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thumpnut

Jetting for TT500

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Can anyone give me jetting specs for a 34mm VM round slide Mikuni for a 1980 TT500? I'm replacing the stock dual throttle cable carb with this one. I know everyone uses the 36 or 38 as the replacement but I'm not looking for more power just simplicity. Also, need a throttle cable to fit a Gunner Gasser and the 34mm Mikuni. Thanks

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:cry: Thumpnut,

Try a posting on thumperpage.com. Lots of vintage TT/XT/SRs there. Got lots of info a few years back when I built and HL500 Replica. I'd use a 36 or 38. Mine ran best with a VM38. Jetting for a 34 should be basically the same. Pilot jet, needle jet, slide cutaway, etc. should be about the same. Main jet will be a little smaller. My notes went with the HL so I can't give you specs.

If that's an old two smoke carb, be prepared to throw away/replace just about every metering circuit inside$$$. They use different needles, needle jets, slide cutaways,air jet, etc. Pilot, main jet are the same style just different numbers. It's usually cheaper, unless you've got a big pile of VM mikuni parts, to find a VM36/38 that came off a TT on ebay or buy a prejetted VM. Try thumperstuff.com. or vft.org (vintage flat track)

Don't know about the cable for a gasser. Good Luck!!! :cry:

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If you are after a reliable turnkey setup then the stock goods are great. Very easy to work on too.

If you are looking for a simple setup that provides good performance then use a 36mm roundslide. The 34 is rather small and I don't think anyone has gone through the hassle of jetting such a small carb. For a 36 or 38 or even a 40 it would be easy to come up with some jetting specs. It would help to know the build of the engine... Airbox? Exhaust? Etc...

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It would help to know what altitude you are jetting for. I'm at 5000 feet and run a 2.5 slide, 180 main 30 pilot and a 159 series nozzle. There are different combinations of nozzles and needles that can be made to work with one another...I recommend a Mikuni tuning manual. Check Ebay for one. They are invaluable and you will learn what changes affect the carb's performance.

Pete

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