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Post by 2strokd on Apr 19, 2011 9:44:10 GMT -5
i bet sliders give it a MPH or two?...
My Cobra wont rev over 8,500 or so with the stock exhaust.
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Post by 90GTVert on Apr 19, 2011 13:03:31 GMT -5
Yeah, I think 8,800 is a little high. That's absolute max tucked for a long stretch though. Under more normal conditions, it operates right in the range it should be for the most part. Best power seems like it's in the 6,000-8,000 range.
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Post by reiko1078 on Apr 19, 2011 18:04:16 GMT -5
Hey 90 can you shoot me a link for the thread when you first got this 90cc and you tore it down and prepped it? I know I've seen it before but I can't seem to find it
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Post by 90GTVert on Apr 19, 2011 18:17:59 GMT -5
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Post by reiko1078 on Apr 19, 2011 23:33:52 GMT -5
Thanks! Did you ever use a 90cc out of an atv that you had to mod to run a scooter wheel? Or am I goin crazy
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Post by 90GTVert on Apr 20, 2011 0:05:28 GMT -5
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Post by detonatortuning on Apr 20, 2011 8:14:07 GMT -5
Brent, isn't this project 90 engine a longcase ? if so, is there any alternative wheel tire combo's that could be used to back into a slightly better overall gearing ?
steve
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Post by 90GTVert on Apr 20, 2011 8:37:04 GMT -5
It's a longcase. I could bolt on something as small as a 10" wheel I know, with a low pro tire. I think it would look weird though... not that T2 doesn't already look weird. lol
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Post by 190mech on Apr 20, 2011 9:12:22 GMT -5
The ratio you have now would be ideal for a modded 100!
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Post by detonatortuning on Apr 20, 2011 12:20:33 GMT -5
Yeah, I think 8,800 is a little high. That's absolute max tucked for a long stretch though. Under more normal conditions, it operates right in the range it should be for the most part. Best power seems like it's in the 6,000-8,000 range. from this i thought you were looking at seeing if you could pick up some mph by dropping the rpm's out of the over-rev back toward the power peak. so i was looking at a taller wheel / tire combo. you must be thinking of going on the other way, toward more rpm. steve |
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Post by 90GTVert on Apr 20, 2011 12:49:55 GMT -5
Oh, I thought you were referring to what I said with the vari mods about long gears and lacking power.
I'm not really looking to change final drive ratio at this point. I think this is about what some others said their 90 crate motors came with. I don't feel like that's a step the average rider would take at this point either. I really don't think it needs more of an upgear. It lacks power to pull what it's got IMO. Heavier rollers would drop the RPM out if I wanted to, but it's quite nicely in tune for average riding. It takes being tucked for a long stretch for me to squeeze out that last bit of speed and RPM anyway.
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Post by detonatortuning on Apr 20, 2011 16:02:09 GMT -5
interestingly, the stock grand axis 100 is rated at 9.8HP @ 7,000rpm from 52mm B x 47.6mm S.
if you drop that by 10% for the 90 we might expect 8.8HP at nearly the same rpm ?
actual experience, esp. with the evidence you've provided is much more dependable than any spec. sheet, so if you say it's light for the gears i believe it.
it would however be over 2 times the power i would need for my project at an rpm i would consider more reasonable for steady cruising. a side point being that for my purpose i could reconsider the engine placement and convert it to sprocket output ( like the polaris atv units ) and have nearly unlimited final gearing options.
it makes me wonder what gears are in this 90cc we got from scrappy ? i'll have to try to figure that out and get an ACCURATE speed check on it.
thanks for a great informative thread, sorry i got off track"thinking" again.
steve
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Post by 90GTVert on Apr 20, 2011 18:02:56 GMT -5
I'm horrible with HP figures. I really have no clue what these things put out. I need a dyno. ;D 7,000RPM-7,500RPM may be peak HP on these, not 100% sure. Even if that is the case, they still make good power into the 8,000RPM range. Really, the power doesn't start to come on strong till 6,000RPM. Dunno if that shows well in the vids, but you can sure feel the difference riding it after 6,000RPM.
That's a good point for your project. That's the thing I miss so much about my old pitbikes, well... other than shifting sometimes.... the ability to simply change a sprocket. So much easier than changing out primary or secondary gears.
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Post by lauderdaleboats on Apr 20, 2011 18:45:42 GMT -5
"it makes me wonder what gears are in this 90cc we got from scrappy ? i'll have to try to figure that out and get an ACCURATE speed check on it."
The 100cc I just got from Scrappy has 10.125:1 gearing
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Post by 90GTVert on Apr 20, 2011 18:57:17 GMT -5
That's what I thought. Thank you. Same thing I have in this one. ;D
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