Engine tuning Question.. idle
 

I just got out my 1/8 buggy (my only nitro model) after about two years on the shelf. It's a Thunder Tiger .21 Pro engine.

I noticed it acts funny at idle. When I let off the throttle and let it idle, it idles nice and low for about 2 seconds and then revs up some... and idles higher. Otherwise it runs fine... except I had it running rich on the high speed needle, maybe too rich.

Is it too lean on the low speed needle? I don't recall adjusting this needle before.

Thanks

RE: Engine tuning Question.. idle
 

I know what your problem is but I won't tell you how to adjust your carb. I think its best for you to learn by experimenting a little to get it set just right.

note where your low end needle setting is and make a small adjustment in one direction. If problem gets worse then adjust in the other direction. Don't be afraid to make multiple adjustments in the direction that yields the improved performance you seak. Be patient and take your time. I have had some very troublesome engines and carbs that were very finnicky and took as many as a dozen adjustments to dial the carb in.

Good luck, you'll do fine.

PS Remember low end needle affects idle and transition to full throttle. It is generally effective at 1/2 throttle and below operation. High end needle affects 1/2 throttle to wide open throttle and is adjusted at wide open throttle to give a slightly rich mixture so engine doesn't overheat.

RE: Engine tuning Question.. idle
 

Ok, you don't have to answer of course. Obviously I can keep playing with it and learn that way. But that DOES kinda defeat the purpose of a public forum like this, does it not?

The reason I asked is that last time I ran the car, I don't recall it doing this, and I understand that the low speed needle is normally left alone once the engine is initially tuned.

This engine does seem very finicky to keep in tune on the high speed needle.

Also I asked because when I ran the car, I kinda snapped a front arm in two and so my runtime and experimenting are on hold for now.

I probably should toss the .21 and put in a brushless electric setup, right? That's the plan eventually....