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Repair of crankcases with chopped gearbox.

Oldhaven

Well Known and Active Website User
VOC Member
Never mind, davidd's link explains the probable answer as an Argentinian makeshift.
 

clevtrev

Well Known and Active Website User
VOC Member
Mike White repaired a set of "C" shadow cases many years ago by putting a new set of lugs onto the back of the transmission to replace those that had been removed to fit the engine into a featherbed frame..not the same I know, but difficult nonetheless..
I`ve done several of those, but it was Mike who repaired the tractor run over ones.
 

Ken Tidswell

Well Known and Active Website User
VOC Member
I lost the plot and made a new thread. This was a question for another thread.

But I am curious to know if any one has repaired a set of chopped cases. I am also interested to know if anyone has seen a chopped motor with a norton box in a regular RFM and UFM.

Thnx.
The answer is yes Bob Dunn did one
 

davidd

Well Known and Active Website User
VOC Member
I am fascinated by the Comet racer's double float chambers at different heights. Can you explain, Davidd?
For some reason, I missed this question many years ago. I can only speculate that a single round float chamber fails to provide sufficient capacity. The 302 and the 504 float bowls are amazingly slow at supplying fuel. They may be run in series to provide some fuel closer to the carb. Fuel starvation probably would not happen often on a track, but whacking the throttle open at the beginning of the straight and holding it open at 7,000 may result in a misfire at the end of the straight due to fuel starvation. I was told by Maurice Candy in 2009, who was racing his Manx, that the only float bowl to use was the 510. Anything else would fail to deliver enough fuel.

David
 

highbury731

Well Known and Active Website User
VOC Member
The two float chambers are at different heights. Two different float levels, two different fuel levels. So how does that work?
Paul
 

davidd

Well Known and Active Website User
VOC Member
The two float chambers are at different heights. Two different float levels, two different fuel levels. So how does that work?
Paul
I believe they are in series, not parallel. The float nearest the carb being the last in line, so it would set the fuel height in the carb. The forward float is acting as a reservoir, it only has to drain completely into the rear bowl that sets the height. That is probably why the forward float is much higher. This is just a guess.

I would note that when Alp turns on the Nitro in top gear on his bike the fuel bypasses the float bowl and enters the carb directly. This is because the float would slow the delivery of the fuel down considerably. At wide-open throttle in top gear, the engine pulls in all the fuel it demands (thus ignoring the fuel height). He does not want the float slowing down the fuel delivery.

David
 

Phil Davies

Well Known and Active Website User
Non-VOC Member
Here is the original post on the chopped engine mentioned by Mark:

http://www.vincentownersclub.co.uk/index.php?threads/herb-harris-rapide-cycle-world.6278/

David
Sorry to be a bit late to this party, the web site was recently so slow for me I stopped coming here.
I remember that engine being on the bench at Bob Dunn's place - Bob did all the repair work on it, mating it to that gearbox so it could be run in a bike again, the then owner (who I know of) had the engine and put a chassis around it again, he then sold it to Herb when Bob finished the motor.
 

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