I have an engine that slowly increases rpms when going from low to high throttle settings. There isn't any stumbling or anything like that. It just slowly but steadily increases in rpm. The engine starts and runs fine. It is a Super Tigre GS 40, with about a half gallon or more fuel through.

Once it gets to full throttle, does it run with good RPM's?

this is usually due to the low end needle valve. do the pinch test and see whether it is lean or rich, and go from there. search for pinch test and you'll find out how to do it.

If you can CAREFULLY do the pinch test while it is trying to accelerate, this can tell you a lot too. PLEASE be careful during pinch tests.[:@][&o][sm=cry_smile.gif]

Yes it runs with good rpms at full throttle.

I will try the pinch test.

Thanks for the help everyone!

Did the pinch test while accelerating and it accelerated right up like it should.

Yup, if pinching it causes it to accelerate like it should, then the low end is too rich.

Someone may have adjusted the low end idle too far in an attempt to cure transition problems.

The SuperTigres are notorious for mid range problems, that often can be fixed by adjusting the mid range...

( Yes you CAN adjust the mid range on most SuperTigre engines seperately. )

Check the SuperTigre faq pages for infor on this.

Opjose, Thanks a lot for your help. I really appreciate it. The low end needle is still where it was from the factory. I will get another half gallon of fuel through it before I make any adjustments though.

Thanks for everyones help!

Ninety % of the engines I have come across and observed do not have the proper low needle valve setting as set at factory. As one major example the Magnum 52 XLS low speed needle comes from the factory at about 2 1/2 turns open. The final setting on these engines turns out to be between 3/8 and 3/4 turn open on the low needle. Please don't take any setting that someone else has set as being correct. You will have to learn how to set up a carburetor for each and every engine you come across. They are all different. If you will Email me direct I will lead you to an excelent write up on tuning engines. [email protected]