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Discussion Starter · #1 ·
1981 CX500C

I've ridden the bike about ten minutes so far, just long enough to get it home. There is a fair bit of clattering from the engine and I was wondering how quiet they normally are?

Peter Haynes
Grand Bend, Ontario
 

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Does this help? Three bikes, left to right. 81red CX custom, 88 VT 1100 Shadow, and 82 G-Loria. The red bike is long gone to other ventures.

[video]http://s939.photobucket.com/user/ramprat06/media/WinterHarmony.mp4.html[/video]

Joel in the Couve
 

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Its a pushrod engine, so will be noisy

I keep thinking mines loud, but a friend who's had a few said mine is a lot quieter than it used to be. Plus I did the tappet clearances a while back that made it quieter and start much easier as they were slighty too tight on the exhaust and too lose on the inlet after I checked and adjusted them initially. Must have been the settling down period as it hadn't run for about 8 years stored in a garage when I bought it a couple of years ago


My BMWR80ST sounded terrible to me, but others said it was really quiet. I used to hear a local 80's Moto Guzzi before I saw it as the engine was so 'tappety'
 

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Adjust the camchain and tappets before you judge it.

These motors were described as 'eerily quiet' when new by some road testers of the day but developing a few minor knocks and rattles in 30 years is to be expected.
 

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Ignoring exhaust and intake noise, most of the sound is valve train clatter and, on an older bike, clutch basket clatter (squeeze the clutch lever). I think one reason CXs didn't get the 'sex appeal' tag when they were new was because they really don't sound all that peppy at idle - the small ports, buried cam chain, and water jacket over the cylinders keep everything pretty quiet at idle. A properly tuned stock CX idling really sounds like a piece of well-oiled industrial machinery. The characteristic Honda 'primary whine' reinforces the impression.

Most of the engine noise on contemporary bikes was piston slap being radiated by cylinder cooling fins or cam drive noise and valve noise being radiated by cylinder head fins. That's the reason, incidentally, why Harley riders have a persistent belief that you have to rip the stock pipes off a HD the instant you get it home - the mufflers really did choke them to death back in the '90s when the sound regs clamped down because the air cooled V-twin was pretty loud no matter what mufflers it had. HD's only option was to make the exhaust really quiet which, of course, killed performance.

Stock pipes and airbox keep a CX quiet even by modern (quieter) drive-by sound standards. The instant you do something to the plumbing (pods or more open pipes), the breathing noises will be louder than the engine noises - it takes a lot of breathing to get 45 BHP out of .5 litre, and there's a lot of noise associated with that.
 

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Where did that 45hp come from? It is the lowest claim I have seen. Back in the day The CX500 and CX500 Deluxe claimed 50hp, the Cusom 53hp, and the GL 48hp. Maybe I have those mixed up but they are the only numbers I had seen claimed. any thing else is probably a typo.

Apparently, the perforations in the extension tubes in the H-box on the Custom gave it the ext ra3hp. The GL's were supposedly very slightly detuned (another H-box mod?) to run smoother at lower rpm's. Apparently, that H-box was a very trick device, and most of the guys here seem to want to get rid of it. But then who wants to run a Cafe Racer at 2000 rpm anyway?
 

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Discussion Starter · #8 ·
I did adjust the cam chain tension, according to the Haynes manual, and set the valve clearances. the left cylinder had no clearance at all when I started.

Have to try pulling in the clutch lever I guess. It sure does rattle a lot.

Thanks all.
 

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Are you sure these adjustments were made on the compression stroke? If not, they will be VERY noisy with HUGE clearances.

While the valve clearances may have had zero clearance this statement makes me wonder if at least the left side was adjusted on the exhaust stroke.
 

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Discussion Starter · #10 ·
Fairly certain the clearances were set properly. it was hella noisey before I set the clearances, pretty much as noisey after.
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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Check it again. If you did set them on the exhaust stroke, the valves will be loose AND the cam chain will be loose.


R
 
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