Mikuni TM40 flatslide carb with accelerationpump

This carb is just awesome. We ordered it at Paul Ritzen and after a long time of waiting (the supplier in the Netherlands is SLOW) and fitting we mounted it on the KLR650. With a bad jet setting we had some very nice dynoresults. Look for yourself: blue is stock setup, red is TM40 + DAM exhaust + K&N replacement filter.

As you probably noticed the Air/Fuel ratio isn't good, the bike is running lean but that is just a plus. We can add more fuel to it and have more power. As Paul would say: everything can go faster.

We made some more dynoruns to find the best setup. Finally we found it, after 14 runs we got the setup which gave us the best performance. We started with mainjet 165 and ended with 134. (We used the following mainjets 165, 170 (an error analyzing the data), 155, 150, 140, 134, 136, 134)). The pilot jet was stock 17.5 and changed it to 25. The stock gasneedle went to clip position number 5 (richest). The result of this setup is very nice.

As you can see there is something wrong with the A/F ratio, that is caused by the acceleration jet which gives to much fuel at once and empty's the fuel reservoir of the accelerationpump to fast but that is just a minor problem to solve. The overall setup of mainjet, pilotjet and gasneedle is finally found. A little overview of the setup:

Pictures of the TM40-2 installed on the KLR650 

 

Fitting the TM40 on the KLR650 wasn't easy. First we needed to build a spacer so the carb could be positioned more backwards because the bottom end of the carb hitted the electric starter. We needed to cut in the frame so the throttle lever could move freely, but where you cutted away you needed to place a little plate to ensure the strength. The airbox tube was to long so we removed it from the box and modded it so the tube could go deeper into the airbox. This is al what you need to do if you want a Mikuni TM40 carb on the KLR650. It is some work but it is worth doing.