the .25 i think would be in between the .21 and .28, might be a little easier to control then the .28 but give you more bottom then the .21, i dont think people are realistic with there fuel consumption numbers, i could get barely get around 10 mins on my grp tuned in race conditions, now if i was practicing it would easily get that 12-14 minute run time, im sure the people stating that they can get 10 mins out of a .28 are not going by racing run time, they are going off of what they get for run time when they time it in practice

The OS plug will fit and work fine, O'Donnell I am pretty sure will not. Had someone ask me why their engine was leaking fuel last weekend by the glow plug and they were using an O'Donnell brand turbo plug.

whats a good pipe for the tuned .21 grp?? i was planning on breakin my motor in with the supplied grp plug number 4 then switching to a os p3. but i need a pipe for it.

At the recommendation of someone else I bought and found that the Thunder Tiger 2035 worked well. I tried the JP-1, it didn't hit power band on the bottom side like I thought it would.

I didn't think you were going to skimp on the plug. In the nitro pit thread you said " I dont skip on the details. Ill spend the extra dough and ill use the grp plugs." Funny how 5 bucks will add up quickly. That plug that came with it is way too cold for this time of year toss it and run an OS P3 and never look back.

Those that have leaks must of had defective plugs or head button is all I can think.

Novarossi and OD plugs will not work.

Did you get the 2053 in the promo kit? You might like it in Buggy.

2035 of nova 9853 is what i found worked the best on the grp,i also used the os p3 for the glow plug, i found the grp plugs to be unreliable

i did say that, i asked many people and they said that i would have no problem runnin the os plug, the only issue i had was leaks from the plug, but if there were no problems i would like to save 7 bucks on a plug lol. and no i didnt get the promo kit i got a hell of a deal for the grp. and i was told to run the grp 4 for break in and then once break in is over switch plugs. How much is it for the grp promo exhaust

i wouldnt waste the money on the grp pipe, mine came with it i ran it for around a month and wasnt really happy with the engine, once i switched to the 2035 p3 and 7mm restrictor the motor really started to work well, pulled real well from the bottom to the top

They go for like $80.00 new. I have a used one listed on eBay right now. Had I known a local guy was in the market for one I'd given you a deal on it. It's item# 190273301826. Check it out. It might go for cheap. If you win I can take it to SRS this weekend or you could swing by my place and pick it up.

I didn't like it for Truggy.

I don't know why you wouldn't want to break in an engine on the plug you intend to use. But if that is what you are set on go for it...

it would be easier to break in with the os p3 plug, i am with desert bird i would just start with the os and stay with it

hey bro ...was just on the the phone with alan burton ...he said to check your post on the possibility that o.d. plugs dont work in this engine ...i had a question for ya ....

on the guys motor that you checked out that was leaking ....do you know what kind of plugs he ran before the odonnels ? because it seems if you run an o.s. plug then try to change to an odonells plug it will piss fuel out of there .....that i have seen first hand ...but it seems if you go with the odonells plug straight off ...it does not ...thanks man

I think I've read early on in this thread that OD and Novarossi plugs have a different tapper. But, it was proven by a tool and die guy that the tapper of a OS is excatly the same as GRP, but is ever so slightly longer going into the combustion chamber.

Search P3 and read for yourself.

no offense ..but ive read the whole thread...and if you read it you will find as many people had good luck with o.d. plugs as well as o.s. plugs ...but that the problem comes into play (i think ) when you swap from o.s. to o.d.
nothing personal against o.s. plugs ...i just have never had good luck with them in any motor ....but i know plenty of people who do .....i think alot of the problem with "the glowplug issue" and grp motors came from swapping back and fourth ....or well thats the way it seems when you read the thread ....i will know for sure this weekend ...as im breaking mine in .....with o.d. plugs ....or well unless they dont work .....

Well, I would guess that the change in plugs and subsequent leakage would be due to a tapper and length issue between plugs. I would only trust that OS has the same tapper as GRP, based on the measurements proven in this thread. No one, that I recall, has proven an OD plug to fit the same tapper or length. Maybe I just don't remember correctly, but I thought Novirossi and OD were interchangable, and that novirossi didn't fit GRP head period. I could be wrong, it's been 5 months since i've researched. So please do not take my word as gold, and feel free to correct me if i'm wrong. Hell, running that P3 is probably why my GRP had a sucky bottom in my truggy.