Thumper Racing 450 Big Bore Kit

CR Swade

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Jan 18, 2001
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#1
I just got back from riding and thought I'd share some impressions of Thumper Racing's kit for the KTM 400's.

First off, I'm comparing to the other 450's in the class (KTM, CRF, and WR) plus the 525 EXC. I've owned both the 525EXC and the WR450 (shutter), and spent time on the CRF as well as the KTM 400.

This may be the ultimate engine/bike package to come out yet, short of factory rides. The engine gives comparable feel in hp to all of the 450's out now, with exception to the WR-which has major pull but is a bear to ride in the woods.

This kit, the short stroke TR kit, pulls cleanly (almost no hit) all the way to the top-end with no vibration to speak of. It doesn't pull quite as long as a stock KTM450 or 525, but it has already done its magic long before the stretched out areas needed for a KTM in top-end boogie mode. Need to loft the front end for a log? Just a little twist and its done. The major difference is the delivery of power is almost perfect...CRF too revvy at times for woods, WR too much flywheel effect w/ too much stalling, KTM 400-well, it's a llittle sluggish/poochy (which can really affect handling), KTM 525 just waayyy too fast at times for tight woods, which leaves the KTM450 (power is almost identical, but feel of teh TR kit is superior w/ regards to handling).

In terms of the handling question, the short stroke engine has a lower COG in terms of the recpirocating mass. What does that mean? The TR short stroke kit has a revvier engine, with a lively delivery that makes the chassis feel much more precise. Take away the rec. mass up high and the bike feels so much lighter even though it weighs no less at all. If you doubt this, try flogging a WR450 through the same place the KTM just traversed, weight is close, engine is identical cc's, but the KTM feels more nimble. Why? Some in part to chassis, but much has to do w/ engine characteristics. Heck, even the difference between stock KTM450 vs 400 handling is dramatic, mainly in part to engine characteristics. This kit makes the bike feel downright small, dare I say 125ish.

The quality of parts/workmanship seems top notch, and the bike runs and sounds like OEM (no weird noises, overheating, etc.)

If you are looking for a lower cost alternative to new, with arguably better power than new, a clean KTM400 with the TR kit is a great way to go.
 
Joined
Aug 30, 2003
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#2
I COULDN'T HAVE SAID IT BETTER.
ONE RIDE AND THIS KIT WILL BE YOUR VERY NEXT DREAM.
ILL BET THE ONLY REASN LAFFERTY IS ON THE 450 IS BECAUSE ITS AN EASY PRODUCTION PIECE.
MY TEST HAD A REVLOC AND IT STILL FELT LIKE IT ATE THE PANTS OF THE PROD. BIKE MINUS OVERREV BUT NOT AT A SMART SPOT. WHEN YOU RIDE THIS BIKE YOU WNT 2 CHALLENGE THE WORLD FOR A WHOLE 24HRS. IT WAS JUST ALITTLE OFF OF THE EXCESSIVENESS OFTHE 520. RIDE A 400 AND U WILL KNOW RIGHT WHAT U WANT. INSTALL THE 450 AND YOU HAVE MORE POWER ADN IT MAKES IT TO THE GROUND. IT REALLY IS A 400 OWNERS DREAM WITH THE ADDED BENFTS OF THE 400 HANDLING.. THERE REALLY IS A GYROSCOPIC DIFERENCE. I WEIGH 150 ADN THE 03 EXC WAS FRESH FACT CON. 180LBER WHILE THE 02 TR450LOCREV WAS SET FOR THE PRO SUMOFASTER HAIRSCMBLAE FARTNERHEHEHEHEHEHEHHEHHE ALLL OF THE FACT CON FORSKS WERE USED AND DONT EVEN KNOW WERE AT ON THIS 20 MIN JORNEY WHILE I MIGHT HAVE USED 3IN OF SUPERHHAIRS. THE 03 IS STILL MORE TOP HEAVY AND FEELS MORE LIKE A DANG WR WHILE 02'S RIPPIN WITH COMFORT. I WISH I COULDVE HADM BOTH 4THE DAY JUST TO SETEMUP. THERE IS STILL MORE POWER AND REVS ALL AROUND2THGROUND WITH THE OLD SCHOOL.
THERE IS HOWEVER 1 BETTER BIKE


HUSABERG 470



HOWS THAT FOR AN EXOTIC DANCER NO TEASN JUST PLEASN