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xr650r - TM40 or TM42? Also which jets?

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Getting sick of the trouble with the stock carb on my xr650r with idling so am going to lay some money down for a pumper...
Have read lots of threads, but can't seem to find any distinction as to which is better? The tm40 or 42?

Looking to do stage 2 hotcams and eventually an exhaust, not really sure which. Likely an fmf powercore or such.

Also can anybody help with what jets I will need or will the stock ones cover me? Am from the uk roughly 60ft absl.

 

Thanks :)

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I've just picked up a TM42 that someone had purchased for a build and didn't end up going through with. I'm interested to hear people's opinions on the two models...

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I picked up midrange torque along with throttle response when I went to the TM40. Niche Cycle.com has pretty good prices on them. If you get the individual parts of their kit from them instead of their kit , the price is less. I went down two sizes on the main jet from what it came with and that was it. 

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i am thinking of the 42. it has a superior roller bearing slide , so less sticking throttle.

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A slide isn't going to stick if everything is working normally and bearing won't help if it's not , that's what dual cables are for , although a lot of people remove them without any problem.

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well the stock carb sticks under high vacuum. makes it unrideable on the street. known problem with any big thumper. 

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I went with the TM40 from niche cycle as well.

Still haven't nailed the jetting bang on yet. So i cannot comment on fuel mileage since I'm pretty sure its running rich.

The stock Keihin was dialed in awesome. I had to replace the air diaphragm which caused some issues. But I had great throttle response. Started second kick once it was dialed in. Great fuel mileage. Had to really roll on the throttle tho.

The Mikuni woke the beast up. I can launch off ledges. The throttle response is great. I still have to roll on it from the beginning but I think that's more with my jetting being off. Starts first kick, just a couple twists of throttle. I got the extended choke cable. Starts first kick with choke every time.

The reason I got the pumper was I was having trouble with the Keihin. Turns out it was something else entirely and after replacing every part in my Keihin, I was left with the pumper. I would like to dial the Mikuni in to see my fuel range. But if i was to do it again I would make sure its not something else first. The Mikuni ran me around 740 CAD to my door.


Good luck!

 

 

 

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