Sunday, October 31, 2010

close shave

The FCR parts from Sinceros Speed Works have come in.  These are the jets, needles, and intake bell required to convert the 39mm carb originally off of a yzf426 to work with the DRZ -- essentially the same carb as sold on the E model DRZ, and also available as at kit for $500 or so.  I spent considerably less; here's hoping it works as it should.
You can see that this carb has provision for a throttle position sensor, which I am told is not supposed to be hooked up -- makes sense, as the carb was originally from a Yamaha.  Idle wheel can be seen to the lower left; red knob is for a hot start -- very important when MX'ers crash during a race and need to kick-start the bike in a hurry while warm.  Black knob is the choke.

Like all MX throttle cables, what came with the bike is far too long.  Will leave it as-is for now, and try to track down some brass ferrules in order to make a short cable of the proper length.  Ran out of them with my earlier Venhill kit I got from the UK.

Only one cable is needed, as the return spring action of the slide is considerable.  Not sure if I should bother covering the upper hole, as I don't intend to get a lot of dirt in there!

This is where the "close shave" comes in -- the lower bolt on the float chamber misses the frame tube by 1/2 a millimeter!  The whole conversion would have been a big "fail" had my welding or the carburetor forging been microscopically different.  Result!  According to all the experts, this mod alone should be good for a couple of hp.  Just need to get the jetting right for my application and altitude.  Won't bother trying to run it till the spring, as it is below freezing regularly these days.  Fettling on this bike is done for now.

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