Not a Combat

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aboone

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I'm re-entering the street scene with a nice stock (mostly) '72 Roadster and thought I'd ask for comments as to essentially non-visible upgrades.
My priorities are: stopping power (must be drum, dealing with TLS now), reliability, more "grunt" and less engine clatter. Have Pazon so it is a good starter.
Anybody familiar with Newby or NEB belt primary's?
Not at all interested in revs, so gearing, overbore, stroke?
 
Seconded .

Though a 18 in rear is going to gain a bit of traction and ground clearance .
Spend youre time getting to know it . Its bound to have its own ideas as to whats required .
 
Nice stock '72 roadster that isn't a combat in the US....unusual unless it was originally a high rider or a '71 model with '72 title. To be a '72 model, will have an engine/frame/gearbox number >200001.
Drum brake is a priority for you? It's going to cost plenty to get stopping anywhere near a disc. TLS stiffening kit and arc'd shoes matched to lathe turned drum. If you get the drum turned & shoes arc'd, make sure the rim you will use is laced to the drum and trued first.
Cables - Venhill and Barnett are good...others are also. Stay away from those made in China until the quality improves.
 
Lot's of guys running belt drives. I have no problem with the "C" (hain) word, an efficient transfer of power.
 
The two I've done to my 71 that have made the most difference in engine performance:
Electronic ignition and improved crankcase breathing with one of Jim Comstocks reed valves.
I have yet to do any TLS brake upgrades, but if yours is anything like mine it's well worth the effort. Nothing quite like having to make an appointment to stop one of these things :shock:
 
I agree with the let it be and see what it needs group. I have a belt primary and it is great. Much lighter and the bike spins up much faster but at a significant cost. I did it because the primary was leaking. I know it is not a non-visable mod but when my left cylinder started popping at idle it was a problem with the left carb. The cost of resleaving the two Amal's was about the same as a new Mikuni single conversion. Did it, love it and have never looked back. Let the bike tell you what it needs.
 
Wow, thanks everybody! it is great to get some "over the shoulder" coaching!
so, propelled by the comments and my own research , the following is under way:
front brake out for backing plate boring per Old Britt's website (tip of the hat for their selfless help!)
true up rim, turn, arc new Ferodo shoes to match drum.

Next is clutch lever pull which (thanks, concours!) is probably a disc stack issue. My only other Commando was a 71 (+/-?) Dunstall and I don't recall such a non-propositional lever pull. That's why I thought about a belt/coil spring set up like Newby's.

As to combat status: matching s/n 204657 and 30mm Amals that appear stock, so...?
Where would the "c" be stamped? The bike likes 3500-5000 w/o any sign of getting on the cam...

As to the 18 steel rims, seems less fluid than my memories of the Dunstall with 19" Borianni's...

thanks again everybody! Please chime in!
 
Two points to be aware of:
definition:

Combat "breather" cases are 200000+ until the end of 750

separate issue is combat "tune" with 2S cam and milled head and 32mm carbs.

plenty of 72 that were not combat tune like high riders, and they had drum brakes not disc.
 
The power poop-er of the Combat i found was the over size sharp turn ported CHO head required very hi rpm to wake up the 2S cam. The best combo I accidentally found for low down to damn fast grunt was the standard head w/o a cylinder base gasket and dual Amals. With a bigger single carb it dulled the off idle a bit but woke up the over the ton glee. So might just tear down to inspect insides, like to clean up the broken cam thrust washer tabs or replace before they clog-chip the oil pump and stick in a good 2S cam then be careful on giving much throttle taking off with any leaning or get used to recovering a crossed up slide or picking up a low side. If wanting even more grunt work up a 2-1 exhaust with single muffler to remove about a hp of excess mass off the excess heavy primary side of Cdo's. Then must back off spark timing a bit d/t the faster burn pressure rise or may hurt ya on kick back starts.
 
aboone said:
I'm re-entering the street scene with a nice stock (mostly) '72 Roadster and thought I'd ask for comments as to essentially non-visible upgrades.
My priorities are: stopping power (must be drum, dealing with TLS now), reliability, more "grunt" and less engine clatter. Have Pazon so it is a good starter.
Anybody familiar with Newby or NEB belt primary's?
Not at all interested in revs, so gearing, overbore, stroke?
Click to expand...

I've used Bob Newby's belt drives for a couple decades now in race Nortons, and I love them. They are very high quality. I don't know much about the NEB drives. I recall them using polyurethane Syncroflex belts instead of the more commonly used HTD style belts, but that's about all. I seem to recall that the poly belts are better if you are running them in an oil bath primary, like with a MK3 Commando, but I don't think you have that concern.

Ken
 
Again, thanks all!

Ken, saw NEB's used on Manx's at Goodwood last week. guys said they liked them because it uses a sealed bearing where Newby doesn't. still researching...

Another general question (maybe this is covered elsewhere): on a '72 roadster, how are the front fender stays and fender bracket supposed to finished, cad, silver paint, chrome?

thanks in advance!
 
I vaguely recall Crazy had grey ones but I sprayed silver . There is a spray-on chrome paint rattlecan that I will try next scratchup.
 
aboone said:
Again, thanks all!

Ken, saw NEB's used on Manx's at Goodwood last week. guys said they liked them because it uses a sealed bearing where Newby doesn't. still researching...

Another general question (maybe this is covered elsewhere): on a '72 roadster, how are the front fender stays and fender bracket supposed to finished, cad, silver paint, chrome?

thanks in advance!
Click to expand...

Not true. All the Commando belt drive conversions I've ever seen, including the Newby, use a sealed bearing in the back of the clutch basket, to replace the stock one which was lubricated by oil in the primary. Not sure what they do for Manx conversions, considering that the Manx only had a drip lube to the primary chain, not an oil bath like the Commando. Since you are looking for a belt drive for a Commando, it doesn't much matter how they do it on Manx conversions.

Ken
 
ken,
I agree, just parroting the comments. I have not seen either clutch in detail, just trying to determine best course of action.
BTW they hammer those Manx's!
 
aboone said:
BTW they hammer those Manx's!
Click to expand...

Indeed they do. And they make at least ten more horsepower from a modern Manx than the originals ever made, thanks mostly to modern materials and big bore/short stroke versions. I had one for a while that I was restoring, but finally gave up on it and sold it to someone who would actually finish it and get it back on the track. As cool as the Manx is, I'm afraid I'm still more of a Commando kind of guy.

Ken
 
well, got everything together for the "old britt's" front brake upgrade, even had the backing plate polished...
as I was cleaning the drum ofter having it skimed I noticed that the bearing lockring on the port side was all bunged up as if someone had used a punch and no common sense...also the spacer didn't want to center...
so, I have deburred the lockring and everything is fine until I start to tighten the spindle nut...the dust cover is wanting to spin with the hub, so when I tighten the spindle nut the wheel stops, the dust cover doesn't rotate, right?
I put a straightedge and the lockring is flush with the lip of the spacer...I have never had the bearings out so I'm in the dark..it appears to me that the dust cover should contact the spacer and thereby the inner race and not rotate, that's is how it was when I disassembled the hub?
I called the shop that turned the drum and they claimed they didn't fool with the bearing...but both the lockring and the seal on the other bearing look funky...anybody have concrete knowledge of what goes on when the drum is turned?

bummed
 
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