Fastest Isle of Man Commando?

J.A.W. · Jun 19, 2012

Well, I`ve found the Seeley-URS quoted as " Speed trapped @ 144mph -only 8mph down on the Works Honda at the I.o.M.", so ~ 152mph for Hailwood then, maybe top speed dont make that much difference there?

Matt Spencer · Jun 19, 2012

post132573.html?hilit=peter williams#p132573

ni na ni naa ni naa , 155 I think . :wink: Not Metric . :lol:

anything for a excuse ( for nice pictures . )

See below post . = They BANNED the SUPERCHARGED A.J.S.
Tecnically , Tuned Pipes on a 2 stroke is SUPERCHARGEING .
Therfore , for parity , Supercharged 4 strokes Vs 2 Stokes .
or NO Pipes .

Slick Tyres , and TRACK IMPROVEMENTS count for a good deal.
Whay , its sealed these days , and you dont have to stop and open Keppel Gate even .

J.A.W. · Jun 19, 2012

Well then, so the G.P. Honda was slower than the F750 Norton in top speed?, a few years after that 107mph lap, Mick Grant took it to 114mph average, but was speed trapped at over 190mph doing so.

Matt Spencer · Jun 20, 2012

Argh , here the garbage is . ( works F-750 tripe )

how-the-west-won-eventually-then-shut-shop-t11783.html

The determined rider was in hospital by this stage ,

The caption there is " Norton Triumph Raceing " . N V T . Norton Villiers Triumph .

http://en.wikipedia.org/wiki/Motorcycle ... eed_record

Therefore im disgusted the new Thunderbird wont take 80 % Nitro , and . . anyone got one lying around looking for a purpose in the grande scheme of things ?

Villiers ?

Non Supercharged .

Matt Spencer · Jun 20, 2012

NOW ,

WHERE Were We .

:? :shock: :| Would YOU trust This Man , on Youre Motorcycle . :lol: 8)

Bernhard · Jun 20, 2012

Rohan said:
xbacksideslider said:

To go 160MPH, they likely spent time in a wind tunnel to get the fairing/rider shapes just right.

Click to expand...

I would actually doubt that.
Knowing Nortons and how tight their race budget was.....

MotoGuzzi reportedly had the only wind tunnel in the motorcycling world.
(Which is why their 1957 500cc dustbin fairing V8 could lap MIRA at 187 mph ?)

Not to say a wind tunnel couldn't be found somewhere for testing - but they were rather uncommon back then....

??

How little do we know, it was an open air wind tunnel, just a big fan in a ground dugout was the picture I saw of the Moto Guzzi one :!:

Bernhard · Jun 20, 2012

Rohan said:
highdesert said:

Interestingly, Norton itself had machined and tested very briefly a desmo 500cc twin in the late 50s!

Click to expand...

Actually, the desmo tested was a 350cc Manx. (single cylinder).
But we won't let the facts get in the way of a good story !!

However, the Domiracer 500cc twin, in manx style frame under Doug Heles guidance, did lap the Isle of Man at over 100 mph, with Tom Phillis on board. Think it was 1961.
Which means the Commando was only a few mph faster...

Cheers.

You appear to fall into the trap that the Commando was only a few mph faster, when the lap of 105 compared with the lap of 100mph of the 500 Domiracer is a colossal difference on lap speed.

johnm · Jun 20, 2012

daveh said:
This is part of a story from NZ on the Britbike Forum, when Peter Williams was invited to Pukekohe.

"Peters influence on the bike was very wide but he was especially happy about the results in reducing drag. He talked about testing in wind tunnels, working out precise rider position. He said he could feel when he was in the right place because his back would go cold from the wind flow. They took the numbers and patches off the backs of their leathers to smooth the surface. The drag coefficient on the 1970s monocoque has only been bettered recently by GP bikes. They had to do all this because they were so far down on hp."

I think I might have written this on the Britbike website.

A Norton crazy friend of mine was one of the main guys who organised Peter Williams to come to NZ. And because I put a bit of sponsership money in I got invited to a private dinner one evening with just a couple of us plus Peter Williams and Norman White (his mechanic back in those days).

Basically we were able to sit and talk bikes for about 4 hours and I can put the evening down as one of the high lights of my motorcycle experiences.

Peter talked about a great many things.

his Dad - who did much of the development on the AJ 7 R and G50

The 4S and PW3 camshafts, the design and engineering criteria.

The early days of disc brakes and the Arter G50

Racing in England, Europe the TT and Daytona

He gave me a lot of advice on tuning my 500 Dominator motor

-and as I said in the quote above he spent a long time talking about how they designed the aerodynamic faring and seat units etc to minimize drag. He spent days in the wind tunnel and was very proud that the results they achieved were not reached by other factories for 10 or 15 years.

The faring looks very wide and "chubby" by comparison to other bikes but it worked.

I use a Peel Mountain mile faring on my 500 Dommie and this increased top speed over the unfared bike by about 8 mph at around 120 mph - electronic timing. So Im a beleiver in these wider farings which enclose the handlebars etc.

John

daveh · Jun 20, 2012

johnm said:
daveh said:

This is part of a story from NZ on the Britbike Forum, when Peter Williams was invited to Pukekohe.

"Peters influence on the bike was very wide but he was especially happy about the results in reducing drag. He talked about testing in wind tunnels, working out precise rider position. He said he could feel when he was in the right place because his back would go cold from the wind flow. They took the numbers and patches off the backs of their leathers to smooth the surface. The drag coefficient on the 1970s monocoque has only been bettered recently by GP bikes. They had to do all this because they were so far down on hp."

I think I might have written this on the Britbike website.

A Norton crazy friend of mine was one of the main guys who organised Peter Williams to come to NZ. And because I put a bit of sponsership money in I got invited to a private dinner one evening with just a couple of us plus Peter Williams and Norman White (his mechanic back in those days).

Basically we were able to sit and talk bikes for about 4 hours and I can put the evening down as one of the high lights of my motorcycle experiences.

Peter talked about a great many things.

his Dad - who did much of the development on the AJ 7 R and G50

The 4S and PW3 camshafts, the design and engineering criteria.

The early days of disc brakes and the Arter G50

Racing in England, Europe the TT and Daytona

He gave me a lot of advice on tuning my 500 Dominator motor

-and as I said in the quote above he spent a long time talking about how they designed the aerodynamic faring and seat units etc to minimize drag. He spent days in the wind tunnel and was very proud that the results they achieved were not reached by other factories for 10 or 15 years.

The faring looks very wide and "chubby" by comparison to other bikes but it worked.

I use a Peel Mountain mile faring on my 500 Dommie and this increased top speed over the unfared bike by about 8 mph at around 120 mph - electronic timing. So Im a beleiver in these wider farings which enclose the handlebars etc.

John

Click to expand...

Thanks for that insight, John. It's also good to read factual evidence for increases in top speed. I never thought very much about Peel Mountain Mile fairings, but it makes sense to enclose the handlebars. I read that Peter Williams also paid attention to streamlining the rear of the bike since he understood that it was no good having clean air flow over the front, only to have massive turbulence at the back. I remember having a top box that opened fully at speed on my Honda 350 when I was a student. That demonstrated how just how bad the aerodynamics are on a naked bike!

Hobot · Jun 20, 2012

http://www.tga.co.uk/catalog/product_in ... ucts_id=35

speirmoor · Jun 20, 2012

No front fenders back then either?

SteveA · Jun 20, 2012

I have just purchased a fairing based on the JPN design but with an increased depth in the lower section to allow fitment to taller bikes than the works Nortons.

I have also got a more typical Seeley type fairing so may eventaully be able to do comparisons, but don't hold your breath, this will be years in the coming.

On the topic of Primary Drive outriggers, the Redfern guys used an outrigger in the late '70s. I wanted to do the same and managed to get some information sent to me, 35 years later god knows what happened to it :roll: , I am sure there were a couple of sketches but I recall the words 'trapan a hole' and thinking....out of my league, I havent even got a drill stand at home....but I recall that the idea followed works practice using a (production?) cast inner primary case as the base and inserting a bearing into that amd fixing the gearbox mainshaft to crankshaft centres. They also welded the primary to the crankcase to gain maximum rigidity. Like the Mk III they used a chain tensioner arrangement. This was also a limitation for me since my engine was vertical in a Rickman, so I would have needed to change the engine plates, exhaust, carb manifolds and head steady to tilt it all forward.

The outer primary cover was made from welded plate to make a much lighter affair, but as the works with lots of screw bossed to add to the sealing and rigidity.

This would all work so much better now with a belt drive, but it is of questionable need with a TTi box, and BTW TTi's own clutch is smaller and lighter than the average diaphragm belt drum and runs 62 teeth! It was questionable for me back then, my alternative was to remain with the 4 speed box that was by nature stronger and the 33 tooth triplex engine sprocket and Commando clutch that actually did not cause me a problem in 4 seasons apart from spitting the triplex primary once, but that was made from two to get the longer length and never lubed as well as it should have been! I didnt take the outer cover off of the box once I had built it....

Today I would say if you balance the cost/effort of making a really good outrigger set up and using a more original style of box, it would be about equal to just paying for the TTi box and using a very lightweight belt cover...and your reliability would still be better!

Brooking 850 · Jun 20, 2012

Hi John, ay chance of some pics of your fairing set up, if not on here , then to my email
Regards Mike

J.A.W. · Jun 20, 2012

J.P.S. racing Norton front mudguard, weren`t they removed when the mono` had cooling/overheating issues due to the close frame/engine airflow clearances? The Kawasaki triple front guard was reputedly smooth[no stays] as a deliberate airflow device for the centre cylinder. As for M.S.`s assertion that equates 2T sonic-wave exhaust tuning with super-charging, well 2Ts can be fundamentally viewed as pulse-jet units that utilise the reciprocating mill as a mechanical transfer system by the harmonic gas-flow, for turning shafts.
As Sir Stanley Hooker, famous R.R. & Bristol aero-engineer said -"4 strokes = 1 stroke for power, 3 to wear the engine out."
& of course 2Ts can be super[mechaniacally, turbo, or chemically]charged as well, they are just not lazy without it.

johnm · Jun 21, 2012

Hi Mike,

Should be able to find some photos of the Peel faring in a few days. They are not on my computer so need to find them.

I got mine from Australia but it looks the same as the TGA one.

With modern tyres and riding techniques we found we needed to modify it. Firstly it ground very easily even when mounted as high as possible. This could also be from 18 rims and modern tyre profiles.

Secondly my bike was being ridden by a very good modern style rider and he found the top of the side panels and the outside of the faring over the handle bars were stoppping him getting forward and over onto his knee. So for the interim we had to trim it back.

For a perfect solution you would need to modify the mould to bring the faring in tighter earlier at the bottom and open up around the handle bar area to fit modern riding styles and tyre capability.

If I can find it I will post a photo of the NZ Lodge ES2 # 88 bike which has won the 500 Australasian Historic championship several times now. In my opinion this bike has the perfect faring match of stream lining and adaption for modern riding style for historic racing.

John

pommie john · Jun 21, 2012

For what it's worth, I put a JPN fairing on my BMW race bike. It went slower at Phillip Island with the JPN than it did with a Ducati 900SS top half fairing.
The JPN has quite a bit more frontal area and although I thought I was going in the right direction, it didn't work and I don't know why.
Maybe it keeps the heat in and the carbs get hot air and I lose power, or maybe there's a low pressure region just where the carb is,
I don't know but I took it off again. I think it looks really nice, but it makes it a pain in the arse to work on the bike and just wheeling it around the pits is hard because you hands are tucked inside the fairing when you're trying to walk along side it. Also you need very narrow clip ons which make it hard work hefting a heavy bike around tight corners.

Ducati fairing

JPN fairing

It's a shame it didn't work. I'd be interested in any theories.

daveh · Jun 21, 2012

pommie john said:
It's a shame it didn't work. I'd be interested in any theories.

Possibly because the JPN fairing was designed with the rider as an integral part of that particular package, and was specific to the shape of that bike. Not only that, but the airflow through the front of the fairing over the engine would be different. You would need to look at front and side views of how the rider fits behind the screen of the works JPN and also the seat unit was designed to smooth the air flow over the rider's back and hips. Two big cylinders sticking out in the breeze probably doesn't help either!

Did Norton duct air to the carbs, which are in a different position to the Beemer's?

Bernhard · Jun 21, 2012

pommie john said:
For what it's worth, I put a JPN fairing on my BMW race bike. It went slower at Phillip Island with the JPN than it did with a Ducati 900SS top half fairing.
The JPN has quite a bit more frontal area and although I thought I was going in the right direction, it didn't work and I don't know why.
Maybe it keeps the heat in and the carbs get hot air and I lose power, or maybe there's a low pressure region just where the carb is,
I don't know but I took it off again. I think it looks really nice, but it makes it a pain in the arse to work on the bike and just wheeling it around the pits is hard because you hands are tucked inside the fairing when you're trying to walk along side it. Also you need very narrow clip ons which make it hard work hefting a heavy bike around tight corners.
JPN fairing

It's a shame it didn't work. I'd be interested in any theories.

I would try and fit 2 small plastic funnels on the front somewhere and run a rubber hose pipe from them to each carb bell mouth.
I have done this on petrol and diesel engines and get an extra “kick” at around 60mph but I did not change the jetting as the engine was not run flat out as on a race track.
This would confirm on top speed if the fairing is starving the carbs of air, but you may have to run richer main jets.

johnm · Jun 21, 2012

You are certainly correct about the big farings being a P in A to move around in the pits.

On the photo of the JPN faring BMW is that the carb bellmouth sticking out from behind the faring?

Airflow over the carbs is something I would think hard about.

In fact the whole issue about carbs, airfilters, dyno results with carbs versus airflow at speed is all something I know basically nothing about and its all guess work and rather unsatisfactory. My bike has two big open bell mouths but knowing at least two bikes that suffered very serious damage due to large stones going in I really should do something about it. I won't of course and one day the inevitable will happen!!!

pommie john · Jun 21, 2012

johnm said:
You are certainly correct about the big farings being a P in A to move around in the pits.

On the photo of the JPN faring BMW is that the carb bellmouth sticking out from behind the faring?

Airflow over the carbs is something I would think hard about.

In fact the whole issue about carbs, airfilters, dyno results with carbs versus airflow at speed is all something I know basically nothing about and its all guess work and rather unsatisfactory. My bike has two big open bell mouths but knowing at least two bikes that suffered very serious damage due to large stones going in I really should do something about it. I won't of course and one day the inevitable will happen!!!

Yeah that's the bellmouth you can see.

I went to the dyno, got 8 horsepower more, fitted the fairing ( which I had to bring on a plane from England 'cos no postal service will send anything that big) and it went 200rpm slower down the straight.
Sadly, Phillip Island is 2000 kms from my place so I don;t get there very often so I probably won't get to test it again in the near future.

Fastest Isle of Man Commando?

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