Design Disadvantages of the CB1100

[thessler3_imp]

All inline 4 engines have good primary balance (2 pistons up and two down simultaneously) but inherently bad secondary vibration. Secondary vibes occur at twice engine speed and create a high frequency buzz. I believe the CB1100 has a single balance shaft. Some other Hondas, like the Blackbird had two, which is a better solution. However, pistons go up and down and balance shafts rotate, so they only reduce secondary vibration, not eliminate it. By the way, most 4 cylinder bikes have cylinders that are separate from the crankcase, not cylinders bored into the block. Also, parallel twins can have several configurations, like Triumph's 360 degree crank with both pistons up and down together, Honda's earlier 350 & 450 have 180 degree cranks with one up and one down and the Yamaha Tenere with crankpins at 90 degree separation. I have studied vibration for years and the smoothest engines are straight sixes, boxer sixes and 90 degree V-twins of smaller displacement. In my opinion, any other engines would be better served with rubber motor mounts, even if it adds weight.

 

[Mick65_imp]

The early Norton Commandos were indeed rubber mounted, if my memory serves me well, they were smooth, Nortons from the 60's, The Atlas were very bad for vibration.
Flat 6 Goldwing is superbly vibration free..
Vibration is always top of my list when buying a new bike...

 

[Red Mist_imp]

The early Norton Commandos were indeed rubber mounted, if my memory serves me well, they were smooth, Nortons from the 60's, The Atlas were very bad for vibration.
Flat 6 Goldwing is superbly vibration free..
Vibration is always top of my list when buying a new bike...

That was the "Featherbed" frame.

 

[the Ferret]

Actually RM the featherbed frame came out in 52 or 53 long before the Norton Commando. It was a good handling designed frame designed for racing I believe. The isolastic frame with the rubber mounts replaced the featherbed frame and came out on the Commandos around 1967, the year before I graduated High School.

 

[Mick65_imp]

You used to shim the swinging arms to adjust side play, I can remember calling them "Rubber Bands"

 

[Capo]

Thessler3, great first post, and thanks for the science behind it all! Triumph also engineers in some dissonance with the 270 degree version of the vertical twin used in the Scrambler and cruiser variants of the Bonnie. Done for 'character' along the lines of Honda twisting the timing on two of the CB1100's cylinders, I suppose. As for the Atlas, I can attest to it's vibratory nature, as it powers my Norton P11, which is a Matchless Reynolds scrambler frame. It is hard to describe the level of vibration, and hard to imagine that journalists of that era described it as a 'mild and acceptable.'

And correct, the rubber mounting came with the 'Isolastic' frame of the Commando, not the Featherbed.

 

[the Ferret]

Anyone who has ridden a British 500 single from the 50s can attest to the OH MY GOD THIS THING VIBRATES, as if all the motor mounts were loose, and the realization that anyone who actually raced one of those shaking beasts was a SUPER HUMAN.

The I 4 like the CB 1100 may not have perfect or secondary balance even with a counter balancer or two, but in comparison, they are silky smooth.

 

[thessler3_imp]

Thanks for the compliment CAPO. Note that the new Norton has a 90 degree crankpin separation. So does the Husqvarna Nuda (now discontinued). They sound like Ducatis when running. I once owned a Norton Combat Commando with the isolastic suspension. It was a bit like a rubber mounted Harley in that the engine shook a lot at idle but was smooth at highway speed. I am thinking of buying a CB1100 and confirmed it has a single balance shaft running at twice engine speed geared off the crankshaft. It also appears to have rubber grommets on one of the rear engine mounts. Suzuki has done this before too to help quell vibration into the frame near the footpegs. I am very sensitive to vibration and have studied it quite a bit. In line fours are hard to get smooth over about 5000 RPM. I currently own a '73 Ducati 750GT and that 41 year old motor is quite smooth.
I once restored a mid-sixties BSA 441 Victor. It was indeed a paint shaker and would also kick back violently when trying to start it. The all-time vibrator I have ridden was a friend's 1956 Harley '74, which would vibrate your feet right off the floor boards at 70MPH. My '66 Triumph Bonneville would go through light bulbs every month or so when the filaments would get vibrated to an early death. Smoothest I have ridden - a CBX six, a Gold Wing six and my restored 73 Ducati 750GT on which you could balance a quarter on the crankcase when it was running - no exaggeration. It now has replacement pistons and is not quite as smooth as it was originally. My Foggy Monster with 916 engine was also pretty smooth, but not as smooth as the 750GT.

 

[flynrider]

I was cruising down the freeway last Sunday when I noticed I hadn't bothered to shift into 5th (as usual). I was turning 5K rpm in 4th and that feels normal to me, since that's what the CB750 does in 5th at 75 mph. When I shifted into 5th and the rpm dropped to 4200, I noticed that I actually felt more vibes in the bars than I had at 5K. I thought it was a bit strange, so I shifted back and forth and it definitely seemed shakier at the lower rpm. Maybe that's why my brain so often forgets to shift up from 4th gear.

I used to own a lot of twins with 360 cranks, so vibration was just a normal part of motorcycling. When I took my first ride on an I-4 bike ( a Kaw Z-1) I was stunned. I never knew a motorcycle could be so smooth. In fact after I started it, I had to double check the tach to verify that the engine was running. I don't think I'll ever go back.

BTW, the shakiest bike I've ever ridden was a Yammie XS650 twin that was converted to a "twingle". The cam was modified so that both cylinders would fire simultaneously. Interesting bike, but it couldn't be kick started by anyone under 250 lbs. and the electric start would only work if you hooked a car battery to it. The guy that modified it didn't think of adding a compression release

 

[the Ferret]

I've had 3 of the Yamaha 650 twins, a 73 TX, a 79 XS and an 81 XS Special. I obviously have a soft spot for them. Bought the 73 brand new. Yes they vibrate. At redline they would blow these little round instrument bulbs. Used to keep a handful of bulbs in my pocket and rerouted the sockets so I didnt have to remove the instruments to fit em. On the centerstand you could rev them up and they would walk across the floor. Still smooth as silk compared to an old British single. If you ever get the chance to ride one of the Brit bikes do it, you'll see.

Also had 3 harley Panheads 49, 56 and 57 and yes at high speed your feet would just walk off the floorboards. (and 2 harley Sportsters 59 and 94 which would make your hands itch and go numb at 55 mph and above)

Looking back at it, no wonder I think I-4s are so smooth

 

[Scoobynut_imp]

I was cruising down the freeway last Sunday when I noticed I hadn't bothered to shift into 5th (as usual). I was turning 5K rpm in 4th and that feels normal to me, since that's what the CB750 does in 5th at 75 mph. When I shifted into 5th and the rpm dropped to 4200, I noticed that I actually felt more vibes in the bars than I had at 5K. I thought it was a bit strange, so I shifted back and forth and it definitely seemed shakier at the lower rpm. Maybe that's why my brain so often forgets to shift up from 4th gear.

I used to own a lot of twins with 360 cranks, so vibration was just a normal part of motorcycling. When I took my first ride on an I-4 bike ( a Kaw Z-1) I was stunned. I never knew a motorcycle could be so smooth. In fact after I started it, I had to double check the tach to verify that the engine was running. I don't think I'll ever go back.

BTW, the shakiest bike I've ever ridden was a Yammie XS650 twin that was converted to a "twingle". The cam was modified so that both cylinders would fire simultaneously. Interesting bike, but it couldn't be kick started by anyone under 250 lbs. and the electric start would only work if you hooked a car battery to it. The guy that modified it didn't think of adding a compression release

That's an interesting observation which I concur with. I've found when I rev my bike beyond 5k rpm up toward 7.5k rpm the motor definitely passes out of the 'vibe' range and smooths out again at those higher rpms. You might call me crazy, but I think a freer-breathing exhaust helps a motor run smoother at higher rpms. I have a staintune on my bike, but then again I didn't really rev the bike high when it had the stock exhaust. The reason I say this is that I had a Subaru that got very vibey above 5k with stock exhaust, but once I installed a free-flowing exhaust it was smooth as glass all the way to redline, as if the stock exhaust choked the motor up and caused vibes at higher rpms. In any case, that was my experience with that car.

 

[thessler3_imp]

I am now 66 years old and have been riding nearly 50 years on more than 30 bikes of many brands. I have read that your arms, hands etcetera can become sensitized to vibration. Lots of studies have been done on users of hand tools that vibrate and the hands can lose feeling completely over years of abuse. I started out on Triumph and Honda twins in the Sixties and always tolerated the vibes until the last 10 years or so and I am now a lot more sensitive. I have yet to find an in-line four that is really smooth, but it is all very relative to what you rode previously, as Ferret mentions. I have 3 bikes now, a 2003 Gold Wing, A '73 Ducati and a Tuono V4. All are smooth enough for me. I tested a CB1100 the other day and like that it has a pleasant smooth zone around 70MPH in 5th gear. I am dickering with the dealer and will likely buy it. The Tuono V4 is going up for sale. Great bike for a fast guy but very stiff suspension and hard seat. I am getting too old and actually appreciate that the CB1100 is a much milder bike and good for these old bones.

 

[the Ferret]

Gee thessler 66 puts you into one of our upper age brackets lol

Average CB1100 Rider Age

 

[Red Mist_imp]

I was cruising down the freeway last Sunday when I noticed I hadn't bothered to shift into 5th (as usual). I was turning 5K rpm in 4th and that feels normal to me, since that's what the CB750 does in 5th at 75 mph. When I shifted into 5th and the rpm dropped to 4200, I noticed that I actually felt more vibes in the bars than I had at 5K. I thought it was a bit strange, so I shifted back and forth and it definitely seemed shakier at the lower rpm. Maybe that's why my brain so often forgets to shift up from 4th gear.

I used to own a lot of twins with 360 cranks, so vibration was just a normal part of motorcycling. When I took my first ride on an I-4 bike ( a Kaw Z-1) I was stunned. I never knew a motorcycle could be so smooth. In fact after I started it, I had to double check the tach to verify that the engine was running. I don't think I'll ever go back.

BTW, the shakiest bike I've ever ridden was a Yammie XS650 twin that was converted to a "twingle". The cam was modified so that both cylinders would fire simultaneously. Interesting bike, but it couldn't be kick started by anyone under 250 lbs. and the electric start would only work if you hooked a car battery to it. The guy that modified it didn't think of adding a compression release

That's an interesting observation which I concur with. I've found when I rev my bike beyond 5k rpm up toward 7.5k rpm the motor definitely passes out of the 'vibe' range and smooths out again at those higher rpms. You might call me crazy, but I think a freer-breathing exhaust helps a motor run smoother at higher rpms. I have a staintune on my bike, but then again I didn't really rev the bike high when it had the stock exhaust. The reason I say this is that I had a Subaru that got very vibey above 5k with stock exhaust, but once I installed a free-flowing exhaust it was smooth as glass all the way to redline, as if the stock exhaust choked the motor up and caused vibes at higher rpms. In any case, that was my experience with that car.

Exhaust design absolutely can contribute to perceptible vibration. That's what an exhaust muffler is, it resonates in sympathetic frequency (sound cancellation) as well as changes the direction of the sound the engine makes. Some bikes, first generation FZ1, for example, actually have a weight added to the pipe mount to absorb vibes.

You put on a straight pipe and the shakes will go away cuz the gases have a clear path, unobstructed.

 

[Scoobynut_imp]

I was cruising down the freeway last Sunday when I noticed I hadn't bothered to shift into 5th (as usual). I was turning 5K rpm in 4th and that feels normal to me, since that's what the CB750 does in 5th at 75 mph. When I shifted into 5th and the rpm dropped to 4200, I noticed that I actually felt more vibes in the bars than I had at 5K. I thought it was a bit strange, so I shifted back and forth and it definitely seemed shakier at the lower rpm. Maybe that's why my brain so often forgets to shift up from 4th gear.

I used to own a lot of twins with 360 cranks, so vibration was just a normal part of motorcycling. When I took my first ride on an I-4 bike ( a Kaw Z-1) I was stunned. I never knew a motorcycle could be so smooth. In fact after I started it, I had to double check the tach to verify that the engine was running. I don't think I'll ever go back.

BTW, the shakiest bike I've ever ridden was a Yammie XS650 twin that was converted to a "twingle". The cam was modified so that both cylinders would fire simultaneously. Interesting bike, but it couldn't be kick started by anyone under 250 lbs. and the electric start would only work if you hooked a car battery to it. The guy that modified it didn't think of adding a compression release

That's an interesting observation which I concur with. I've found when I rev my bike beyond 5k rpm up toward 7.5k rpm the motor definitely passes out of the 'vibe' range and smooths out again at those higher rpms. You might call me crazy, but I think a freer-breathing exhaust helps a motor run smoother at higher rpms. I have a staintune on my bike, but then again I didn't really rev the bike high when it had the stock exhaust. The reason I say this is that I had a Subaru that got very vibey above 5k with stock exhaust, but once I installed a free-flowing exhaust it was smooth as glass all the way to redline, as if the stock exhaust choked the motor up and caused vibes at higher rpms. In any case, that was my experience with that car.

Exhaust design absolutely can contribute to perceptible vibration. That's what an exhaust muffler is, it resonates in sympathetic frequency (sound cancellation) as well as changes the direction of the sound the engine makes. Some bikes, first generation FZ1, for example, actually have a weight added to the pipe mount to absorb vibes.

You put on a straight pipe and the shakes will go away cuz the gases have a clear path, unobstructed.

Red Mist, thanks for that explanation. I could feel it by the seat of my pants, but wasn't sure what the reason was. I guess it wasn't just all in my head! Subaru flat-fours are supposed to have near perfect primary balance, but I guess a restrictive exhaust can make more vibes than the motor itself. Interesting.

 

[Cormanus]

It's a lovely thing. Thanks for posting that photo, Chris. You know f*$k all about beer.

Haha--I might surprise you Pal. I raced bicycles in Limburg and lived there for 3 years--down in the little geographical Dutch nutsack dangling between Germany (West Germany back then), and Belgium. Was just about 70km from Cologne/Koln, and I was a regular at all the best Kolsch breweries. After visiting me, my father started brewing his own microbrews and won many awards; (this was back in the dark days of Coors & Budweiser, before microbrews caught on in the US.)
And now I live about 4 miles from ground-zero of San Diego's microbrew big bang. I have growlers from 8 of the ~20 different breweries here (though most of them are obsessed with this IPA fad right now, which doesn't make much sense to me in a time of refrigeration and sanitation.)

I was a little tipsy on the pilsner last night, and was just joshing about Aussie beer. Cheers mate! If you ever make it to the upper half of the world, bring your boots & helmet. We've got some terrific breweries here, and even better silly-string roads.

This brewing business can lead to all sorts of disagreements. Thought you might like this, Chris.

http://www.nytimes.com/2014/03/30/magazi...azine&_r=1

 

[avsbezzy_imp]

The only disadvantages for an I4 that I know of came from reading Kevin Cameron (Cycle World.) He puts some people to sleep but he did one article comparing I4s to V4s, mainly in racing applications, and since I own a V4 Interceptor I was able to stay awake for that one.

First, an I4 with a 180* crankshaft has a dead inertial moment twice every rotation as the pistons bottom out/top out at the same time. IIRC, this creates a need for beefier counterweights on the crank. Racing engines where the counterweights were lightened up too much resulted in "shuddering" at corner exit as power was applied at lower RPMs. In the V4, when two pistons are at the top/bottom of their stroke, the other two are in the middle of a stroke, resulting in continuing inertia, and the ability to use lighter counterweights.

With the heavier counterweights and a generally longer unit, the crank has much more of a gyroscopic effect, resisting turn in, and making the bike feel heavier. Again, V4s by nature have a narrower crank and produce less such turning resistance.

As Ferret mentions, the engine is wider in an I4 and can create a teeter totter effect compared to an V4, which is more centralized in the bike like a bowling ball.

Another difference between these two isn't an advantage/disadvantage, just a difference. The I4 makes its power fairly evenly with power pulses like x-o-x-o-x-o-x-o. That's a gross oversimplification, I think, but you get the idea. The V4 is more like x-x-o-o-x-x-o-o. That is also an oversimplification. In racing, the V4's gap in power pulses aided corner exit by acting like a kind of traction control as the "rests" helped the tire reconnect in moments of too much throttle while the bike is leaned over. However, in a street riding application, this has little utility.

Finally, there's the sound. An I4 can have that angry-hornet-riding-a-jet-turbine sound while a V4 has a distinctive growl often described as half of a small block Chevy. Both, frankly, are music to my ears.

Great post! Learned a lot again, Thanks.

 

[DAC]

Glad you enjoyed it!

 

[thessler3_imp]

I see a lot of mis-truths posted in this article about inline 4 cylinder vibration. Inline fours with 180 degree cranks have very good primary balance and very poor secondary balance. Primary vibration is at crankshaft RPM. Secondary is at twice engine RPM. Most inline fours have balance shafts. The CB1100 and ZX-9 and most other fours have a single balance shaft that turns at twice engine RPM. Some bikes, like the Blackbird have two shafts that turn in opposite directions. In either case, the shafts help, but rotating weights are a compromise when trying to cancel reciprocating motion. Balance shafts were first invented and patented by British engineer Frederick W. Lanchester in 1904. Most 4 cylinder cars have balancer shafts and rubber mounts. Think of it as belt and suspenders. CB1100 does have one rubber mount at rear. Nearly every engine configuration on motorcycles has inherent vibration of some sort. Exceptions are the sixes - CBX and Gold Wing are quite smooth and need no balancer shafts. 90 degree V-twins are smooth in moderate displacements, but have some secondary vibrations. I have a classic Ducati 750GT that is pretty smooth. I am sensitive to vibration in my hands after riding for more than 50 years and I have studied the subject extensively.

 

[treytexag_imp]

thessler, good write up here. I learned alot in your short paragraph - thanks for sharing it my man.

Trey

I see a lot of mis-truths posted in this article about inline 4 cylinder vibration. Inline fours with 180 degree cranks have very good primary balance and very poor secondary balance. Primary vibration is at crankshaft RPM. Secondary is at twice engine RPM. Most inline fours have balance shafts. The CB1100 and ZX-9 and most other fours have a single balance shaft that turns at twice engine RPM. Some bikes, like the Blackbird have two shafts that turn in opposite directions. In either case, the shafts help, but rotating weights are a compromise when trying to cancel reciprocating motion. Balance shafts were first invented and patented by British engineer Frederick W. Lanchester in 1904. Most 4 cylinder cars have balancer shafts and rubber mounts. Think of it as belt and suspenders. CB1100 does have one rubber mount at rear. Nearly every engine configuration on motorcycles has inherent vibration of some sort. Exceptions are the sixes - CBX and Gold Wing are quite smooth and need no balancer shafts. 90 degree V-twins are smooth in moderate displacements, but have some secondary vibrations. I have a classic Ducati 750GT that is pretty smooth. I am sensitive to vibration in my hands after riding for more than 50 years and I have studied the subject extensively.