After a bit of lurking here as a guest and other webpages here (USA) and abroad, I decided to pump my thumper. I wanted a little more feedback from the throttle than the BS40s auto slow roll-on. The Mikuni TM40-6 was a recommended replacement carb for my '05 LS650 from afew other carb stores.

Got a hellofadeal from Powersport Superstore on Amazon on a TM40-6 (almost 1/3 less than a new BS40SS and at last check almost 1/2 less as of 1/6/13).

1) My biggest problem besides finding any info other than an exploded veiw diagram is that the TM is likened to the Mikuni HSR model. Any tech search online always point me to the HSR.

2) My Main pain is the float level adjustment, since after installing the new carb (4X now with a new 2mm increase level), the carb pukes fuel out of the overflow tube on the ground. The HSR Tuning Manual states 18mm float height from the cup base. At last attempt it was at 24mm and still puking at start up.

The needle seat and needle are perfect, but are 3.8 size (largest for the model as shipped), should I drop it down to the 3.2 size or the fuel pump version of 2.2 on my gravity/vac feed system?

Any help is appreacdiated other than suggesting a different carb. I plan on getting a jet kit to adjust for the high desert climate and flow characteristics of the TM carb.

justin_o_guy2 wrote on 01/10/13 at 05:37:38:


I have been lowering the float level 2mm each attempt. My current measurement is now 26mm and on hold.

I waiting for the winter winds to die down so I can mount it again a do a check.