New pin and bushes

Finally I got so far that I can mount the new bronze bushes and pin for the rear fork. Taking off the primary drive, I noted the chain was really tight (tighter than a snare). I had to clean the threads of the adjuster first and then loosen the gearbox for some slack in the primary chain. Gear box bolts were not completely loose, but not really tight also. I expected the worst taking off the nuts from rotor and clutch, but they were almost loose. The engine had wetsumped, so I had to replace the bolts from the case to stop oil coming out, will drain the engine tomorrow. The frontsprocket was quite loose also and the 21 will be replaced by a 22. Glad I worked on these parts as I now know all is tight and properly adjusted. The rear wheel has a new tire. A new chain and rear sprocket are waiting, so hopefully I will have a tight steering, easy shifting light clutching bike for next summer.

I'm thinking this should be in the rebuilds section , but that said , I would pull the gearbox and rebuild it if the primary was running that tight. New sleeve gear bushes and an opportunity to fit new layshaft bearing too.

NIX said:

Finally I got so far that I can mount the new bronze bushes and pin for the rear fork. Taking off the primary drive, I noted the chain was really tight (tighter than a snare). I had to clean the threads of the adjuster first and then loosen the gearbox for some slack in the primary chain. Gear box bolts were not completely loose, but not really tight also. I expected the worst taking off the nuts from rotor and clutch, but they were almost loose. The engine had wetsumped, so I had to replace the bolts from the case to stop oil coming out, will drain the engine tomorrow. The frontsprocket was quite loose also and the 21 will be replaced by a 22. Glad I worked on these parts as I now know all is tight and properly adjusted. The rear wheel has a new tire. A new chain and rear sprocket are waiting, so hopefully I will have a tight steering, easy shifting light clutching bike for next summer.

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A lot of owners have fitted a second adjuster on the primary Now would be a good time

Torontonian said:

I'm thinking this should be in the rebuilds section , but that said , I would pull the gearbox and rebuild it if the primary was running that tight. New sleeve gear bushes and an opportunity to fit new layshaft bearing too.

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You are probably right. The box was rebuilt 5000km's ago, no idea how much it ran like this was as the previous owner also tried a belt for some time but switched back to chain. I just about drained my wallet and will try to run it this way. I have no trouble taking things apart, but I will let you know if I should have listened to you right now.

Be sure to use locktite on the three small bolts holding inner primary cover to crankcase. They are quite low torque as case is thin aluminium and the tab washers didn't hold mine secure first time I replaced them. One bolt came out and rattled around in case, damaged the chain. Also why grease should not be used here...as it will not penetrate/spread as needed.

Did any of you enlarge the tiny holes in the spindle hoping for better lubrication?

NIX said:

Did any of you enlarge the tiny holes in the spindle hoping for better lubrication?

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If you mean the swingarm spindle, then no. The bushings are porous and oil only needs to be in contact somewhere on the material and it will spread/seep throughout the material. There are some images on the forum someplace showing this effect.

The 850 cases are quite thick where the inner primary cover attaches, they were thin in that area on the 750 but Norton elected to use the same 1.5D Helicoil as used on the 750 in the 850 cases.
That Helicoil could be swapped for a 2D or even 2.5D insert for more thread engagement for the three (to short) bolts.

The new swing arm spindle and bushes might not be a plug and play affair.