abhaysaraff

Dear Aeromodellers,
My Tiger Trainer 40 GP is over heating after the head was remachined to remove warpage. I agree this must have resulted in increasing compression ratio. But i have added extra gaskets of thickness which is eqivalent to the material relieved.
Now the engine is overheating to the extent of almost seizing. I am lucky in the sence I decided to run it on ground . And when it starts petering down R.P.M. I could stop it and avoid seizing.
Any suggestions or advise will be highly appreciated.
Thanks,
Abhay saraff

Alex7403

I’m no expert, but here what I do:
My motor would seize when on the ground I adjusted the needle valve to max rpm and then fly it and it would over heat in the air and dead stick…
What I did to avoid this – when you reach this max rpm point take the needle valve 2-5 clicks back so it will rum a little bit more rich.

Alex

abhaysaraff

sir,
Did the adjustments, Even went ahead with slow needle adjustments the problem is still persisting.
A fellow modeller has suggested reopening of engine and measuring the head and find out if there is problem with the gaskets addition. Will do this day after tommorrow and post results. thanks for suggestions.
Abhay saraff

MrMotor

Are you having a lubrication problem from your fuel? That is a bushing engine and needs at least 20% oil in your fuel mix. The GP 40 has not been produced in many years, could the engine be worn out? The GP40 was made before Thunder Tiger modernized their factory many years ago.

bigedmustafa

My Feedback: (2)

It sounds like an air leak is causing the engine to run overly lean. This could be caused by a less-than-perfect seal at the cylinder head, a loose or missing cylinder head bolt, a loose backplate or missing backplate bolt, a loose carburetor or carburetor o-ring, or a small crack anywhere along the crank case.

You should carefully examine the engine while it's running for any signs of fuel leaks and/or exhaust residue where you wouldn't normally expect it.

abhaysaraff

Thank you Mr Motor And Mr Musthafa,
I will check and also try the suggestions made by both of you this week end and post the Results.
Thank you for giving the advise.
ABHAY.

abhaysaraff

Sir,
Mr Bigedmusthafa you are right . As per your list I checked everything and finally the troublemaker is found . This is less than perfect fit of cyllinder head. There is a fine leakage
which becomes apperent when the engine reaches operating temperature . A drop of oil starts spraying from the cyllinder head and cyllinder joint. I tried to tighten the head but the leakage
continues and then the engines Starts loosing RPM.
I am now thinking of putting a copper gasket between Head and cyllinder. But would like to have suggestions before I do that So dismantleing and assembling can be done less number of times thereby reducing the risk of damaging the threads as well as bolts.
Thanks for your advise.

Abhay

fiery

My Feedback: (2)

A gasket cut from an aluminium beer can / soda can may be the best?

abhaysaraff

Hi,Mr Fiery,
Thanks for the input. Personaly I thought that if I use copper gasket which is heared red hot and then quenched in water to make copper soft would be ideal.However If your experience
with aluminium is better than copper then I would try cutting aluminium gasket first.

Thanks, Abhay

abhaysaraff

Thank you modellers for your inputs,
The machinists removed almost 20 Thou (inch) of head material and at the time of assembly a gasket of 20mm was added Which increased the comp ratio and therefore leaking head
After replacing with appropriate gasket of aluminium (I adopted the suggestion and changed my of copper to aluminium)
The engine is now running fine. I think these are the engines one should not compare with O.S.
I have couple of both O.S. and T.T. But I think I am more comfortable with O.S.

Thanks everybody,, Abhay

MrMotor

If you are going to compare the two brands, you need to compare engines that are not 15+ years old. Thunder Tiger made great progress after they quit making clones of OS engines many years ago. Todays Thunder Tiger engines are among the finest produced and very consistent in quality.

abhaysaraff

Mr Motor Sir,
Yes you are absolutely right. If the comparison is with new O.S. Some of my friends on the field had difficulty with O.S. L.A and Fl 70 4S recently.
In one case I was asked to dismantle a out of box fl70 because it would not start and on dismantelling we found lot of machining shavings in the crankcase.
I was just thinking about difference between FSR AND SF (O.S.) With GP AND Pro (TT)
All of them are old But Still I like These
Thank you Sir And Happy Landings.

Abhay

bigedmustafa

My Feedback: (2)

I'm very glad to hear that your problem is fixed, abhaysaraff, and that your engine is once again running well!