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Old 10-29-2011, 03:41 PM
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Location: clarksville tennessee
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Originally Posted by mtk View Post
Hey everyone,

I recently acquired a 2002 CR250 that came with a FMF Gnarly pipe and ProCircuit Shorty silencer on it. Since the Gnarly pipe is advertised as a "low end" pipe that, by their own admission, takes away some of the top end hit, I decided to check out some other alternatives.

Thanks to the wonders of Ebay, I've now got an FMF Fatty pipe, Power Core 2 silencer, and Turbine Core 2 silencer to test out on it. I also acquired a ProCircuit Platinum pipe to go with the Shorty silencer. On top of that, I've also got the stock pipe and silencer to play with, if I so choose, but I admit I'm partial to the bling bling of the nickel-plated pipes over the black stocker.

I opened up the carb and the bike was running a 410 main, which explains the very poor top end performance it had with the Gnarly pipe (it was clearly WAY rich on top, judging by all the raw fuel in the pipe), the stock needle, and a 30 slow jet (stock is 32.5), which probably also explains why it didn't foul more spark plugs on me (lean slow jetting and way rich main jetting). I ordered a jet set from Honda (12 different needles, 4 slow jets, and 12 main jets) so I'd have plenty of jets to play with, rather than nickel and dime myself to death buying a few jets at a time and making this process drag out for months. The bike also has V-Force reeds in it.

What I'm looking for is some baseline jetting suggestions for the bike with the FMF Fatty/Power Core 2 and also with the ProCircuit Platinum/Shorty combo. The Turbine Core 2 will only be used when I need a spark arrestor, in all likelyhood. I realize that set-ups vary due to lots of factors, I'm just trying to get a decent starting point and save myself a few iterations.

And yes, I know the hot ticket is probably to get a Keihin PWK carb from a 2000 model, but I've got to beat my head against the wall for a bit with the stocker before I jump ship to the Keihin. I'm stubborn that way.

Thanks for the help.
The 410 main jet and 30 pilot position 2 on the needle is what I am running. VF-3 reeds Gnarly pipe, 49 tooth rear sproket. Fuel pump gas 93 octane at 50:1 Mine runs great. This is the recommended jetting from JD Jetting as well
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