Go Faster Tips from Dynobike
NEWS FLASH, WR400/426 beats 450’s
So now I have your attention... keep reading and you'll find out how
easy it is without spending large amounts of money.
First thing to do is strip down the top end and inspect all the parts.
You're looking for any excessive wear to the conrod, big end, cylinder
bore and valves. To check the conrod remove the piston and look for rough
surface in the small end and piston pin. Put the pin in the small end of
the rod and make sure it does not rock excessively or move up and down.
Now hold the conrod and gently try to feel any up and down movement. Some
side movement is normal but it should not move up and down “at all”, if
it does replace it.
Remove the valves and make sure the sealing surface is not grooved,
if it does or you can feel it with your fingernail replace the valve or
valves.
Now for the good stuff. Fit a high compression Wiseco piston, make sure
you check the piston ring end gap in the cylinder first.
Next is the cylinder head, this is a specialist job so don't try this
on your own because you will stuff it up. Send us your cylinder head and
we'll port and flow test it, cut the valve seats and blend in the valves.
You can then assemble it all using YZ cam timing specs. The end result
is just unbelievable, you won't be able to keep the front wheel on the
ground and 450’S will have a hard time keeping up. FEEL THE DIFFERENCE
| Model |
Wiseco piston kit |
Gaskets |
Strip and assemble |
Port and flow test cyl head |
Total price* |
WR400F
98-00
YZ400F
98-99 |
$235.00
including piston rings, piston pin and circlips |
$140.00
head gasket, base and exhaust gasket, valve guide seals, tensioner gasket |
$265.00
strip, inspect wear, clean and decarbon, assemble set valve clearance
and cam timing |
$350.00
machine head, cut seats and valves and blend, assemble |
$990.00 |
| WR426F
YZ426F |
$255.00
including piston rings, piston pin and circlips |
$140.00
head gasket, base and exhaust gasket, valve guide seals, tensioner gasket |
$265.00
strip, inspect wear, clean and decarbon, assemble set valve clearance
and cam timing |
$350.00
machine head, cut seats and valves and blend, assemble |
$1010.00 |
| WR450
YZ450 |
$235.00
including piston rings, piston pin and circlips |
$140.00
head gasket, base and exhaust gasket, valve guide seals, tensioner gasket |
$265.00
strip, inspect wear, clean and decarbon, assemble set valve clearance
and cam timing |
$350.00
machine head, cut seats and valves and blend, assemble |
$990.00 |
| WR250
YZ250F
00-04 |
$275.00 including
piston rings, piston pin and circlips |
$108.00
head gasket, base and exhaust gasket, valve guide seals, tensioner gasket |
$265.00
strip, inspect wear, clean and decarbon, assemble set valve clearance
and cam timing |
$350.00
machine head, cut seats and valves and blend, assemble |
$998.00 |
* Prices are subject to change without notice
More on motocross and enduro dirtbikes
WR/YZF250 Hotup
WR450 Hotup |
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