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MN_Kevin

JD, some hep on the varying diaphragms for the accel pump.

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JD and everybody else,

Do you know how the yamaha part numbers for the AP diaphragms coincide with the stroke travel of the accelerator pumps?

I see the following diaphragm part #'s:

5BE-14940-15-00 (YZ ONLY)

17 (standard on the 99 WR)

18

19

There is no standard listed for the 99 YZ...

Do you know which one has the most limiting AP stroke?

------------------

'99 WZ with all YZ mods, FMF PowerBomb header, Stroker SX-1 silencer, SS front brake line, forked over by Pro-Action , OEM YZ tank and IMS seat.

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Last summer the local bike shop tried to get all of the optional pump diaphrams for my '00 WR and they were not available from Yamaha. It is still a mystery what the differences are.

The stock diaphram height, 8.1mm, does not limit the stroke, the cam profile does not stroke that far. At a height of ABOUT 8.5mm it would start to reduce the 3mm of stroke.

Anyone else?

James

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JD: When I first read your response about the "Cam" profile.....at first I thought you meant the camshaft. Well, obviously you meant the little plastic cam on the carb slide shaft that operates the accelerator pump plunger rod, right? I had a brain burp.... :)

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Yes, that was the plastic cam on the carb linkage. :)

Does anyone know if the 2001 models use a different plastic cam to alter the pump stroke or timing?

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