dyno differences

[WAKEBOARDDAVE1]

I had my shee built up 4 mil crank, case packed, flywheel lightened, better pistons, longer rods, and other extras end result 72 HP. went and got 35 mil carbs is set a little to rich on bottom end and ran on a different dyno and only got 67 HP the dyno's name is heart breaker. still runs like a bat out of hell and I havent been able to race my buddy with the same set up but stock carbs yet.They ran neck and neck before.

[2003LimitedBanshee]

So to make sure I've got it right, you swapped carbs in between dyno pulls? If so it sounds as though the jetting was off on the second, and/or the 35mm carbs are just too big for what the motor can pull. You can over carb, and many people make the mistake of thinking bigger carbs will always be better. One thing you have sacrificed with the bigger carbs for sure is some intake velocity, although this normally effects torque more noticeably. But torque is a factor of HP, so it would carry throught to some extent. Also keep in mind that dyno readings are likely to vary between dynos, air temp from day to day etc. etc., but 5HP is probably more than I would expect. My bet is that the jetting could be improved, but the carbs may simply be too big for your current setup.

[FIRST BANSHEE]

different dyno, different day, new carbs.that sounds like the problem.

try back at the first dyno,and tweek the carbs a little. good luck

[s-540]

i took my street bike to a dyno and had a couple of runs on one. i cleaned the filters and got 5 horses out of it. i had to clean them all the time. there are alot of variables that can affect jetting and horse power. i would dial in your carbs and not even worry about it unless you have money to burn or you are a hard core drag racer.

[s-540]

what do you mean by case packed.

[odaen]

Dynos even made by the same manufacturer can vary. Some builders have dynos that are considered "stingy" compared to others. Could be why they call that dyno "Heart Breaker".

 

2003LimitedBanshee brings up some good points though. I ran stock carbs in my 4mm stock cylinder and dyno'd it at 76HP with pump gas domes on a "stingy" dyno.

[bansheefreak]

read my signature!!!!

[odaen]

read my signature!!!!

466408[/snapback]

 

Ain't nothing wrong with using a dyno to get a baseline of how your bike performs before and after mods. Otherwise you get the "new shoes" syndrome, where you think you can jump higher and run faster because of your new Nike's. So, unless you got timeslips to compare against, dyno plots are very useful.

[bansheefreak]

yeah i know i would prolly get a dyno sometime too after mods.. i just like the qoute...

[hittintrees srh]

No Way are your 35's too big for you set-up! (im assuming your ported)

 

My shee got huge gains from my 36's, and ive got a stock stroke.

 

it must be the tuning was way off

 

......or maybe you need a bigger boost bottle

[[email protected]]

No Way are your 35's too big for you set-up! (im assuming your ported)

 

My shee got huge gains from my 36's, and ive got a stock stroke.

 

it must be the tuning was way off

 

......or maybe you need a bigger boost bottle

466590[/snapback]

 

 

you need to try the new two lieter boost bottle custom modification

[Banchetta]

You can't compare numbers w/ different dynos for one....two, I've seen 4hp difference from one day to another w/ no changes and the same dyno...of course I run on a car dyno so we have to use like 8 straps to hold it down, that alone will affect it dramatically...when I do dyno testing, I leave my shee on the dyno and change mods, then rerun. Only way you can do it. Otherwise your wasting your time....

[odaen]

No Way are your 35's too big for you set-up! (im assuming your ported)

 

My shee got huge gains from my 36's, and ive got a stock stroke.

 

it must be the tuning was way off

 

......or maybe you need a bigger boost bottle

466590[/snapback]

 

 

Pretty pathetic when someone asks a valid question on here and gets ridiculed. Whatever it takes to stroke your own ego though, ehh?

[Wallrat]

I've heard of some of some shops setting up their dyno's to give better results. I guess you can tweak those things quite a bit. All I know is that I've seen 75hp machines on one shop's dyno consistently murder 100hp machines from another shop's dyno. Dyno #'s have to be taken with a grain of salt. Really they're more of a measurement tool to gauge how certain mods affected your machine than a way to compare one machine to another, or one shop to another. Pick one dyno and stick with it. Pay more attention to the increase/decrease you get before and after mods than the actual #.

Edited February 2, 2006 by Wallrat

[WAKEBOARDDAVE1]

well I got back to the first dyno I stayed for this one and it ran at 67hp also, but when we started rejetting he went from a 150 jet to a 138 and then found out the adj on top of the carb was way out and they didnt synch the carbs. I got screwed basicly they half assed it, and gave it to me. I figured N motion would do a better job. so any way after we got done it was making 71hp which is a one HP down from the stock carbs but it has alot more grunt and power through the pull of each gear. its lean down on the low end and he said a different needle will give more HP down low and go throughout the pull to the high end. possibly one to four HP. does that make since or is everyone dumber now.Oh and yes I clean my filter every time I go ride. I cant wait to hit the drags at little sahara, to bad it took a extra hour and ahalf longer on the dyno and alot of cash, but shes cheery now.