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Discussion Starter #1
First ride of the season I noticed a squeak/squeal coming from the top end of the rear cylinder. It sounded like something going bad with the cam shaft. The engine was running just fine, but there was a bit more popping on deceleration (a clue). It turned out to be the air valve that supplies fresh air to the reed valve. It is located directly above the rear cylinder under the seat. It appears that the vacuum valve diaphragm has failed and is now producing noise. I blocked the vacuum line for now (noise is gone) and will marble or coaster when I get the parts.

Sometimes mods are just thrust themselves upon you!
 

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Best thing to do is get rid of that entire system. It's a huge mess. But it is fairly easy to get rid of the whole thing and be done with it. Remove the rubber hoses from each head, leave the fittings/covers on, do not remove them. now look up under the gas tank and find where the third large hose goes into the airbox. Pull it out. then disconnect the small vacuum line from the right side of the rear carb. Take the whole mess somewhere and throw it as far as you can. Now, go down to the local auto parts store, like Autozone, O'Reillys, Pep Boys, etc. And get a couple of those heater hose block off caps for cars, a vacuum cap that will fit the nipple on the rear carb, and a rubber plug to plug the hole left in the bottom of the airbox. That makes a nice clean job. You can also just cut off short sections from all that rubber hose you took off, and use it to make plugs out of by screwing the appropriate size screw or bolt into one end, and putting the other end back in place. You'll swear your bike feels 50 pounds lighter without all that crap.

I see you are in Portland, OR. I have relatives up there, in Forest Grove. I'm going up in early June to spend a couple of weeks. They told me it doesn't rain any more and is rarely even cloudy. I just loved the weather up there. So much nicer than the Phoenix, AZ desert.
 

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Discussion Starter #3
Best thing to do is get rid of that entire system. It's a huge mess. But it is fairly easy to get rid of the whole thing and be done with it. Remove the rubber hoses from each head, leave the fittings/covers on, do not remove them. now look up under the gas tank and find where the third large hose goes into the airbox. Pull it out. then disconnect the small vacuum line from the right side of the rear carb. Take the whole mess somewhere and throw it as far as you can. Now, go down to the local auto parts store, like Autozone, O'Reillys, Pep Boys, etc. And get a couple of those heater hose block off caps for cars, a vacuum cap that will fit the nipple on the rear carb, and a rubber plug to plug the hole left in the bottom of the airbox. That makes a nice clean job. You can also just cut off short sections from all that rubber hose you took off, and use it to make plugs out of by screwing the appropriate size screw or bolt into one end, and putting the other end back in place. You'll swear your bike feels 50 pounds lighter without all that crap.

I see you are in Portland, OR. I have relatives up there, in Forest Grove. I'm going up in early June to spend a couple of weeks. They told me it doesn't rain any more and is rarely even cloudy. I just loved the weather up there. So much nicer than the Phoenix, AZ desert.
Thanks Jerry, I plan to do just what you described with the air valve removal (no longer works anyway). I am very familiar with Forest Grove, OR as my wife and I ride our road bikes through there most weekends (planning to ride there tomorrow in fact). If your in Oregon between June 5 - June 9, check out Fleet Week in Portland. They haven't posted the official list of ships on display, but there is usually at least one missile destroyer.
 
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