Want to make a fast bike go faster? The WR450 in this example was an 03 model all stock other than a slip on muffler.
On these bigger bikes itís very import that you make sure the crank will stand up to the work load, if in doubt rebuild the bottom end and you wonít have to worry. So having checked that, remove the stock piston and replace it with a Wiseco high comp forged piston.
Give the bore a very light hone and carefully fit the new piston in the barrel... easier said than done.
The tricky bitís the head, like the 250 itís a fine line between success and total failure so we spend a bit of time carefully porting and flow testing to ensure it doesnít become scrap metal.
Once weíve got what weíre looking for, the seats are cut and valves are seated and the whole thing is assembled. At this stage if youíre the competitive type measure up the clearance between piston, valves and head, if there is sufficient clearance you can squeeze some more compression into it by removing the middle section of the gasket. I donít recommend this unless you have rebuilt the bottom end or itís a new bike. After some tuning on the dyno hereís the result: 52hp.
What it costs*:
Wiseco piston kit $190.00
Port and flow head $395.00
Strip and assemble $295.00
Dyno and tune $195.00
* Prices are subject to change without notice
Article on WR450 Engine Rebuild
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