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Who's Vincent/Hrd has the most power?

Brian Thompson

Well Known and Active Forum Website User
VOC Member
Hello Gents,
Thought I'd start a new thread so you don't have to discuss power levels in "Valve lifters with TP cams".
But it does raise a good question on how much power is easily obtained , rather than the expensive way which I have taken without knowing really how much HP I'll end up with?
I'll have 1200cc ,Mk5 cams ,electronic ignition, 1'' 3/8'' gp carbs with 30mm crankshaft and 5 speed.
What can we expect on pump fuel?
Then will the standard chassis/frame take this added HP? Hence why we where looking at fitting the first engine into a more modern chassis/frame.
Like using the Buell swingarm with the oil tank in it? Then you only need a top frame similar to the D series. Just a thought.
Then how do we fit a wider wheel with out some sort of extension housing and off set sprocket?
Could offset the engine? What have other people seen?
Thank you for your thought's.
Cheers
brt650
 
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Monkeypants

Well Known and Active Forum Website User
VOC Member
Re the question of a wide tire and chain clearance, offsetting the engine works. If using a standard UFM, this can be done by making special head brackets. Glen
 
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Bill Thomas

Well Known and Active Forum Website User
VOC Member
While I think Glen's is a super build, I don't think you need that big a tyre, Reg Bolton is over your way, In AUS,!! See if you can find out what he uses, I have a photo, I don't think it's that big, I think he is one of the fastest round a track. Good luck, Bill.
 

Monkeypants

Well Known and Active Forum Website User
VOC Member
You are likely correct Bill, however once the permanent engine is in place that question will be answered. What I like about the 180 rear and 120 front is that they really soak up the bumps when on a rough stretch of highway. The large front tire is also needed to get the full benefit of really powerful brakes. Double disc brakes with a narrow tire would be quite dangerous.
Even changing the standard skinny Vincent Rapide tires to 120/90/18 rear and 100/90/19 front makes a big difference in ride comfort. The tradeoff is that the Rapide no longer handles like a ten speed bicycle, more rider input is now needed on cornering.

Glen
1
 

davidd

Well Known and Active Forum Website User
VOC Member
Hello Gents,
Thought I'd start a new thread so you don't have to discuss power levels in "Valve lifters with TP cams".
But it does raise a good question on how much power is easily obtained , rather than the expensive way which I have taken without knowing really how much HP I'll end up with?
I'll have 1200cc ,Mk5 cams ,electronic ignition, 1'' 3/8'' gp carbs with 30mm crankshaft and 5 speed.
What can we expect on pump fuel?
Then will the standard chassis/frame take this added HP? Hence why we where looking at fitting the first engine into a more modern chassis/frame.
Like using the Buell swingarm with the oil tank in it? Then you only need a top frame similar to the D series. Just a thought.
Then how do we fit a wider wheel with out some sort of extension housing and off set sprocket?
Could offset the engine? What have other people seen?
Thank you for your thought's.
Cheers
brt650

Thanks Brt and it was an interesting question that Roy posed. As always, there are certain limitations that street riding imposes, but in general, my racer is dyno tested on pump gas with no issues. I run race fuel at the track because of availability, but premium unleaded seems to do fine. With the exhaust system I am running now I am stuck at 37-38 BHP at the rear wheel, but with a straight pipe it is 41. I think I can do 43 with some investment in exhaust tuning, but I have not been able to do that at this time.

Just speaking generally, the bike idles well, I believe, as the carb has no stop, but it does not want to stop or stall. With say 40 hp on a single, this is 80 or so on a twin. I would guess that a reasonable limit on a twin would be 90 on a stock Vincent. You can go a little higher, but I would guess that you will run into heating issues. I was told by someone who dyno tested stock engines (that is stock heads, cylinders and cases) that 100 bhp was about the limit. Obviously you can go much higher, but only for land speed records or short bursts. This is the advantage of the Terry Prince heads and cylinders that have double the finning. They provide a great advantage over the stock items.

In general with the lower hp, tires width does not matter much. The vintage racing tires we use are very difficult to brake loose unless it is greasy or you are on paint.

David
 

vibrac

Well Known and Active Forum Website User
VOC Member
All this talk of Vincents and wide tyres is uniformed anyone who has seena good vincent with 80-100 BHP perform against more powerful bikes with wide tyres in corners will know what a disavantage the lager rolling radius of a wide tyre is.
Quite simply if you dont have the HP you dont need the tyre.
if you dont have the wide tyre you have the egli frame check that weight against all those suggested above
have a look at our 1275 racer on www.oldracer.co.uk skinny tyres rule Ok
NB: Irving Vincents are a different kettle of fish
 

Monkeypants

Well Known and Active Forum Website User
VOC Member
My point was that the wide tires give a comfortable ride when going fast on rough roads. If you want to run five or six hundred miles in a day and not feel destroyed, comfort is important.

And changing the standard Vincent from skinny stock tires to something a bit wider was done to meet the tire manufacturers load rating. The only Avon Roadrider sized for fitment onto the stock rear wm2 rim is the 3.25x 19 universal. The load rating on that tire is 467 pounds. With two people on board and luggage, this little tire is grossly overloaded.
The switch to wm3 x18 rear rim permits fitment of a wider and deeper tire which gives a 620 pound load rating, just enough to cover the load. The improvement in ride quality is a bonus.

"NB The Irving Vincents are a different kettle of fish" How different? Their first really fast 1300, the one that did so well when it debuted in 2003, was rated at 135 hp by them. It used Terry Prince top ends with the Trease head design. , On later bikes they built their own top ends, but power per cc was about the same according to their numbers. Up until the four valve head, did they stray far from that Trease design?
From article "The project began in 1999, when Ken began searching for suppliers of remanufactured Vincent engine components. Finding that parts were exorbitantly priced and insufficient for the goals he had in mind, he decided to build the engine from scratch with some help via Terry Prince Vincent in New South Wales. Ken designed and manufactured the bottom end components and crankcases at KHE, while TPV provided updated reproduction heads" I think this article is almost correct except I recall from another earlier interview the bike actually used complete 92mm TPV top ends. Glen
 
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Brian Thompson

Well Known and Active Forum Website User
VOC Member
On the TPV bikes , They made a modified(Casting) that allowed an offset sprocket to be fitted. I guess so they could keep the engine in-line? But the kick start can't be used with this set-up. As the off set sprocket covers the splines for the kick start gears.
I came across this design http://www.bottpower.com/eng/?p=328
Quite simplistic and using the Buell Oil in swingarm.
While looking simplistic I'm sure it would be difficult to make.
Cheers
brt650
P.S For the purest's we are doing several original framed bikes.
 

Bill Thomas

Well Known and Active Forum Website User
VOC Member
That Buell swing arm, Does look like a D !! Which is what I use on my Special, I wonder if that spring unit will fit on mine !! That top tube with a bend in it is not right !! Just a bit of Fun, Cheers Bill.
 
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