How close should the fins be to the cowling

[coaster]

You could also firmly attach a spacer (like a huge washer) to the inside of the cowling to fill the space between the cowling and the fan to create the correct clearance. Don't know quite how you would achieve this but it might be reversable if required. (unlike the leathering with a hammer )

That's what Rocscla was hinting at

On my AF flywheel there's 19mm to the fans, the future is chopping boards....

A teflon chopping board is about 5mm thick, cut a template out of cardboard then trace it onto the chopping board, 5 minutes with a jigsaw...simples. Attaching it might need some thought, small screws and nuts recessed into the teflon maybe? Pretty sure someone has already done this, was it Knowledge?

[Gazbo72]

Thanks for the replys.

I will haveto liberate a chopping board out too the garage. She already moans about the missing plastic bowls and the state of the dishwasher after cleaning the casing. Women !!!

[Boothy_the_makem]

Sorry to jump in but i lost all but one of my cowling bolts on the way back from rhyl. Well the two end ones top and bottom were already missing. Ive put them in but the two that rattled out did cos the threads are fooked.

So do i try and tap the thread or just throw two self tappers in ?

[dapper]

A common problem on mag housings. I always fit helicoils anyway on all the flywheel cowl holes on the mag housing with a bit of threadlock so they stay in. Just a little on the outside of the helicoil and let it go off before fitting the bolts.

[rosscla]

So do i try and tap the thread or just throw two self tappers in ?

You don't want to be using self tappers on anything that goes in and out a lot ...ooo..errr

you might also try rivnuts

http://www.memfast.co.uk/

[Boothy_the_makem]

Cheers dapper. Didnt realise you could gerrem that small. Ive used star washers from a spare set of fork buffer bolts on the others. Al have a look fer a helicoil kit

[Boothy_the_makem]

So do i try and tap the thread or just throw two self tappers in ?

You don't want to be using self tappers on anything that goes in and out a lot ...ooo..errr

you might also try rivnuts

http://www.memfast.co.uk/

Haha the self tapper were a bodge joke hence the smile

Thought i might get a bit abuse fer it

[rosscla]

just an excuse for me to use the in / out joke

[coaster]

My cowling screws did the same last year. I drilled them out, tapped holes to M8 and fitted allen headed screws. I managed to all but the center top one without dropping the engine. Obviously the ones at 7 o'clock, 6 o'clock and 3 o'clock I managed with a drill but the the top left one at the 10 o'clock position I managed grinding some hexagonal flats on the end of the drill bit and hammering an old 1/4" drive socket onto the end. I then ratched the drill in. Used a small open ended spanner on the tM8 tap. It stayed like that for a few months until I had to drop the engine for something else and I drilled and tapped the otop hole.

[Terrible Taff]

On an RB250 that my mate Richard runs his AF flywheel was about 12mm away from the fan cowl & this ran at 260-280'c riding 80+mph when we closed the gap to 1mm the temp dropped by 30'c!
It now very rarely goes over 230-240'c, running at 80+mph & this has 32bhp @ 8,800rpm.
So it will pay to close the gap down in all cases. When running high bhp figures then use the Indian head cowl & deep flywheel & cowlings. Running a CHT or EGT gauge is a must for a tuned motor, I recommend the Mychron 4 data logger that many racer's are using due to the many features available.