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atreiou

Mikuni TM42 on BRP

8 posts in this topic

I need an Information for a Friend of mine.

He want to install a Mikuni TM42 carb on his XR 650R,

but He need to know the code of the needle and the jetting sizes

Because the carb is an HSR (originally thinked for an HD application) but is ever a TM42 carb.. or not ?

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I have put this carburetor (HSR 42) on my bike for a short time and now have the TM40mm on it. I ran the HSR with 140 main, 25 pilot, 1.2 air jet, I went one step down from the needle jet and needle. Same basic setup that I have now on the TM40 27.5 pilot, 1.2 air jet, 140 main, y-4 needle jet, 9OJY-1 needle. The HSR 42 had a little to much of a pump jet. It ran a little wet (didn't burn all the fuel) If I had a cam and the 680 kit, I would go with this caruretor or the 45mm HSR.

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It seems that the HSR 42 is a little big for a stock XR 650R... mhh is not a good news for my friend... :)

thanks for the answers

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You can change the pump jet and make it work. But, you have to run holes in the filter cover, no back fire screen and a header and free flowing muffler would help. Then it will be tunable. My bike is about as free flowing as I can get it with out engine work.

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My Friend have, an "HRC" exhaust (built on HRC schemes on the HRC kit manual), holes in airbox, open air filter and CRD collectors. do you know the number of the pump jet that he need ?

thanks again :)

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No, I didn't change the pump jet because, I went with the TM40. It shure did hit hard with the 42HSR! I get the jets from a Harly shop.

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