12-26-2022, 08:25 PM
This is the induction system on my project bike build. The bike originally had BS38 CV carbs, but I ditched them and bought a couple of VM34s. The carbs came with manifods which were rubbih and sited the carbs right under the petcocks, so the carbs had to be angled to fit them. Didn't ike that idea, so I turned up a couple of manifolds on the lathe. The manifolds are two piece aluminium and presed together.
Originally I had pods on the carbs to filter the air, they looked ok, but were a little restrictive, so I ditched them and made up a couple of pancake style filters. The inner section wa turned up from a block of 101.6 mm aluminium and wa preessd over the carb bell mouth with a .10mm tolerance, so won't come adrift any time soon.
The outer section is made of 1.7mm 7000 grade aluminium with a 3mm lip beaten around the edges. Whilst induction isn't perfect, however, the carb bell mouths have a stack shape, o it breaths pretty good. Had I recessed the filter a bit burther back and rounded the out edge of the bell mouths, that would have given the perfect induction shape, however, I only had 10mm to play with.
I also tidied up the fuel delivery system, instead of having hosing going everywhere joined by adapter T pieces and what not, I machined up a fuel distributor block. The block sits above and behind the filter and is bolted to the forward lip of the battery carrier The block has a through hole linking both sides of the 8mm outlet spigots, fuel comes in via the two brass barbs I turned up and presed into place on the front of the block.
Thi sytem, as well as supplying fuel to both carbs, also links one ide of the tank to the other, so the fuel levels in either side are the same and thus, one carb doesn't starve when the fuel level gets below the tank tunnel. And, it's a hell of a lot neater than having a jumble of hoses snaking around under the tank.
Originally I had pods on the carbs to filter the air, they looked ok, but were a little restrictive, so I ditched them and made up a couple of pancake style filters. The inner section wa turned up from a block of 101.6 mm aluminium and wa preessd over the carb bell mouth with a .10mm tolerance, so won't come adrift any time soon.
The outer section is made of 1.7mm 7000 grade aluminium with a 3mm lip beaten around the edges. Whilst induction isn't perfect, however, the carb bell mouths have a stack shape, o it breaths pretty good. Had I recessed the filter a bit burther back and rounded the out edge of the bell mouths, that would have given the perfect induction shape, however, I only had 10mm to play with.
I also tidied up the fuel delivery system, instead of having hosing going everywhere joined by adapter T pieces and what not, I machined up a fuel distributor block. The block sits above and behind the filter and is bolted to the forward lip of the battery carrier The block has a through hole linking both sides of the 8mm outlet spigots, fuel comes in via the two brass barbs I turned up and presed into place on the front of the block.
Thi sytem, as well as supplying fuel to both carbs, also links one ide of the tank to the other, so the fuel levels in either side are the same and thus, one carb doesn't starve when the fuel level gets below the tank tunnel. And, it's a hell of a lot neater than having a jumble of hoses snaking around under the tank.
