1975 Norton 850 Restore

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MS850

MS850

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Jul 12, 2015
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Hello, Ive had this bike for about 2 months, drove it home. Its down to the frame, only found a few problems, water pitting in one cylinder, replaced guides and valves. Going back together. not going to be for show, just a nice driver. Seems to be a good group, tons of knowledge, already learned a few things.

http://s926.photobucket.com/user/rtbmrgl2/slideshow/1975 Norton 850 Commando



1975 Norton 850 Restore
 
welcome to Commando Central!

It looks like you know what you are doing having already stripped it down, you have a great project on your hands.

Ask the experts here anything as you go!
 
1up3down said:
welcome to Commando Central!

It looks like you know what you are doing having already stripped it down, you have a great project on your hands.

Ask the experts here anything as you go!
Click to expand...

Oh yeah, Ive lurking around,

There on thing I'm a little concerned about, when I remove the engine all but a few of the case bolts were left out, when I installed back into the frame and installed and tightened all the case bolts a small amount of oil came out between the case in one area. Looking back when i removed the engine I should have re-install the case bolts while I had the engine out, I had no reason so I didn't split the cases. I hope it doesnt leak.


Mark Roseville, ca
 
Mark it's ultimately up to you but seeing how stripped down it all is now I would pull the motor ,split the cases and re-apply some fresh sealant to the case faces. It will continue to leak ,perhaps minimally , but you would hit your head on a wall for not dealing with it now. You could clean out the sludge trap in the crank whilst yer at it. Good luck. :D
 
Torontonian said:
Mark it's ultimately up to you but seeing how stripped down it all is now I would pull the motor ,split the cases and re-apply some fresh sealant to the case faces. It will continue to leak ,perhaps minimally , but you would hit your head on a wall for not dealing with it now. You could clean out the sludge trap in the crank whilst yer at it. Good luck. :D
Click to expand...

Yeah your right, Its easy to get the engine out now. I have investigated but can the case be split without disturbing the timing gear side. If I have too no big

thanks mark
 
That's the best course of action. Your project is nice and clean, keep up the good work!
 
Im in Roseville, Its in No. Calif near Sacramento.
also there is no sludge that i could see in the crank case.
Its 6:30 am PDT (Scotch) im pulling the engine out, wife has a honey-do list when she gets up, I drugged her last night so she'll sleep in. hehehe :twisted:

mark,
 
MS850 said:
also there is no sludge that i could see in the crank case.
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Sludge (if any) would be in the crankshaft gallery (sludge trap) see manual, section C19.
 
L.A.B. said:
MS850 said:
also there is no sludge that i could see in the crank case.
Click to expand...

Sludge (if any) would be in the crankshaft gallery (sludge trap) see manual, section C19.
Click to expand...

Ok Ill check there, thanks,

and WOW a couple of taps with a rubber mallet and the case came apart, my puller bolts weren't quite long enough

thanks, mark
 
What do you recommend for sealing the crank halves, Permatex motoseal, Honda/Yamaha bond, gaskacinch
 
There's one little thing I'm concerned about seeing as we are now opening up casings. You fit the better layshaft bearing into the gearbox ,right ? :)
 
Torontonian said:
There's one little thing I'm concerned about seeing as we are now opening up casings. You fit the better layshaft bearing into the gearbox ,right ? :)
Click to expand...

Dang it, :mrgreen: you guys are killing me, :D
No i didn't, did the 850 have the upgrade or were there problems on all models.
 
MS850 said:
did the 850 have the upgrade
Click to expand...

No unless a PO has done it.


MS850 said:
or were there problems on all models.
Click to expand...

Yes although this basically applies to all Commandos, the Portuguese brass-cage FAG 6203 bearing that the factory fitted to the MkIII models seems to have the highest rate of failure-but any existing standard driveside layshaft ball bearings whether brass or steel cage, should be replaced with either the NJ203E roller bearing or the Mick Hemmings FAG 6203TB P63 phenolic cage ball bearing for the sake of safety as the standard bearing has been known to fail with little or no warning which can result in the gearbox locking-up solid at speed.


http://www.doov.com/apps/nortoncompanio ... ng-upgrade
 
Well let's crack open that gearbox whilst we're at it. Better buy a heat gun and put that new outer bearing in the freezer. Sorry about giving you work after all the polishings.. :!:
 
Here are pics of the layshaft bearing, not sure you can tell if its the old style or new

1975 Norton 850 Restore

1975 Norton 850 Restore

1975 Norton 850 Restore
 
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