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Originally posted by andrewpogany
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VERY interesting posts, guys. Now, from my car hotrodding days (vw and ford) and having read several very interesting hotrod books -most notably by David Vizard, I have a few things to say:
1. Looking at your gs1100 numbers, I now must seriously question the dyno numbers I paid for/given to me w my current setup which were 90hp peak at rear wheels (columbus, OH, mid 90's, I forget the shop).
2. Indeed, torque is more important than peak HP. The big thing the dyno #s almost never tell you is part throttle feel. My setup before my current setup was a MAC header with baffle totally removed (talk about "wake the neighbors"
) and carbs jetted dead on. Bike was loud as hell at all speeds, cantankerous as hell at all but full throttle, but absolutely ran like a "rapedape" when wide open.
When I changed to Yosh "race" header with "street" baffle (current setup) I had to rejet. It wasn't as fast but much more civilized at part throttle, lower rpm range, and much easy to ride/more fun. After I changed from 630 to 530 chain along with One Less sprocket tooth (or was that 1 more? I always forget
for more acceleration/less top speed), the bike felt about the same at wide open throttle as before. Albeit with lower top speed.
3. I think the peakHP/peakTorque relationship is a bit more complex than 49er and PosPlayr are saying here. Yes, yes, exhaust backpressure is a factor. But also important factors, besides valve overlap, potentially so is valve lift (both intake and exhaust), as well as intake manifold design as far as air speed & restrictions, as well as carb tuning (idle / part throttle / full throttle), not to mention spark, combustion chamber shape/flame front pattern & speed, compression ratio, as well as gas quality and ignition timing.
You can dog the dyno, but it's the only real empirical none "seat of the pants"/not subject to psychological self-brain-washing-into-believing-"bygodyes,I now have more Power" delusion.
4. Unless you have a GS1100 or GS1150 and are the dragracer type, and which dragracers still use to this day (just like Dodge 426 Hemi's), if you want "more" power and a "more civilized" bike WITH the more power, the easiest way to do that is to buy a newer bike (sorry). Any 600 sold in last 5 years will kick the crap out of my hotrodded old late70's/early 80's 750 both in power and weight (and power to weight) and handling etc.
5. Last but not least, if you DO hotrod an older GS, hang in, endure the pains, then you will ultimately have a GREAT running bike that is virtually mechanically bulletproof, cool looking, great sounding, you can ride with anyone to anywhere, AND be able to "run with the kids" (i.e. today's 600's and 750's) - at least in a straight line against kids who don't quite have your "old guy" skills. Not to mention riding NOT= racing. So what if your bike isn't as fast? Is a '65 mustang not cool regardless?
1. Looking at your gs1100 numbers, I now must seriously question the dyno numbers I paid for/given to me w my current setup which were 90hp peak at rear wheels (columbus, OH, mid 90's, I forget the shop).
2. Indeed, torque is more important than peak HP. The big thing the dyno #s almost never tell you is part throttle feel. My setup before my current setup was a MAC header with baffle totally removed (talk about "wake the neighbors"
) and carbs jetted dead on. Bike was loud as hell at all speeds, cantankerous as hell at all but full throttle, but absolutely ran like a "rapedape" when wide open.When I changed to Yosh "race" header with "street" baffle (current setup) I had to rejet. It wasn't as fast but much more civilized at part throttle, lower rpm range, and much easy to ride/more fun. After I changed from 630 to 530 chain along with One Less sprocket tooth (or was that 1 more? I always forget
for more acceleration/less top speed), the bike felt about the same at wide open throttle as before. Albeit with lower top speed. 3. I think the peakHP/peakTorque relationship is a bit more complex than 49er and PosPlayr are saying here. Yes, yes, exhaust backpressure is a factor. But also important factors, besides valve overlap, potentially so is valve lift (both intake and exhaust), as well as intake manifold design as far as air speed & restrictions, as well as carb tuning (idle / part throttle / full throttle), not to mention spark, combustion chamber shape/flame front pattern & speed, compression ratio, as well as gas quality and ignition timing.
You can dog the dyno, but it's the only real empirical none "seat of the pants"/not subject to psychological self-brain-washing-into-believing-"bygodyes,I now have more Power" delusion.
4. Unless you have a GS1100 or GS1150 and are the dragracer type, and which dragracers still use to this day (just like Dodge 426 Hemi's), if you want "more" power and a "more civilized" bike WITH the more power, the easiest way to do that is to buy a newer bike (sorry). Any 600 sold in last 5 years will kick the crap out of my hotrodded old late70's/early 80's 750 both in power and weight (and power to weight) and handling etc.
5. Last but not least, if you DO hotrod an older GS, hang in, endure the pains, then you will ultimately have a GREAT running bike that is virtually mechanically bulletproof, cool looking, great sounding, you can ride with anyone to anywhere, AND be able to "run with the kids" (i.e. today's 600's and 750's) - at least in a straight line against kids who don't quite have your "old guy" skills. Not to mention riding NOT= racing. So what if your bike isn't as fast? Is a '65 mustang not cool regardless?
on the final results too, but decided my post was already rather large.
Rays got a good point too. I think an 1150 that was punched out to 1400 would have some serious reliability issues though, for road use !!
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