Primary rumbling

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grandpaul said:
This advice goes for ANYONE who has their primary case open, and especially those who have removed your alternator for WHATEVER reason.

CHEAP INSURANCE!
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Can someone explain the difference between the welded and non welded rotors offered as replacements? I'm assuming it has something to do with this phenomenon related to the rotor de-staking itself from the center
 
Ok now my brain hurts. I’ve ordered a new clutch bearing and circlips. I’ve also coincidentally ordered a new Lucas rotor and stator. I figured what’s a few hundred dollars while the primary is open. I’ll test the rotor as Grandpaul instructed. I really don’t like the idea of replacing more than one thing at once since as the man said in Dirty Harry “ I gots to know!” If the rotor test loose maybe I’ll leave the clutch alone and re test the bike with the new electrics. Thanks everyone. Ben
 
So I pulled the inner chaincase and measured runout on the countersprocket output shaft. It measured just under .007”. This seems to me not significant for the shaft. Am I right?
Primary rumbling



I did find that the final drive chain rivets were rubbing against the inner side of the inner primary cover plate.
Primary rumbling

Primary rumbling


The inner primary plate holes were a little oblong from the plate being thrown around by the chain. I think that’s what set up the vibration.

The parts book calls for a variable number of inner chaincase shims no. 060399. I’ve ordered several for fitting.

I also ordered Dynodave’s clutch pushrod seal for fitting while in there. I’ll post a separate question about using my podtronics single phase RR with the new three phase Lucas stator.

Any feedback will be appreciated as always. Memorial Day wishes to all.
 
Check the inner chaincase all around the three crankcase bolt holes for hairline cracking.

Fit up the dry, clean inner chaincase to the dry, clean crankcase with a new gasket and just nip up the three bolts. Measure the gap from the shoulder of the hex stud to the back of the chaincase, remove the 3 bolts & inner case, and fill that gap as near exactly as you can with shims/washers. That job's done.
 
It appears as though the gear box sprocket is on backwards. The nut's chamfer should face the sprocket so that the nut would seat properly.

Peter Joe
 
Make sure your gearbox spacer,item 34 part # 03-0023 in the parts list, is between gearbox top mount and inside of cradle. It looks like a thick flat washer. One of the first things I learned from this forum. Mine was in the wrong place for years. Cut a groove on the inner primary even with the original chain. Once sorted, I had enough room to run a heavy duty replacement chain without interference. Have since switched to an x ring conversion from CNW. I live on a gravel road so it saves a lot of mess and maintenance.
 
I just went back and saw your posts Peter Joe and Bill C. After tearing the primary apart four times, I think I found the problem:

Primary rumbling


What an idiot. I noticed a clunking sound when putting it on the center stand so I ch caked the engine mount bolts. I’ll install new bolts and report.
 
maylar said:
One of the great things about a belt drive is that you can run the engine with the primary cover off and not have to contend with oil slinging everywhere. I suppose it's possible with a chain drive too if you thoroughly wash the oil off everything first. Just for a few minutes mind you, for diagnostic purposes.
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Have a friend turn the throttle while you watch the chain. It really does a dance when the RPMs climb.
 
The best part of rear sets is that I can whip off the primary cover with one nut.
Nothing beats regular inspection. You will not be surprised by the surprises you
find.
Aircraft maintenance is all about inspection. There is a reason for this. A bike and
its rider face a similar situation.
 
Scout63 said:
I just went back and saw your posts Peter Joe and Bill C. After tearing the primary apart four times, I think I found the problem:

Primary rumbling


What an idiot. I noticed a clunking sound when putting it on the center stand so I ch caked the engine mount bolts. I’ll install new bolts and report.
Click to expand...
Can't seem to view your pic for some reason. (Not too handy with computers etc.) Hope you get it sorted. Been really enjoying mine. Never be able to repay all the helpful info I got from this amazing forum!
 
I seem to have it fixed. The rear bottom engine mount bolt was missing and the rear middle bolt was sheared off inside the engine case passage. I had to remove the inner primary case ( and clutch, rotor, stator, primary sprocket etc) to remove it as the bolt head was on the primary side (ugh). I replaced the two bolts and tightened and loctited all engine mount bolts ( all other engine to cradle bolts were loose). I rode about 10 miles and the bike feels great - very smooth above 3500 and some low vibes below that.

I didn’t adjust the new vernier ISO’s during the rebuild and I think I ended up with them fully tightened - maybe this caused stress on the mounting bolts. I figured I would ride it for a bit and then adjust them - I should have adjusted in some play up front. I haven’t thought this through and it doesn’t make complete sense to me as overtight ISO’s should pass vibes to the frame and rider, not increase stress on the engine to cradle connection. The bolt that sheared was stainless. I replaced it with an Andover Norton part.

Fingers crossed that this issue is resolved. Forum responses have been so helpful. Many thanks.
 
Had that happen when I first had my bike in 1977. Broke a piece out of the cradle. I've kept a close eye on them ever since. Old Brits says this can happen if the cradle has been powder coated without proper masking for the bolt heads.
 
Did you have the cradle powder coated? It looks like it as there are round areas of coating missing under where the washers were. This is typical of powder coating.

Do keep a close eye on things in that area, this is how the mounting hole areas on the crank cases get cracked.
 
Cradle was not powder coated. It was sandblasted and painted. I’m going to keep checking the bolts. The one behind the primary is now a stud with a bolt and washer on each end so I won’t have to pull the primary if it happens again. I’m hoping I’ve paid my dues for this bike. It’s such sheer pleasure to ride.
 
Hope everything works out now. Just got back from a 70 mile morning ride. Just love to hear it run! It's therapeutic!
 
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