I have a Combat...help me.

André Bourbonnais · Mar 11, 2018

Hi everone. I'm restoring my older brothers 1972 Norton Commando and because it was my brother's it's very special to me. He bought it off a guy 25yrs ago and it's been sitting since. I recently bought it off him and am taking on the restoration. I'm not a mechanic but I can read and I'm pretty handy. Lol. I don't know or think any mods have been done to this bike but I keep reading about Combat problems and I would like to adress these while she is in pieces. I do have the C stamp and S/N 203*** so I know it's a Combat. I don't think I want to drill holes in the crank case but Is replacing the roller bearings to Superblend a sufficient fix?

All help is appreciated. Thanks.

kommando · Mar 11, 2018

Superblends will be a good upgrade, but without the drilling of the cases you will need to make sure you do not use high revs for extended periods, the cases will be apart anyway and if you have a decent drill press its not hard to do. You don't need to cutaway the large amount that Old Britts shows, instead drill lots of 1.5mm or 2mm holes down into the cavity so they act as a crude strainer and stop any large pieces of shrapnel going directly into the oil return side of the pump.

pantah_good · Mar 11, 2018

It might help if you explained what you would like your end result to be, for example as original as possible, or any sensible upgrade is ok, or keep stock Combat state of tune, etc.

brian4.2 · Mar 11, 2018

Welcome Andre', you won't be building it alone. I am undertaking a similar project the year. 1972 Combat LR Fastback.(201182) Parts are readily available and there are many here putting their hard work into making parts to make these machines better than they were off the floor. About ready to split the cases today to change out the bearings.

Is there a picture of the drilled modifications?

Avatar is my brother's Triumph that I inherited when he passed. It had been sitting outside for over 10 years.

kommando · Mar 11, 2018

This will be my guide for drilling my Combats holes.

and you need to block the front pick up hole to force the oil to follow the new route.

Courtesy of Bill (Windy) who thought this easier and more effective mod.

Atlas Commando · Mar 11, 2018

Welcome aboard! I finally got going on rebuilding the '72 Combat I bought back in '85, was running but head was off for a valve job. So far, I've got the tank and covers painted, and have the cases split. Inner bearing races removed, outers await my attention. I also have the crank split and was pleased to find very little sludge at all. I need to set up a project bike thread and get some pictures going. In addition to getting some World Class Support here, I'm hoping it keeps me motivated to finish the thing and hear her run! Maybe this week I can make the time to install my new superblends.

dynodave · Mar 11, 2018

kommando said:
This will be my guide for drilling my Combats holes.

and you need to block the front pick up hole to force the oil to follow the new route.

Courtesy of Bill (Windy) who thought this easier and more effective mod.

So is Windy taking credit for the process I developed? The severe flaw with what you are showing to people is that the HIGHEST hole is the lowest level that the oil will get sucked out. Timing side shown is horrible. Or maybe I guess it is not really my mod design after all.... INOA and old brits method is quite terrible IMO.

André Bourbonnais · Mar 11, 2018

Well I want her to run well for the next 30 yrs. Lol. I only want to have to do this once. Do I need 2 Superblend bearing? Also max details in drilling these holes would be appreciated. I don't want to mess it up. Is the purpose to maximize oil flow ? What about those breather valves?

laurentdom · Mar 11, 2018

Salut André,

While your cases are apart to install the superblend bearings, it is a good idea IMO to consider drilling holes in the crankcase to relocate the oil pickup. Good idea too to consider plugging some holes, drilling a new one at the bottom left corner of the oil pump location in the timing side crankcase and to fit a breather valve.
Both Jim's (Comstock and Schmidt) can provide one which is a straighforward fit on Combat crankcase.
Those three mods are very well documented in several posts on this site.

Laurent

CanukNortonNut · Mar 11, 2018

dynodave said:
The severe flaw with what you are showing to people is that the HIGHEST hole is the lowest level that the oil will get sucked out. Timing side shown is horrible.

+1 eek! No holes on the timing case side.
Thomas

André Bourbonnais · Mar 11, 2018

Thanks everyone.

Nortoniggy · Mar 11, 2018

You don't say how many miles/kilos this bike has covered. There is a good chance that it has superblend bearings already. The original roller bearings didn't last long. Mine lasted just 4,000 miles from new. It still has the superblends that were fitted then.

Ian

dynodave · Mar 11, 2018

CanukNortonNut said:
+1 eek! No holes on the timing case side.
Thomas

For me it's not that there are holes on the timing side ( my mod has them there) but they only point down and to the rear to keep the holes low. I aim them for the bottom of the rear troughs. That way the oil gets scavenged out to a significantly lower level. Remembering that the highest hole is the lowest the oil will ever go...

André Bourbonnais · Mar 11, 2018

Nortoniggy said:
You don't say how many miles/kilos this bike has covered. There is a good chance that it has superblend bearings already. The original roller bearings didn't last long. Mine lasted just 4,000 miles from new. It still has the superblends that were fitted then.

Ian

I really don't know the history of the bike but apparently she ran fine before the "big sleep"

CanukNortonNut · Mar 11, 2018

dynodave said:
For me it's not that there are holes on the timing side ( my mod has them there) but they only point down and to the rear to keep the holes low. I aim them for the bottom of the rear troughs. That way the oil gets scavenged out to a significantly lower level. Remembering that the highest hole is the lowest the oil will ever go...

Yes, I agree Dave. I understand that if your holes are all at the same height as the Primary side then your "straw" (I use a straw as an example)is pulling oil at the highest hole for the suction of the pump.
The many smaller holes are sized to stop big bits of metal from getting to the oil pump and jamming it, but still maintaining the same total volume for the pumps intake. That's why you did your mod this way, right? Your mod was to mimic this. The pre/ post Combat engines had the big sump plug which has the filter.
cheers,
T

dynodave · Mar 12, 2018

CanukNortonNut said:
snip
The many smaller holes are sized to stop big bits of metal from getting to the oil pump and jamming it, but still maintaining the same total volume for the pumps intake. That's why you did your mod this way, right? Your mod was to mimic this. The pre/ post Combat engines had the big sump plug which has the filter.
cheers,
T

quite true. The mod total area of openings is larger than the original hole. My "original" hole ate the break off tab from the thrust washer and killed the oil pump instantly. Only a few minutes prior I was doing a 100 mph on the (no traffic) highway. Oil pressure gauge saved my ass...

I already lived through one commando blow up-lock up @ 110mph (1971)
I will never run a combat engine with out up graded cam bearings. 850 or MKIII style

André Bourbonnais · Mar 12, 2018

Dumb question, what happens if or when the bearing fails?

concours · Mar 12, 2018

Not combat bearings, but you get the idea.

OP, please tell us more about your skill set....

grandpaul · Mar 12, 2018

André Bourbonnais said:
Dumb question, what happens if or when the bearing fails?

Typically, the crankshaft over-flexes and one or both rods blow through the crankcase, and sometimes, the resulting damage can lock up the engine's rotation, INCLUDING damaging the clutch, which would lock up the rear wheel (even if you pull in the lever). Many times, riders are thrown to the ground, sometimes with deadly results.

grandpaul · Mar 12, 2018

I have a Combat...help me.

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