Questions re: fins and air cleaner holes>>

[1911tex]

I would appreciate your suggestion and help:

1) Rear head fin is warped upwards, almost touching the next one...don't want to break it off; is there a way to bend it back?

2) The original air cleaner has 2 ports under the carb outlet; one I understand is for the tube from carb manifold; what is the other for?

Thanks fellas and 'HAPPY 4TH!'

[Spokes]

The 2nd one is for the engine vent at the top of the head.

I have tried to straighten fins on some donor heads. They always broke off. Unless someone has a better way, I would leave them bent.

[Jetblackchemist]

Ride the bike til it gets good and hot, leave it running and very gently with a wood wedge; that tapers to the same thickness and depth as the other fin gaps, wedge it out. That's the only way I've been able to do it with out snapping one. Bear in mind has to be running...I've tried a torch, but it wont heat the whole head at once like running will, the rest being cold sucks heat away from it leaving cold spots.

[1911tex]

Jetblackchemist; Thanks, I will try to get up enough nerve to try it and will report back...the only thing that concerns me is that the wedge puts pressure on the good fin as well. Maybe put a wedge between the good fin and the next good fin in order to lesson pressure...if you get my drift. Still nervous about it, but you make good sense.

[Spokes]

Yes, do be careful. I hate to argue a point, but the bent fin is already stressed. Bringing it back to its original position, even when hot, will be risky. Maybe Jet did this, but the fact remains that the fin is weak. Let us know what happens.

[Jetblackchemist]

If you're worried about shifting the other fins, fill them with something and they won't budge. I've managed about 5 fins this way 1 on my Benly. Take your time in making a proper wedge, a nice soft wood like pine is best.

I used to volunteer at a blacksmith's shop, and I was chatting about bent fins one day with the resident black smith Danny and he said ride it here tomorrow...I rode it there and that's exactly how he showed me to fix it, he said he learned it from his grandfather; that used to fix fins on planes that way in WWI. Those alloys were far less advanced then too.

There's two ways to go about it with the wedge; one quick sharp blow, which I don't suggest unless you have extremely good aim with a hammer...or just a little tiny tap tap tap, wait a minute tap tap tap etc. til it is straight.

[Smithers]

Rememebering all the old 2 stroke dirtbikes that were air cooled with massive fins. A lot of them had big rubber blocks that were slotted for the fins to keep them from ringing. Ahhh the old ringing 2 stroke dirtbikes. Anyhow just talking.

Get the whole assembly as hot as you can within reason and give it a try. Give it time in between any movement that you see when you are hammering it. I've watched a lot of body menders/steel workers and have learned that you must give it some time to move while you are stressing it. You can always find another one later. It's so annoying to have a bent fin I know. Plus people ALWAYS will look at your bike and point it out to you. :P I tell people "don't point anything out unless you are going to fix it for me!"