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Old 01-17-2013, 08:57 AM   #6616
southern xr rider
Joined: Nov 2008
Location: Columbus, GA
Oddometer: 4,154
it appears I had a crack! Final tm38 flatslide tips

Hey dudes, for all those that helped with my kickback scenario a few months back...after getting my clutch installed and all here is what I concluded.

1. It appears I was both lean and rich on the idle circuit, how I had some small cracks on the xr intake boot, what was weird is the many air leak tests did not alter the idle, however when riding the idle would creep...I also had too fat a pilot jet on the mikuni, a 20, instead of the 17.5 that made hot starting worse too...I would kickback every 3 or 4 solid kicks....If my jetting would of been leaner I might of not had enough time to get a kicker...jajaja

2. The xrl boot I have now installed was newer than both xr boots I had, one had a brocken lower bolt mount and the second developed these weird cracks.

3. If you decide to use an aftermarket carb that has fitment issues I found out through reading many threads that the xrl boot has a slight DOWNWARD angle to it that points a bit down and to the right when facing the bike from on top...thise helps with the different cable adjusters or pulleys on some is also slightly shorter, pulling the carb towards the head...

THINK FCR41, TM38, etc...they have big bodies and addons that make fitment somwehat of an issue

Finally, jetting

for my altitude changes of about 3500feet from up in the city to the sea I had to compromise...

so for my tm38(xrsonly) flatslide my jetting is:

pilot 17.5 2 turns out(in is rich out is lean on these carbs)
6fj41(leanest needle) in second from leanest clip(I need to be lean since I have cw hrc cam which requires less fuel at this position)
220 main jet

I beleive my throttle slide is the #2

Hope this helps anyone in a similar situation, although I dont hear of many guys switching to these old school carbs anymore

To notes is these carbs are what all the ballards guys and mostly asutralian racers used in the 80s and 90s, they were the defacto carb for big bore racers...

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