help needed to identify noise

Grant,
Yes that was my meaning...stater rollers not gripping, which I had.not a problem to ride once going, I.e if they did grip enough on occasion to start it.
Of course it might not be that....get  vid  with sound to Keith or anybody expert?!
 
Starter rollers not gripping is caused by collapsed springs, makes no noises once the engine runs.  Nothing to fear by running the engine, except when switching off... gotta push then.  Loose nut behind the alternator causes clunks and rattles, eventually wears the nut, bearing and clutch housing.  Lots of engines are run for decades without anything actually exploding, everything in the starter housing is eventually fucked though.

Broken starter clutch inner ring, knackered rollers and/or loose tin plate cover can cause sqealing and all manner of funny noises with the engine running, not advisable to use it before the issue is attended to.  Repair bill will only increase... massively!

Mk I starter clutches are quite reliable, far more so than the later type.  Main cause for failure are weak batteries not able to turn the engine while having the ignition give off a reliable impulse, the back-firing quickly destroys the clutch innards.

piet
 
Hi all.
Home safely (at a very stately speed).  Noise is no better, no worse. 
Before I do get stuck in, just to clarify.  The starter works fine, no slippage or squeals.  The noise is almost the same as a knackered ball race, but comes and goes at tickover, gets lost in general engine noise as revs rise.  There is a noticable vibe through the R/H footrest when its making the...... sound. 
Be an interesting one when I get to delve deeper, but as it rained, hard, all the way home I think I'll defer the spannering until tomorrow.
Cheers, and really, thanks for all your input once again.
 
I know it's a bit late in the day to come up with another suggestion.....but

You have checked that all the engine mounts are tight? Anything loose can make an 'orrible buzzy graunchy noise as the revs rise and fall. Quick to check and cheap to fix  ;)

Just a thought...

Pete
 
Good to know you got home without incident. I hope it's nothing more than a bearing in the starter clutch assembly and not a crank bearing as Phil eluded to earlier. The noise and level of vibration is only something you can evaluate but we'd be interested to know what you discover when you pull the alternator and sprag clutch off.

Ian
 
Well gentlemen, I'm feeling a little smug as my diagnosis of a Donald Ducked ball race was absolutely correct.  The race between the rotor and starter clutch has failed quite magnificently. 
I'm doing a complete check for any missing bits that might have wandered off, but all looks to be good with no other damage
Anything special about this bearing, any thoughts as to why it failed?  Can't see it being under any great load or stress so maybe natural failure?

Anyway, well deserved cup of tea in hand, its time to unpack a weeks worth of smelly undies and get them in the washer.


Cheers one and all.
 
Check crank run-out, may be quite a surprise!

Sometimes these bearings are starved of lube and run rather dry, haven't really figured out why though.  Holes to crankcase proper should be large enough to garantee a plentiful supply of oil. 

Any evidence of the sealing nut having been loose at some stage (shiny polished surface where it butts against the inner bearing race)?  Instead of providing support, the bearing will recieve a right pummeling once the crank starts spinning with the alternator rotor hanging off its end.  Also check the fit of the bearing in the housing, should be quite tight, a snug sliding fit at most.

piet
 
Yes Clem,

The factory specified a C3 bearing.  But that has nothing to do with the fit in the housing or on the shaft.  Simply denotes the bearing has increased internal clearance, ie, between inner and outer race.

If the crank runs true to within 0.02mm or so, you could get away with a standard clearance bearing. :D

piet
 
If you are enough of an anorak  :D

C3 bearings are made to have a larger average clearance internally which is a matter of microns, you would be hard pressed to tell a C3 from standard without the numbers.
However there is a 'tolerance range'. The slackest CN (standard) bearing could actually be be slacker than the tightest C3 according where each one is in this range.
 
sfcpiet said:
Yes Clem,

The factory specified a C3 bearing.  But that has nothing to do with the fit in the housing or on the shaft.  Simply denotes the bearing has increased internal clearance, ie, between inner and outer race.

If the crank runs true to within 0.02mm or so, you could get away with a standard clearance bearing. :D

piet
Click to expand...

Those original housing bearings seemed to have been a problem. I had to replace one in my then new 75 3C many years ago when the engine/bearing only had low miles on it.

On my 74 3C (I still own it) that original housing bearing also went out at about 4100 miles, I used a replacement bearing with a C2 clearance as no 3C clearance bearings were available locally. I also replaced the sprag bearing too as some preventative maintenance and the proximity to the knackered housing bearing..used a C2 bearing there too. The bike has gone many miles and has had no problems since..

Maybe the lack of running/lubrication for some period of time has some negative effect on the housing and sprag bearing..or maybe some heavy handed bearing installation at the factory when the engine was built.
 
Just a quick update.  Bearing fitted, all is as peaceful and quiet as any Lav is going to be.  Fitted an SKF as original, a ?12 bearing that managed to spoil a really good holiday, (grumble, whinge). 

I could go on to say, why?  Why balance a rotor so far away from the main casings?  The Japs just bolted the starter clutch to the back of the rotor, would have saved about 2 -3 inches of overhang and given plenty clearance for taking R/H corners.
As my brother would say, 'It's Italian, what do you expect?'

Cheers
 
jdugen said:
Just a quick update.  Bearing fitted, all is as peaceful and quiet as any Lav is going to be.  Fitted an SKF as original, a ?12 bearing that managed to spoil a really good holiday, (grumble, whinge). 

I could go on to say, why?  Why balance a rotor so far away from the main casings?  The Japs just bolted the starter clutch to the back of the rotor, would have saved about 2 -3 inches of overhang and given plenty clearance for taking R/H corners.
As my brother would say, 'It's Italian, what do you expect?'

Cheers
Click to expand...

well - at least they put the ignition on the left side, which gained a lot of R/H clearance back on the later models. One reason I only have these - but scratched the tarmac, still, 3 or 4 times...  :o
 
jdugen said:
Just a quick update.  Bearing fitted, all is as peaceful and quiet as any Lav is going to be.  Fitted an SKF as original, a ?12 bearing that managed to spoil a really good holiday, (grumble, whinge). 

I could go on to say, why?  Why balance a rotor so far away from the main casings?  The Japs just bolted the starter clutch to the back of the rotor, would have saved about 2 -3 inches of overhang and given plenty clearance for taking R/H corners.
As my brother would say, 'It's Italian, what do you expect?'

Cheers
Click to expand...

Yes but you could have fixed it very easily on the IOM, they aren't hard to take apart. Saying that my old 3C got through a couple of these bearings, as Piet said they seem to run dry for some reason. Another 3C I bought had only shrapnel where the bearing used to be. there were bits of bearing everywhere and the ignition pick ups were damaged too. The owner told me its last outing was a track day.
 
I didn't, quite, pack a rattle gun and suitable socket, puller, drill to get the pickup rotor grub screw out, a tap to re-tap the hole, a stainless bolt, a hacksaw and a vice to hold said bolt while cutting to size and a long box spanner.... Oh, and a 16006/C3 bearing!  I had a day and a half to try and sort that lot out, it was raining cats and dogs on a very windy and exposed sea-front.  Don't think I did too badly, once home, total time to strip, source bearing and refit 2 hours.
 
If you're in there, it might be sensible to replace the sprag clutch springs and even rollers...you know they will give up once you have it all back together... ;)
 
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