I have a 99 XR250. It has a white brothers
e-series pipe,and McCord's pulse charged
intake system. And it rips. I highly recommend it. A friend had this bike for sale
and I rode and liked enough that I bought it.
Im a woods rider and I have always had
MX 250's, 3 CR's and 1 KX. I don't think you will be disappointed.
the pulse charge is simply AWESOME!! I rode someone's bike that has one and it was unbelievable(on an XR250). It was for sale and another friend(easily a fast B-Class/possibly an A-Class Harescrambler) bought it to replace his '97KX-250.
The bike will pull the front end up at will, something most XR250's have a problem with, yet it revs out very well. What ever it does, it works.
Wolf - Maybe I can shed a dim bit of light. Based on lots of previous experience with XR6s and having worked with Eric Gorr on the original patent US04457267 for a pulse setup ( http://www.delphion.com/details?pn=US04457267__ ) I would lean toward the pumper carb. This is not to say there isn't potential value in a pulse system (there is), it's more a matter of bang for the buck on a 400 is going to lean heavily towards a pumper. Just don't go too big on the carb
"If you live a long time and pay attention, you'll know a whole bunch of useful things"
- Gordon Jennings
I INSTALLED McCORD'S ON MY 96 XR 400 AND IT MADE A WORLD OF DIFFERENCE ,MUCH BETTER THROTTLE RESPONSE,STARTS EASIER,AND DOSEN'T STALL AS EASY,THE GUY I SPOKE TO(RON I BELIEVE) THERE OWNS THE COMPANY ,HE WOULD BUILD THE SYSTEM AFTER HIS DAY TIME JOB,FROM WHAT I UNDERSTOOD THE WAY THE SYSTEM WORKS IS THAT ONCE THE ENGINE IS AT A GOOD RPM AND YOU CHOP THE THROTTLE ,THE SYSTEM GIVES YOU MORE INTAKE VOLUME,SO WHEN YOU OPEN THE THROTTLE IT DOESN'T TAKE THAT EXTRA TIME TO BUILD UP INTAKE PRESSURE TO SUCK THE FUEL FROM CARB,I ALSO OWN A 00 KTM 400 EXC WITH A PUMPER CARB AND THE XR HAS A BETTER LOW END RESPONSE THAN THE KTM,SO I THINK THAT YOU WOULD GET MORE BANG FOR YOUR BUCK WITH THE PCIS THAN THE PUMPER CARB,THE ONLY DRAW BACK IS THAT YOU NEED TO BE A LITTLE HANDY WITH A DREMEL TOOL SO THAT YOU CAN MODIFY THE THE CARB,HE'LL TELL YOU TO SHAVE OFF THE END OF THE CARB THROAT BUT I FOUND IT WAS EASIER TO SHAVE THE INSIDE OF THE INTAKE BOOT WITH A UTILITY KNIFE,HE ADVERTISES IN THE BACK OF MOST DIRTBIKE MAGAZINES,HIS NUMBER IS 406-248-5595 AND THE PRICE IS ABOUT 190 BUCKS
A four stroke only fires 1 time during 4 cycles. So you want to get the most fuel air mixture in to the combustion chamber once the intake valve opens.
When the intake valve opens, the piston is going down. This causes a vacume, pulling air mixed with fuel in to the combustion chamber. Then when the valve closes, all the air/fuel that was on its way "CRASHES" into the closed valve and stops.
With Rons system the air/gas on the way to the combustion chamber hits the closed valve and is then routed through a hose(never stoping). This hose is a certain legnth so that when the air/gas makes the loop it is back at the intake the exact time the valve reopened.
I purchased Rons system a year ago and I like it. The system is about 1/2 the price of a pumper and gives good results. A pumper may give better results, but they are a pain in the BUTT if you fall or stall out. With the pulse system starting my bike after a crash is no different than stock and might be easier...