I am picking up an '05 YFZ450 project with a bad crank for my 16 year old. I'm planning on doing the oil mod w/ '07 oil pump and spray nozzle. Does anyone have an opinion on a Hot Rods crank vs. the OEM Yamaha crank? I know Yamaha beefed the connecting rod up in the 2006 models when they stroked it. I don't know if the Hot Rods crank has a beefier rod or if they are the same or lesser quality than OEM???

I noticed on Hot Rods' website that the '06 and newer crank can be used in an '05 with the stock piston which made no sense to me since the '06 and newer crank has a 1.4mm longer stroke. All things being the same that would raise the piston .7mm in the bore. I looked up the Yamaha piston part numbers for '05 and '06 and they are identical, so the '06 and newer cylinders must be slightly taller or maybe the rod in the '06 and newer engines is .7mm shorter to make up the difference? I'd just like some independent verification of how durable the Hot Rods parts are.

Also, can the stock cylinder be honed since it doesn't have an iron liner?

I'm sure it will have WAY more power than a 16 year old "needs" stock. (probably not as much power as he'll want, but hey, I'm paying for this thing [img]i/expressions/face-icon-small-happy.gif[/img] )

Thanks in advance.

 

Well...I'm answering part of my own question here. Thought I'd post what I found out to help somebody down the road that searches for something similar.

Per Hot Rods, the connecting rod on the '06-'09 engine is 101.50 mm center to center, while the '04-'05 rod is 102.50 mm center to center. With the '06 and newer crank having a 1.4 mm longer stroke, the rod throw is .7 mm longer. Add a 1.0 mm shorter rod and presto, it all fits in the cylinder. Slightly longer stroke tends to add to compression ration, but subtracting .3mm from the piston deck height lowers compression ratio and you have a net loss of .7:1 in the stock compression ratio. ('05 is 11.9:1, while '06 is 11.2:1). Kinda makes me wonder what good 10 cc is if I end up loosing .7:1 compression ratio. Something tells me I'll never notice the difference. (This all assumes the combustion chamber in the head is the same on the '05 vs. '06 heads?) I guess the slightly stouter rod on the '06 and newer crank might be worth it?

Still wondering what everyone's experience with the Hot Rods Crank is verses the OEM unit strength/qualitywise?