What kind of problems am I going to have if install a TT91 4c in the inverted position? Will it be a bear to start? Will I have to set up an auto glow igniter for low thottle operation?


Jawsmon

my experience with inverted four strokes you wont need a glow driver only on two strokes. with yours you should have no problems a thunder tiger. starting will be no problem if tuned properly

I don't think 4 strokes are as sensitive to fuel tank position as 2 strokes. I may be wrong it just seems to be the case for me. I've never had any problems with 4 strokes mounted inverted.

Because the glow plug isn't directly on the bottom as in most 2strokes, the 4strokes don't tend to be as problematic inverted. Still, use a good plug (OS F) and the most important item to ensure success is PROPER TANK PLACEMENT!

The tank centerline should be about 1/4" BELOW the carb centerline. Get as close as you can to that and you can likely adjust the richness out. Too high and you will always need glowheat if you ever expect a reasonable idle.

I have only seen one TT .91 at the field and it was mounted at about 8 O'Clock in one model and completely inverted in its second model. It ran absolutely superbly in either position once the idle mixture was leaned to optimum.

This particular example was a very impressive runner indeed. If they were all like this one (they may or may not - I just haven't seen enough of them to verify), I would recommend the TT .91 in an instant.

I had one give me fits in the 8 o clock position. The glow plug would be completly full of oil. Ran fine completly inverted. Got a lot better after it broke in, but still had to use a hot plug and no castor. I suspect the ring gap was on left side which would allow the oil drip and blow past more easily. Only engine that gave me trouble like this, but it was a good runner right side up.