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2000 WR400 Jetting Quest

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After running Stock (mostly) since I bought the bike (new) and having rode some other friends bikes (mostly KTM's) etc... that dont have the off idle-stumble like mine I thought I'd finally make it right. (Its always been this way)

I ride 100% single track Mtn trails/climbs. Mostly 1000' - 3000'. Mid-late summer there will be some higher elevation rides (3500-6000ft) so Ideally dont want to have to chg jetting up higher, but will listen to the experts...

I have the stock spark plug still in-never had to touch it. Starts 2nd or 3rd kick when cold, 1st when warm. Reliability/Dependability has been Excellent!

Airbox lid off, stock header & pipe w/Vortip insert.

Above 1/4 throttle rips good, but off idle will bog/die if I blip throttle too much/quick. So can be tricky lifting front wheel over trees etc...

Overall would like to improve low/mid range torque since thats is where my throttle is the majority of the time and eliminate the off-idle bog.

From the book, my current stock jetting is:

MJ #165

PJ #42

OBDRS 3rd Clip

WR Timing

I just bought one of those Kouba fuel screws to make on the fly adjusting easier-have not tried it yet. http://www.koubalink.com/fuelscrew.html

(WR400 version is different from pic)


[ April 09, 2002: Message edited by: zmr ]

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From what you posted, one of the best things you could do to increase performance is to put a new plug in. Over time the electrode edge rounds off and the spark can not maintain the same intensity. The plug is a few dollars and can make a difference. You should consider a new one.

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