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Vincents are smooth

Vincents are smooth

Postby worntorn » Thu Sep 17, 2015 7:08 pm

Just rode two Rapides back to back after spending some time recently on a 2004 Guzzi Lemans 1100. The Guzzi is a paint shaker compared to the Rapides. Same with the 2011 BMW 1200 rt I rode awhile back.
On the positive, the Guzzi is a nice looking bike with very good brakes and it handles well.

But sometimes you wonder if we have moved forward much at all in nearly seventy years. And these Rapides have both been in continuous use for nearly 70 years!
But to be fair they have both been carefully overhauled some time ago by the best, the late John Mcdougall.


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Re: Vincents are smooth

Postby Bernhard » Sat Sep 19, 2015 3:37 am

Re "The Guzzi is a paint shaker compared to the Rapides"
The original Guzzi engine came from a Italian 3 wheel farm tractor , (Moto Guzzi Triporteurs) smoothness in a motorcycle frame was not on the designers drawing board :!:

https://en.wikipedia.org/wiki/Moto_Guzzi_Triporteurs

http://www.bing.com/images/search?q=mot ... ORM=HDRSC2

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Re: Vincents are smooth

Postby worntorn » Sat Sep 19, 2015 10:52 am

What is the excuse for the BMW? I thought a 2011 BMW touring machine would be smooth and shift beautifully. Wrong on both counts!

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Re: Vincents are smooth

Postby nickguzzi » Sun Sep 20, 2015 2:10 am

No, Guzzi's aren't really smooth. Of the several I have ridden, there was a variance, but that could be down to point and carb settings. On the other hand they are not horribly vibey or desparate shakers either.
There is some talk that having the rotating assembly dynamically balanced can improve matters. One tuner always said Guzzi failed to take into account the volume of oil in the big end, which threw out the balance. Not sure how much 8cc's of oil will affect smoothness, if true.

The BMW's airheads I have ridden have all been very smooth, maybe that is just in comparison to Guzzi's.

The agricultural vehicle linked to in Bernard's post is a single cylinder, as can be clearly seen in the photo he posted. Called Motocarri Ercole in Italian. Agreed that NVH was probably not a high priority for the design team.

Guzzi also made several other 3 wheelers for commercial purposes, looking very like the Lambo, and still current Piaggio APE.

The engine in the military Mullo Mechanico, according to the display in Guzzis own museum, is not an ancestor of the 700cc V twin used in the bikes. In the only poor quality pictures I could find, the crank case is totally different, as are the rocker covers - the rest is hidden under ducting or the picture is too blurred.

I never got to ride a Vincent, although I was offered a running twin for £90 back in the mid 60's.

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Re: Vincents are smooth

Postby worntorn » Sun Sep 20, 2015 9:33 am

nickguzzi wrote:No, Guzzi's aren't really smooth. Of the several I have ridden, there was a variance, but that could be down to point and carb settings. On the other hand they are not horribly vibey or desparate shakers either.
There is some talk that having the rotating assembly dynamically balanced can improve matters. One tuner always said Guzzi failed to take into account the volume of oil in the big end, which threw out the balance. Not sure how much 8cc's of oil will affect smoothness, if true.

The BMW's airheads I have ridden have all been very smooth, maybe that is just in comparison to Guzzi's.

The agricultural vehicle linked to in Bernard's post is a single cylinder, as can be clearly seen in the photo he posted. Called Motocarri Ercole in Italian. Agreed that NVH was probably not a high priority for the design team.

Guzzi also made several other 3 wheelers for commercial purposes, looking very like the Lambo, and still current Piaggio APE.

The engine in the military Mullo Mechanico, according to the display in Guzzis own museum, is not an ancestor of the 700cc V twin used in the bikes. In the only poor quality pictures I could find, the crank case is totally different, as are the rocker covers - the rest is hidden under ducting or the picture is too blurred.

I never got to ride a Vincent, although I was offered a running twin for £90 back in the mid 60's.


The Guzzi that I sampled was a modern 2004 fuel injected model. It shook very hard from side to side on acceleration.
Most of the shake was felt through the seat.
The BMW shook in a similar way on acceleration, but not quite as hard.On the other had, the BMW shook through the bars, footpegs and seat all at once when accelerating. Both had clunky gearboxes compared to the Vincent, which is an OK shifter but not as good as an AMC. The AMC box still seems to one of the best or the best shifting transmission ever.

The shaking problem of the BMW 1200 RT is discussed in some detail on a couple of BMW forums. Not much discussion of the Guzzi vibrations as this has been renamed "character" by Guzzi fans :D

I know there are some smooth modern bikes out there, the triumph Triple being one, but it surprised me that there are still bikes being made that are this clunky to operate and yet considered high end.

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Re: Vincents are smooth

Postby tricatcent » Sun Sep 20, 2015 10:42 am

Glen

I had a 2004 Lemans for three years. It was a great bike. I rode it down to Bonneville and around Nevada. It didn't vibrate very much at all. They do rev more than Vincents. I think normally you don't rev them less than 3000 RPMs. If you do they will shake sideways as you describe. I think these engines are not suitable for lugging them at 2400 - 3500 RPMs as Vincent are. The thing is about the newer Guzzis is that the flywheel is lightened in order so the engines can rev quickly to 8500 RPMs. I don't think there are very many Vincents that can rev to 8500 RPMs. Also the V11 has pretty close to 80 HP at the rear wheel and runs about 10.5 :1 pistons.

It is amazing how smooth the Vincent is when you consider that the cylinder angle of 50 degrees does not allow for the near perfect balance you get with a 90 degree cylinder angle (or the opposed twin BMW)

The only reason I sold my Lemans was because the original owner wanted it back and paid me the same as I had paid him three years previously. I got to ride it for three years and 25000 kms for only the price of tires and oil.

My friend Graeme has a Yamaha MT-01 with a 1700 cc vee twin engine with a 48 degree cylinder angle. It has no counter balancer shaft and he says it doesn't vibrate much. I am going to have to try it out someday.

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Re: Vincents are smooth

Postby worntorn » Sun Sep 20, 2015 12:36 pm

Hi Nigel

Maybe I wasn't revving it high enough then.
I did find that it smoothened out when cruising, so the vibration was escapable. This was true of the BMW as well, it only shook when climbing a grade or when accelerating. For both bikes it was more of an actual shake than a fine vibration.
Maybe that is easier to live with than a high frequency vibration.
I liked the low stance and the narrow feel of the Guzzi. But those gyrations would take a little getting used to!

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Re: Vincents are smooth

Postby tricatcent » Mon Sep 21, 2015 4:08 pm

They do rev more. I don' t think you really open them up at all unless you have 3000 RPM. The bore and stroke of the V11 is 92 X 80 mm so those figures are pretty much the reverse of the Vincent. I think a Triumph 650 has an 82 mm stroke. Norton Commandos are 89mm. The long stroke is not all disadvantages though. With the long stroke the hemi combustion chamber works better than with the shorter stroke. The engine ends up working more like a steam engine with power from very low revs. Today I am riding a VTR 1000. (98mm X 66mm stroke!) It is a great bike. It backfires on de acceleration like a proper bike should. If you open up the throttles and the engine is at 2500 RPM it doesn't do much. It shakes and feels like you are hurting the engine. Once you have 3000 then it is ready to go though, this is what passes for low end power today.

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Re: Vincents are smooth

Postby gortnipper » Mon Sep 21, 2015 5:32 pm

tricatcent wrote:Today I am riding a VTR 1000. (98mm X 66mm stroke!) It is a great bike. It backfires on de acceleration like a proper bike should. If you open up the throttles and the engine is at 2500 RPM it doesn't do much. It shakes and feels like you are hurting the engine. Once you have 3000 then it is ready to go though, this is what passes for low end power today.


That is basically the same thing that happens with my Ducati ST4s - which has the 996 motor (98mm X 66mm stroke). But, it really doesnt come into its own until a bit higher revs than that - more like 4k. It is geared pretty tall, too.
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Re: Vincents are smooth

Postby worntorn » Tue Sep 22, 2015 5:09 am

The modern bike I ride is a 955i Triumph Daytona. It also needs some revs to really start to pull, but the smoothness of that bike is incredible. There is zero vibration to be felt from idle to 12,000 rpm, even if you lay a hand on the fuel tank. Somehow I thought all other moderns were like this, but obviously not.

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Re: Vincents are smooth

Postby tricatcent » Tue Sep 22, 2015 7:16 pm

The Triumph triples pull from lower RPM than most other modern engines, even the highly tuned ones like your Daytona. I have a Sprint and it is very smooth also. The three cylinder engine with a balance shaft is smoother than most four cylinder engines. The new Triumph 800 Tigers can be run well even a bit below 2000 RPM. I think they are even smoother than our 955 motors. The VTR was tuned to run at lower speeds than the 996 or 916 engines. The VTR has more power at 7000 RPM and below than a 916. I am not sure how it compares with a 996 but it has a lot less peak power. It is a very pleasant engine that's for sure.

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Re: Vincents are smooth

Postby gortnipper » Tue Sep 22, 2015 8:30 pm

I think the issue with my ST4s is not the 996 motor - I find that very smooth, with gobs of mid-band and top end power - but it is geared pretty low for comfortable city/traffic use which is what I do mostly on it now.

PRIMARY DRIVE Straight cut gears, ratio 1.84
RATIO 1st 37/15, 2nd 30/17, 3th 27/20, 4th 24/22, 5th 23/24, 6th 24/28
FINAL DRIVE Chain; Front sprocket 15; Rear sprocket 38

A lot of guys riding on the street with either the 40 or 42 tooth back sprocket on makes the bike smoother and more relaxed.

But, I digress.
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