Cooling Lambrettas

[J1MS]

I leave the inner lip intact on the mag housing and trim only the portion in front of the vent to the head cowl... It seems to work, but the main thing that shifts the air (and its a big difference)... is the fan fitting as close as it can to the cowling, and the aperture in the center lining up with the inside edge of the fins... This way the whole of the fin area is shifting air...
This makes more of a difference at high revs as the pressure being created would try to overcome the smaller area of the fins that traps air on an unmodified cowling... But if the whole fin area is being employed this then adds more force to the air supply at higher revs, which is where its needed most...
Especially on Tuned motors, or RB's when using the AF style light flywheels... Or using the larger SIL cowling on a standard flywheel...

[soulsurfer]

I've trimed the floorboards, on the right for carb clearance and on the left for more cool air, but I have also removed the splash plate to let more air through. The flywheel cowl is also as close as possible to the fins. I have also seen the flywheel cowl filled with expanding foam to maximise airflow.

[Adspeed]

Interesting stuff!!

Just bought a carbon cowl from PM and on fitting its made for long fins

So now looking for a mid weighted long fin flywheel, the replay ones look ok. I'm not overly worried about it but always a thought, is that the long fins could cause the loss of a horse or so because of the extra drag

I too wouldn't think cutting the rear runner back would be a benefit, my thoughts would be that it will be easier for the fan to move the air above the runner and behind the panel as its designed. Cut away its open to a lot of turbulance and forces at high speed. IMO

Adam

[soulsurfer]

Interesting stuff!!

Just bought a carbon cowl from PM and on fitting its made for long fins

So now looking for a mid weighted long fin flywheel, the replay ones look ok. I'm not overly worried about it but always a thought, is that the long fins could cause the loss of a horse or so because of the extra drag
Adam

I'm using the PM cowl, you'll still need to shave a few mm off the fins due to the thickness of the carbon. I used a lightened 2kg long fin flywheel and took around 2mm off the fins to gain clearance but at the same time it maximises the cowling.