The plug that came with the engine is decent and it is great for breaking in the motor, I would suggest replacing it with a P6TH before race tuning it.

I used P6TC for breaking in and racing with P7TC This plug give me the best performance
where 1800ft temp 70F 30% nitro fuel 9% oil

Jeff,
Try using a PT6H/C, it will run better than the P7TC, P7TC is too cold for a
.12 motor, it is best for a .21 motor.

Has anyone had one lock up on them? I broke it in properly, ran it thru several tanks after, raced it on a track and then haven't touched it in a couple weeks. I tried to fire it today and it (flywheel) would get stuck. I would loosen it and bump it again. Then it got stuck and I cannot free it. I have removed the plug and am now taking it out of the car. Any suggestions on what it could be or how I should go about checking it over?

Thanks for the help! I am really bumming because for the short time I have ran this, I have really enjoyed it. I will be truly depressed if it is broken.

did you put after run in it?

Chris A.,
Try this, Take off the glow plug, then drop a few drops of after run oil thru the hole to lubricate the piston/sleeve, then using a heat gun or a hair dryer heat up the motor to about 180 degrees then fire it up.

Has anyone broken a lot of springs with this engine. I broke 4 in 6 qualifiers. Then I ground off the bosses that where touching the spring and made 35 minutes with no failure.

Which spring are you pertaining to?

You mean manifold-engine spring? I broke two in last race.. don't know what causing this but hopefully I use two
Sam I tried the P6TC today and the engine rev much better thanks

gearhead13: yes, I used after run. I bet I have not put 12 tanks thru it yet.

Hi Sam! I took the engine out tonight and was able to free the flywheel with my hands. It is still very tight. I hope that is a good thing and nothing else is wrong! I will put a few drops in and turn it over a few times with my starter box before puting it back in. It should fire right up, it is such a consistant engine. If not, I will try the hair dryer trick. Whew!

Thanks for the replies guys!

Bucknuts,

What gearing are you using on your g4s?

In regards to my engine "locking up", I took it out of the car and was able to free the flywheel by hand. It still seemed awefully tight. So I took the head and back plate off. Everything looked/seemed fine. When I put it back together it seemed smoother. Tomorrow I will get it back into the car and try to start it. I will let you know how it goes.

Thanks for the tips!

I think you still may have had some fuel in the engine, that will cause it to lock up!

Hi qcrc
I did exactly that. I sand the collet where it faces the clutch nut and now I can tighten firmly
thanks for your precious tip

Glad that I could help. Hope that you like the motor. I love mine!