Nothing wrong at all with it, wish I had done that before I went twisting on them.... I searched GRP with no luck is the only reason I asked.

Thanks for posting those! Much appreciated.

Yea man no probs im like you hate trying to find out things later on if i ever have a tuning prob i always like to go back to stock and start again always works for me

How you finding ya GRP how dose she like to run i know me Ninja loves it at about 5 1/2 on the LSN and about 3 1/2 in the high and screams, always temps after a 10min Q at about 120c (248F) thats running 25%Nitro and 12% oil (10%syn & 2% Cast)running a Ninja C6 plug idels all day long and plug last for a few club meets to so hope me new GRP is just as easy to tune and run im hearing about all this flame out issues just want me new engine to run as good as me last she's been a dream coming from Novarossi's which gave me nothing but headaces

My GRP is set exactly what your Ninja liked 5 1/2 LSN 3 1/2 HSN +/- and hour or two. I find I only need small adjustments no more than 3 hrs. I have never had a flame out. My problem is I start temping low as the night goes on, 190ish, running a OS P3 plug in hot ass Arizona. I then start leaning it out to get the temp up and put her into a lean bog. I'm running that ultra hot plug to open up the tuning window, not sure my logic is the best on that, but it's been working; except for how quick I can lean bog when leaning it out.

190 is not bad the last race i was at the pros motors were coming off of a 15 min run at 160

Yeah, next race I'm not going to twist the screws if smoke is good and performance rocks, but temps seem low. My lowest temp was 186, and am concerned that the cooler temp is not good for conrod life. But I also hear this is a cool running motor, so I should probably not try to fix what ain't broke, but I am learning.

Those poor motors are going to freeze to death. Lean it out.

One thing i noticed with the grp is when you temp it you have to temp it immediately after the run, the engine will cool significantly cause of the huge head, the temp will drop greatly even in a short time like the walk from the drivers stand to the pits.

my grp likes to run around 230, thats when it gets around 11-12 min run times, i have been running the associated pipe with 6.5 restrictor and p3 plug, really seemed to wake the engine up

Looks like GRP engine users are happy using the OS P3 plugs.

1/2 gallon and the bearings are making noise.....? What are the bearing sizes? I want to get some TKOs for it.

Front: 7 x 19 x 6mm

Rear: 14 x 25.4 x 6mm

Are these the same engine as we can get in the US? The picture on the 21 looks correct, but if you look at the GRP 28 on that site, it has a smaller cooling head and the wrong header pictured. So either there are different versions internationally, or they have knock off 28's.

I would second that about the OS P3 plugs. After reading an earlier page on this thread, I was reluctant to try anything other than the GRP plug, but I gave the OS P3 a try and it works great. I don't have any sealing problems, and it seems to run better all around, from idle all the way up to WOT. I have also run about half a gallon through it and haven't had to change the plug. Tuning was never really a problem, but hasn't become one either with the use of this plug.

Has anyone tried the non-tuned GRP? How are they?

Desertbird - Run the motor anywhere between 175-195. As someone already pointed out they have a massive cooling head. Anything too much hotter than that and its too much IMO...

I also run the GRP at the Pit and I always try and run it around 180.

You may want to try the GRP 5 again or try a ODonnell 97T.