chatter? and other issues.

First I've noticed an irregular chatter that seems to come from the top end at around 1500- 2000 rpm. Kinda comes and goes. Any thoughts?

Second, the springs on my new hagons are rubbing the paint off the shocks. Too much flex in the swingarm? Its not the gusseted type. '72.

What do you all think?

A definite chatter reproduced in specific rpm band sure sounds like it needs more mechanical elbow grease by its owner to solve. Suspect anything from loose connections in head steady or coil bouncing to carb slide still being chewed up before spit out or maybe a valve guide loose or finally time for its regular 5000 mile cam chain and valve adjustment. Look in now or just wait till it goes away or becomes badly obvious.

Had the timing cover off today to check chain. Chain is within spec. Pulled and cleaned inspected oil pump while I was in there. Every thing is good and tight. No metal shavings or anything noteworthy.
The headsteady is an old britts adjustable replacement. Haven't checked it out yet. Front iso is at. 012in. Haven't checked rear yet. I'll have the tank and covers off next week and check everything out. Its been making the noise since I got it a few months ago. Hasn't gotten worse, or better. Just annoying. Makes me worry. Trying to get through the summer and will do tear down rebuild next winter. Being this is my first norton i was wondering if its just one of those norton noises.

As far as my other question, it looks like the springs are just bowing under compression and rubbing the shock body. I can push the spring into the body with my finger while sitting on it. Strange its only on the front and rear of the shock bodies, and not all the way around. Any one experiencing this?

Hm, on my first ever Cdo, I didn't know what was normal either, so early on I rode slow to listen to the head ringing sounds, hoping it stayed regular to imply a normal old engine sound, till my heart dropped to hear out of cycle identical tinkling rings, implying that something was loose and banging around from road lumps or engine vibes and it'd soon bust up a ways from home, then I heard an extra tinkle in my face as a bat dove in and out, then another and another for a mile or so. May just be normal ring-a-dingle Norton twins make when happy
and wind blast or exhaust bark not covering it up. A Roadster tank lets more of the top end sounds through than Interstate and a fairing with lowers can magnify reflect a lot more head sounds back up too.

No mater about what is initiating the sound, they will all sound about identical I've found as its only the whole head ringing you can hear, no matter if tapping on rockers, valve springs or spark plug or edge of rocker box. Even the headers can cause a ring ding sound in their pipes that then rings head too. When I wrapped headers it quieted the front down so purer head sounds come through.

MIght try a stick on engine to ear or probe on a stethoscope to hunt for the source.

[video]http://www.youtube.com/watch?v=F8muUHt6OHs&feature=related[/video]

Chatter in an RPM range like that makes me think it is something to do with the isolastics. But it will end up being one of those things where you work on a bunch of stuff and when you run the bike it will be gone and you won't know for sure what it was!

Russ

Not going to say you should ignore it but a long time ago on a freeway offramp far far away I thought I heard what must be "bad noises coming from my 72, 750. Being the ambitious young twit that I was, I actually tore the motor apart looking for a broken "something"... I found nothing, did have the Head gone through although the local Norton guru said it didn't need it. New rings & a hone job it all put back and when hot still made the noise. I'm not going to admitt I took it all apart again then when it STILL made the noise when hot I finally took it to my local Guru who laughed in disgust at me while he said " A healthy Norton is supossed to make that noise!!! In my defense all I can say is I was very young, had no role modle growing up to teach me and I was generaly just stupid!!! Now I TRY to "let the thing sing"...

Im thinking iso's as well. Seems to be a harmonic coming and going as the revs fluctuate in the 1500 range. More annoying than anything. Not about to tear apart and search.
My pop was the guy that would run vehicles to the ground. 250,000 miles was not uncommon on a car of his. Regular maintenance and little else. I'm a bit more anal when it comes to mine. Any little sound that's not "right" and I want to know what's making it to correct. Unfortunately i dont know whats right sounding for a norton. There are no other commandos in my area that I can listen and compare it to. Kinda on my own here. But... That's why I have you guys!

About 1500 rpm new start up sounds, barely hear the head tinging.
[video]http://www.youtube.com/watch?v=Migqk7xdI80[/video]

This is about best fidelity video that matches my own up close and slow. I love that Commandos sound so much bigger than they really are.
[video]http://www.youtube.com/watch?v=_dUuEQ-jryI&feature=related[/video]

Thanks hobot. I've seen the second before. My bike is alot rappier than the black bike. Sounds like the blue bike but a bit higher timber. Could be cam or pipes. Don't hear the mystery noise though.
Could be somethin loose like you said. Rattling around at that frequency.
Sound waves / vibrations are powerful strange things. Makes stuff do all kinds of crazy tricks. Had some funny looking trucks out here doing sonic mapping of an aquifer under my house they are using for natural gas storage. These things had an emitter (big pad thing) that dropped down from the center of the rig and onto the ground. The emitter ranged through about 20 frequencies. From barely audible to about the middle c range. Anyway. The lower freqs shook the garden tools off the pegs in the barn and rattled some cans off the shelves. The glasses in the house were dancing around in the cabinets. They would do this about every 100 feet or so. Drove the dogs and livestock in the neighborhood crazy. In power industry care with cableruns must be taken as 60hz vibration has worn insulation away at points of contact with surfaces causing shorts.
The walls of jericho... Cool stuff.
Except when my bikes doing it. Not so cool.

Oh my oh my, sonics are a big factor on all scales. Ms Peel will be able to produce such a sonic THUMP it will call out every alphabet agency and local crisis crew for a county wide shock wave of reports flooding in of super bomber crash or space capsule break up re-entry implosion. Not from her engine running though.

One of my plans is to get a transducer and record, spectrum graph samples from various spots, and monitor over time and with various alterations. I' bet at some point if sampling enough Commandos, patterns may show up to ID various components when eventually reported to fail, or discovered in my own bikes. I really wonder if Ms Peel was the smoothest Cdo every was, after the tri links and few other things. I've tasted 6 Cdo's 750'850's and all mostly annoyed me until at full hiway speeds, often too fast for conditons, so vibed me a bit, but still nice compared to other cycles. How could we objectively measure this stuff sonically?

Keep digging, good for character testing and avoiding new faults distrubing stuff in and out, ugh. Hope its just quality wasted time practicing Commando worshiping postures.

In Fla hunters used to make gator holes to attract game by fertilizer/diesel 55 gal drums, we feel em more than hear them. 5-6' deep x 10-12' wide per drum.

[video]http://www.youtube.com/watch?v=i20zvZ-3MMw&feature=related[/video]

caddy chris,

My high milage 850 had a rattle like that for years, it came just off tickover and stopped at just under 2000 and only when warm. I was convinced it was the ISOs. A couple of years ago I replaced the crank cases and fitted new main bearings, not because the old bearings showed any signs of wear other than they'd done a lot of miles, I also changed the clutch basket bearing and main shaft ball race at the same time, and the rattle stopped. :?

My conclusions right or wrong were; Less play in the new cam bushes, the old ones were shot, and, or, it was the old mains thrusting out causing the rollers to rattle. I've heard that rattle on big vibration motors that are fitted with roller bearings as they run up. However, my mates Mk2a has started doing it and strangely he's just started using synthetic oil, the same as I've used for years. He reckons it could be the lower friction of the synthetic oil that allows the crank to end float easier. :? He's heard the vibration motors run up too.

Anyhow, I reckon I must have covered 50k with that rattle. Try ear plugs very cost effective.

Best of luck,

Cash

Hahaha! Ear plugs! Got tons of them. Guess I could go one step further and crank up the mp3! I find blugrass is good for cruising. Im running royal purple 10-40 for winter, so I guess that makes sense. Going to 20-50 once it warms up, maybe the heavier oil will quiet it a bit. Thanks!

Interesting, I've wondered if I'd enjoy stereo while riding over the wind and slight exhaust - engine sounds that get through. I've got the sparker to work exhaust flame thrower, but the 'Brown's Gas' fuel/air implosion can not be filtered out by ear covering. Nortons always sound like something loose and about to break off and jam to me with its normal tinkling dinging ringing rattle sounds. Leaves me pensive but w/o cause as you can't hear and respond in time to prevent much when something lets go just lightly riding alone. You've checked what ya can, so ride it and learn to live with a noisy obsolete delighter.

Wait... you've got flamethrowers on your bike??? That's crazy! You should rig up some injectors and two plugs per pipe. Seen a car throw flames bigger than it was. Of course some unburned fuel puddled up in the bumper and it caught itself on fire a bit later. Oh, what drunken fun that was! Dude just drove around till the fire went out. The true killswitch style throwers are the best imho. Good way to kill your motor tho...

Well Peel only has one megaphone so only one flamethrower planned. The ignition system is the guts out a tube type stun gun. I don't think spinning up engine and hitting kill then the sparker hurts engine, just night vision and stuff too close.
I'm a propane guy and that often added for bigger effect but I've about run out of places to stick stuff and retain mostly desert racer paired down look. Hehe, a kill button tap sure made a good Pow out the hollow megaphone in past.

I've got to have a way to clear deer before I get on top of them so paint markers also in plans, but maybe my own design for dozens of rounds a second out put, likely pushed by ~200 PSI LPG, so if I put sparker at barrel ends flames could scare deer but also melt my knees paint off by the blow back : ( Would entertain crowd at rallies while parked.

If ya come across a real good Puma scream send it my way as also need something intense hair curling to scatter animals before I even see them. Could switch it to Dixie or ice cream jingle bells for city travel.

ah, ya know Ms Peel is also a low rider like the Latino hoppers don't ya?