have to go any smaller than a 160. I thought maybe the air filter was over-oiled (there was oil running out of it), so I dabbed some of the excess off. Maybe I should just clean it and re-oil it correctly?

Thanks in advance.
 

mtngoat

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Jun 12, 2000
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#2
On my buddy's XR, we removed the "smog pump" along with the rubber hoses and sealed the exhaust hole using an IMS part. This appears to be a common mod to most of the XRs I've seen and it eliminated the off-throttle bobble. White Bros sells the part too. You may be under-sizing the main to fix an unrelated problem. I don't recall the "post hop-up" recommended main jet size, but you may want to restore it.
 
Joined
Mar 15, 2000
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#5
The power up exhaust is much more free-er flowing than the 2" hole cut out. At 7,000' I get proper plug readings with a 168 main in desert racing type conditions. At sea level I'm running a 175.

The screened area of the power up exhaust insert is about 6X the stocker.

My power up exhaust is not too loud.....

Check your right footpeg bolts regularly

Mark Buckholz
40+ A enduro racer and DS goober.

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