Be there done that (reset my WR400f's and a buddies WR426F's exhaust cam to YZ timing and loved it)
My WR450F '03 was left stock with regard to YZ-cam or timing change because
I didn't want to purchase a YZ cam nor did I want to loose e-startability.
Now I've got me a 2012 WR450F EFI and am wondering which of the zillion posts on that topic I should believe.
For instance when someone claims "a 2006 YZ450 cam is the best one for any modely year WR450"
he might be correct THEN, but was in fact referring only to non EFI engines.
So what is the current - 2015 - take on which YZ cam "works"
(e.g. doesn't kill the engine, the e-Start- ability, and adds power)
in 2012/13/14 WR450F engines?
The chain pitch is identical on all 450 (2003-2014) so basically that is no issue.
WR generations deducted from intake cam part nubmers;
- WR generation 03 - 05 intake 5TA-12170-00-00 ex 5TJ-12180-10-00
as the intake cam is identical on all WR450s AND YZ450s from 03 till 05
the YZ exhaust cams outght be interchangable
-WR generation 06 intake intake 5TA-12170-10-00 ex 5TJ-12180-20-00
only for 2006 WR and YZ
YZ06 in 5TA-12170-10-00 ex 5TA-12180-10-00
- WR generation 07 - 13 intake 5TJ-12170-00-00 ex 5TJ-121800-20-00
here the YZs do differ even in the intake cam:
YZ07 in 5TA-12170-10-00 ex 5TA-12180-10-00 WR ex 5TJ-12180-30-00
YZ08 in 2S2-12170-00-00 ex 2s2-12180-00-00 WR ex 5TJ-12180-30-00
YZ09 in 2S2-12170-00-00 ex 2s2-12180-00-00 WR ex 5TJ-12180-30-00
from here on YZ with EFI + reversed cylinder
YZ10 in 33D-12170-00-00 ex 33D-12180-00-00
YZ11 in 33D-12170-00-00 ex 33D-12180-00-00 WR ex 5TJ-12180-30-00
YZ12 in 33D-12170-00-00 ex 33D-12180-00-00 WR ex 5TJ-12180-40-00
Please respond IF your ACTUALLY DID THE CHANGE, and do specify whch YZ cams you've tested.
5TJ is "WR specific" modification of 5TA YZ part.
the '06 ex cam with -20- suffix brigdes from pre-07 to 07-13 generation
While tinkering with the ~300€ GYTR Power tuner might be fun and have nocticable effect,too,
I strongly would like fix the "cam issuse" first.
The original '98 engine was a YZ MX attac weapon that was deliberately detuned for WR usage by:
- CDI rev limiter down from 11500 to 10500 rpms
- higher cylinder foot gasket to reduce compression ratio
- more flywheel weight for low rpm tractability, and less flame out stalling
- and advanced (e.g. earlier!) exhaust valve open phase to beeld off power!
Which means the early WRs did deliberaytely blow some power into the exhaust (hence the red glow) instead of turning it into mechanical work.
In '99 there were people that upon comparison eagerly went back to glowing-header WR timing as they didn't like the YZ power.
Personally I was trilled at getting power for free w/o sacrificing off-road low end tractability and lovee my WRYZ400F as did my buddy love his YZ-timed WR4236F
Edited by WRF-Rowdy, May 02, 2015 - 07:00 AM.