1972 Norton Commando Combat Rebuild (8) - Crankcase mods

Here are a few clips showing the latest progress with Dave's Combat rebuild.
Here’s a link to the Playlist for this project:
• Feature | 1972 Norton ...
Here's a link to the AccessNorton forum thread on Dave's rebuild:
www.accessnort...
Here's a link to Dave's TH-cam channel:
/ @swooshdave
Here's a link to Jim Comstock's website and TH-cam channel:
www.nortonmachi...
/ @jamescomstock3352
Here's a link to the recent OVM (Oregon Vintage Motorcyclists) show at Corvallis, Oregon:
• OVM - Oregon Vintage M...
Music: CRASH by Ikson
@iksonofficia
/ ikson
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[@johnb5519]

I bought a 69 commando back in 1973, when I was in high school. For a bike that was only four years old, it was pretty abused. The red metal flake on the tank was all botched up, and the original mufflers were gone and replaced with megaphone style ones. I sold it in the early 80's, and have been lamenting over doing so ever since. It had the larger oil tank and side covers like the fast back, and they were silver. It also had the external tach drive, and the points on the inside to the rear of the cam drive case. With the advent of the internet I found out it was a rare R model imported to Canada. It was pretty fast for the day. Today I have an old 87 Yamaha rd350 lc ypvs , and a 1000 Honda hurricane, but they definitely don't have the feel of being alive like my old Norton did. Love your videos, and it makes me wish I still had it so I could do a complete restore, which back in the day I never had the patience for. When we were younger all we cared about was riding.

[@nelsong4719]

My buddy bought a brand new Combat in 1972. It was a beautiful machine with outstanding performance but began breaking down a lot the first summer he owned it. Had he known about these mods he might of kept it longer. My 1968 Matchless G15 Mk2 with an Atlas engine and a Dunstall kit was much more reliable but I still liked the looks of the Combat. Norton The Unapproachable.

[@desmo54]

I had a 72’ Combat which I restored. I had a piston seize on me when going up I-80, a long fairly steep grade up through blue canyon. I was doing about 80 mph when the motor locked up. I simply pulled in the clutch and rode to a stop. I let the engine cool, and was able to break the piston loose by kick starting the bike. I was able to get it running but there as a knock in the motor. At the time I didn’t know the Combats had an oil starvation issue, especially under load up long hills. I bought a new piston an fixed the cylinder. About a year later I was going up the grade, south on 101 toward San Luis Obispo, I think. I got maybe 50 yards from the summit and the bike seized again. I was able to get it started and rode it to LA and back to Sacramento with a bad knock. I assume this fix you showed in the
Is video would fix the problem I had? Too bad I didn’t know this info, as I put in another piston, honed the cylinder and sold the bike. It was a real beauty.

[@erwinballings9155]

Thanks for the info gentlemen, top

[@tadpoles10]

Thanks for sharing guys, some interesting modifications fingers crossed for you Dave.
Hope you are able to get this all back together very soon & try it out before summer is over.
atvb t ..

[@TheMightyGarage]

Thank you Terry, this should be a fun project! Best wishes, Mike

[@swooshdave]

My first target was the show in May. Obviously missed that one. Another show in early August so that’s my new target.

[@stevewalden3814]

Thank you for the improved sound volume Mike.

[@swooshdave]

Steve Walden The new mic might have helped.

[@TheMightyGarage]

Thanks Steve, your feedback really helped. Dave and I spent some time exploring options and I think it should be a bit better now. I really had to turn it up (20 Decibels!). Cheers, Mike

[@Wooley689]

Interesting concept.

[@jimh.5286]

Very interesting.

[@01jimmyjazz]

Thanks Dave and Mike it's good to see your progress. Following this with interest . All the best Jamie.

[@TheMightyGarage]

Thank you Jamie. It's going to be fun! Best wishes, Mike

[@peterturnham5134]

Interesting, most of your mods seem to be related to the tilt of the engine. As my combat spec motor is vertical mounted in an atlas frame not necessary. However, at some point in the 750 development they incresed the diameter of the input oil feed so I drill that out. I also use an 850 Oilpumpp which has higher output. The oil pressure release valve is sensitive can stick and block. If it is not silky smooth on a rebuild replace the whole unit, not just the piston. To put a 2S cam into Atlas cases I have to relieve the crankcase for the high lift cam lobes. Timing case breathing is not great. I tried copying TC Cristenden's timing case breathers as on Hogslayer. Not verry cosmetic. The cam end crancase breather on atlas and early commando engines was not satisfactory. I have blanked mine off, drilled the crank and mounted a Nourish flapper valve. I use 850 electric start crank The strongest and latest 750 rods which are far stronger than Atlas rods.

[@adaptableadventurerider]

Superb thanks for the post!!!

[@billmago7991]

I use a PC Valve on my atlas ..... different beast i know but it works well and i dont get a puddle of oil under the breather hose😂

[@MrBeracah]

How was the crack at the base of the barrel repaired please?