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Who has a big bore kit, what brand and how do you like it.

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I am trying to decide if I should big bore a KX 250f. I ride around 4000ft elevation most of the time, but I do trail ride a tad as high as 8000ft. I spend most of my time on the track and ride the vet class with a bunch of 450's. I like the power of the 450, but I am faster and don't get near as tired on the 250. I need more power for the holeshot to Run with the 450's so I am thinking of a big bore. What do you think? Thanks in advance.

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Two Options:

1. The full race treatment = Ignition, Mega-Compression ($$ Race Gas), Cams, Head-work, Jetting, Pipe...Best bet=Pro-Circuit. The results speak for them. You have to ride one of their bikes to believe it. More like a well built 450 than you'd think. Unbelievable "Pull".

I believe Big Gun is using a really good engine guy, also. The ignition is an option that's pretty much only needed on a "Built" motor (In '05...that is).

2. 280 kit. Muzzys, for my money. Still gonna need the Pipe and Jet deal; However, they should have most of that info.

Sub-option: There's a lot of power to be had by simply indexing your motor, bumping compression and getting a good pipe/jetting combo.

Good Luck,

Manny

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Hey Teamgreen,

How are the bottom end charicteristics of the full race preped motor? Have you ridden one? I do trail ride some and would like to maintain low end ridability. I realize I cant have everything, but I guess that is why I was looking into a big bore. I know Carl's cycle in Boise, ID offers one, but Don't know anything about it.

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Indexing the Motor:

1. Precise Timing of Each Cam (i.e...when the valves open and close) to the Piston Stroke and Ignition Timing.

2. Adjusting the Valves "Exactly" as required to meet the 'Correct' spec's.

3. Sometimes includes 'Correcting' the compression ...which can mean having the seats and valves reground/machined and/or machining the Cylinder/Head to the "Perfect" dimensions.

And then there's "Balancing"...

As for the "Power Characteristics"?

More Bottom and Mid...with plenty left on Top.

Manny

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