1996 VT1100C bucks at low RPM

I recently purchased a 1996 Honda VT1100C with a four speed tranny. It's geared quite high, which is OK, but it bucks violently when lugged down, especially in fourth gear. Has anyone else experienced this problem, and have you found a fix for the problem?  

Hi.  You use the term "lugged down".  This sounds like you've not geared down far enough and kept your revs up accordingly.  If you stay in a gear that's too high for the speed your travelling and the reduced revs your dropping down to, when you try and accelerate you can't generate enough torque to pull properly.  If that's the case, you need to gear down and get your revs up.  The problem should go away.  If this doesn't work for you, I'm sure there are other readers who will be able to offer better solutions.  Cheers.  Herb.  

Yep, get the rpm's up. You can damage the drive train doing that. If you want to be able to operate the engine at that rpm under load, get a bike with a 4 cylinder engine.

regards,
Joe  

Perhaps I mis-stated the problem. The problem occurs at speeds below 55 MPH in fourth gear. The bike doesn't have a tach, so I don't know what the RPMs are at 55 MPH, but it daesn't buck at lower RPMs in second or third gear. I had a 1983 VT750 Shadow and it was much more tolerant of lower RPMs. I have a GL1500 and a GL1800 Goldwing, and yeah, those engines will pull smoothly down to 1000 RPM.  

Looking at a dyno of a Vt1100 motor, they are basically worthless at less than 3 grand. 3 grand 42hp, 2.5g, about 34 and dropping rapidly, 4 grand about 52hp.

I've got a gl1800, and it'll pull reluctantly from 1000, it wants at least 2 to 2.5.

The reason it doesn't buck at the same rpm in lower gear is simple to explain:
You are in a lower gear, and the available torque has been multiplied by the lower gear ratio of 2nd or 3rd.
As an example. Sport bikes put out lots of HP at high rpm, but not a ton of torque. HDs put out a ton of torque at low rpms. In stock trim, the average sport bike will blow past the HD because of the gearing. The sport bike generates lower torque, but at higher rpms. The gearing converts that to more actual push on the pavement.  

Let's put this in perspective, Bob B.

Go riding on the GL1800 in high gear, slow down until the engine is turning at 800-850 rpm. Then twist the throttle and see if it behaves similarly to what the Sabre does at 55 mph in high gear. At 800-850 rpm, the 6 cylinder engine will be firing about the same number of cylinders per second as the 2 cylinder engine does at 2500 rpm, which is about what your Sabre should be doing at 55 mph. The Sabre has much larger cylinders, so the GL won't be bucking nearly as strongly, but the feeling should be about the same if you really twist the GL's throttle.

regards,
Joe  

Yeah, sloowpoke, I agree that the GL1800 would not respond well to extreme throttle at 800-850 RPM, but it will pull nicely at 1000 RPM with a moderate twist of the throttle. The Shadow, on the other hand won't take even a small amount of throttle at 45 or 50 MPH without going into a spasm.  

Bob, at 55, your bike is doing 2500rpm, which means 34 hp, and no torque multiplication to help you. You have an engine that likes high rpms, and a rider that likes low rpms.
That's the bottom line. You either decide to ride the bike you have like it wants to be ridden, or, you buy a bike that will do what you want it to. That means 1500+ engines.
I had an 800cc and in my hands, it kept up with Kawi 1500s, HD tc88 stage 1 and 3 kits. I learned where my engine made power, and I kept it there. Most of those other people never did, so, my job was not to blow their doors off. They tried to keep the rpms low, and were strangling their motor. I let it rev. The Kawi 800 red-lined at 50mph in 1st gear. You are crabbing about not being able to get peppy acceleration in top gear. If I was running my 800, I'd be in 2nd or 3rd (out of 5) at that speed if I'm trying to accelerate.  

I think we're dealing with a matter of degree here. At 45 (@ 2000 RPM), the Sabre is being asked to do what the GL would be doing at about 700 RPM. While the V-twin isn't making a lot of power then, it should still be able to pull fairly steadily at mild throttle settings. I routinely cruise around at speeds down to about 40 mph on my Sabre in high gear and it will still pull steadily at mild throttle settings.

The bucking is a sign it is making plenty of power, but not with both cylinders. This could be a spark problem or the carbs could be out of balance. After 13 years, high voltage wiring isn't all that reliable and if it's a low miles bike, the carbs are probably dirty too. If it's a high miles bike, it'd probably be a good idea to do a compression test on it.

regards,
Joe  

I forgot to mention the rubber dampers in the rear wheel. It's not as bad as a harley, where the rubber dampers are inside the primary housing and subjected to so much heat that they only last 10,000 miles, but with an older bike they may be contributing to poor low rpm performance. Older bikes generally have multiple interacting causes to problems, rather than a single cause.

regards,
Joe  

If Bob is determined to get it to accelerate reasonably from 50 in top gear, he could replace the intake with something like a thunder air kit. Don't replace the exhaust.
If you replace the exhaust, you interfere with the back pressure, and could actually decrease torque (the stuff you want). You increase HP, but, that's at RPMs you aren't dealing with.

I did the mod on a Kawi 800. Before the mod, 30-50 in 3rd was 5 sec. After 4sec. The bike also went from lugging at 50mph in high gear to lugging at 40mph.
My only complaint was that at higher rpms, I did smell gas. A slightly smaller main jet would have worked better in my application.  

Seems like a lot of work and expense to me, when it would appear that our original suggestions to gear down and get the revs up is the answer.  He's got a bike that's got it's own specific design features and therefore it's own operational idiosyncracies.  You can't make a silk purse out of a sow's ear...deal with it and shift gears.  Or get rid of the bike if it doesn't suit your riding style, tendencies, and preferences, and get one that does.  Cheers.  Herb.  

Thanks guys! I really appreciate the various suggestions. I will checks the dampers in the rear wheel. I have cleaned and sync'd the carbs. I'll also check the spark intensity, and I'm wondering if there might not be too much timing advance. I agree that there's probably multiple contributing factors. Apparently, Honda has resolved much of the problem, as the newer 1100's are much more tolerant of lower RPMs. Anyway, the bike is fun to ride and gets 60+ MPG, but the GL1800 is still the epitome of comfortable, powerful bikes.