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By: Pete Clyne

Many thought that with the introduction of newer and more fancy 4-Stroke quads from Yamaha, Bombardier, and Honda, that the TRX 250R would fall by the wayside. Quite the opposite has become true, with companies doubling their efforts on making faster and better engine kits for the 250R. As a 250R owner, I keep close tabs on engine builders and what they are doing, and one company that constantly comes up with good reviews and comments is LRD Performance Specialties , located in Gresham, Oregon. LRD constantly improves and tests their setups both on the track and on the dyno, always looking for that sometimes small, but important, edge.

O-Ringed CylinderA common setup on the stock OEM 250R cylinder is to install the LA Sleeve 72mm big bore sleeve. This actually equates to 293cc on the stock bore. LRD goes one step further, installing a 227 Hardness sleeve, milling and reshaping the stock head, and porting the cylinder for your type of riding. They also machine O-ring grooves into the cylinder for use with Viton O-rings, which eliminates the need for a head gasket. Leaky head gaskets are a common problem on the 295 kits, and LRD does away with this, while also eliminating the heat barrier caused by a head gasket.   

piston The piston in this kit is a 72mm Wiseco 86' style piston, used in conjunction with a custom spacer plate. For those of you unfamiliar with a 250R engine, the 86' style piston had the piston pin location 5mm lower than the 87-89 piston. Hence, the rod on the 86' was shorter. When using the 86' piston in the later year engines, the use of a spacer plate is needed to prevent the piston from slamming into the head. The piston gets a ceramic coated crown and dry film coated skirts, which helps reduce friction and keep temps down.

Exhaust PortThe porting chosen for this cylinder (generously supplied by Janssen Racing) was LRD's drag racing porting. The compression was setup to use a 50/50 mix of AV Gas (100LL from your local airport) and 93 octane pump gas. Upon kicking this motor over, it seems to have a good 200-210 pounds of compression.

Installation was a bit of a bear, due to the OEM studs being frozen in the bottom end.  You need to take them out to install the longer studs that are needed for the spacer plate. Installation of the piston onto the rod was the same as putting any other piston on..install the pin bearing,Cylinder on Base piston, wrist pin, and circlips. Then the rings were installed, some assembly oil was put onto the piston, rings, and cylinder walls, and the cylinder was installed and torqued to factory specifications. Then the o rings were installed into the cylinder, lubricated, and the head as slid onto the head studs. Use of copper spacer washers is needed underneath the OEM head nuts in order to prevent the nuts from bottoming out on the stud, as the nuts have a closed top. The nuts were then torqued to factory specifications. All of the other components recommended by LRD were then installed, which were a Boyesen Rad Valve, LRD Team A/B Pipe, and a 39mm Keihin PWK.

After letting the silicone on the pipe joints seal overnight, we poured in some AV Gas and fired the motor up to do some break-in heat cycles. Proper break in of a motor is a must. After a few heat cycles, we took the motor for a few short rides, never using more than half throttle. After about a tank and a half of gas, the rings were well seated, and the piston was ready for some serious action.

LRD recommended a 200 main jet due to the cold weather here in Northern Minnesota. I decided that was way too rich, and started with a 192 main, and we eventually ended up at a 175 main to allow the motor to fully rev on topend. After jetting the motor in, we took the quad out for a quick acceleration run down a deserted stretch of bare pavement. This thing hauls! Completed ProjectWhile being a drag racing ported cylinder, it had more than ample low end, while really picking things up in the mid-range and top end. I would have no qualms about riding this motor on the trails, as it only has a slight power loss off the very bottom of the powerband before it hits in the midrange, and pulls all the way up to a high revving topend. This motor has considerably more power than my previous ported motor, plus the added reliability of the O-ringed combustion chamber is a nice thing to help ease the mind. The thing that impressed me the most about this cylinder and kit is its wide, broad powerband. It always seemed to have power on tap, with no traction losing power hit or flat spots.

For those 250R owners that have been thinking about getting a big bore motor, but don't want to shell out all that extra cash for a Pro-X cylinder, this 300 LRD kit is the one for you. Putting out about the same power as a Pro-X 310 cylinder (again, a 293cc on its stock bore) it offers far more performance per dollar. With the O-ringed combustion chamber, all of the problems associated with the big bore resleeves of the stock cylinders are eliminated. This kit is a great way to up the performance level, while still keeping that stock sleeper-like look.

LRD Performance Specialties
200 N.E. Victory Ave #A
Gresham, Oregon 97030
Phone: 503.661.6700

Janssen Racing
Phone: 920.766.3411

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