I've Got a 426

Yamaha once made YZ and WR models designated 426 from 2000-2002.
That's a nice, well-rounded figure, eh?
It is catchy-sounding, and is probably why it was used.

It's Saturn's Day morning, and this past week each morning before jerk, I spent time checking the WR-250FP valve clearances (they were just fine and dandy and, in fact, I believe measured at the same specs. as they were when I first checked them a year ago) as well as retarded the exhaust cam one tooth, giving the bike what guys on the In-Toe-Net call "YZ timing".

This means the WR comes with the exhaust camshaft advanced a tooth compared to the cam timing of the 2002 YZ-250FP, the bike my 2002 WR-250FP is based on.
Why?
Opinions vary a bit, but I believe (and nobody from the Yamaha factory in Japan is sitting me down to explain the whys) it's to do with reducing exhaust emissions by advancing the WR exhaust cam a tooth in order to have the exhaust valves close sooner, reduce valve overlap (when both intake and exhaust valves are slightly open at the same time), and reduce those exhaust nasties that are killing all the birds I ride past, no matter how far away they are.

The reason the WR gets subjected to tougher EPA regulations is because the bike is sold with intent of being used on public lands open to legal off-road riding, where the YZ is sold in a closed-course-use-only state (like a local motocross track that's privately owned).
The side effect of this EPA tuning is less power.
Now, that's not anything new, is it?

So, tomorrow's Pachaug enduro loop ride will be the real acid test to see just how I like this new setup.

I took the bike for a 2-mile putt up the street before jerk yesterday morning just to ensure that all was well after putting the bike back together, and I immediately could tell the bike does indeed have more power, pulls stronger, and pulls through the revs with more force.
Easily noticeable, so there's no question the bike runs stronger like this.
The experiment is to see if low-end torque (especially way down just above idle) is effected and to see how I get along with it in the tricky, ugly, tight sections of the rocky Pachaug loop, of which there are more than a few along the way.

Stay tuned.

-John