How many pounds = 1 hp

[dirtwiz]

Here's the deal...my DRZ has a FCR, full Yosh, 3x3, and seems to run good. I have a friend with a 3x3, JD Jet Kit on his stock carb, and a slip on. The way I see it I should have about 3 or 4 HP on him at least....from a roll we pin it and go thru 3rd 4th and hit 5th gear. We have identical gearing and we stay dead even all the way. There is one difference...I out weigh him by about 55 Lbs. so I am figuring this to be most of the difference. The question is: Has anyone ever come up with a formula for how many pounds equals 1 HP using a dyno and different weights? I know Eddie has probably tested it but I have never seen any results here. Someone give me your best guess. According to my estimate on my situation it may be about 10 pounds per HP.

[Rej]

there was a decent discussion about this recently ...

https://www.thumpertalk.com/forum/showthread.php?t=666088&highlight=pounds+hp

I think somewhere along the lines of 10-20lbs feels like 1hp .. but read the thread, lots of good stuff in there.

The key word is "feels" like 1 hp, you won't see a difference on a dyno.

Cheers,

Rej

[Bobhope]

about 6

[MesserSchmidt]

divide the number of pounds (295 dry weight for an SM), divide by the horsepower. Stock at the wheel is about 35, so that works out to about 8.5 pounds per horsepower as your power to weight ratio...with no rider on the bike. Of course you must include rider weight for a reliable number so that number probably will be more like 10.

The lighter you get and the more power you're making, the less weight it will take to equal 1 hp.

[UncleBob]

Have to add the rider weight since bikes don't ride themselves (very far anyway) ?

[djchan]

10 pounds feels like 1 HP.

[MesserSchmidt]

According to my calculations, with a 150lb rider, 310lb wet weight, and 40hp, it's more like 11.5. If the original poster outweighs his buddy by 55lbs, he's gotta be significantly heavier than 150. For him it will probably be more like 13.

[Keatron]

well if this is all true then i should go pretty good, im only 150

[MesserSchmidt]

well if this is all true then i should go pretty good, im only 150

me too! ?

At 6'0"...They keep telling me my metabolism is gonna slow down one of these days...but it hasn't yet and I'm a week from turning 25...I'm going to enjoy it as long as it lasts, lol

[dirtwiz]

One other thing I did not mention about this speed test. We were going up hill, so according to the link that Rej pointed out, some people think that this uphill test would magnify my results as far as the HP to weight difference. When I first got my DRZ I read in here about all the people shaving ounces off their bike by buying titanium pipes, replacing bolts, cutting off their helmet locks, etc. I went on a diet and lost 25 Lbs. in a couple months. I still shaved some of my stuff off my bike but I still weigh in at about 215 Lbs. now. That was the cheapest HP that I got out of my bike so far I guess. Thanks for the input guys....it makes us all realize what an advantage you light weights have on us.

[stephenfarris]

@7lbs=1hp thru the entire RPM range. He would have you since you don't make the extra HP until you get to 6500 rpms or so:thumbsup: He has the 50lb lighter bike from 0-10,000 rpms.

[supermotogreg]

Hi wiz,

25 pounds is a significant amount of weight to remove, from bike or rider... and that is a net gain of about 2 horsepower. ?

The actual running weight for an SM with oil and a full tank is 318 pounds. Most riders will naturally remove at least some of that weight from their bikes. I've removed all of the obvious stuff and replaced other heavier components with lighter ones to get the running weight down to 302 lbs. Just recently bobbed the rear fender and cut the sub frame short including the helmet lock to lose another pound which put the running weight at 301 lbs (278 lbs. dry weight)...

Stock engine with modified exhaust = 35hp.

Bike, me, and 10 pounds of riding gear = 441 lbs.

Yields 12.6 lbs. per hp... or about .08 hp per lb.

Take Care,

Greg

[angry perch]

Have to add the rider weight since bikes don't ride themselves (very far anyway) ?

I don't know. I seem to remember my 1980 Can Am Qualifier going pretty far by iteself... until it hit a tree. That's a fond memory that I'll always have.

[GreenHornet450]

me too! ?

At 6'0"...They keep telling me my metabolism is gonna slow down one of these days...but it hasn't yet and I'm a week from turning 25...I'm going to enjoy it as long as it lasts, lol

It will happen you one day Grasshopper. I could eat 10 Pizza Pies, 5 Turkeys, 9 Chocolate Cakes & still loose 10 pounds. Now I watch a KFC Commercial & put on 10 pounds:busted: