

With 13-49 sprockets and 4.75 gallons of gas our heavily modded CRF450X is good for 175 miles before we start getting really worried about fuel. The 3.77 gearing in this platform is extremely versatile - allowing our CRF to stretch its legs on everything from gnarly single track to fire roads.

After a few rides we decided to replace the stock 450X head and valves with a 450R head and aftermarket valves (Wiseco titanium intakes and Kibblewhite stainless exhaust) and raised the needle one clip setting. The 450R valves are bigger with stouter springs and we are happier with the extra horsepower and less nervous about fragility (Note: After swapping out the OEM head and valves for the R upgrades we went 20 months and two seasons of racing before we found a valve even close to being out of spec). A little of the down-low torque appears to have been lost with the R head (verified on the dyno) so we modified our final drive ratio for a little more low-end grunt.



The much lighter than stock but really allows the engine to breathe. It's a little loud, though far from obnoxious, and the stainless steel header is a thing of beauty all by itself. When coupled The Pro Circuit T4 CRF450R full system we installed is not onlylighter than stock but really allows the engine to breathe. It's a little loud, though far from obnoxious, and the stainless steel header is a thing of beauty all by itself. When coupled with the airbox/emission mods and the Hotcams Stage 2 cam the CRF leaps forward in every gear and surges to furious top speeds (100+ mph with 3.13 or less gearing).



At the same time we added a Jagg oil cooler to reduce engine temperature and add a little more oil capacity. Recently replacement parts for the Jagg have become scarce so we recently replaced it with Trail Tech Cooling Fan and IRP billet Oil Cooler . We replaced the stock coolant with Engine Ice and bolted on a Boyesen Supercooler We also installed a Rekluse Core EXP and left hand rear brake



We had Power Sports perform a dyno run on our 450X once it was all put together. With very conservative tuning (a rich engine, as far as we are concerned, is a cool running engine) our CRF cranked out 45 bhp and 30 ft-lbs of torque on the dyno - with a big old ding in the header!. What is even more telling is that it produced more than 40 horsepower all the way from 7000 to 10,000 rpm, and over 25 ft-lbs of torque from 5500 to 9400 rpm. This is about the same as our highly modded XR650R but the manner in which the two bikes get that power down is revealing. Though the XR650R will get you from 60 - 100 mph faster, the CRF450X is so much quicker from 0 - 60 mph that it will leave big brother well in it's wake on the way to the same top speed. Subtract 60 lbs of weight, much of it up high, add the miracle button next to the right grip and the first impression contest is over pretty quickly.