Well...I was finally able to beat the YFZ

[ghott]

I could never beat my YFZ on my R (yes I own both). The Alba Pipe gave the YFZ gobs of power all over, especially on top. I put an HMF Pipe and cut the airbox lid on the R, but the YFZ would still pull 5-6 bikes in a short drag....but not anymore :)

SPECS on both bikes as of right now:

TRX450R:
Full HMF Pipe
13.1:1 Wiseco
Hot Cams S2
Airbox Lid Off
14T Front Sprocket
20" Rears
170lb. Rider Weight

YFZ450:
Full Alba Pipe
K&N Filter
Airbox Lid Off
13T Front Sprocket
19" Rears
130lb. Rider

Here is the videos recorded today (9/10/06):
Couple of short drags..video is huge 31.8MB, so 56kers beware. (but i think Youtube scaled it down)

http://www.youtube.com/watch?v=TFzwv13Ygl0

I'm going to put my 13T front sprocket back in next weekend. Dragging will be much easier, and should yield even better results against the YFZ.

Let me know what ya think.

BTW: The YFZ is for sale: http://www.exriders.com/vbb/showthread.php?s=&threadid=243118&perpage=15&pagenumber=1

[Chino886]

they say that every 7 lbs is a HP, so the 40 lb weight difference is 5 + HPs.....

[ghott]

Originally posted by Chino886
they say that every 7 lbs is a HP, so the 40 lb weight difference is 5 + HPs.....

Thats very interesting...I've never heard of that. Is that from a reliable source?

I've heard of 100lbs. is a tenth in the quarter for cars. I figure'd weight difference would be a little more extreme with something as light as sport quads...

[GPracer2500]

The 7lbs = 1hp thing is an old "rule of thumb" that I believe originated among automotive 1/4 dragracing (and it's probably best left there). I seem to remember Mopar publishing a chart of some sort that helped convert a car's weight loss to HP values and 1/4 mile times. But I don't think it was as simple as a single ratio that could be applied across the board--it varied as trap speeds changed or some such thing. AFAIK, the 7:1 ratio was just a boiled down guestimate of those charts for the most common circumstances.

Weight definitely makes a big difference--especially in up-hill drags--but I wouldn't put too much stock in the 7lbs = 1hp thing. Traction, gearing, and other factors are just as influencial in producing results.

Consider this: 400lb quad + 150lb rider = 550 lbs. Lets say the quad is putting 45hp to the ground (we're discounting traction considerations here), so that would be about 12lbs per 1hp. In that sense, I supose if you shaved off 12lbs it might be close to adding 1hp (now you'd be at 538 but still have the same HP). But the more weight you shaved the more that ratio would change.

Or something like that...lol...I don't really know, just trying to think it through.

[ghott]

I definitely appreciate the thought GP!

Thanks brotha.