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Carb Oil Cap Loosens

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RAC68

RAC68

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When out for a ride yesterday, the car began to occasionally backfire when accelerating. Sure enough, the cap on my rear carburetor was open. This has become a common problem for me and, although not a major issue, is an inconvenience that I can’t seem to fix.

Has anyone had this problem and found a fix?

Ray (64BJ8P1)
 
RAC68 said:
When out for a ride yesterday, the car began to occasionally backfire when accelerating. Sure enough, the cap on my rear carburetor was open. This has become a common problem for me and, although not a major issue, is an inconvenience that I can’t seem to fix.

Has anyone had this problem and found a fix?

Ray (64BJ8P1)
Click to expand...
I had the same problem several times over 30 plus years of ownership. You can use a bigger wrench to tighten the cap or FIX the backfire problem which IS the real problem. Sounds like a lean carb engine. Lean could eventually damage your piston(s).
Do the usual: check timing, carb mixture, etc.
 
During my SU CARB TEST
https://picasaweb.google.com/lh/photo/27ibpEuXIWd9yQIj-yoF-NMTjNZETYmyPJy0liipFm0?feat=directlink
I have find that with light oil and loose or missed CAPS
The issue is more backfiring
Turning to 20/50 oil and CAPS strongly fixed- backfiring is very reduced- with accurate CARBS tuning and Strobolight Distributor regulation backfiring disappeared
This operation is easy if charged on old mechanic experienced
as my friend BORIS-alternative (but not so easy)
https://www.sucarb.co.uk/TechnicalDetail.aspx?id=61
Cheers
Andrea
 
A possible cause of backfiring is a leak in the exhaust, usually at the bottom of the down pipes. I actually had the damper shaft burst through the black plastic cap.
 
Hi All and thanks for the comments.

Backfiring is not a problem for me and only happens when the cap works its way off. I am using 20W oil in the carbs and usually shift at around 5K RPM with no misses. My HD8s (and I assume all HD8s) have a plastic cap and I am a little insecure tightening too much. I have tried Teflon tape but it did no good. I also exchanging the caps between carbs and even tried a new cap but have had no success. I am really not sure what conditions cause the cap to vibrate off but I am open to any suggestion.

Patrick, I trust you are OK and did not have any damage from the Tornados the other day. Good Luck.

Thanks again,
Ray (64BJ8P1)
 
RAC68 said:
Hi All and thanks for the comments.

Backfiring is not a problem for me and only happens when the cap works its way off. I am using 20W oil in the carbs and usually shift at around 5K RPM with no misses. My HD8s (and I assume all HD8s) have a plastic cap and I am a little insecure tightening too much. I have tried Teflon tape but it did no good. I also exchanging the caps between carbs and even tried a new cap but have had no success. I am really not sure what conditions cause the cap to vibrate off but I am open to any suggestion.

Patrick, I trust you are OK and did not have any damage from the Tornados the other day. Good Luck.

Thanks again,
Ray (64BJ8P1)
Click to expand...
Thanks for asking about those Tornados Ray. There was a period when there was a deathly calm while the Tornado was passing through and over my house. We were all huddled in the closet with bike helmets on, pillows and dogs waiting for the Tornado to touch down but it decided to pass us over.
Thanks again,
Patrick
 
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