ST 3250 transition problems
 

Hello from Italy !!

I have just finished the construction of S2G tow, the TUG, motorized with Supertigre 3250.

With the original muffler, perry pump and mixture 12% oil, 1% nitro I can get (with 18 x 8 prop) 7700 RPM, terrible.

Great problems to take off with the tow alone!! (9,5 kg of model)

Replaced the muffler with a KS 50 tuned pipe tuned at 63 cm, with the same fuel, pump and propeller, I obtained a fantastic power. 9400 turns and towing of glider 12 Kg and 5,5 mt.

Only a problem now.

Full throttle - No problem.
Idle - 1900/2000 rpm for hours.

Half throttle - Haaarrrrgggg. Smokes, too rich, a real disaster.

I heard abount replacing the carburetor with a OS 7, to turn some degrees the spaybar, take a trip to Luordes......

Someone has good ideas?

Thanks to all Denis

ST 3250 transition problems
 

Denis,

Usually, if the midrange of the engine is too rich, then the idle mixture will need to be leaned a bit. This will require you to raise the idle RPM a bit and reset the high-speed needle. You should be able to eventually get an adjustment that will work nicely.

Don't worry about raising the idle RPM a bit. The idle RPM you're getting would be considered on the extrememly low side. We normally idle the engine at about 2,200 RPM or so. This insures a good transition.