Does a belt in tin primaries need venting

[ArizonaMike]

Hi Everyone,

Remembering Harley's discontinuance of its belt primary due to overheating problems, I was wondering if tin primaries with a belt drive need to be vented, such as my idea of drilling many holes along the bottom of both primarys. Anyone experienced any heat problem with a belt drive inside tin primarys? Thanks in advance for any advice.

[mbskeam]

hello,
I have had a belt set up for about 12,000 miles. this is in the stock primary cover. I run the std belt . If you think that you might have a problem with the belt breaking , you could use a belt with kevlar. But they are twice as much.
So as I was writing, I have not had any problems with heat, trying to kill the belt.
Now rocks on the other hand ...... have killed 2 of them.
1st time I had the outer cover off because set up was new, and I was checking it out.(all summer long).
2nd time, I think a rock got in thru the inner cover tranny shaft hole , I think it was put in there by the slinger on the tranny. It is not there any more. just cleaned up the pits and dings with a round file, put on new belt and away we go. belt technology has goten better than the 70,s. But I will say a chain set up works well also,if the parts are not all worn out.
mbskeam

[dj]

My stock "style" outer primary cover has holes drilled in the front and back to facillitate "flow thru ventilation" for the belt.
It came this way. I can't give any reports on performance because I'm not up and running....yet. The holes seem to be about 5/16" in diameter.

[caschnd1]

I use spacers to keep my outer primary about 1/4" out from the inner tin. This allows good air flow and is rarely noticed by someone looking at the bike. Just needed to use longer primary cover screws. Don't know if heat would have been a problem but I went with the recommendation from Primo. I live in Arizona so we get well over 105F here in the summer on a regular basis. Didn't want heat to be a problem for me.

[dj]

It would be criminal to drill holes in an OEM primary cover for this purpose....but you knew that.

[junker]

just to be safe i took the inspection cover plate off my outer cover,and made a wire one out off a old aircodition grile.a picture of it is in this site looks alright to me.if i go back to chain just have to change plate.

[ArizonaMike]

Hi,

Yes, I agree it wouldn't be a good idea to drill holes in OEM primarys.
(Mine are aftermarket).

[108]

Two years ago I added a group of stagered 3/8 holes around the lower front and lower rear of the inner tin primary on my "48 FL to let air flow through since they do develope heat and I thought it might help the belt. You cant see the holes unless your on your knees ( mine is painted black). But one the other hand , the 1 3/4'" belt already had 10K on it and looks like new now so it may not be a big issue !