This engine package was developed by JGR’s testing staff
with the help of a dyno. This bike hauls the mail.
To adjust the height of the typical subframe it would need to
be cut. JGR sells a subframe that offers 10mm of adjustment.
JGR’s adjustable shock linkage lowers the rear of the bike
and stiffens the initial part of the stroke.
provide a performance advantage—were left off. Instead,
a true-to-life race-centric YZ250F was the objective, and
JGR hit its target. Below are the primary areas of focus
that led to a masterful machine capable of winning the
most prestigious Amateur race this side of Nanyang.
ENGINE: JGR developed its YZ250F engine package
via the efforts of its testing staff and a dynamometer to
determine the best profile. The goal was to maintain the
same engine characteristics of the stock YZ250F (
excellent bottom-end hit and strong overall power) and to
avoid compromising any of the bike’s best traits.
JGR installed its own cams and piston. They also
ported the cylinder head using in-house specifications.
They rim-finished the crank and transmission for greater
durability and less friction.
Rim finishing is a chemical process involving a treatment that makes the carbides in the metal stand up. If
you looked through a microscope at the material, the
carbides would look like a field of grass. Once treated,
the metal part is placed in a media and vibrated until
the carbides are knocked down. The result is a hard
outer layer that has a polished sheen. Rim finishing is
advantageous on engine internals, where decreasing drag
is pivotal to improving performance. JGR also uses rim
finishing on fork springs in order to lessen friction and oil
HOW MUCH DOES THE JGR-TUNED
YZ250F ENGINE COST? THE TOTAL
BILL WAS IN THE NEIGHBORHOOD
OF $6500. THAT PRICE IS PROBABLY
TOO STEEP FOR THE WEEKEND
WARRIOR, BUT IT’S THE COST OF
DOING BUSINESS IN THE HIGHLY
COMPETITIVE AMATEUR RANKS.
GYTR, Yamaha’s in-house aftermarket company,
provides components for the JGR race bikes, so it was
natural that JGR would utilize GYTR clutch components.
In fact, most of the parts on the JGR YZ250F came
from companies that sponsor JGR’s professional race
effort. Those companies include FMF Racing (Factory 4.1
exhaust system), Carrillo (rod) and Xceldyne (titanium
valves, valve springs, titanium keepers and locks). The
only difference was the Vortex ignition (the team is
sponsored by GET). In our opinion the Vortex is less
confusing to dial in than the GET black box, so we were
happy to see the Vortex on the JGR YZ250F.
How much does the JGR-tuned YZ250F engine cost?
With the Vortex ignition, FMF exhaust, complete clutch,
engine parts, labor and modifications, the total bill was
in the neighborhood of $6500. That price is probably too
steep for the weekend warrior, but it’s the cost of doing
business in the highly competitive Amateur ranks. JGR
claimed a 5-horsepower increase over the stock YZ250F
powerplant throughout the range, and we’d have to
agree. Off-idle, the Yamaha sparked to life in a similar
manner to the stock profile, and the rpm quickly climbed
into the midrange. We could pull the 13/49 gearing,
although adding a tooth to the rear sprocket would have
helped. The JGR YZ250F engine wasn’t as impressive as
the engines found on top-tier professional 250 race team
bikes, but it never claimed to be. For $6500 you’ll have
the satisfaction of knowing that you have the fastest
YZ250F on the track—unless Jeremy Martin or Cooper
Webb crashes the party.
SUSPENSION: What do you get when handing over
$3500 and your Yamaha YZ250F suspension to JGR?