Ben's '72 Interstate Rebuild

Scout63 said:

There is a "G" stamped to the right on the gearbox just on the edge of the picture. Any idea what this means?

Click to expand...

Gearboxes occasionally have that additional letter stamp, not necessarily 'G'. They were factory codes, the meanings of which were generally unknown outside the factory, so can be ignored.

grandpaul said:

I have never seen one of those paper stickers on the 40+ Commandos I've had my hands on...

Click to expand...

I have seen 'factory' pictures showing those engine number stickers on the top of the timing cover, usually placed over the crankcase joint.
It seems they were removed at some point before the bike was sold.
I have no idea how it ended up on the cradle.

It didn't appear glued on. Maybe it just ended up there and didn't fly off. There was a fair amount of oil and grease on the tube.

I finally found a few extra minutes to work on the bike. I removed the tires - Avon GP front and Dunlop Roadmaster TT100 rear. They couldn't be original since the bike has 12k miles and they had good tread. I did get the license plate and current title for the bike though - 1975 title and last stickered in 1980. I really like the plate but it won't work in MA.

Scout63 said:

Messing around with how to post pictures.

Click to expand...

I like the blue.

Thanks TinMan. I'm keeping the color the same.

Hello everyone. I’m finally starting up my restoration after putting the disassembled bike to the side for a couple of years.

I’ve painted most of the steel parts. I had the frame media blasted and then professionally painted, which turned out to be a mistake. The body shop did such a horrible job (missed spots, bumps etc) that I sanded it smooth and spray canned it myself. I didn’t have the heart to go back. I should have known when he charged me about half of what it should have cost. He had a great reputation but just sold his shop and was halfway out the door.
I used two cans of paint with many light coats. The finish looks good and we’ll see if it holds up.



Both hubs are cleaned up with new sealed bearings installed:


Thanks to Fred and Ella at Old Britt’s for parts and patient advice over the phone..

I’m starting to lace the wheels:


I ordered stainless 19” rims and spokes from Central Wheel and they look great. This is a new task so I expect it to be very trying.

Also, I’m practicing zinc plating as I want to re-use as much of the hardware as I can. Here s my setup:


I’ve done quite a bit of practice plating and the results are getting better. The learning curve is steep and prep takes more time than I thought it would. I’ll post pics of parts when I get it right.

Next up fork rebuilding.

Hopefully I can have a rolling chassis by springtime and be able to rebuild the engine and transmission next winter.

My best to all.

Ben Zehnder

The epoxy rattle can paint I have used seems to hold up pretty well. Not as well as sprayed urethane, but better than regular rattle-can enamel. Powder coat is veerrrrryyyy durable, but you have to make sure to do a lot of masking because it's so thick it can crush down and cause fasteners to come loose. Make sure you don't have it slathered on too thickly, especially over another finish, so you don't get the same effect.

This pic will give you an idea of all the areas that should be masked to prevent damging the paint and having you nuts and bolts come loose.

I'm looking at this for touch up on my frame.
https://www.kbs-coatings.com/BlackTop.html

Interesting white rabbit. Good write up Scout, hope you get it done for this season. I repalced some bolts, did a lot of degreasing, and cleaned my existing bilts. As I did not paint the frameI was happy with patina. My 75 frame was cosmetically in nice shape, just needing somne touch-up. I used POR 15

I’m kicking the project back into action. Here are some recent photos:











Super blend main bearings are in and end play is good. The head just went to the machine shop for valve seat cutting and cleaning up the surface. New Kibblewhite valves and springs came in today. Plating is going well - a steep learning curve but very satisfying reusing original hardware. These cylinder and head and case bolts and nuts were pretty rusty before zinc plating. Frame is painted. Cylinders within spec and lightly honed and painted. Cam followers installed. Pistons installed. Waiting for ring compressors so that I can install the cylinders.

I have some noob questions though:

1. Do I install the cylinder base gasket dry or use a gasket compound.
2. Do I install oil seals on all valve guides? Mine is a 72 combat head and when I took it apart there were seals only on the inlet guides.
3. Do I use heat insulating washers only under exhaust spring seats or on the inlet side also. They were only under the exhaust seats when I disassembled it but the parts schematic shows them under all springs.

Thanks to all. Ben

Scout63 said:

1. Do I install the cylinder base gasket dry or use a gasket compound.

Click to expand...

Dry, although others might disagree.

Scout63 said:

2. Do I install oil seals on all valve guides? Mine is a 72 combat head and when I took it apart there were seals only on the inlet guides.

Click to expand...

Inlet only. The exhaust guides don't have the seal location groove.
Exhaust:
https://andover-norton.co.uk/en/sho...de-dommi-also-in-500-750-std-d12-140-nmt2011-
Inlet:
https://andover-norton.co.uk/en/shop-details/15952/in-valve-guide-750-std-

Scout63 said:

3. Do I use heat insulating washers only under exhaust spring seats or on the inlet side also. They were only under the exhaust seats when I disassembled it but the parts schematic shows them under all springs.

Click to expand...

They were normally omitted from the Combat inlets so as none were fitted then don't fit any on the inlet side.

Nice clean work, project is moving right along!

Looking good Ben - I did quite a bit of nickel over copper plating on my ES2 project a few years back . All the naysayers claimed home plating systems were bogus - glad I ignored them. Caswell system worked beautifully for me . I’ll be watching this with interest - RT

Richard Tool said:

Looking good Ben - I did quite a bit of nickel over copper plating on my ES2 project a few years back . All the naysayers claimed home plating systems were bogus - glad I ignored them. Caswell system worked beautifully for me . I’ll be watching this with interest - RT

Click to expand...

Basic science says it's not bogus. A bit of a fiddly mess, but not bogus. The more careful you are, the better the results.

Back from a long weekend to Vermont. All of you who live up there are so blessed with great roads and scenery. I took my /5 for lunch rides with my wife and my SR500 for longer solo gravel road mountain rides. I can’t wait to try these on the Commando but maybe not on the dirt.

Thanks so much for the replies and the encouragement. I went back and forth on the gasket question and finally used a sealer since the manual said to. It took a bit of fiddling to get the clamps to,work, but the cylinder went on nicely. I don’t have a means for measuring torque on nuts I can’t get a socket on so I used the years of feel and experience gauge. I hope it is ok.



The pistons are Emgo standard size with Hastings rings.

I find that the more I use the plating system the better the results. Small batches work best. I’m plating the fasteners for each assembly as I go along so as not to mix anything up. It slows the process down a bit but not as much as I thought it would.

Now off to check out other builds...

I started trying polishing since it is time to install the timing cover.


I can see how it will take a while to figure out how to get a really good shine. It is nice to be able to do it myself though.

I need help figuring out where this part goes:




It was in my bag of cam chain parts. I thought it was the 2s cam extra thrust washer so I tore off the cylinders again last night to check that I installed it. I did. Maybe I should photograph the build in more detail so that I can check install questions later. Up to now I’ve just been taking self congratulatory photos. I am much too lazy to make install notes other than tolerance measurements.

Any ideas what this is? Thanks. Ben

That is the thrust washer for the timing side end of the cam -some had two - inside the crankcase and another in the timing chest . The tab is meant to go in the hole adjacent to the cam bushing but cut the tab off - you can see in your photo where it is already fractured on the outside of the bend - they have a history of breaking off and destroying oil pumps and other expensive things. I polish my aluminum castings with 400 silicone carbide wetordry and then two stages on buffer - Tripoli on on spiral cotton buff and then White Rouge on loose cotton buff. If you don't have buffing equipment it can be done by hand by going at it with progressively finer grades of paper then metal polish - I like Blue Magic. Remember that these are porous sand castings and you will never get all the oxidation out of the pores . These freckles are part of the charm.

Just clip off that ear of the cam washer and smooth with a file. It isn't needed.

Thanks Richard and Htown. This must go in the timing chest under the cam sprocket. It is not shown in the parts diagrams. Off come the timing parts again.