Topic
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Air cutoff valve on 1977 XL350
My 1977 XL350 has been having a strange problem that I believe is rooted in the carb. I've long suspected a vacuum leak, but I've been unable to locate one. When warm, the engine doesn't want to come down from high revs. Even if I bring them down using the compression of the engine on deceleration, the revs still jump back to 3K or so once I put it in neutral and wait a couple of seconds at the light/stop sign. When first started, it idles fine, maybe even a little low - some adjustment needs to be made there for sure. Also, when revving it in neutral from idle, it seems to jump from 3k - 4 or 5k with only the barest hint of twist... the spark plug is a nice healthy tan color, if that matters... Anyways, while looking at it today I pulled off the air cutoff valve and saw that the O-ring between the cutoff valve assembly and the body of the carb itself was out of its recess and a little squashed on the side. This O-ring doesn't sit in a round recess, rather it has a lobe at the bottom of it. In my Clymer manual on Honda Singles 69-82, it's labelled with a number 21 on the exploded view of the carburetor for 1977-78 XL350s - if that means anything to you out there. Does anybody think that this could the culprit? I've so far been unable to source the original O-ring, though I've got one that might work (the bike is currently at a friend's shop)... in the case that this is NOT the culprit - or even if it is - is this really a necessary part? Other sources I've found on the internet say that its main function is reducing backfiring... Any further ideas? This has me and the two much more experienced mechanics helping me a little flummoxed... I'd post some pictures, but I have no camera :( Thanks, Sam |
, good luck, Chuck
