Sad Dyno run

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warriorguy

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I just got me my first Vmax this spring.The bike is fast to me but we all know even a slow max is still faster than most other bikes.Anyways we have a bike rally this wknd and i went.Well there it was like a pretty girl calling my name a Dyno trailor,so i thought give it a try.The bike has 4-1 UFO exhaust and a stage 7 jet kit.To make a long story short i was pretty let down with the results.Should i be happy with these numbers or should they be higher? Dyno run 1 was 109.48 hp and 69.36 torque 2nd run was 111.46 and 70.57 torque.
 

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Well as we all know dynos are not always accurate. So without a comparison reference to maybe another Vmax it's hard to tell.

That be said those numbers would be considered poor for the mods you have done. HP and TQ both. Of course it could be as simple as changing the jets to get it where it should be.
 
Had a customer that was getting poor numbers and when asked if they had the rear tire at the normally accepted testing point of 40 psi. He was around 32 psi and when aired the tire up they gained 6-8 rwhp! Also gained another couple of HP by running the bike multiple back to back passes (they don't pull the best numbers until the 5th-6th pull many times).

Sean
 
I have come to the conclusion that just because you bolt on parts, does not mean you gain horsepower. Everything has to align just right for the HP to appear... this includes outside factors such as altitude, temp...even weather (barometric pressure). Take a stock bike and do a dyno run... get a baseline say 100 (just for giggles)... bolt on a 4-1 exhaust... you will expect your numbers to increase... not always true... if the bolt on is not in sync with everything else... numbers could drop by 2-3... just because of lack of backpressure. add some jets to give it more fuel... expect numbers to grow.... maybe... if jetted for the proper altitude, intake etc... Lots of R&D is required for each individual bike. 2 bikes with exactly the same mods, 1 in California coast and 1 in Colorado will dyno completely differently.
 
I have come to the conclusion that just because you bolt on parts, does not mean you gain horsepower. Everything has to align just right for the HP to appear... this includes outside factors such as altitude, temp...even weather (barometric pressure). Take a stock bike and do a dyno run... get a baseline say 100 (just for giggles)... bolt on a 4-1 exhaust... you will expect your numbers to increase... not always true... if the bolt on is not in sync with everything else... numbers could drop by 2-3... just because of lack of backpressure. add some jets to give it more fuel... expect numbers to grow.... maybe... if jetted for the proper altitude, intake etc... Lots of R&D is required for each individual bike. 2 bikes with exactly the same mods, 1 in California coast and 1 in Colorado will dyno completely differently.

not dismissing sfcmcgan's comments, because in part i agree. however, a key point to discuss is that a truer series of tests would need to be performed in an climate-controlled environment. point being, for example, using sfcmcgan's suggestion of substituting the exhaust as the first change, if done in a diy garage, by the time the exhaust was installed, the temperature and relative humidity has undoubtedly changed. in some parts of the world, this may not be as much as a factor as, for example, during the summertime in Florida, where by the time the afternoon arrives, the RH has jumped by 5-10 percent compared to the early morning and exacerbated by sporadic afternoon thunderstorms. this change in environmental factors compromises an accurate observation of the upgraded exhaust's performance
 
not dismissing sfcmcgan's comments, because in part i agree. however, a key point to discuss is that a truer series of tests would need to be performed in an climate-controlled environment. point being, for example, using sfcmcgan's suggestion of substituting the exhaust as the first change, if done in a diy garage, by the time the exhaust was installed, the temperature and relative humidity has undoubtedly changed. in some parts of the world, this may not be as much as a factor as, for example, during the summertime in Florida, where by the time the afternoon arrives, the RH has jumped by 5-10 percent compared to the early morning and confounded by sporadic afternoon thunderstorms. this change in environmental factors compromises an accurate observation of the upgraded exhaust's performance
Totally agree!
 
From what i understand all mods were done by Jon Cornell.As far as the clutch i was told it was new.Also by Cornell.Im very happy with the bike dont get me wrong i love it,but if i can and should be pulling better numbers i would love it even more.
 
i'd love to get a couple dyno pulls under my belt, but i can tell you right now, that even though my greatest fault is perfectionism, until i can afford a climate-controlled workspace and the time to experiment, i've mostly given up trying to squeeze out that last drop of HP and torque out of my bike. reason being, my max pulls like a redbull-induced silverback in the early mornings, like a half-torn gazelle being chased by hyenas around noon-time, and like a charging african elephant stuffed with marula fruit in the late-afternoons to early evenings.
 
i'd love to get a couple dyno pulls under my belt, but i can tell you right now, that even though my greatest fault is perfectionism, until i can afford a climate-controlled workspace and the time to experiment, i've mostly given up trying to squeeze out that last drop of HP and torque out of my bike. reason being, my max pulls like a redbull-induced silverback in the early mornings, like a half-torn gazelle being chased by hyenas around noon-time, and like a charging african elephant stuffed with marula fruit in the late-afternoons to early evenings.

I assume this is some fermenting fruit which affects the pachyderms significantly?:rofl_200:

The thing you need to look-at, from being told by my friend who has many pulls under his belt, on a variety of bikes, is if the fuel/air mix shows well, then that is going to be an accurate figure, on that dyno, on that day. Two bikes dynoed on different dynos on different days are going to be very different given the atmospheric conditions, including mean height above sea level, relative humidity, and temperature. As Sean mentioned, tire pressure, how tightly the rear was cinched-down to minimize drum/tire slippage, and even operator experience all will play a part.

I installed a used stock engine to avoid doing a case-split to repair a 2nd gear issue, and the bike was seemingly running very-well w/the replacement engine. When I took it to the dyno, it was to 'baseline' for discovering how-much mods affected the output. I had planned a new full 4/1, Dynojet Stage 7 complete kit, COP's, and a DYNA 3000.

The bike on 3 pulls did 109+ RWHP, which I thought was OK, not outstanding but a known starting point. Then leaving the dyno shop, I lost a #3 cyl big-end conn-rod. It didn't break, but it had ~2mm extra-play! (on tear-down) So I had to split the cases after-all. I ended up rebuilding my original engine (I had it done at Under Pressure, Dania Beach FL) and installing an undercut tranny my machinist friend cut for me. That included a new head job, which actually was in pretty-good shape, saving me from replacing valves, seats, or extensive additional machining. He did a 'clean-up' surfacing of a few thousandths on the heads' mating surfaces.

Now, I am "dyno-adverse!":rofl_200: The bike is running well, it pulls well, doesn't overheat, and I have surprised some late-model sportbikes who wonder, "how is that old crock able to stay w/me?":rofl_200: No, it's not the world's fastest, or worthy of any accolades, except that it's mine, and is running reliably, is safe, fun to ride, and it makes me smile every-time I ride it, which it did before, but it now has given-me a greater perception of delivery of power, but without quantifying the enhanced power via a dyno set. So-what? Yes, a good engine should be-able to survive some dyno pulls, but stung-once, I am not going to run a dyno again. It works for me, the way it is, and I can live w/o a slip of paper squiggles, especially if it means a $2K rebuild (I know it shouldn't, but it did this one-time for me).

So, my advice is, if you are thinking of installing a used engine, take the time to open the cases, and inspect and measure your clearances on the main bearings, and the conn rod big-ends. Do it for peace of mind. And, if you're wanting to dyno-thrash your bike, doing it before the runs may save your engine expensive repairs. :confused2:

If you're happy w/the way your bike runs, don't get too hung-up on trying for some ego-feeding dyno numbers. Enjoy it for what it does for you in daily use. If you really want to see what changes did, run it at the strip before and after, and a rev-limiter and shift light would help to preserve your engine, and optimize your bike's performance. :punk:
 

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Dyno's are only for bragging rights anyway, the only real way to know how much power your making is to race it and do the math from your mph... Most dyno's on a well running Vmax set up like yours will say approx 120rwhp, if you do the math on mine it only makes like 116rwhp and I'm running slightly better than average than most other guys with the same mods and I'm 60+lbs heavier.. The only point I'm trying to make is just because a dyno says you made 120hp doesn't mean you actually are making that kind of power.

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Dyno's are only for bragging rights anyway, the only real way to know how much power your making is to race it and do the math from your mph... Most dyno's on a well running Vmax set up like yours will say approx 120rwhp, if you do the math on mine it only makes like 116rwhp and I'm running slightly better than average than most other guys with the same mods and I'm 60+lbs heavier.. The only point I'm trying to make is just because a dyno says you made 120hp doesn't mean you actually are making that kind of power.

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You wouldn't happen to have that formula? I would be curious to check my wifes bike dyno sheet against the formula you used.
 
HP = (MPH ÷ 234)³ × Weight, there are also multiple online calculators to do this as well (I've got a app on my phone that does it) so just google "horsepower from mph calculator" and it'll make things easier for you.

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I also must add that you must know a precise weight of your bike when you race it, that includes yourself with all your gear on.. In my case it was 880lbs

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HP = (MPH ÷ 234)³ × Weight, there are also multiple online calculators to do this as well (I've got a app on my phone that does it) so just google "horsepower from mph calculator" and it'll make things easier for you.

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Thanks Brother!
 
You need a/f readings and most dyno have a way of doing this. I had my vmax on a dyno more than a few times with a lot of pulls and on the last pull i got like 126 and near 80. I have almost the same set up. You should be able to get 117 hp with your set up if engine compression is good. Jon cornell is as good if not better than the tech that tuned my bike. You need to find out what jets you are running and make sure everything in the tune is working good. Start with compression and valve adjustment than go forword with the rest of the tune. 5hp and 2fp is splitting hairs on a dyno. If you have a spark box with diff switchs you might be on the wrong click. Just because Jon sold you the bike dont mean he tuned it and if he did i would have to think the bike has a good tune for the day he tuned it weather makes a big differance when you are splitting hairs. When i did the last tune on my bike we changed jets and clicks on the spark box to come up with better numbers but when i took it for an all day ride it dident feel as strong as the Hooligan-B- Good ride that me Hi jacker and damon went on. I feel it had the best bottom end power it ever had on that day. I was 10 pounds lighter and the spark box was full advaced the weather was just right. But that dont mean the bike would turn a better 1/4 mile time. If you get the bike to 115hp and 78 f/p or more be happy with it and ride the shit out of it. One last thing what gear was the pull done in.
 
Thanks for all the input guys.The chances of me doing another pull is pretty slim.The closest Dyno to me is about 100 miles.Like i said im very happy with my bike and will ride it like i stoled it till im to old or i lose my license,which ever comes first.Sorry Mike dont really know what gear he run it in.I took a video of it and if i can figure how to upload it i will.
 
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