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Discussion Starter · #1 · (Edited)
Hello, have a 1972 cl 350 that I have been working on for some time and have put about 300 miles on it all back roads. The bike runs well accelerates , idles , and has great power, seems like more than my CB360. I installed new points, condenser, coils , rebuilt carbs using original brass except one part that was supposed to be pressed out but previous owner must had tried to screw it out and it was chewed up. Set my float height to fsm specs for my carbs 722a. I did replace brass floats because they were kinda rough, although not holding fuel I was little suspicious, the bike had a problem between 3500-5500 rpm but is resolved. So with all that being said , on my rides I take there is a long down hill about 1/2 mile that comes to a stop sign and when I go to take off from the stop it seems like I’m starving for fuel , maybe in just one cylinder, but if I stop for couple seconds or blip the throttle and let it catch up , then it does fine and this is the only time this happens. Could this be in my float heights or maybe one carbs float height? Thanks for any input.
 

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I'm not sure that this is the answer to your problem: I just dealt with an intermittent issue on my '72 CB350. There were times it would run fine, then act like is was starving for fuel. I'd come to a stop and wait, then it would be fine. Then after a weeks it got to a point where it would start bogging and just die - I would coast to a stop, let it sit and it would start back up. I finally figured out that it was my gas cap vent slowly becoming clogged. I tried to clean it out without success. I finally I bought a new one. I checked all kinds of crap on that bike before I figured it out. Good luck
 

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Discussion Starter · #3 ·
I'm not sure that this is the answer to your problem: I just dealt with an intermittent issue on my '72 CB350. There were times it would run fine, then act like is was starving for fuel. I'd come to a stop and wait, then it would be fine. Then after a weeks it got to a point where it would start bogging and just die - I would coast to a stop, let it sit and it would start back up. I finally figured out that it was my gas cap vent slowly becoming clogged. I tried to clean it out without success. I finally I bought a new one. I checked all kinds of crap on that bike before I figured it out. Good luck
I’ll look into that this weekend, maybe try to blow some air through the cap with it open. It’s just odd that it only does it on the down hill coast on my five mile route that I take , when it does it the idle is lower , guess because it’s only running on one cylinder but with a second or two and Couple blips of throttle it’s good and no we’re else it does it but that’s the only coasting spot that I go down, I’m usually in 2nd tacking between 5 or 6000,
 

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I'm not sure that this is the answer to your problem: I just dealt with an intermittent issue on my '72 CB350. There were times it would run fine, then act like is was starving for fuel. I'd come to a stop and wait, then it would be fine. Then after a weeks it got to a point where it would start bogging and just die - I would coast to a stop, let it sit and it would start back up. I finally figured out that it was my gas cap vent slowly becoming clogged. I tried to clean it out without success. I finally I bought a new one. I checked all kinds of crap on that bike before I figured it out. Good luck
I think I am having a similiar issue with my 350. When it is turned off I can hear air coming out of the gas cap like if pressure was slowely being released. Does that sound like the issue you were having? I've had bogging issues too then it will die and start right up after waiting a little bit.
 

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I think I am having a similiar issue with my 350. When it is turned off I can hear air coming out of the gas cap like if pressure was slowely being released. Does that sound like the issue you were having? I've had bogging issues too then it will die and start right up after waiting a little bit.
Yep. When I was having my issue I was sitting on my bike after it had died, and on a whim I flipped open the gas cap to make sure I had fuel. And I barely hear some air let go. Then it started right up. I instantly knew the problem. The fuel is gravity fed and that cap needs to be able to breath. Good luck
 

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Yep. When I was having my issue I was sitting on my bike after it had died, and on a whim I flipped open the gas cap to make sure I had fuel. And I barely hear some air let go. Then it started right up. I instantly knew the problem. The fuel is gravity fed and that cap needs to be able to breath. Good luck
Thanks for your reply. So are you saying that it does need that suction (for lack of a better term) or that's what is causing the problem? If that is what is causing the problem theoretically if you leave cap open it would run fine right? Not that I would actually do that.
 

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Thanks for your reply. So are you saying that it does need that suction (for lack of a better term) or that's what is causing the problem? If that is what is causing the problem theoretically if you leave cap open it would run fine right? Not that I would actually do that.
Yes. The gas cap needs to vent to allow gas to flow down into the carbs, and also relieve any pressure build-up in the tank - for example due to changing temperatures. In my case I tried to blow air thru the tiny hole on the underside of the cap - tried sticking a paper clip in there to clean the obstruction out. I ended buying a new one from Common.
 

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Yep. When I was having my issue I was sitting on my bike after it had died, and on a whim I flipped open the gas cap to make sure I had fuel. And I barely hear some air let go. Then it started right up. I instantly knew the problem. The fuel is gravity fed and that cap needs to be able to breath. Good luck
Thanks. I don't think mine has a stock cap. A screw on one not the flip up one. It's a 71 CL350. I'll trouble that and see if that works for me. I also noticed that when it's on that the fuel filters barely have any fuel in them.
 
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