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  Topic Review (Newest First)
11-17-2013 04:09 PM
VN750Rider/Jerry I thought the actual RWH was around 50. It feels like it. The Vulcan 750 will blow the wheels off a Honda Shadow 750 (the late models) Mine will accelerate hard up the steepest hill in the state in top gear, with my 230 pounds and some other stuff on it. I only need to downshift it while riding in the mountains when I slow down, to keep the rpms up. I ride at an indicated 85 all day (that's an actual 79, speed limit is 75) with no problems. It's as smooth as silk at those speeds. Remember the redline is 8500, so you have plenty of rpm. It was not meant to run at 3000 rpm like a Harley with a 5000 rpm redline. Ride the Vulcan 750 like a sport bike. The powerband goes above 6000 for sure, maybe past 7000. This engine has a top end rush like an inline four. I think I've pretty well proven it won't fly apart at high rpms. Just make sure your cam chains are not loose.
11-16-2013 12:40 PM
wmsonta
Quote:
Originally Posted by Jakzen View Post
I wonder if running an oversize rear tire has anything to do with the higher rpm?




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I (I) would expect this result when ear shaved and de-goated.

I would also say, anybody who can match or exceed factory published numbers can be proud. IMO, most factory numbers are not exaggerated, but are taken from carefully prepared/assembled/optimized units. For example, in 1970. I was asked to help with an LS6/454 (450 hp) chevy to see if it was competitive in Pure Stock drag racing. It was not. After complete dis assembly/blueprint/non legal exhaust manifolds it made 435. 410 hp from GM with non Chevelle manifolds.
11-16-2013 12:06 AM
Jakzen
Quote:
Originally Posted by wmsonta View Post
Tq and hp peaks appear to occur at a slightly higher rpm than OEM. No way to say if the torque curve is down as would be expected.
I wonder if running an oversize rear tire has anything to do with the higher rpm?




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11-16-2013 12:01 AM
Jakzen
Quote:
Originally Posted by wmsonta View Post
How would you know? I think guess is the right way to say it.
I am guessing. It pulls strong up to around 5500 and tails off above that (in any gear). when the guy running the dyno had her wfo she wasn't spewing black exhaust, so I'm assuming that I'm running lean Mains.



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11-15-2013 06:25 PM
Old Dog My Sportster will smooth out at +/-3.2 - 3.4k rpm, I know that is not it's strong point, but you can just feel the vibes settle there... I have seen over 7k on the tach, but it's stage 1 + and the rev. limiter has also been re-calibrated... The 750 Vulcans, I didn't mind runnin 8-9k as they were stronger there... I dropped my 03 VN in the damp yard grass to the right side and tried to hold it up by the throttle side of the bar, and I swear I saw 11+k on the tach on its way back down, I believe it must have pegged ...lol... It didn't seem to do anything, it run the same as always... I don't advocate running that 11k, but the VN750 does seem to like high rpm for a V-twin cruiser...JMO...
Have a good one...Old Dog...
11-15-2013 04:00 PM
Knifemaker
Quote:
Originally Posted by gibbo View Post
Just to add my thoughts on RPM's. I have always understood that a more critical factor is the piston speed. A short stroke motor will rev higher for a given piston speed than a long stroke motor.
Yep, and mass figures in too.. You can have two motors with the same stroke, same displacement...but one has much smaller pistons (inline 4 or six) than the other (single or twin).

Most small displacement multi cylinder bikes will have a much higher redline than larger displacement bikes, so it's not just length if stroke but the actual weight of the components.(rods, wrist pins, pistons and clips)
11-15-2013 02:40 PM
OleDirtyDoc
Quote:
Originally Posted by Mercury View Post
I wanted to add that if you never brought a bike to redline before, you will be amazed at the power you have in reserve.

kenny
I agree 100% Kenny
11-15-2013 12:44 PM
Mercury
Quote:
Originally Posted by gibbo View Post
Just to add my thoughts on RPM's. I have always understood that a more critical factor is the piston speed. A short stroke motor will rev higher for a given piston speed than a long stroke motor. 7K revs on my 750 Norton Atlas is close to calamity as it is a long stroke engine, whereas the same piston speed on my ZZR250 is probably over twice the RPM.
The Atlas is safe to about 6K in standard form, The ZZR 250 is redlined at 14K. Not sure about now, but I seem to remember things get a bit chancy with a piston speed of much past 3K feet/min.
that is why those inline 4's (street racing bikes) have redlines around 14K, my 800 has a 8K redline.

The bikes today also most if not all have rev limiters.

These jap bikes just love to rev.

I am not sure what you mean by feet / min, if my stroke is 2.6" and the formula for feet / minute is stroke x RPM x 2 then we get 3466 ft / minute if my rpm is 8K

But that is my redline, I mostly run @ 5K when riding aggressive... so

2166 ft / min interesting, don't know if I can do anything with this data, but interesting hehe


kenny
11-15-2013 12:26 PM
gibbo Just to add my thoughts on RPM's. I have always understood that a more critical factor is the piston speed. A short stroke motor will rev higher for a given piston speed than a long stroke motor. 7K revs on my 750 Norton Atlas is close to calamity as it is a long stroke engine, whereas the same piston speed on my ZZR250 is probably over twice the RPM.
The Atlas is safe to about 6K in standard form, The ZZR 250 is redlined at 14K. Not sure about now, but I seem to remember things get a bit chancy with a piston speed of much past 3K feet/min.
11-15-2013 11:57 AM
Mercury I wanted to add that if you never brought a bike to redline before, you will be amazed at the power you have in reserve.

kenny
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