A YZ250 RESTORED

 
(1/9/2012)
 
Jay Clark has a knack for scanning the classifieds of his local SoCal paper and browsing Craigslist looking for deals on dirt bikes. His latest find was this 2005 YZ250 two-stroke for the sweet price of $1000. Jay didn’t even have to fire it up to know it was a smokin’ deal, especially when he spotted the Metal Mulisha graphics, and the guy selling it admitted he spent more time drinking beer than riding the bike. The YZ250 hasn’t undergone a radical change in the past seven years. We checked the bike out before Jay went wild with it, and trust us, Jay might have scored a once-in-a-lifetime deal. Jay being Jay, he couldn’t just do the simple stuff like new tires and levers. He went for the heart—the engine and suspension.
The engine ran fine, but as with any used bike, Jay didn’t know how many hours were on it, and with the seller holding a beer and the title, it needed to be inspected. Since he was pulling the cylinder off to replace the piston and rings, the head and cylinder went off to Tom Morgan for some added boost to the already-strong YZ engine.
Tom Morgan (TMR) has many engine specs for the popular YZ250 two-stroke, and for this bike, he used his “long track” outdoor motocross setup that provides more power over the entire rpm range while retaining a wide powerband. In addition to cylinder and head work, TMR offers full blueprinted engines with crankshaft and crankcase modifications, a very popular 265cc, and a 285cc stroker engine (if going bigger than 250cc is your thing). When TMR ported the cylinder, the open port area and shapes were modified for correct flow and optimum power characteristics, and the port chamfers were correctly completed. The port volumes and shapes were also modified for correct velocity. The port heights were checked and adjusted for correct port open timing. Tom says, “Cylinder head configuration on a two-stroke is very important. It requires as much testing as cylinder porting to get it correct, and it is a key item in shaping the power delivery of the engine.” Tom modified the squish angle, the piston to squish clearance was changed and the dome shape was modified. The carburetor, intake manifold and reed valve were matched and modified to improve part-throttle and full-throttle airflow into the engine. The carburetor slide was also modified to alter the cutaway and to optimize the jetting specs. All the engine work, including the carb work, was a very reasonable $549. If you break it down, it was $249 for the cylinder mod; $169 for the head mod; $169 for the carb, manifold and reed mod; and only $35 for the slide mod.
 

THE SWEET SMELL OF TWO-STROKE
With a fresh-looking, seven-year-old bike, we headed out to our favorite tracks. When Jay does up a bike, it is as much about how it looks as how it performs. As people wandered up to our “old” bike in the pits, no one ever guessed it was more than two years old. Besides looking good, the old beater was a rocket! We had our bone-stock 2011 YZ250 on hand to compare back to back with Jay’s, and the difference was very clear. The stocker was strong and smooth, while Jay’s YZ hit hard and pulled stronger all the way through the rpm. We had to dial in a little throttle play just to reduce the jumpy feeling. When we were fresh and the track was loamy, we loved Jay’s hard-hitting YZ; but as we got tired and the tracks got hard and slippery, the stocker was easier to ride. For the aggressive guy who wants a bike to back it up, the engine mods were great. After testing at different altitudes and temperatures, we ended up with a 48 pilot jet, 172 main jet and the needle in the third position.
To give the suspension a more 2012 feel, MB1 did a fork and shock revalve, changing out the old oil and valving it for a fast intermediate rider who likes to moto hard. Faster riders preferred the MB1 setup to stock, praising its ability to absorb huge hits and stay in a straight line over fast rollers.
PATIENCE IS A VIRTUE
For Jay, patience is the key to finding a good used bike. He keeps his emotions out of it and waits for the deal to come to him. If he checks out a bike for a great price and has a funny feeling after talking to the owner, he walks, then runs away, knowing there will be another chance at a great deal. This seven-year-old YZ250 didn’t need all the goodies to go ride, but since Jay only dropped $1000, he felt he could afford to make it a sweet ride. We couldn’t agree more. For nearly the same price as a nice used bike of the same year, Jay’s bike is better. And, he has the benefit of knowing every nut and bolt on it. We still think Jay goes a little crazy with stickers, but that’s why—when he’s out of earshot—we call him “Sticker Jay!” o

CONTACTS
Vertex: www.vertexpistons.com, (515) 270-2302
Cometic Gasket: www.cometic.com, (800) 752-9850
FMF Racing: www.fmfracing.com, (310) 631-4363
CV4: www.cv4.net, (800) 874-1223
MotoTassinari: www.mototassinari
.com, (603) 298-6646
DeCal Works: www.decalmx.com, (815) 784-4000
MX Plastic: www.mxplastics.com, (800) 843-8244
Works Connection: www.works
connection.com, (800) 349-1475
Dunlop Tire: www.dunlopmotorcycle
.com, (800) 845-8378
Renthal: www.renthal.com, (877) 736-8425
Uni: www.unifilter.com       
VP: www.vpracingfuels.com
Moto Seat: www.motoseat.com, (951) 258-5229
MB1: www.mb1suspension.com, (951) 371-5045
TMR YZ250 Two-Stroke: tmm_tmr
@yahoo.com, (949) 421-7112

 

Comments:
Monday, October 01, 2012 10:34:41 AM by sean
so cool
-----------------------------
sean

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WARNING: Much of the action depict­ed in this magazine is potentially dan­gerous. Virtually all of the riders seen in our photos are experienced ex­perts or professionals. Do not at­tempt to duplicate any stunts that are be­yond your own capabilities. Always wear the appropriate safety gear.

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