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Porting vs bigbore

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What gives better overall power, going to a 480 bigbore or having the head ported with oversized stainless steel valves installed.

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from what i have read they are different kinds of power.big bore adds power but slows revs. porting adds power but higher revs.im no expert but everything ive read points that way.plus big bore has torque because of increased ccs

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Neither. Just swap out the 450 motor for a ported CR500 mill. Mucho faster. Much more reliable. Sounds much better. Smells better, too.

And makes riding a standard 450 seem like riding a XR250...

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A big bore gives you more power through torque by not turning more RPM which is usually more ridable in most instances a ported motor makes more power through turning more RPM usually. Any time you go for a good amount more HP through porting you will always have to turn more RPM and lose some torque. It is all trade offs if you are looking for more MPH HP is the way to go but for excelleration from lets say 0 to 60 torque is the way to go.

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What gives better overall power, going to a 480 bigbore or having the head ported with oversized stainless steel valves installed.

Let's see- Burned is making 60hp with stock displacement.

If it was me I would have RHC port the head, J&E piston, use his cam and carb mod.

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Go for even more HP and you will start to lose torque unless you go bigger displacment or a super charger or turbo.

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thats a general statement that doesnt necesarily hold true.

in the case of my bike,its definately not true.

thats the coolest part about the RHC 187 cam.

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thats a general statement that doesnt necesarily hold true.

in the case of my bike,its definately not true.

thats the coolest part about the RHC 187 cam.

I looked at Ron's site and couldn't find the cams. I want to put a cam in my bike, but wasn't sure if I wanted a Stage 1 or 2 Hotcam. What's the deal with Ron's cam? I don't need a ton more power, I would just like a nice boost. My bike's stock other than a Dr. D exhaust. I don't want to port or anything else at this point. Give me the low-down on this.

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it is rons own grind.he developed it in addition to his 208 cam wich is the "top end" cam of the 2.

its easier on the valve train than the stock cam.has less lift than stock but more duration.

my crf is makingn 60hp with this cam and the valves have never moved.

give him a call.he has them ins stock and ready to ship.i promise you wont be dissappointed.

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chm sm1 pipe

RHC187 cam

RHC full race head (RHC springs,stock valves)

RHC modified carb

JE 13.5 to 1 piston

VP U4 fuel

KN Xtreme air filter

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chm sm1 pipe

RHC187 cam

RHC full race head (RHC springs,stock valves)

RHC modified carb

JE 13.5 to 1 piston

VP U4 fuel

KN Xtreme air filter

Nice. . .

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This is just my opinion, but I would leave any CRF450 stock. I do and I never regretted it. The bike is fast enough and its one of the best stock power bands available. Most people can't even use the available stock power and it does not make them any faster on a track. Some of the most highly modified bikes are owned by the slowest riders in the planet (not all). If you are not RC fast, spend your money on other things! (plus your bike will last a lot longer).

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A big bore gives you more power through torque by not turning more RPM which is usually more ridable in most instances a ported motor makes more power through turning more RPM usually. Any time you go for a good amount more HP through porting you will always have to turn more RPM and lose some torque. It is all trade offs if you are looking for more MPH HP is the way to go but for excelleration from lets say 0 to 60 torque is the way to go.

Not so if the head is properly ported cylinder filling will be better @ low rpms also if you start making large changes in port cross section to gain flow than you will loose power and some times even @ higher rpms i dont think you will find any of my customers complaining of a loos of low end power with my porting .

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What is the longevity with the modifications. Most riders / owners are already complaining about maintenance intervals. I think Honda is already at the horsepower to maintenance borderline. Just a thought…..don’t kill the messenger! Mine is a stock 2003 CRF 450R and the motor is untouched to this point. I bought it new and maintain the hell out of it.

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this is why i wont big bore a crf.stock bore and stroke mean the piston velocity and the piston weight are unchanged.which besides auto cam chain tensioner failures are imho the leading cuase of blown up modified motors.

i dont maintian mine any differently than a stocker other than im not shimming my valves all the time becuase of the harsh stock cam.

i worry much more about my 4.5mm big bore and 5mm stroker drz.although it has proven to be very reliable as well.

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