Changing front sprocket, what other work should I do?

I'm pulling the primary case off to change out my front sprocket. Is there any other work that I should do while I have this off?

The outer cover had grey sealant on the bottom of the cover, is there a solve to fix this leak or is this it? The primary never leaked much, just a few drips after a ride.

Appreciate your help!

Thanks!

Re: Changing front sprocket, what other work should I dp?

Belt drive? :mrgreen:

Re: Changing front sprocket, what other work should I dp?

What year & model? How much are you prepared to spend?

It's a '73, I honestly don't know the model. I don't want to spend that much, basic upgrades/ routine maintenance. I've looked at belt drive but don't want to spend $400+ at this time.

It's got a single carb, oil cooler and electronic ignition so I'm not going for concourse ready, just reliable (as can be) regular rider.

Here's a photo - the highway pegs are long gone!!!!

Nice looking Roadster. It appears someone has replaced the disc brake front with a drum brake.

While you have the clutch out for the sprocket change, you might want to consider adding one of Dyno Dave's clutch rod seals to keep the gearbox oil where it belongs. When you put the primary cover back on, try putting a thin bead of RTV silicone in the groove of the outer cover and then seat the rubber band into it. If desired you can add a swipe of RTV on the sealing surface of the inner cover as well. Use ATF in the primary and fill to just touching the bottom run of the primary chain.

Does this have the five plate clutch or the four?

Not sure if its 4 or 5 plate. I have to make my tuna can clutch compressor yet, plan to do that tomorrow. Where do I get the clutch rod seal?

Nice looking bike---last of the 750's if it's a 73 model.

If you have the inner P/cover removed---clean everything well. May as well replace the L/side crank seal while in there.
Replace the inner cover without sealer--torque fasteners to specs and then check to see what you may have for clearance behind the center stud--should be snug not loose.
Use a flashlight to see from the right side----use a long flat screwdriver to try and spin the washer---it should spin with a little effort but not easily.
Sometimes it might be better if you leave the washer/washers off then use feeler gauges to get close to the shim thickness needed. Different ways you can do this.
Main point--the inner cover should be straight and not bowed inward or outward---which then causes oil leakage and other problems.
Always use new keys when replacing the drive sprocket and charging rotor and the large washer as well.
Use a new circlip on the main shaft and the recess on the spacer covers the circlip--keeps it in place.
Check the bearing in the clutch hub--replace it if any sign of lateral looseness or roughness when spun--or chatter. Replace it if peace of mind dictates.
Remove all the clutch plates and clean with kerosene or ?? dry off and if you have a 12x12 piece of thick plate glass---or surface plate--check the metal plates for warp.
If you have the bronze clutch plates they will probably be ok but also check for warpage. I use a green 3M scouring pad to clean the bronze pads. If you have access
to a bead blaster---use it to clean off the metal plates and this will etch the plates a bit for a good grip---not a necessity but your call.
When assembling the rotor/stator assemby--use a brass feeler gauge to make sure you have clearance 360 deg around the rotor---no contacting the stator. Clearance
will be around .008" plus/minus as long at it does not rub.
Get a service manual for this model if you don't have one----most of this is in the manual---and then there are personal do's and don't's as always-- everyone has a
different procedure they use to satify their level of perfectionism. Follow the manual and you will be ok.
Install a new o-ring /rubber seal in the outer cover. I like to use a good quality sealer like 3 Bond in the groove first---use a small rounded doll rod to make an even
layer of sealer in the bottom of the groove---allow to set up to harden off a bit---maybe 30 min or so---then insert the o-ring on top of the sealer. The sealer will act as
as slight shim to make a tighter fit to the inner cover. Different ways to go about this as well----some folks use a string in the groove--some use nothing but the
o-ring---then sealer on the outside facing the innner cover. Nothing will work if the covers are already distorted due to improper assembly and shimming.
Use a good quality torque wrench on all fasteners---torque to the factory specs.
If stuck on anything during the procedure--you will find someone on the forum here to guide you along---- good luck.

I'm sure if i may have omitted something here---someone will address the issue---and some will have a different method---just pick & choose from the lot and follow
the service manual as you go along.

Hmm, nice bike, but why do you have that piece of cardboard under it? Come to think of it, I do too. Now if we could straighten out those decals on the panels, but I'm being picky.

The above post pretty much gets it all.

Nice.

Check in more often.

Dave
69S

Clutch seal from: http://atlanticgreen.com/

Or send a PM to member dynodave.

Russ

Double checking msyself on the primary run downs above.
Check clutch hub splines are rippled rough to snag plate slide. No is normal, fair amount common. Check plate teeth are essentially square not vampire points.
Feel edges of the stamped out plate, put slightly round edge to face inward so spring press not resisted. I found a 1.5" end wrench works a treat on the big nut which turns CCW. I use ~ 1" Al squares 1/4" thick to trap basket and hub to nip and unnip. Big vice grips for down and dirty chain trapping to nip up and unnip. No need to put air impact amounts of torque on the sprocket nut as ain't much slide load and trapped by the clamp ring and screw. This has two set screw positions but usually one is buggered up except for new sprockets of course. Put ATF in the chain case, less mess if any on clutch plates and a few drops about evaporate if ya forget the blotter mat. If pure factory ain't a factor I like to replace the 3 small bolts with studs loctied in. Hope the sliding felt seal is still sealing, but might think about getting a couple of them to wet and stuff in to dry out. Pack grease around the adjuster rod to back up Dyno's front seal.

Hard to adjust the rotor/stator clearance if there's clash, If just questionable close a good smash on the stator protected by wood may do it, but otherwise its
hard drilling or grinding the stator steel plates for some slack. Inspect the rotor if loose on its core and good pull on metal yet.

Now would be good time to put degree wheel on and definitely mark TDC and the full adv time mark. I knife edge em through paint/ nail polish on the stator seam. Then can know what the factory gauge set at or knocked too.

Also---install a new rubber grommet in the inner case where the stator wires go through. I also use a bit of sealer here to keep oil from leaking out---it will---always.
I have cut down an old spark plug boot from a BMW 318I; "could be from many different autos' and used this as a grommet. its longer on the backside and you can pack more sealer into it. Best part---it dosen't seam to become a lump of coal after a few years---it stays flexable. Has worked for me. Just another one of those many divergent different methods and parts used by Nortonians. And the beat goes on--and on---and on and..........

If you have the inner primary off,It is a good time to check the alignment of the motor sprocket to the clutch basket.
I put them on with out the primary chain and use a 12 inch straight-edge to see how they line up.There are different
shims that go behind the clutch basket to correct this situation.
YING

You might just want to check right through the engine, frame and gearbox numbers and markings to be sure it really is a '73 with that drum brake on it.

Though I cant see a breather tube coming from the cam end so the cases at least probably are later.

Should have had a disc from '72 on I think, maybe '71, my '70 FB was drum.

The only nice thing about the drum is you can junk those high bars and put some flat bars on without having the M/Cyl hit something and then you can shift your weight over the front a bit without getting uncomfortable. Probably the cheapest handling improvement out there, which is of course only important if there are some twisties near you :lol:

Good colour :wink:

SteveA said:

Should have had a disc from '72 on I think

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Not necessarily, as the front drum was often fitted to the standard tune models through 1972 and still fitted to some '73 750 Hi-Riders. The front drum was still listed in the 1973 parts book.

It has the smaller Hi-Rider headlamp, so perhaps it was a Hi-Rider model originally or has had a Hi-Rider front end fitted to it?

I am with LAB probable start as a highrider. engine breather (72-73 ) and tail light show as 73 so all it would take is a roadster tank to be where it is now.

bill said:

I am with LAB probable start as a highrider. engine breather (72-73 ) and tail light show as 73 so all it would take is a roadster tank to be where it is now.

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And handlebars. Good catch on the small headlight. Would originally had silver barrels and the five plate clutch.
If the engine number begins with 22XXXX then it's definitely '73 model year.

Ron L said:

If the engine number begins with 22XXXX then it's definitely '73 model year.

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Or 212278? Because, as we know from previous discussions, the factory was building Commandos to MkV specification (at least for the US market) prior to the official 1973 22xxxx series.

Hi,
Just like to add that when torquing up the clutch center nut you may find references to a torque spec of 70 ft/lbs.
The common thought is that this figure is too high and that 40 ft/lbs is the spec that should be used. Some have found that when using the 70 ft/lbs spec that they have sheared the locating circlip in back of the clutch. Use the 40 ft/lbs spec and you will have no problem. It actually only needs to be tight enough not to come loose as the shaft is splined not tapered and the clutch offers no thrust support to the mainshaft.

GB

L.A.B. said:

Ron L said:

If the engine number begins with 22XXXX then it's definitely '73 model year.

Click to expand...

Or 212278? Because, as we know from previous discussions, the factory was building Commandos to MkV specification (at least for the US market) prior to the official 1973 22xxxx series.

Click to expand...

Yes, but if it is a 22xxxx series there is no doubt.

Wow! This thread really took off, thanks for all the great info.

Couple of answers to some points earlier.

I do have a service manual, however I'm not a fan of it compared to the newer ones I used for my Aprilia and Honda MX bikes.

Stickers are messed up as the current paint is a re spray, the old sticker were painted over. Yes I know, less than ideal.

Engine is 235XXX, not sure what that tells you guys. I appreciate you working through the linage of the bike.