True Horsepwer?

[Donald02max]

I just have a question. Everything I ever heard about a VMax was that they all have 145 hp, now i get on this forum site and see that people are only getting 120 or less with slight mods. I understand the difference between flywheel horse power and actual horsepower at the wheel but come on is the bike actually losing about a 1/3 of its power between the flywheel and the back tire or; and here is my question.

Is yamaha full of crap with the stated hp of 145?:ummm:

 

[Thevmaxrider]

It is 145 at the crank, 110-115 at the rear wheel. Yes, you lose quite a bit in the drivetrain. Remember you have 2 90 degree gearsets which rob you of power. Yamaha told the truth, from a certain point of view.

 

[SpecOps13]

+1 to what Jim said......

 

[gamorg02]

Why do 90 degrees rob power?

 

[Thevmaxrider]

All gears lose power, it just varies. Here is a quick and dirty exerpt from a car magazine on drivetrain losses.






Dynamic drivetrain losses, on the other hand, include the rotational inertial losses from angular acceleration occurring within the drivetrain while accelerating. In fact, during acceleration there are losses from the rotational inertia of spinning transmission and differential internals as well as driveline components like driveshafts and prop shafts, but also from the increased load and friction being generated between the gears within the transmission and differential(s). And as you already know, with increased friction comes increased heat (more on that later)

 

[Rusty McNeil]

Food for thought; and these are long and well established hot rodders rule of thumb numbers.

A rear wheel drive car with an Automatic tranny loses between 19-23% of it's power from the crank to the ground.

The same car with a manual loses around 15-17% of it's power from crank to Ground.

These are pretty easy to verify if you compare enough various car mfgr's advertised HP ratings to what these cars end up putting down to the rear wheels. You can cruise just about any forum you can think of and see the numbers stockers are getting. The mfg's may play games with the numbers occasionally but not like in the old days, some have been sued for false advertising when they do.

It's very easy for me believe that the Vmax crank HP is 145 if it's putting down 117-120

 

[DakRatFink]

This thread gets me thinking...
Since just about everyone who has gone through all the trouble/expense of chain conversion has probably already done jetting and exhaust, if not extensive mods, it would be interesting to see dyno results of a chain conversion on a mostly stock max.

 

[Rusty McNeil]

This thread gets me thinking...
Since just about everyone who has gone through all the trouble/expense of chain conversion has probably already done jetting and exhaust, if not extensive mods, it would be interesting to see dyno results of a chain conversion on a mostly stock max.

Me too. I'd bet maybe 12-15 hp increase?

A chain is way more efficent than a shaft, not like comparing cagers manuals versus autos??

I'd bet the weight drop would make a big diiference too...

 

[Thevmaxrider]

There is a ~15% increase in rear wheel horsepower when you go to a chain drive. If I was still running Vmax carbs I could dyno and give you a ballpark anyway. As for weight loss, it is HUGE, all those gearboxes weigh in at around 35lbs and you get savings on the rear wheel not having that huge hub! Someday I need to remember to throw Toxic on the scales, when I can remember LOL.

 

[Donald02max]

Thanks for all the replies, I bought my vmax because I have loved them since I saw the first on back in 1985. I was finally able to buy one about 3 yrs ago. I have mine as an everyday rider mostly back and forth to work. I don't ride like most vmax riders seems to ride that I have read about in these forums and others I have spoken to personally, that is wide open balls to the wall see how fast I can go. I just ride for the enjoyment of the bike, don't misunderstand me I get a great rush from getting into the boost but I just mostly do it to get up to hwy speed.
I dont really have any issues with the power my bike has if actually only 110 at the tire. OMG I am guessing if it actually had 145 I couldn't hold onto the grips. Lol.
Just a bit sad to see the true numbers. Surprised the rush I am getting from my MAX is from
Way less hp than I thought.
I will now be dreaming of the 2011 Model now.

 

[[email protected]]

HP is just a number. All that matters is you enjoy the ride

 

[Miles Long]

Re: True Horsepower?

Dynamic drivetrain losses, on the other hand, include the rotational inertial losses from angular acceleration occurring within the drivetrain while accelerating. In fact, during acceleration there are losses from the rotational inertia of spinning transmission and differential internals as well as driveline components like driveshafts and prop shafts, but also from the increased load and friction being generated between the gears within the transmission and differential(s). And as you already know, with increased friction comes increased heat (more on that later)

Aw shucks, Jim. That's exactly what I was going to say.

 

[RaWarrior]

Power can almost be thought of as a physical object, it behaves similarly.

Say you toss a tennis ball against a wall straight on. When it hits the wall, nearly all the original energy is still with it, with a bit being lost to wind resistance. Now toss the ball at a 45 degree angle, in theory giving it a 90* bounce angle. After it bounces, it's got considerably less energy since some of it was absorbed by the wall to change direction.

In your bike's drivetrain, the weight of the driveshaft and gears absorb power(energy to rotationally accelerate those parts). This applies to a chain or belt as well....the sprockets, chain/belt, and all the transmission gears all absorb some energy....why it's essentially impossible to have zero losses from crank to wheel in any application.

However a chain or belt does not force the power flow to change direction. The direction of rotation stays the same. The output of the transmission is still in the same rotational plane as the crank. The middle gear moves that to perpendicular, then the final gear moves it back to parallel again.

It's the price paid for essentially a maintenance free driveline. Change the oil in the pumpkin like every 20k miles and forget it.

Why the enclosed chain never caught on I don't get though.....you'd think that would combine the benefits of both....low maintenance without the power loss of a shaft drive. Guess belts have just replaced them anyway.

So 145 is technically accurate...your bike does produce that much power....it just doesn't manage to get all of the ponies to the ground. 110-115 is typical for stock. A full exhaust and well tuned jet kit will put it in the 120-125 range. Beyond that takes motor work.

 

[Fire-medic]

With an honest stock Gen 1 110 hp and the Gen 2 hitting the dynos about 165+ hp, you can see going from the 1200 cc to 1700 cc nets you about a 50% increase in hp.

 

[a113ycat]

HP is just a number. All that matters is you enjoy the ride

Thats what she said!!!:rofl_200::rofl_200::rofl_200::rofl_200:

 

[sdt354]

It would have been nice if Yamaha offered a chain drive version of the Vmax Gen 1, a workable F.I.or just bigger carbs (which I think Sean is going to offer us soon).A Nice USD front end option. 130-145 hp to the wheel maybe, instead of 100-110. I t would have made ME a happy camper. Instead Yamaha made sure no parts swapping between the gen 1 and Gen 2 would be possible. Wheels really are a major piss off. Gen 2 wheels on ebay for way cheaper than Gen 1 wheels,which are priced like solid gold? Good thing for after market venders. Yami take your head out of the sand I almost said your ass, dam!
The weight loss and additional power to the asphalt would have been way cool with a chain. Too bad it's so expensive to convert or I'd do it in a heart beat. The shaft is what I like least about a Vmax. Doesn't sound it, but I like the Gen 1 & 2. If I ever split the cases, I'll investigate how reliable the shaft is. I'll bet Jim, Sean, John Gainey could all tell me. But, I realize many do like the convienince of the shaft. Just my personal opinion.
Steve

 

[sdt354]

HP is just a number. All that matters is you enjoy the ride

Can't argue with that Mike.
Steve

 

[chainednitromaxx]

OK, i got some exact #s from shaft to chain on my v maxs. It comes out to a 10 to 12 % power increase. Thats it ,15% will be fudging it. One of my bike dynoed at 162 shaft drive 1500cc shaft drive. the same bike went 178 to 180 with sprocket. This was on the same dyno at same time of year.

Perks of shaft drive is it hits hard on first shock of good throttle. Hits hard, there is only .002-.003 play with gear so when you whack it, it hits hard. Chain does not hit as hard, the crusher hub and chain absorb alot of the hit. Its not as violent and i do miss that.

The chain i love the sprocket selection especially since i can gear it more for top end since i got so much torq (115 motor 145 nos) on bottom do not need gearing. The bike also handles so much better,night an day difference. The weight no big deal 35 at the most unless you pro racer no big deal, go on a diet do the same

 

[chainednitromaxx]

Yammy screwed us on new update, idiots built a bike with wrong rims to small tank and shaft drive. wow sounds familiar. Still only bike like it.

 

[sdt354]

Yammy screwed us on new update, idiots built a bike with wrong rims to small tank and shaft drive. wow sounds familiar. Still only bike like it.

+1 to that Bro , love my Max despite the bitching. Nothing like it and a blast to ride. No matter what is wrong. A ride puts the smile on. The chain? Only a dream, but I said that about radials and my wheel is in the mail today. Now, I'll see if I need frame braces, once I get the radials on.
Steve-o