hey everyone i just picked up my first norton 750 commando, i've been search for close to five years. My father actually came across one i could afford he had one in the early 70s, so i've kinda of made it my mission to restore one so he can ride it once again. I have been doing a lot of reading and came across some things that were troubling me what i have is a 750 combat commando, and through all of my reading i have found that is potentially a "grenade" that the main bearing and pistons have a tendency to disintegrate and cause catastrophic failure. I am not sure if norton made any adjustments to fix the problems in production and if the did i was wondering what serial numbers the fixes might be under and if they did not fix any issues if there was anything anyone would recommend. I would hate to restore this bike just to have it blow up on me on the road thanks for the help.
Proud new owner of a norton commando
- Thread starter dlou0338
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If you are going to restore this bike, then one important area to look at is the engine bottom end - the crank.
If it has had the so called 'superblend' bearings in it, then all is probably good. If not, and it has survived OK anyway, then you can fit them and all will be good. Some folks here have these bikes, and they have survived quite happily anyway, so all the doom and gloom didn't happen to everyone !
We look forward to seeing pics and reports of how its coming along.
And remember, this is all about FUN, so make that happen.
Cheers.
If it has had the so called 'superblend' bearings in it, then all is probably good. If not, and it has survived OK anyway, then you can fit them and all will be good. Some folks here have these bikes, and they have survived quite happily anyway, so all the doom and gloom didn't happen to everyone !
We look forward to seeing pics and reports of how its coming along.
And remember, this is all about FUN, so make that happen.
Cheers.
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Welcome!
I bought a used Combat over two years ago from a guy who rode it regularly,
I have done a lot of upgrades and mods to the bike but have not had to do anything to the engine except adjust the valves.
Most Combats have had the bearings replaced many years ago by owners that became paranoid about the bottom end.
Worth checking, but not worth losing sleep over thinking you have lemon on your hands.
Good luck and keep us posted.
BTW - I find the tinkering and wrenching ALMOST as much fun as riding the old beast.
I bought a used Combat over two years ago from a guy who rode it regularly,
I have done a lot of upgrades and mods to the bike but have not had to do anything to the engine except adjust the valves.
Most Combats have had the bearings replaced many years ago by owners that became paranoid about the bottom end.
Worth checking, but not worth losing sleep over thinking you have lemon on your hands.
Good luck and keep us posted.
BTW - I find the tinkering and wrenching ALMOST as much fun as riding the old beast.
Craig
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Yup same here .... '72 Combat , bottom end is original , about 8000miles , top end has been refreshed and regular maintenance done , I don't flog it , you can find doom and gloom about any brand or model on the internet and you learn to sift out the doomsdayers .... enjoy your Combat and Welcome ! ....
Craig
Craig
Sorry its been so long between replys Thanks everyone for being so helpful. I have the head and barrels off slowly getting her stripped down haven't come across anything major yet the piston rings were seized in the right side piston so I'm going to have the cylinders checked I haven't figured out how to post pictures yet as soon as I do I will post pictures the only thing I'm concerned about at this point is the tank had some spider cracks in it I was curious how serious it was and ho to fox it or if I could paint over thanks Dave
Welcome dlou0338, I think that you have definitely come to the right place. Lots of good people here who are glad to help out with lessons learned in the past, helping us to avoid pot holes along the way. Also many great vendors who love these bikes as much as the next guy. Jim of JSMotorsports, Matt of cNw, Fred & Ella of Oldbritts, Steve Maney, Don Pender, Jim Comstock, RGM, Andover, Homeslice of NYCNorton and many more. Parts are not a problem as you can get everything you ever wanted for the bikes and then some! Remember a picture is worth a 1000 words and we love pictures.dlou0338 said:
Mr. Rick
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In reply to the original question of serial numbers and fixes made: 200976 was the first Combat motor, and several improvements were implemented.
With regard specifically to the main bearings, the improved "Superblend" bearings were introduced by the factory at S/N 207197.
The first "de-tuned" post-Combat was 211110, and the last 750 was 230935.
All of this according to the INOA Tech Digest.
Hope your resto is going well, and Happy New year!
With regard specifically to the main bearings, the improved "Superblend" bearings were introduced by the factory at S/N 207197.
The first "de-tuned" post-Combat was 211110, and the last 750 was 230935.
All of this according to the INOA Tech Digest.
Hope your resto is going well, and Happy New year!
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Mr. Rick said:
That is an error in the Tech Digest.
http://www.nortonownersclub.org/support ... e-releases
Factory Service Release N2/6 July 1972 regarding premature main bearing failure, specifies that replacement bearings should be "Skefco" (SKF) type NJ306.
The Service Release further states that: "Models subsequent to Engine Number 207197 incorporate a nominal increase in bearing housing diameter to overcome any significant tendency to excessive closure of the single lipped outer series of roller bearings."
The SKF NJ306 is not the "Superblend" bearing and is not referred to as such in that particular Service Release.
The Service Release detailing the change to the Superblend (R&M 6/MRJA30) is N2/9 August, 1972.
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HI David
The seat on your machine is a '73 basket weave. The reason I comment is if this is engine/frame number above 220xxx all of the combat issues are updated from the factory and it would be a '73 750 MkV. My first Norton was a new '72 combat. My current combat...have owned for 20 years and has >56,000 miles on the odometer. They can be reliable, but a bit more maintenance than an 850. Valve guide wear, especially the intakes, is a place to watch as the milled head changed the rocker angle unless you use available shortened pushrods. Norton didn't compensate here.
The seat on your machine is a '73 basket weave. The reason I comment is if this is engine/frame number above 220xxx all of the combat issues are updated from the factory and it would be a '73 750 MkV. My first Norton was a new '72 combat. My current combat...have owned for 20 years and has >56,000 miles on the odometer. They can be reliable, but a bit more maintenance than an 850. Valve guide wear, especially the intakes, is a place to watch as the milled head changed the rocker angle unless you use available shortened pushrods. Norton didn't compensate here.
Thanks for all the help everyone im in the middle of a move so haven't had much time to put the work in but I have the new bearings and multitude of other parts that will start going on in the next couple of weeks I'll post pics of the progress thanks again
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