Purity of design...

Fast Eddie · Dec 24, 2019

4 valve heads, blah, blah.

Some of us are men of action, not just dreams...

I started out putting Ducati 4 valve heads on my Vincent.

The frame to head mounts didn’t work so I swapped out the frame.

Then I beefed up the bottom end with stronger crank and cases etc.

The enhanced performance necessitated upgrades of brakes, suspension, etc.

So here it is... my 8 valve Vincent...

Chris · Dec 25, 2019

Terrible lash up Nige lol

acotrel · Dec 26, 2019

I think a standard Vincent which has all the bushes shimmed and tight, might be a very nice bike to ride. My silly mate got chucked on his head at 70 MPH. He blamed the friction adjusters under the seat.

I rode a much-modified methanol-fuelled Rapide back in about 1962. I wondered where all the urge was coming from. But a good 650 Triumph accelerated faster up to about 100 MPH. From there on, you had to hang on tight.

Fast Eddie · Dec 27, 2019

Chris said:
Terrible lash up Nige lol

Its the best I could cobble together with the bits I had to hand... as you can kinda tell by the (lack of) styling !!

desmo · Dec 27, 2019

Fast Eddie said:
4 valve heads, blah, blah.

Some of us are men of action, not just dreams...

I started out putting Ducati 4 valve heads on my Vincent.

The frame to head mounts didn’t work so I swapped out the frame.

Then I beefed up the bottom end with stronger crank and cases etc.

The enhanced performance necessitated upgrades of brakes, suspension, etc.

So here it is... my 8 valve Vincent...

View attachment 13739

congratulations in true vincent spirit we have another dodgy clutch
when my pal simon Linford sold his 3 yes 3 vincents he bought 2 ducati s4rs tricolours for him and pam
now thats a coincidence

desmo · Dec 27, 2019

acotrel said:
I think a standard Vincent which has all the bushes shimmed and tight, might be a very nice bike to ride. My silly mate got chucked on his head at 70 MPH. He blamed the friction adjusters under the seat.

I rode a much-modified methanol-fuelled Rapide back in about 1962. I wondered where all the urge was coming from. But a good 650 Triumph accelerated faster up to about 100 MPH. From there on, you had to hang on tight.

might have been the onset of the famous girdraulic terminal tank slapper

acotrel · Dec 28, 2019

Friends of mine own road-going Vincents and have said the same thing about the girdraulic forks. Apparently they need to be kept tight. But those two adjusters under the seat play a part. Often what happens at the rear of a bike affects the feel at the handle-bars. Vincents are what they are - a 1930s design. The only Vincent solo that I have seen which handles is the Horner's Irving Vincent. And that is not really a Vincent - it is what a Vincent might have become.
A few years ago there was an ex-pat Brit who believed in Vincents and tried to race one as a solo. After it slid up the road on it's side at 100 MPH, it became a sidecar. Most of the Vincents which road-race in Australia are Norvins.

https://ibb.co/Lh8Gcdy

desmo · Dec 28, 2019

acotrel said:
Friends of mine own road-going Vincents and have said the same thing about the girdraulic forks. Apparently they need to be kept tight. But those two adjusters under the seat play a part. Often what happens at the rear of a bike affects the feel at the handle-bars. Vincents are what they are - a 1930s design. The only Vincent solo that I have seen which handles is the Horner's Irving Vincent. And that is not really a Vincent - it is what a Vincent might have become.
A few years ago there was an ex-pat Brit who believed in Vincents and tried to race one as a solo. After it slid up the road on it's side at 100 MPH, it became a sidecar. Most of the Vincents which road-race in Australia are Norvins.

ive had a couple of scary tank slappers
one on a 250 ducati full on lock to lock then spat off. Another more recent on a garden gate inter after a little airborn stuff standing on the pegs ,when the bike landed slightly at an angle it was enough to make it shake its head violently
very scary at 90mph
it was a great invention from a belfast blacksmith that set the standards for all future motorcycle frames ,not renolds
as some english lay claim to !
if you look at an early unit consruction
New Imperial ,or a Brough Superior these are possibly where Phil Irving got his inspiration for his frame ,the forks look like 30s autocycle ,

i for one would be very wary of this known high speed handling glitch
id probably leave it in the front room and polish it to death instead

998cc · Dec 28, 2019

(Tried unsuccessfully to quote desmo' s post relating to the experience on his 250 Ducati.)

Having only ridden one Vincent, I can only speak of experiences with my Black shadow. In that experience, I will say the stock Vincent suspension does not respond well to potholes other major bumps in the road.

My only tank slapper occurred while cruising at about 60 MPH in a slight curve in the road. This rural road was a frequented by logging trucks which had forced up rippled mounds of asphalt in the warm roadway. I hit one of these mounds which vaulted the bike; similar to desmo's incident, it landed just slightly out of plane with respect to the direction of travel resulting in an instantaneous violent, hammering tank slapper. I was sure to go down, but the slapper miraculously stopped at maybe 15-20 MPH allowing control to return.

That was about 30 years ago, and I am confident the Gridraulics were tight at that time. During the rebuild of 2017-18, I found two worn spindles (stainless) that needed replacement along with their mating bushes.

Was this a design flaw? Properly assessing the mechanical resonance and resonant frequency of a motorcycle comprised of hundreds of components that exist in a continually changing geometrical relationship to each other must be difficult. It is well-documented that the Kawasaki 900 Z-1 suffered from tank slappers, so even into the 70's this malady afflicted new production bikes.

How do others here deal with the possibility tank slappers on their stock Vins?? Hydraulic steering dampers?

Regards,
~998cc

Fast Eddie · Dec 29, 2019

IMHO the girdraulic forks were a very clever design for their time. Remember that telescopic forks were in their absolute infancy, most were pretty rubbish, engineers could see their many inherent flaws (yet to be overcome) and it was by no means certain that they would come to dominate as they have.

Modern tele forks are a different ballgame. They’ve had 80 years of extremely competitive continual development. There’s no more point in comparing modern tele forks to girdraulics as there is comparing a modern 1000cc sports bike engine to a Vincents!

If, at end of they day, they genuinely were a superior design, they’d have dominated, become mainstream and enjoyed development over the least 70-80 years. As it is, they’re just ‘novelty’ fork options these days on a few ‘exotic’ bike brands.

Fast Eddie · Dec 29, 2019

Can’t recall where I read it, but shortening the handle bars was reported to help reduce the risk of tank slappers. I therefore shortened mine accordingly (inch and a bit off each end IIRC) and never experienced any issues. Of course, I have no idea whether or not this had anything to do with the bar shortening. Cudda just been a placebo mod ...

acotrel · Dec 30, 2019

Vincents are a 1930s design. Have a look at what the rest of the bikes were like. For it's time the Vincent was excellent. I think the only other bike with swing arm rear suspension was the KTT Velocette. Even Broughs were rigid frame. I once rode a rigid frame Triumph at 100 MPH - only once and that was enough. The rear wheel never touched the ground. What a lot of guys do not realise is how dangerous some of those early motorcycles were - anything pre-1920 is very suspect. The guys who rode them weren't idiots and still got killed.

I think our problem is we look at Vincents in terms of modern motorcycles. Ken Horner's Irving Vincent proves the design had unrealised potential, but it is still pretty much fantasy.

acotrel · Dec 30, 2019

Lindsay Urquardt admired the Claude Temple Anzani, so he made one. The trouble is there was never a frame for them.

desmo · Dec 30, 2019

acotrel said:
Vincents are a 1930s design. Have a look at what the rest of the bikes were like. For it's time the Vincent was excellent. I think the only other bike with swing arm rear suspension was the KTT Velocette. Even Broughs were rigid frame. I once rode a rigid frame Triumph at 100 MPH - only once and that was enough. The rear wheel never touched the ground. What a lot of guys do not realise is how dangerous some of those early motorcycles were - anything pre-1920 is very suspect. The guys who rode them weren't idiots and still got killed.

I think our problem is we look at Vincents in terms of modern motorcycles. Ken Horner's Irving Vincent proves the design had unrealised potential, but it is still pretty much fantasy.

its all relative isnt it .
if you compare the cars that were being used in England post war to a Vincent
no wonder they had an awesome reputation,must have been like an exocet missile back then , imagine trying to keep your reversed tweed bonnet on at that speeds ! most were mostly 4 cyl sidevalves with a top speed of 50 mph if you were lucky of course there would be the odd xk jaguar that xould give it a wuppin
you could buy a small bungalow for the price of a new vincent post war so you were regarded as a promenade percy if you owned one. most peoples sporting aspirations would be getting that echelon of performance an engine with overhead valves or a cammy one if you were lucky

performance dont come cheap thats why theres always been guys grafting bits together and modifying! some of the best bikes are cobbled together in tin sheds

Bernhard · Dec 30, 2019

998cc said:
(Tried unsuccessfully to quote desmo' s post relating to the experience on his 250 Ducati.)
Having only ridden one Vincent, I can only speak of experiences with my Black shadow. In that experience, I will say the stock Vincent suspension does not respond well to potholes other major bumps in the road. Regards,
~998cc

Hands up-who didn't know that?

Bernhard · Dec 30, 2019

acotrel said:
Vincents are a 1930s design. Have a look at what the rest of the bikes were like. For it's time the Vincent was excellent. I think the only other bike with swing arm rear suspension was the KTT Velocette. Even Broughs were rigid frame. I once rode a rigid frame Triumph at 100 MPH - only once and that was enough. The rear wheel never touched the ground. What a lot of guys do not realise is how dangerous some of those early motorcycles were - anything pre-1920 is very suspect. The guys who rode them weren't idiots and still got killed.
QUOTE]

This statement made into the 1980s would have been blown out of the water – why? - I once saw at Brands Hatch a one off all-comers, open fuel race, where,against a production 750 Trident which finished 2nd, was won by a rigid rear frame 500 Scott Flying Squirrel running on menthol!

The winner was a vintage champion, so the bikes may be old, but they can still teach modern bikes/riders how it is done.

desmo · Dec 30, 2019

perhaps the rider had a bad cold hence the' menthol , once that flyin squirrel past you you wouldnt be able to see through the smoke trail

a scott with a couple of tz liners grafted in there would be a hoot

ye canny beat us scotts
you can take our oil but not oor freedom

holtcorseaux · Dec 30, 2019

acotrel said:
Vincents are a 1930s design. Have a look at what the rest of the bikes were like. For it's time the Vincent was excellent. I think the only other bike with swing arm rear suspension was the KTT Velocette. Even Broughs were rigid frame. I once rode a rigid frame Triumph at 100 MPH - only once and that was enough. The rear wheel never touched the ground. What a lot of guys do not realise is how dangerous some of those early motorcycles were - anything pre-1920 is very suspect. The guys who rode them weren't idiots and still got killed.

I think our problem is we look at Vincents in terms of modern motorcycles. Ken Horner's Irving Vincent proves the design had unrealised potential, but it is still pretty much fantasy.

Hi i get your point and still some riders excel on rigid framed bikes like the Stratford Rudge mentioned above & Troy Corser 1930s BMW rigid frame, girder forks.
it is astonishing.

Thank you all for the good entertainment in 2019 and

e guets Nöis

Martin

Bernhard · Dec 31, 2019

desmo said:
perhaps the rider had a bad cold hence the' menthol , once that flyin squirrel past you you wouldnt be able to see through the smoke trail
a scott with a couple of tz liners grafted in there would be a hoot
ye canny beat us scotts
you can take our oil but not oor freedom

The rider carries a packet of Tunes (sweet candy) in his leathers and sucks one while racing the bike to be in perfect harmony . . . .

acotrel · Dec 31, 2019

If the AJS Porcupine had ever been supercharged as the designer intended, it might also have been fast. If you watch Corser on that Rennsport BMW- note the speed differential in a straight line.

A Jaguar car which could best a Vincent once the speeds got over 100 MPH, would be interesting. Back in the day, I was playing with hotted-up Triumphs which would make any Vincent look stupid up to 100 MPH. After that they would say goodbye and leave me for dead. I had three friends - all of whom ended up road-racing. Their road bikes were - a converted long-stroke 500cc Manx, a 1959 650 Bonneville and a Vincent Rapide. The Vincent was the bike which got towed home the most. I think you would have to be very brave to ride one at it's top speed.

http://www.gregwapling.com/hotrod/land-speed-racing-history/land-speed-racing-bob-burns.html