My chipper is having a bad day..... When you try to start it, it will turn over, but then it runs really slow, backfires black smoke, then turns off. I don't know how to adjust the carborator (I confess that I have been turning the little screws). Could this be the problem. I checked the gas and the carborator, both are clean, no gunk, also air filter is new. What could be causing this and how do I fix it?

J Godfrey with lots of hurricane depris to get rid of..., November 2005

does some1 have an extra idleing screw? if you do e-mail me at Fatback_pimp12@yahoo.com my idle screw fell off my go-kart carb, which is the 9HP HM-90 and plz i you have 1 or an extra, i will like it . i will buy it if you want me too.

Daniel, May 2006

OK My reference says it's a Tecumseh HM90 engine.
There should be 2 adjustment screws on the carb. The main mixture screw is on the bottom of the float bowl, and the idle mixture screw is on the side of the carb.
Turn both screws in until they just seat, not too tight or you'll ruin the needles! Then back them both out 1-1/2 turns. Start the engine and let it warm up for at least 3 minutes. Start with the main mixture screw. (Bottom of the float bowl) With the throttle set on high, slowly turn the main screw in until the engine starts to run rough, Then slowly turn it out, counting the turns, until it starts to run rough again. Then turn it back in half way between the lean and rich settings.
Now set the throttle on low, and repete the above, only this time turning the idle mixture screw on the side of the carb.
That should have it.

Rick, November 2005

The Engine number is 143-959001 and it is dated Jan 2, 2001. I don't see a type number.

J Godfrey, November 2005

Give me the engine Model and Type numbers that are stamped into the blower housing, and I can tell you how to adjust the carb.

Rick, November 2005