500cc GP Replica thread

[roogazza]

Back in the days of two stroke GP bikes the mechanics used to take a conrod and cut a piece of the little end out in such a way that the conrod functioned as a bottle opener. Alex Briggs produced some aluminium replicas and I bought one, which is as close as I'll get to owning any of that confectionary.

Think I met him, Rossi mechanic right ??? nice fella....

[jellywrestler]

Marshall Motorcycles owner Wayne has made a stunning job of this weapon with the help of Steve Roberts in wanganui
they are on the start finish line of the cemetery circuit

[pete376403]

Back in the days of two stroke GP bikes the mechanics used to take a conrod and cut a piece of the little end out in such a way that the conrod functioned as a bottle opener. Alex Briggs produced some aluminium replicas and I bought one, which is as close as I'll get to owning any of that confectionary.

Not a bottle opener but back in the swansong days of the NR500, but while the exact configuration of the engine was still unknown, Cycle magazine was given a single conrod. From that they (either Jennings or Cameron) were able to posit the design of the engine to what turned out to be a remarkable degree of accuracy. I miss that degree of technical journalism. Cameron does still write for Cycle World, but not quite to the same depth

[Grumph]

Not a bottle opener but back in the swansong days of the NR500, but while the exact configuration of the engine was still unknown, Cycle magazine was given a single conrod. From that they (either Jennings or Cameron) were able to posit the design of the engine to what turned out to be a remarkable degree of accuracy. I miss that degree of technical journalism. Cameron does still write for Cycle World, but not quite to the same depth

I miss it too. There doesn't seem to be the required level of knowledge in the current wriers/commentators on the sport now.
You can go back to S.C.H. Davis prewar and postwar, followed by Phil Irving and others in the 50's and 60's then Jennings and Cameron. Don't know whether Cathcart is still writing but he seems to have been the last of the technical writers who could ride as well. The ex riders who do columns don't have the technical background their predecessors did.
When the book on the current fourstroke era is published I probably won't be around to see it. Bugger. No idea who's going to write it either.
If there's a book on the last of the 2 stroke era I'd love to see it. If there isn't one, it had better be done soon as those guys are dying off.

[F5 Dave]

Cameron did a good one on GP engines about 15 years ago.

Not written, but did you hear Crafer explain in about a 20 second burst under live pressure at Mugello what was likely happening with MMs ride height mechanism being the likely cause of smoke over a bump, how it works and why, and what was likely wrong, all without a breath or um, ah.
That was focused.

[Grumph]

Yeah, seen Cameron's book. What's needed is one or more like The Grand Prix Car Vol 1 & 2 By Laurence Pomeroy. Analyses the periods covered in detail, races, results and mechanical trends. Then analyses examples of the cars. In fine, exploded detail. He had been editor of The Motor and his dad Vauxhall designer in the
early years. Qualified Mech Engineer too. Vic Willoughby was probably the closest writer - his The Racing Motorcycle is very similar style. But stops just when things get interesting.

20 second information bursts are what Si gets paid for. He's better at it than you or I would be so he gets the big bucks. And good on him too.

[F5 Dave]

Bradley's book on racing motorcycle is good, bit old and crazy expensive. Only borrowed it otherwise I'd send it down as was considering with the Cameron book.

[Grumph]

Bradley's book on racing motorcycle is good, bit old and crazy expensive. Only borrowed it otherwise I'd send it down as was considering with the Cameron book.

I've got vol 2 and the last one - 3 or 4 ? Vol One is theory. Two you need if you're building anything.
Last one is more about tyres than anything else.

[pritch]

Don't know whether Cathcart is still writing but he seems to have been the last of the technical writers who could ride as well. The ex riders who do columns don't have the technical background their predecessors did.

Hugh Anderson and his Suzuki mechanic used to strip the engines and remove high spots after practice.

Then there's this:
https://mike-thistledown.blogspot.co...adversity.html

Shepherd doesn't mention it in this account but as part of the solution to the lower octane rating in the US he also had to fit extra gasket(s) to lower the compression.

[F5 Dave]

I'll read that more fully later.

My cat is named Kaaden.

[jato]

while not bike related, this "tour" of the factory producing merlins is pretty impressive imho esp considering the stakes were so high and the result was so good. there can't be any weak links building building a light powerful and reliable engine and you've got to say the poms did real good... https://www.google.com/search?q=yout...o7SmNuUU4,st:0

[pete376403]

Hugh Anderson and his Suzuki mechanic used to strip the engines and remove high spots after practice.

Then there's this:
https://mike-thistledown.blogspot.co...adversity.html

Shepherd doesn't mention it in this account but as part of the solution to the lower octane ratio in the US he also had to fit extra gasket(s) to lower the compression.

Honda had to run low octane in the super high tevving multis in the '60s becuase high octane didnt burn fast enough at 22,000 rpm

[Grumph]

while not bike related, this "tour" of the factory producing merlins is pretty impressive imho esp considering the stakes were so high and the result was so good. there can't be any weak links building building a light powerful and reliable engine and you've got to say the poms did real good... https://www.google.com/search?q=yout...o7SmNuUU4,st:0

My understanding is that it was only when Packard redrew the engine with tolerances on parts which made them suitable for mass production that it became a feasible front line engine. Packard out-produced RR and the Packard built engines had a much better reliabilty record.
RR stuff was basically hand built in small batches. Which is what they were used to. Good book by an insider at RR who later became MD, Not Much Of An Engineer.
Author name Sir Stanley Hooker. Designed and developed the blowers which gave big HP gains. Later designed the early Jets.

[pritch]

My understanding is that it was only when Packard redrew the engine with tolerances on parts which made them suitable for mass production that it became a feasible front line engine. Packard out-produced RR and the Packard built engines had a much better reliabilty record.
RR stuff was basically hand built in small batches. Which is what they were used to. Good book by an insider at RR who later became MD, Not Much Of An Engineer.
Author name Sir Stanley Hooker. Designed and developed the blowers which gave big HP gains. Later designed the early Jets.

Umm it's probably also a consideration that the Brit factories had to be hidden from prying eyes despite which there may have been bomb damage to their factories or those of suppliers.
No such concerns at Packard.

https://www.bbc.com/news/uk-england-derbyshire-68383619

[jato]

Absolutely Pritch - and wartime england didn't have too many spare fitter turners in 1939 so the design of the factory processes and to some degree the engine itself had to take into account that unskilled (semi-skilled?) workers would be building the engine. it may of been a different video but even where the entrances to the buildings were planned to help efficiency and firefighting in case the germans bombed the place. i look at the bloke with no glasses or earmuffs banging out con rods on that forging machine and then watch genuine footage of a young pilot screaming down in a steep dive dog-fighting a messerschmitt and you've got to say the poms did real good... (sorry Fraser - plenty of thread drift here...)