Mikuni pumper TM40 fitting. The story so far.....

Hi All

I fitted the new Mikuni TM40 today. This was made easy as I had the airbox out to fit the new rear shock springs. But basically it just went on as per the oem carb. One thing that bugged me was the carb doesn’t seem to push all the way on the inlet rubber. This seems to be due to the little sticking out bit on the inlet rubber that ensures you have your carb upright.

The other issue when fitting these carbs is throttle cables. I'm still not sure if my XR has an oem throttle assemble on or an aftermarket one? Anyway, there is a lot of adjustment at both the carb end and the twist grip assembly. So I was able to take the slack out of the cable and get it working ok. I am not too please with this though. I need to measure my cable and get one made up with an outer cable about 15-20mm longer at a rough guess. More on this once I've actually measured the cable. So please, no one go out and order a cable based on this guesstimate!

I haven't been able to track down any jetting settings for this carb for an uncorked XR600. Which is surprising, as it’s supposed to be a popular upgrade? It came jetted for a standard Xr600, I think. This meant it had a 130main jet in. As my bike has had the snorkel removed and no side cover at al on the airbox, plus a slip on race can, I guess this needed changing. I stuck a 135 in there and gave it a couple of kicks, but it didn’t fire up at all. It may well have done but I only had a pair of training shoes on and my foot slipped off once, as it’s very wet out. I decided to quit at that point, as I didn’t want to smash my ankle. Plus it was getting (very) dark. I'm cleaning and re oiling the air filter ready for the morning and will try again then. Tonight I shall be searching the web for settings for the carb, which will hopefully make life easier. There's nothing worse than guess work on jetting with a kick-start only big thumper!! Is anyone on friendly terms with any of the staff at XRsonly.com? Apparently they know and send out these carbs with appropriate settings for your bike if you buy one from them. If anyone does know any of the staff, perhaps you could try and find out their recommended settings for a bike with my mods. I'd sure appreciate that!!



To be continued......

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