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Ray White
Joined: 02 Dec 2014 Posts: 6316 Location: Derby
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Posted: Fri May 20, 2016 10:51 pm Post subject: |
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When I was just 16 I bought a BMW Isetta 300, thinking I could drive it on a motorcycle license but I quickly discovered that it was a 4 wheeled version with two wheels close coupled at the rear. The problem was that the rear wheels were too far apart to qualify for motorcycle tax and full car tax was levied. As I would have to wait a year to legally drive a proper car, I sold the 4 wheeled bubble car and bought a three wheeled version which, as we know , could be driven on a motorcycle license. |
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Ray White
Joined: 02 Dec 2014 Posts: 6316 Location: Derby
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Kleftiwallah
Joined: 27 Oct 2016 Posts: 222 Location: North Wiltshire
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Posted: Tue Sep 18, 2018 9:02 am Post subject: |
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In the rear of motor cycle magazines there are usually snaps of similar 'barn finds' and it is amazing just how near to the landfill these bikes have been brought back to life.
I would prefer a Vincent Black Shadow, but that's only me!
Cheers, Tony. _________________ It may work in practice, but not necessarily in theory! |
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peter scott
Joined: 18 Dec 2007 Posts: 7118 Location: Edinburgh
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Posted: Tue Sep 18, 2018 9:28 am Post subject: |
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Four cylinders and only two main bearings?? Hmm! Rough Superior.
Peter _________________ http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon |
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Ray White
Joined: 02 Dec 2014 Posts: 6316 Location: Derby
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Posted: Tue Sep 18, 2018 9:52 am Post subject: |
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peter scott wrote: | Four cylinders and only two main bearings?? Hmm! Rough Superior.
Peter |
Yes, I have always thought it strange that Brough would have chosen to use the Austin Seven engine. Not only just two bearings but splash fed too. That might have been acceptable in an Austin Seven but the "mighty atom" was actually quite crude in many ways. Because the driveshaft came out centrally, he had to fit two rear wheels which must have given it some peculiar handling characteristics.! |
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badhuis
Joined: 20 Aug 2008 Posts: 1390 Location: Netherlands
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Posted: Tue Sep 18, 2018 10:41 am Post subject: |
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Ray White wrote: | Because the driveshaft came out centrally, he had to fit two rear wheels which must have given it some peculiar handling characteristics.! |
I would think that a twin rear wheel (or a single wheel but with sidecar) would take the fun out of riding a bike. Lying low in the corners would not be possible?
Why did he (George) not think to mount the engine a bit more at an angle, so that the driveshaft would run beside the rear wheel? Like Hillman did with the mounting of the Imp engine at an angle of 45 degrees at the car. OK - the sump and oil pickup would need altering but as that is just tinwork it should not be much of a problem.
_________________ a car stops being fun when it becomes an investment |
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Ray White
Joined: 02 Dec 2014 Posts: 6316 Location: Derby
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Posted: Tue Sep 18, 2018 10:51 am Post subject: |
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My first thought is that weight distribution would pose a problem but if a sidecar was going to be fitted then that would cancel out that problem. The oil pump on an Austin Seven is situated in the corner of the crankcase so that can't be moved and the sump is so small that a huge increase in the amount of oil needed in a modified sump would add weight and problems with surge. Many motorbikes operate a "dry" sump system anyway so slotting a car engine into a bike seems all wrong to me. Side vale too.
Not one of Brough's better ideas! |
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peter scott
Joined: 18 Dec 2007 Posts: 7118 Location: Edinburgh
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Posted: Tue Sep 18, 2018 11:10 am Post subject: |
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I think an in line four in a motor bike is just a basically bad configuration. Apart from the need to turn the drive through 90 degrees I suspect that air cooled fours were prone to overheating the rear cylinders so that forces you into water cooling and that must add weight and probably high up weight at that. Every way you look at it it's bad.
Peter _________________ http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon |
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Ray White
Joined: 02 Dec 2014 Posts: 6316 Location: Derby
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Posted: Tue Sep 18, 2018 12:25 pm Post subject: |
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Give me a "cammy" Norton any day!
If it HAS to be four cylinders, the Ariel square 4 is a nice bike. |
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peter scott
Joined: 18 Dec 2007 Posts: 7118 Location: Edinburgh
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Posted: Tue Sep 18, 2018 2:24 pm Post subject: |
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I think the rear cylinders in the square four were prone to overheating.
Peter _________________ http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon |
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Ray White
Joined: 02 Dec 2014 Posts: 6316 Location: Derby
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Posted: Tue Sep 18, 2018 2:27 pm Post subject: |
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peter scott wrote: | I think the rear cylinders in the square four were prone to overheating.
Peter |
I imagine that is why the exhaust manifold was discarded with the Mk2. The four separate pipes must have been more efficient as well and looked good too!
The irony with this machine is that despite the overheating issue, the oil rarely ever gets to an ideal working temperature (90 - 120deg. C) ! |
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