Engine tuning question

[needinghelp]

Thunder Tiger Pro .21r

I have read all the how to's here on tuning and they are helpful, I'm learning slowly but surely.

I'm trying to tune my Thunder Tiger Pro .21r engine. I changed fuel % and had to go to standard settings to get it fired up.

Problem is the only way i can get it to fire up is with the trim (throttle) open. OF course when it fires up its automaticly trying to drive away because the throttles open. I have tried the tick over screw to no ends.

What should i do? thanks :

 

[Amoeba]

I'll take a stab at it. Someone will come along and correct me if I'm wrong.

Does this happen when only when the engine is cold or even when warm? Once you get it started and let off the throttle does it idle fine with no wheel spin? Check your idle screw gap which should be ~1mm when at neutral throttle and/or brakes applied. I cut up an old credit card to use as a gap guide.

Make sure you're priming the carb with some fuel before starting. It sounds like your LSN is too rich. When you initially start it up your opening the throttle lets in enough air to overcome the too rich setting and start the combustion. When the engine starts sucking in fuel it starts increasing rpms & moves as you're seeing. Leaning your LSN should fix the problem.

 

[needinghelp]

thankyou will look into it

 

[Scrogg]

Your right Amoeba. Once a engine is broken in the factory settings are way too rich to return too. if you change fuels, simply richen the HSN 1/2 turn and run it easy to let the engine adjust to the new fuel for a tank. Then tune it for power on the next tank. The LSN should only require minor tweaks.
Do what he said. Put your LSN back to where it was and turn down your idle speed.

 

[needinghelp]

the problem is i dont know where it was. the engines never been set up "properly" - this car/engine (schumacer xtr) should be capible of wheelys. Its no where near that level.

i can get the engine started then start messing with the LSN or HSN in a carpark, but all it does is wheelspin no matter what i do. so i can't see how its behaving it just spins. i have tried diff tyres.

 

[Amoeba]

Stock settings from the factory are 2 1/2 turns from closed on the HSN and 1/2 turn out from flush on the LSN for your engine.

 

[Scrogg]

If it wheelspins it is the chassis/suspension or tires, not the engine tuning.
If you want it to wheelie raise the ride height up with some preload on the shocks. If there is multiple shock mounts, use the ones that let the arms come down the most. Schumackers are built for high speed. They intentionally set them up to stay on all 4's.

 

[needinghelp]

Thanks for the replys. I'm not a big fan of wheelies. Would just be nice to know its tuned properly so it has the power to perform them.

When you say "from flush" on the lsn. What is this exactly? i think it means so the screw is level with the ring, but i can turn it half or more either way and it's still level. Or is thta just a ball point figure?

thanks again

 

[Amoeba]

Thanks for the replys. I'm not a big fan of wheelies. Would just be nice to know its tuned properly so it has the power to perform them.

When you say "from flush" on the lsn. What is this exactly? i think it means so the screw is level with the ring, but i can turn it half or more either way and it's still level. Or is thta just a ball point figure?

thanks again

ballpark figure. or you could use a ruler or other straight-edged object to check for flush (level with the ring).