The CRF has room for a 3mm overbore (480cc)

The 450R has a 2.7mm longer stroke than the CRF450!!!

It also has a 2mm smaller bore though!!!

So, that's 5mm to play with if I'm right and Honda used the same cylinder.

Put in the CRF 3mm overbore piston and tada your over 480cc (what the exact number is I'm unsure?)
now cause you started with a 2.7mm longer stroke.

 

i saw a hop-up kit (480) for the crf 450 at Sun honda in Co. did not ask about it .

 

If you are right and you can actually take the cylinder out 5mm, then by simply boring to the largest bore will give you a 500cc quad (498.55cc). The formula is (R devided by 2) to the second power x pie x stroke.

R= Radius (bore)
Pie= 3.14

Cut the bore in half (9.9), this gives you 4.95 centimeters-- times that by itself, gives you 24.5025-- multiply by 3.14, gives you 76.93785-- multiply by the stroke which is 6.48 centimeters and you get 498.55726cc's.
JP

 

Thanks Boogerbub

 

Pleasure4qt, I looked at your picture page and I noticed you have the FST oil cooler. This upgrade is the bomb isn't it. I recently bought back my old 426 and after riding a liquid cooled quad for so long, the hot engine really bugs me so I'm concidering the oil cooler too. My best friend had one on his 440 and it worked GREAT! I might see if I can get an auto transmission cooler to work instead. It would be bigger and cheaper. Not enough people even know about the FST cooler, and most would be too scared to install one since you need to tapp into the head and all. Nice rides.

JP

 

Wouldn't this work for the YFZ also then? It's made exatcally like the Honda having the longer stroke and smaller bore. That would be cool cause you could try it out with the YFZ because it's out and the 450 isn't to see if it work!

 

Thanks JP

BigBubba- I'm not sure right off if the stroke is longer on the YFZ450 than the YZ450F?

I thought that just the bore was smaller on the YFZ! I could be wrong.

 

The yfz has a shorter stroke then the yzf,but it can be bored to 470cc (Dirt Wheels Feb. 2004). The Honda can and will be made in to a 500cc (March 2004).

 

Thank you Mr Dunlap,

I have already decided to ditch the Predator and get a new Honda again.

 

why do you want to ditch the predator?