I have a new .28 promo kit. Any suggestions on carb restrictor size as I want to break this engine in soon. I hear this thing is a beast so I want to tame it down a little and get better run time

probaly a 6 or 6.5

whats a good pipe to run with the grp .21 offroad buggy engine (non-tuned). Im looking to buy my first engine and this one is on sale at amain for $199 which is at the top of my price range. it is a 5 port engine. any help will be appreciated. would any of the jammin jp pipes work ?

Seems as though the Dynamite 053 is the favorite on that engine.

thanks for the advice on which pipe to get. you are the second person on rctech that said the same thing about the grp and dynamite 053 combo. thats what im gonna go with for now. i didnt want to spend too much on the combo since it will be my first nitro build. Ive ran electric for a couple of years but have got a little bored with the brushless and lipo thing. no maintenance is nice when you run 2 or 3 classes but its time for a change. gonna run 1/8 scale nitro for a while, thanks !

The GRP 2053 will give you much better runtime if that's more important to you. It also costs twice what the 053 does.

Any1 ever have there GRP not hold a tune during a race? motor ran fine the first 2 qualifiers and in the 20 min. main the tune was all over the place. one lap it would be fat as heck and then the next would be lean and back-and-forth thru out the race. temp at the end of the race was fine 175Fish, no obvious leakage anywhere on the motor. OS P3, GRP 2053 pipe, nitrotane fuel, motor idles fine, theres really good pinch, and motr has about 3 gallons to the best of my knowledge (bought used). i ran the motor a couple weeks without fault, so I believe it should be something that happen recently. any1 have any suggestions on where to look for the problem first?

there are plenty of places on the track to clear out the motor so i don't know what the deal is...

im still researching the grp engines and will most likely go with the grp .21 non tuned engine because it will be my first engine. I do have some concern though with the difference in price with the grp standard plugs. why so much higher than others ? they are $14.49 at amain.

hard to say ...sounds like an air leak in the fuel system or on the carb ...just my .02

just run od 99-97 plugs or o.s. standard plugs ...the grp plugs are junk ...most every one will tell you the one that came in there motor new didnt work ....dont spend the money on the grp plugs ..but great motors .....contact mark smith at www.powerhousercperformance.com
he has some standard grp's with his race port on them for 260.00 they are great motors and priced right

McCoy MC-9 plugs have been very good to me over may years. My grp likes them too.

I'm thinking the fuel pick up inside the tank may have cracked. Pressure line may have been getting pinched or kinked once in a while or even the fuel line. Could be a plug problem. Pipe stinger getting partialy blocked by the body or something else occasionally. Make sure the carb is tight. Could also be a linkage or servo problem.
Just a few things to check out.

thanks for the input guys. i will be chckn those things next maint. session. the thing that boggles me is the goin fat part. same needle settings, from earlier, and the motor goes fatty on me? really fat, not just a lil. i can understand fuel line leaks, but wouldn't that cause the motor to go lean? when I said lean in my first post, i should have said it was more normal than anything, it was just fast again like normal. probally felt lean cause it was goin way faster than from when i was trying to race with a fat motor (hope that makes sense).

you know now that you say that again ....check the needle o-rings they are probably worn and are self adjusting ...when they get worn out they can allow the needle to adjust itself :nod:

I was with Stipres yesterday, and helped tune it a bit. I have to say that I was boggled also. I have some experience tuning the the GRP since I ran one the majority of last season.

We had it running good during qual's. When it came to the main (even during warm up) it sounded rich going down the straight. Leaned it out (HSN) just before the start, and sounded good the first couple times passing pit lane. The rest of the 20 minutes, it was inconsistent ever pass. I could hear it building up around the track, then by the straight, it would be loaded with fuel, then sound great the next lap or so... then just to hear it building again, then boggy down the straight. After 20 minutes, came in at 178ish. Weird!

All good ideas. He will have to check those things, and seal the engine. It may juts come down to a bad plug or something simple like that. I have had brand new P3's be faulty. We will see.