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Post by fcnomad on Feb 4, 2008 11:30:43 GMT -5
Hi all, I am a newbie on this list and was hoping to get some advise from anyone with experience my current setup- I am working on my '78 SR. I've installed a JE 534 90mm 11.0 (actually probably closer to 10.5 with the thick copper gasket) kit WebCam mild grind sport cam(.440/280˙/260˙/89a) with upgraded springs/retainers, K&N filter, White Bros header, flow thru exhaust (a little loud and raspy... but hey, at least they'll hear me coming). Its still got the stock 34ss Mikuni right now. My challenge is now resting in carbie and jetting choices... Does anyone here have any suggestions on carb and/or jetting? I need to keep some low end grunt for the stop and go traffic I have to deal with these days unfortunately (hence the compromises above) but would like to feel like the effort thus far was worth it on the twisties. Any help would be greatly appreciated! Thanks! Fabien
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Post by colinjay on Feb 4, 2008 16:46:27 GMT -5
The traditional carbie to fit to hotted-up 500 engines is a 38mm round slide Mikuni, how ever these days alot of people are fitting more modern flat slide Mikuni, Kehin and Dellotro(?) carbies. The only real way to get the jetting sorted out is to have the bike run on a dyno. I had my racer run on a dyno a few weeks ago and ended up dropping from a 270 main jet which is a commonly surggested main jet for a 38mm Mikuni on a worked on engine down to a 230 main jet. I also went from a 35 down to a 20 pilot jet.
My final jetting for the 38mm Mikuni is;
230 Main 6F9 needle on the 2nd clip P-6 needle jet #2.0 Slide 20 pilot jet
Of course this is my race engine, which is probable quite different the state of tune of yours, and is running on 102 octane unleaded race fuel.
CJ
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Post by chew652 on Feb 4, 2008 18:22:06 GMT -5
www.siue.edu/~rsutton/SR/mikuni.htm Here is a link to some 34ss mods. You can check out his guided tour page too. I think you are probably a little beyond this carb with your mods though.
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Post by fcnomad on Feb 4, 2008 18:52:17 GMT -5
Wow CJ! That sounds like a dream ride. I only wish I could follow your lead. Sounds like a kick in the pants. F
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Post by fcnomad on Feb 4, 2008 19:00:56 GMT -5
Hey chew652 thanks for the link. I had looked at that site and came to the same conclusion as you. Considering the "mild" mods on the bike now I am seriously considering a flat slide 36mm or maybe even a flat slide 38mm... I looked on the Sudco site and they offer several options plus they have Mikuni TM36mm "pumper" flat slide carbie. Is there any (dis)advantage to going that route? Anyone try this? Thanks F
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Post by caferacercarl on Feb 8, 2008 4:36:46 GMT -5
there is no "dissavantage" all thumpers should run a pumper carb, then pay to get it jetted on a proper dyno. simple, the stock carb isn't all that silly. regards, carl.
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