2000 maxximum performance sleds

We have a special treat for this issue's Dyno Pages report. Usually aftermarket shops get sheepish about divulging dyno runs on their big bore kits. But we were lucky enough to get permission from Maxximum Performance to print the full sheet on the New York company's 787 SRX Big Bore Kit.

We had a version of this kit at last season's Saber Trail Mod Invitational at Old Forge. "The 778 Big Bore SRX we had there had the compression bumped up for a little more performance," explained Maxximum's Bruce Schrader. "We ran high octane race gas in Old Forge, but the base setup from this dyno test was at normal compression levels and we used regular premium pump gas."

The kit involves overboring the consumer's stock SRX cylinders and performing a mild porting job. Once the grinder work is finished, the cylinders go out for replating. They come back ready to be returned to the consumer witha set of machined heads and new pistons. "We made a piston change since Old Forge," said Schrader. "We had been using forged pistons inthe kit, but we found that they would compress and deliver sloppy performance.We have since switched to a more durable cast piston to give our customerspeace of mind. The piston change also took the 778 kit and bumped it upto 787cc."

The kit uses stock pipes and carbs, so that, according to Schrader, "consumers can get the kit, bolt it on and only have to worry about readjusting the jets and clutching before they hit the trail."

A close look at the power and torque lines show that the Maxximum 787 kit follows the same power curve as the stock 700 SRX we dynoed two seasons ago. Of course, that stock sled only made 140.9 hp while the 787 hit an even 165 horsepower.

The 787's torque hits hardest at about 8100 rpm at 106.2 foot pounds. A short 200 rpm later, the engine hits its 165 hp peak. By a strict adherence to the formula in this month's Tech Notes (page 99) we would say this is a peaky engine. But, if you look closer at the numbers, you'll see thatthe torque plateaus over 105 ft/lbs from 7900 to 8200 rpm. Also, the horsepower stays over 163 ponies from 8100 to 8400 rpm. This gives us a much widertarget for clutching and backshifting. The extreme ends of each band areabout 500 rpm apart, which will offer ample torque backup in cornering andsoft snow patches. Remember, this is the same curve profile as the stockSRX, and we know how well that sled performs in the woods.

The Brake Specific Fuel Consump-tion figure tells us that this enginepackage will be very fuel efficient. If the water temp spiked up quickly,we'd be concerned about having the sled jetted too lean, but the numbersall fall within the safe zone. "In testing we've leaned the enginedown so the BSFC was in the .4s on this dyno," said Schrader. "We'revery comfortable with trail riding this sled when it's set to run in theupper .5s and low .6 range. It's a very dependable setup."