Sorry im very new at this, is this good or bad that it is a mc250. My first dirt bike
The MC is essentially the same engine, except it has an aluminum spacer on the right side of the crank where the EC and XC engines have an 8oz "timing weight". This is done to reduce flywheel effect for mx use.
Not that many 4 speeds were installed in the MC250 after 2000, but they were available. A six speed will fit right in the cases.
The 4-speed transmissions were a more widely spaced gearset than the 6-speed, with a spread much like 2nd gear through 6th on the six speed.
Our '99 MC250 4-speed ran the same 93 mph on top as our '99 6-speed MC250, as registered on a Moose P3 enduro computer in the hayfield at the Red River Enduro. At the end of the nearly mile long straight, the 6-speed 250 was a half bike length ahead of the 4-speed 250.
(Messico pipes and the original '96 cdi seemed to allow the bikes to run faster on top than the later models. My '97 EC250 would hit 97mph on the computer with 13/47 gearing.)
I've done several enduros on 4-speed MC models. It took a bit more clutch work than the 6-speed in the tight slick hilly routes.
The EC250 parts will bolt right into your engine. They are essentially the same.
I like 5wt oil in the 43mm WP forks, with a 135mm air gap, measured with the forks collapsed and the springs out. (I right singletrack, not mx, and like forks more plush.)
You can get a parts breakdown on this page. The only real difference in your engine and the '01 and later engines is that the crank bearing setup was changed for 2001. The 2003 EC250 is a good book.
http://www.gasgasmotos.es/en/previous-models/6.html
On the 2000 and earlier models I run 1100cc of oil in the transmission.
On the 2001 and later models, I run 1000cc of oil. This decision was influenced by a dealer meeting tech seminar where the discussion was concerning lubrication of the clutch components. It's never caused me problems.
Most of the bikes in the fleet get Shell Rotella Synthetic 5w40, but my primary ride gets Amsoil 0w40 4-Stroke Synthetic engine oil.
If you are looking for the mud guard that shields the rear shock from the roost of the rear tire, get one for a '99 through 2001 KX250. They are less than $14 (aftermarket parts) at most outlets.
Good Riding and Wrenching to You!
Jim
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Dang its too big to attach. PM me and I will send it to you.
real good info, as this is only fun round the small local track and maby some light enduro/trail so i'm just going to keep the 4 speed, i have read that atf oil is usuable, automatoc transmision oil, as it is omly for gear and clutch. Is the 1% oil in the gas enough, gasgas specs? Previus owner ran a 4% mixture and the is carbon deposits everywere :-(
