i tried a tm 45 on my pred last week and started out with the same jetting as i had with my stock carb and it ran way too rich. i then dropt it down to a 160 and it ran better but it seemed a little dead on the top end. my question is would a 150 be to lean on a tm 45 or about right. how much more of a diffrence is there in jetting between the to carbs or is there something wrong with the tm 45. i just dont want to mess anything up and want it done right. thanks for the info.

 

I'm not familiar with your specific carb, but chances are it's rich in the pilot and needle jet circuits. You need to get these sorted out before you move on to tuning the main jet. The main jet will only control 3/4 throttle and greater. If you notice a loss of power on the top end after going down in the size of the main jet, you're probably too lean on your main jet now. If you have an interchangable needle jet (not to be confused with the jet needle), you may need to go down in needle jet size(s). Possibly the pilot jet is too big too.

Is this the Mikuni TM series? If it is, these carbs are intended for two cycles and would be jetted real rich for a four cycle. If this is a pumper carb, they are intended for four cycles. If this is the HSR45, you will need to go down in a couple of sizes on the needle jet. Why such a big carb on a 500?