I had an issue yesterday with my GRP it would run great and then it was like someone flipped the switch to off and it dies. I changed plugs, had a pro help me with the tune change fuel and then even pull the engine and put in another GRP it still did it. I ended up changing the tank and fuel line and the problem went away. I prob should have done this first but the line was new and the tank had maybe a gallon on it. You just never know. As far as inconsistent tune the o-rings in the needles do go bad. I have seen fuel pool up and come out of the HSN because of bad o-rings. I have seen the idle screw change while the engine was idling because of bad o-rings. The o-rings on this engine need to be replaced periodically. When the needle turns too easily after the engine is warm, it's time to change the o-rings. I also seal the carb and back plate just as a precaution, never had a prob with it but don't want to either. I seal up every engine before I even start to break it in. Saves the annoying air leak tune chasing. GRP's are a good engine but the o-rings seem to get hard after 4-5 gal and need to be replaced. Same thing with the o-rings in the FLS pipe. When they are hard the pipe leaks and time to replace them.

The head on the grp .21, (non-tuned version) the silver one, looks alot different than others. It looks like a solid piece of aluminum with just some ridges cut around it. Why is it different than others and is it a big deal as far as cooling ? can it be changed or does it need to be ? sorry for all the questions, Im just trying to learn as much about it as possible before I buy it from amain.

it seems if you have a non tuned version ...you cannot put the tuned (orange head on it) the head on the non tuned is fine and you will save money on glow plugs ....awesome motors tuned or non tuned ....check out www.powerhousercperformance.com ......i believe mark still has some non tuned versions with his race port on them for 260.00 i believe frank l up there runs marks motors ...as do i ...they are awesome and for 60 bucks more than amain ...you will get a motor that will perform as well or better than the tuned version .....

any1 have any ideas... i had my grp out this weekend and i did post that it was runnin rich but still hot. i was gettin passed on the straight and i barley could make some of the jumps, some of them not at all.... i ran my dads 8ight after the races and he has his vspec in that has prob 5 gallons or so on it and that thing had 3x as much power and speed as my grp. im going to switch to a p4 plug and test for air leaks. this motor has maybe 2.5 gallons on it, is there a way to test the tank?

i mean does it have compression ? i mean if you are chasing other probs and tuning to your other issues ..its not out of the realm of possibility that your motor doesnt have good compression ...my buddy tuned to the dreaded AE gas tank issue and his was toast in 4 gallons ...im just sayin ....its possible ....but ya air leaks and stuff in the carb or fuel delivery system can cause you some strange probs ...god forbide you have run the motor at high temps ...then your really toasty
on a decent tune mine runs in the 160-190 range on temps ..all types of power to spare all across the board ....and for all you tune to temp ding dongs ...no i dont tune to temp ...im just saying thats what it temps on a good tune ...so shut it

hey guys i am looking at putting tko's in my GRP and was wondering for those who have run them for a while how they are holding up? Thanks!

just put tko's in mine after 1 gallon on the stockies ....hopefully i wont have to answer that question i hope they work well ...they should ..they seem to be the best bearings out there ....i would imagine they would hold up better than stock ...tko says they will

Hey guys where would I get some orings just in case mine go bad. Mine is still basically ne (just over a half a gallon but I would like to have them just to be sure??

http://www.amainhobbies.com/product_...ducts_id/23847

http://www.amainhobbies.com/product_...ducts_id/23854

What size bearing does the tuned take front & rear?

Rear Crank bearing 14 x 25.4 x 6
http://tkocompetitiondev.com/product...roducts_id=157

Front Crank Bearing 7 x 19 x 6
http://tkocompetitiondev.com/product...roducts_id=156

You CAN put the tuned head on the non tuned motor. All you need is the turbo button head, and the orange head bolts right up.

one thing i have worked out now on these mptors is how important clutch set up is my grp i wasnt happy with the bottom end power leading up to jumps out of corners worked on clutch set up and now has all the power i need motor ran awsome at the national titles

i hear Mario Rossi has now left grp so the question is what will the motors be like from now once all the grp tuned ones have gone ???????

Curious, what carb insert you guys running in the tuned .21 for truggy.