2006 CRF450X 430cc De-Bore…
by L.A.SLEEVE
Updated: February 13, 2011
2006 CRF450X 430cc De-Bore
L.A.SLEEVE has long been recognized as the industry&squot;s largest rebuilder of worn 2 stroke and 4 stroke cylinders. Not only that, but we&squot;ve also been known to build the biggest of the big-bores around the industry. What most industry insiders are unaware of is we&squot;ve also reduced ( a.k.a. de-bored ) motor displacements on certain bikes so they can compete in specific race classes.
We&squot;ve taken 500cc down to 390cc. We&squot;ve taken 250cc down to 199cc or 125cc down to 100cc displacements. Etc. We&squot;ll do whatever it takes to make our customer&squot;s happy.
We were recently approached by an ATV racer to bring the CR450F motor down to just under 440cc in order to compete a specific ATV racing class. We obliged. What we didn&squot;t expect was an average everyday weekend warrior to approach searching for a bore reduction on a CRF450. What the heck for? The motor is fine by our estimation and most everybody else. But, if a rider is sporting a tiny 140 pound frame, well perhaps we do see a need. A tamer motor for a smaller framed rider breeds huge confidence. Desert, offroad, MX or trail riding. And, not everyone wants to buy orange and black ( KTM400 and so forth ).
This gave us the inspiration we needed to include an entry into the 2006 Dirt Rider 24 Hour. We wanted a smaller bore motor but we still wanted the bike to be loads of fun. What we intended to achieve from the de-bore was basically the old YZ426F power-band. The idea was to create a 426cc to 430cc motor without a violent hit at mid-range. It took a little brain power but we&squot;ve succeded. We researched the bore X stroke combination and discovered that a 94mm bore would be just right with the 62.1 stroke.
The process started by building a custom 94mm Pro-X piston. Then, we made a specially crafted de-bore cylinder sleeve from our benchmark ProMalloy spun-cast chro-moly material composition. It&squot;s hard, slick and durable. But, kind and forgiving on the ring package. We also built de-bore gaskets. That&squot;s what we needed to get "project 430cc" complete.
We spent many hours calculating a number of other engine mods. We considered adding new Pro-X titanium intake/exhaust valves, titanium springs and valve seats. Another thought was a custom grind Web Cam and major head porting. But, after serious thought, the tech department simply figured the mods were unnecessary to the power-band. No real advantage with these additional mods. And, no sense adding to the price tag if they won&squot;t help the customer.
When the motor was pieced back together, broken in and running we ran the bike over to the "Doctor" at Dubach Racing, Doug Dubach. Doug, former long time Yamaha factory pro-rider is the owner operator of D.R.D. They build some of the best 4 stroke pipes in the business. We put our tech minds together with Doug&squot;s "mad scientist" mentality to build an exhaust/header combo that met the desired power delivery we were searching for. We also used Doug&squot;s experience and knowledge to dial the motor in as well ( carb jetting, motor breathing, etc. ).
We like the ergo&squot;s and suspension on the stock CRF450X. Although, for the 24 Hour, we wanted to set the ergonomics on the CRF450 for riders of all levels. First, we had the guys at Precision Concepts work their magic with full near perfect suspension modifications. Then we met up with Team L.A.SLEEVE / Pro-X off-road factory pro-rider&squot;s Mark Tilley and Mike Childress at the secret L.A.SLEEVE riding area located near the Gorman headquarters of the Dirt Rider 24 Hour. They felt it would be best to dial in the suspension while riding in that specific environment. These two guys are amazing. With their combined factory experience they were instrumental, as they somehow were able to set the suspension to make themselves happy, as well as make Dave ( Dave Metchkoff is V.P. of L.A.SLEEVE ) happy with the total suspension package. Why is that an accomplishment? Dave is no longer a level A, B or C rider, but somewhere past F ( if you know what we mean )!!
The bike set-up is exactly what we were trying to accomplish. No loss of usable power-band. But, a gain of confidence and usable power for the intermediate little guy or the far more experienced big guy. All that was left was a new graphics package, and offroad external hardware to keep D.M&squot;s toe nails and finger nails from getting chipped ( can&squot;t hurt his precious golf swing! ). Don&squot;t forget the night time lighting package provided by Baja Designs.
The basic total 430cc de-bore package retails for only $479.95. The D.R.D exhaust package retails for $515.95. The parts we used retail as follows:
Pro-X de-bore Piston $210.00
ProMalloy Cylinder Sleeve $124.90
Pro-X de-bore gasket set $41.05
install sleeve labor cost $104.00
D.R.D. Exhaust $515.95
Precision Concepts $ call
L.A.SLEEVE has long been recognized as the industry&squot;s largest rebuilder of worn 2 stroke and 4 stroke cylinders. Not only that, but we&squot;ve also been known to build the biggest of the big-bores around the industry. What most industry insiders are unaware of is we&squot;ve also reduced ( a.k.a. de-bored ) motor displacements on certain bikes so they can compete in specific race classes.
We&squot;ve taken 500cc down to 390cc. We&squot;ve taken 250cc down to 199cc or 125cc down to 100cc displacements. Etc. We&squot;ll do whatever it takes to make our customer&squot;s happy.
We were recently approached by an ATV racer to bring the CR450F motor down to just under 440cc in order to compete a specific ATV racing class. We obliged. What we didn&squot;t expect was an average everyday weekend warrior to approach searching for a bore reduction on a CRF450. What the heck for? The motor is fine by our estimation and most everybody else. But, if a rider is sporting a tiny 140 pound frame, well perhaps we do see a need. A tamer motor for a smaller framed rider breeds huge confidence. Desert, offroad, MX or trail riding. And, not everyone wants to buy orange and black ( KTM400 and so forth ).
This gave us the inspiration we needed to include an entry into the 2006 Dirt Rider 24 Hour. We wanted a smaller bore motor but we still wanted the bike to be loads of fun. What we intended to achieve from the de-bore was basically the old YZ426F power-band. The idea was to create a 426cc to 430cc motor without a violent hit at mid-range. It took a little brain power but we&squot;ve succeded. We researched the bore X stroke combination and discovered that a 94mm bore would be just right with the 62.1 stroke.
The process started by building a custom 94mm Pro-X piston. Then, we made a specially crafted de-bore cylinder sleeve from our benchmark ProMalloy spun-cast chro-moly material composition. It&squot;s hard, slick and durable. But, kind and forgiving on the ring package. We also built de-bore gaskets. That&squot;s what we needed to get "project 430cc" complete.
We spent many hours calculating a number of other engine mods. We considered adding new Pro-X titanium intake/exhaust valves, titanium springs and valve seats. Another thought was a custom grind Web Cam and major head porting. But, after serious thought, the tech department simply figured the mods were unnecessary to the power-band. No real advantage with these additional mods. And, no sense adding to the price tag if they won&squot;t help the customer.
When the motor was pieced back together, broken in and running we ran the bike over to the "Doctor" at Dubach Racing, Doug Dubach. Doug, former long time Yamaha factory pro-rider is the owner operator of D.R.D. They build some of the best 4 stroke pipes in the business. We put our tech minds together with Doug&squot;s "mad scientist" mentality to build an exhaust/header combo that met the desired power delivery we were searching for. We also used Doug&squot;s experience and knowledge to dial the motor in as well ( carb jetting, motor breathing, etc. ).
We like the ergo&squot;s and suspension on the stock CRF450X. Although, for the 24 Hour, we wanted to set the ergonomics on the CRF450 for riders of all levels. First, we had the guys at Precision Concepts work their magic with full near perfect suspension modifications. Then we met up with Team L.A.SLEEVE / Pro-X off-road factory pro-rider&squot;s Mark Tilley and Mike Childress at the secret L.A.SLEEVE riding area located near the Gorman headquarters of the Dirt Rider 24 Hour. They felt it would be best to dial in the suspension while riding in that specific environment. These two guys are amazing. With their combined factory experience they were instrumental, as they somehow were able to set the suspension to make themselves happy, as well as make Dave ( Dave Metchkoff is V.P. of L.A.SLEEVE ) happy with the total suspension package. Why is that an accomplishment? Dave is no longer a level A, B or C rider, but somewhere past F ( if you know what we mean )!!
The bike set-up is exactly what we were trying to accomplish. No loss of usable power-band. But, a gain of confidence and usable power for the intermediate little guy or the far more experienced big guy. All that was left was a new graphics package, and offroad external hardware to keep D.M&squot;s toe nails and finger nails from getting chipped ( can&squot;t hurt his precious golf swing! ). Don&squot;t forget the night time lighting package provided by Baja Designs.
The basic total 430cc de-bore package retails for only $479.95. The D.R.D exhaust package retails for $515.95. The parts we used retail as follows:
Pro-X de-bore Piston $210.00
ProMalloy Cylinder Sleeve $124.90
Pro-X de-bore gasket set $41.05
install sleeve labor cost $104.00
D.R.D. Exhaust $515.95
Precision Concepts $ call
