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Post by headcase on Jul 15, 2013 23:12:28 GMT -5
I know that's kind of a loaded question, but assuming things all stay put and there are no broken parts yet, how many miles can I expect out of the engine? My ears are funky things, they hear mechanical noises others can't seem to pick up...and I'm hearing what sounds like a still-good-running, but higher mile loose and progressively sloppier bottom end. I just recently passed the 20k mark, and I THINK I saw .025 stamped on the pistons last time apart...overbore (MM?) in the past maybe? As best you can, try to give me a description of the kinds of sounds I need to worry about. I can sort the valvetrain noise out fine, but just not too familiar with what's passable on a roller-bearing crank and gears. The bores, rings, pistons, cam lobes and rockers all looked really good, and the cam has new bearings. Everything else is original from what I can tell...unless it did get a bore/rings from a previous owner. I do realize there are no cooling jackets or water to insulate noise, the stuff I'm talking about seems to be coming from below. Again, nothing serious sounding, but just progressively clunkier downstairs.
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Post by grizld1 on Jul 16, 2013 1:09:29 GMT -5
Dan, it all depends on how the motor has been treated. I've seen XS650 motors that were used up in under 20K miles, and I've seen others that were running great without ever having the cases split at way over 100K miles. If the mains go, they'll make a loud whirring noise. If you're not hearing that and there's no rod knock or piston slap (which you'll hear very clearly if the small end of the rod stretches), you have a lot of miles left on the low end.
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Post by headcase on Jul 16, 2013 21:41:34 GMT -5
A hundred thou?? I am duly impressed. Considering this one has had at least 4 owners (self included) and came to me with a box of parts and dirtier than Lisa Lampanelli, I'm thinking there was a wee bit of neglect in the past.
The recent oil change didn't show any chunks, but the magnets were pretty caked with black dust...yep, magnetic dust. I'm also getting a strange hollow-sounding cyclical low growling from somewhere at 50mph and above. It doesn't match the speed of any rotating parts really, I was thinking maybe chain speed-ish, but it's much slower than that. Is there any reason not to put it up on the centerstand and run it through the gears with the rear hanging fully extended? I'm thinking a decent video with good sound (no road or wind noise) might help diagnose some of it.
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Post by headcase on Jul 19, 2013 19:01:50 GMT -5
Oh come on, you mean there isn't one good growl-detective out there?
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Post by grizld1 on Jul 19, 2013 19:54:18 GMT -5
It's not always possible to logic these things out, but let's go for some WAG's. Does the noise occur in any gear at 50 mph, or just in 5th? If there's anything odd or erratic in the feel of the clutch as it engages, have a look at the damper springs in the primary gear on the back of the clutch basket--they're prone to breaking. That "magnetic dust" is not a good sign; something got (is continuing to get?) chewed up. I'd suspect the clutch or tranny before I'd suspect the low end, just based on the correlation with road speed rather than rpm.
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Post by headcase on Jul 19, 2013 22:49:12 GMT -5
Is the clutch friction material magnetic in any way? Aside from the steels, I mean. It seems to be working great, although I did recently pop for the roller bearing upgrade,new cable, and 6 new springs...yet to be installed. The usual difficulty getting neutral from first, and first from neutral when hot. I plan on checking the cush springs (I think that's the tech name) when it's apart. I do remember now pulling the clutch in at 60 and listening to see if the noise was a rear wheel bearing or the chain, and it went quiet. I haven't been on the thing the last week because of the heat. I needed the 4-wheeler (with ac) to sit in at lunch  |
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Post by grizld1 on Jul 20, 2013 7:47:11 GMT -5
There's no magnetic stuff in any friction plate compound I've seen. Something is getting chewed up, and IMHO you'd be better off to open up the motor and look than to wait and risk collateral damage.
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Post by richard on Jul 20, 2013 21:01:54 GMT -5
It could be any number of things, but those springs on the back of your clutch basket or the thrust bearing behind you clutch could make little shavings like that. One of my bikes had a broken clutch dampener spring and the only way I found it was to pull the clutch off. that kind of stuff makes finding neutral difficult and makes the shifting notchy.
Aluminum shavings can come from the clutch fingers being shave a little by new clutch plates until it breaks in. On the 71 I've had my clutch apart five times getting it sorted out, filed the fingers and everything but now it goes into neutral like butter and shifts like a new bike.
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Post by headcase on Jul 21, 2013 12:41:39 GMT -5
I took a decent ride last night and listened for the noise in 4th as well..yep it's there, but not as pronounced. The thing FINALLY seems so happy to growl along at 50 or so that I really hate the thought of tearing deep into it again. I'd say mission accomplished as far as getting it to run and roll nicely down the road. (The tire issue from another thread is un-noticeable above 45 or so. Smooth as glass really) Where the clutch is concerned, I'm hoping the bearing/spring upgrade will help with various noises when I get back into it. I filed the fingers smooth a few years back and it did make a nice difference. I planned on doing the clutch stuff along with the oil change in one session, but ijjit me forgot to bring the parts to the shop and didn't notice until I got the oil out and cover off.  The magnetic black dust I found reminded me of the same stuff you'd normally see in an auto trans fluid change. In that case it's considered normal, as long as there's not too much of it. I figured clutches..oil..same result. I'll be paying closer attention to it, that's for sure. Might be a week or two before I get back into it, but I'll update whenever it happens. If the springs on the back of the basket are shot, that'll mean yet another drain and tinker session. |
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Post by richard on Jul 21, 2013 18:48:32 GMT -5
Yep and the oil I use is not getting any cheaper.
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Post by XS Rod on Jul 22, 2013 13:06:22 GMT -5
I knew my bottom end was ready for a rebuild when all of the sudden she started to knockin'
and down in a dips she started to rockin'... crankshaft cheek was kissin the inside of my case...
Took the crank out... saw the witness mark where it was kissing the case... tried to insert crank back in the case and it was too big. Which led me to the brialliant deduction that the crank pins were loosing their grip on the cheeks. Took it to Shell Thuet and he did the rod bearings, pressed it back together and welded it up.
As for shavings... how often are you adjusting your valves? Are you noticing a lot of play in the rockers? Could be cam/rocker wear... just a thought.
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Post by headcase on Jul 24, 2013 16:54:59 GMT -5
Rockers and valves seem to be holding up ok, I just wish the adjustments would stay put. It was good for the last 2 weeks, now it's acting tight again on the right side (popping) yet I can hear ticking as well. Could be the chain tension adjustment again, that thing never stays put either. The cam etc. looked excellent last time apart, nothing alarming there. And shavings really isn't the word I thought of, just looked like the normal fuzz you would see on an oil change, just a bit more than I expected is all.
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Post by richard on Jul 24, 2013 19:02:52 GMT -5
I wanted to set my tappets tight because of the clatter in the 100 degree heat. I tried that and got an occasional pop while idling at a stop light which usually that killed the engine, so I relented and set them back to spec. I haven't had another problem with any miss since then. The colder it is the better that bike runs. The positive crank case breather helped a lot in quieting down the whole engine. I bought two a reed type PCVs I figure to install on two of my bikes to see if I can lower the crank case pressure even more. Since lower case pressure equals more oil flow, It would be cool to pull 30 pounds of vacuum on that crank case. but I'll settle for whatever I can get it.
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Post by XS Rod on Jul 25, 2013 12:46:09 GMT -5
Dan... my thinking was if you're having difficulty maintaing your valve clearance it may be an indication you're doing a little grinding on the rockers and cam... could explain the funk in your oil...just a thought.
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Post by XS Rod on Oct 3, 2013 11:19:46 GMT -5
Rule of thumb from my understanding is better with the valve adjustment on the loose side to ensure valve closure. Based on thermal expansion all clearances should be tighter the hotter it gets... thusly there should be less valve clatter the higher the temp gets. If you're misifirng out the exhaust due to the valve adjustment being on the tight side... you could burn a valve.
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