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Accelerator Pump

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I have been rereading all these old posts in order to get an idea how I am going to cure the off bottom bog I have on my 99 WR. The last ride of the season I seemed to have an inordinant amount of trouble lifting the front end over fallen trees in real tight trails.

Here are my specs:

WR timing, FMF powercore IV, full octopus, no airbox lid, #172 main, stock needle (DRS) and a #45 pilot, riding at about 2500- 4000 ft of elevation. Where is my fuel jet screw? I dunno, riding season ended in November!

To further challenge my jetting woes, I have now added a Big Gun exhaust system. I have an EKP needle that I would like to try with the system. It looks like most are suggesting a #178 to #180 main with this exhaust. Being -20 C up here in Canada I have been mandated to debate these jetting changes in the theoretical confines of my computer laboratory rather than hands on in the garage!

The reason I post is that I have noticed over at Ronnies Yamaha parts Fiche that there is two other diaphrams listed. The stock diaphram assembly being # 5BE-14940-18-00. The two optional diaphrams being xx-xxxxx-17-00 and -19-00. has anyone experimanted with these oterh diaphrams? What is the difference compared to the -18-00 STD.? Does the 2001 come with another diaphram that may cure the bog?

Any jetting recs and an answer to this diaphram question would be greatly appreciated.

PS Taffy way to rowl them up up with your Rorich thread over at yzwr400@Yahoo! Ah the self professed internet gurus can be quite amusing at times!


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how much against yz timing are you? it made my power a lot snappier for those types of situations. as taffy said, "no engine builder in their right mind would give a engine like this the wr timing". bonez


Why do we park on the driveway and drive on the parkway?

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I tried to get the optional diaphram parts but they never came, not available.

For your jetting try:


#45 - 2 turns out, or #48 - 1 turn out

#165-172 main

The bigger main jets are usually for the D-- needles.


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