gap between cooling fan and cowl

[davla]

Why not just buy a narrow 50mm cowling? I'm sure I've seen them in with both S3 and GP vents.

[Captain Pugwash]

None of the cowlings for series 1,2 or 3 actually suit the smaller diameter AF flywheel as the fin's do not sit over the flat of the cowling.

AF really could have supplied a matching cowl for these flywheels.

[Adam_Winstone]

None of the off the shelf cowlings fit close to the fins of the AF flywheel, hence buying the long fin type and trimming down to suit, as mentioned in my last comment.

[AlG]

As per Adam, I tend to start with the deeper Indian cowls and cut a band off to get a 3mm gap.
Using the deep cowls also makes it easier to get the new holes in the right place and not have 'indents' left from the old holes that can split over time.
Personally, I find it easier to use a jig saw to cut a wider band off, rather than trim the shallower cowls with tin snips.
Finally, the deeper Indian cowls can often be bought quite cheaply rather than thin 'Italian' cowls.

AlG

[Captain Pugwash]

Sorry Adam I wasn't referring to your post, more the fact that all cowlings, including Indian modified still do not work as well as they should.
This is owing to half of the flywheel fin's sitting in view of the vents and not on the flat of the cowling which they do when used with a standard cowling and flywheel.

[Adam_Winstone]

Don't worry Capt. I understood what you meant and certainly took no offence.

You're quite right that a % of the fins is not well aligned to the inner flat of the cowl, however, it is certainly a much improved situation and aids cooling. Whilst much can be said of theory, before even considering such elements I had simply 'banged on' any old cowling with the AF flywheels and never ran into cooling issues on well set up motors so I'm not too bothered about the small % that might not be ideal, especially if the closer cut cowling offers a big efficiency benefit.

You're quite right... but the modified cowlings do offer betterment.

Adam

[rossclark]

The hole I cut in the plastic is specifically the same diameter as the inside of the fins on an AF flywheel for that reason