New Forum member saying hello...

[B+Bogus]

Hi all,

I've just got hold of a '74 model 850 Roadster in 'needs a re-build' condition, and I'd like to know where to apply the effort (i.e. cash :wink: ) to make the bike useable in modern traffic...i.e. improve the stop'n'go!
I've got the bike down to the crank, and apart from some evidence of previous ham-fistedness (broken barrel fin etc.), the mechanics look OK: The bores are standard with no noticeable wear (but I haven't measured it yet ), the crank feels good but the cam is showing some signs of wear.

Should I automatically change all the key bearings while I have the opportunity? What would be a good cam to liven it up without compromising driveability?
Any 'essential' internal mods before I bolt it back together again?

It has the plastic airbox and black cap silencers - does this make it a MkIIA?

All advice/comments appreciated!

 

[L.A.B.]

Welome to the forum, Andy,

I've just got hold of a '74 model 850 Roadster in 'needs a re-build' condition, and I'd like to know where to apply the effort (i.e. cash :wink: ) to make the bike useable in modern traffic...i.e. improve the stop'n'go!

I would suggest, for starters:

Tri-Spark electronic ignition?
Single Mikuni or Amal carb?
Uprate the front brake (there are various options)
Electronic voltage control box (replaces the rectifier and Zener)
High output three-phase alternator?

Should I automatically change all the key bearings while I have the opportunity?

To be on the safe side, then yes. One bearing that really should be changed is the layshaft drive side ball bearing for the replacement roller bearing, or the special phenolic cage ball bearing, as sold and recommended by Mick Hemmings.

What would be a good cam to liven it up without compromising driveability?

Personally, I'd opt for a new standard cam, however other members probably have their own preferences?

It has the plastic airbox and black cap silencers - does this make it a MkIIA?

Yes very probably, if it has an engine and frame plate serial number 307311 or higher, then it is a MkIIA model, otherwise it could be a MkIA ?

 

[grandpaul]

Hey, Andy, welcome.

You've come to the right place for assistance on ANYTHING Norton-related!

 

[Scooter62]

Andy
Welcome aboard, your doing the right thing by joining this forum. The depth of knowledge on this site is incredible and the blokes that post here are right good guys willing to help anyone with the desire to ride save and maintain the Unapproachable Norton Commando.

as for what to do;
make sure you don't have the "dreaded D rods"
Unless you have knowledge of this bikes past maintenance go for new bearings (nothing more depressing than doing a rebuild only to have to tear it down again to replace a bad bearing or worse!)
I agree with L.A.B. to use the standard cam. Unless your going to do other performance modifications the 850 makes up for HP with torque and the standard cam works just fine for that.
Also the big area to update as L.A.B. also said is to modify the front brake. The least expensive is to simply have the master cylinder re sleeved to a smaller diameter.
Updating the electrics is another good idea. While the bike will function nicely with the stock components, the new electronics (especially ignition) will make your life a lot easier.
I prefer the twin Amals, but have them sleeved too. Bruce Chessel does an excellent job but there are others too that can do this.
If you have the money I would replace the valve guides while you've got it apart. I don't like the cast iron stock guides and if the bike has more than 20k miles on it they probably need to be replaced anyway.
Don't be afraid to ask questions and do a search on past posts for specific issues, it's a real time saver when you're trying to decide whether to put a base gasket in or not.
Lastly I recommend joining the INOA and getting their Tech notes. Years of expertise in that little book.

Good luck with your rebuild,

Scooter

 

[bigstu]

Welcome.
Many guys here will offer good advice.
Best things I did were:-
New set of carbs (I chose standard twin Amals, many folk go the single Mikuni route).
Electronic ign (I chose Boyer on cost, there are better ones).
Belt drive/sureflex ctutch, running dry with a pushrod seal and a teflon lined cable. At least get the teflon cable, Vehill, Surrey, UK, called featherlight.
Better front brake. Reduce the size of your front brake master cylinder piston to 11 or 12mm. Massive improvement. Do this before you spend a fortune on new discs and calipers, as I did
Do do the bearing mod on the AMC gearbox already suggested.
Don't overtune your motor....Mine pulls pretty good as standard.
Stu.

 

[B+Bogus]

Firstly,

Thanks for the warm welcome, everyone, and thanks for the sound advice!
It's also reassuring to get a consistent view from the forum regarding what to do...

I'd initially planned on something like a 2S cam and twin discs up front (I have this set-up on my T140 and it's two-fingers to squeal the tyre), so first off I won't do anything beyond sleeving the master cylinder.
I'd also planned on fitting a Boyer - works well on my T140, but having read all the reviews for the Tri-spark the evidence seems pretty compelling. Next job...persuade the Wife that the Bonnie ignition's in need of repacement :wink:
I haven't got the head apart yet, hopefully this weekend. I'd budgeted for new valves & guides, so I guess it would be plain churlish to leave the old stuff in! Colisbro seem to be 'the' name - any others worth considering?

So it looks like a standard rebuild is the way to go. I think I'll stick with the Amals, the originals haven't been inspected yet, so I'll see what they need. I noticed a couple of people had bad experiences with chromed slides breaking up - Is this exclusive to the chromed ones?

Any recommendations for the belt drive? I read somewhere of one guy having a bit of a disaster with one, but I think it was possibly owner induced, to a point.

I know it's going to be a while yet (still rebuilding a D*c*ti), but I'd also be interested in any suspension mods which would be worth doing. The reason I'm asking is that I just fitted some Ikon shocks to the Duke and it made a massive difference to the ride quality...I had to re-build the forks with progressive springs to get the front end to match, and now it rides like a modern bike - far more confidence-inspiring, and loads safer on the bumpy lanes around here.

 

[batrider]

If it was me....The belt drive can wait until last if you have to have one. There is nothing inherently wrong with the triplex chain drive and a belt drive is easy to add later. Build the bike and see how you like it. If you do go for the belt drive, carry a spare belt.

I'd go for an aftermarket head steady too - high on the list of priorities.

Welcome to the group.

Russ

 

[bigstu]

Andy
I bought the RGM belt drive 'kit' with sureflex plates, clutch pushrod seal and thicker pressure plate (steel, don't get the alluminium one). They use a better quality belt than others, in my opinion. They are also cheaper. I have had no problems....oh, and I fitted my own double sided gearbox adjuster...this is important, alignment issues are the common problems encountered with belt drives.

Remember, with brakes, it is the ratio of master cylinder piston diameter to caliper piston area that counts. I have the RGM 12 " disc and Grimeca caliper with a AJP 11mm piston master cylinder off a GAS gAS bike. It works great. JimC also has the same setup on the wheel and also an 11mm piston up top. He advised me after consultaion with 'vintage brake'. The only thing I need now is a fork brace! Maybe twin discs would help here but you will be into some serious cash. You may also find the piston diameter would be different if you used twin discs....not sure here....My setup is 11mmm to 2 x 42mm below...giving a ratio of about 27:1 (area ratio)......follow this link....http://www.vintagebrake.com/mastercylinder.htm

Also think about Amals....I have chosen this route, I bought a new pair from RGM. Many folk tell me they will not idle for long. Got 2500miles on so far no probs...Many folk go the Mikui route.

I lowered my bike, front and rear, by 34mm......I did this in consultation with CNW....Matt....great guy. At the back I put Progressive Hagons with adjustable damping, slightly shorter than standard......but to me they are under damped even on the max setting....dunno about progressive springs on the front, but I think you can get them.

One more thing Andy, don't just ask questions here. You can use this site I believe to do searches on different topics, like belt drives, carbs etc....You will find this usefull. Study, think, consult and then buy once.

Stu.

 

[B+Bogus]

If it was me....The belt drive can wait until last if you have to have one. There is nothing inherently wrong with the triplex chain drive and a belt drive is easy to add later. Build the bike and see how you like it. If you do go for the belt drive, carry a spare belt.

I'd go for an aftermarket head steady too - high on the list of priorities.

Welcome to the group.

Russ

Thanks Russ, the beltdrive is definitely a 'nice-to-have', if the existing primary drive checks out OK it *may* go back on as-is, but my vintage racing friends consider a belt drive an essential upgrade, even if they throw the belt away at the end of each season.

Co-incidentally, a beltdrive arrived for my Bonnie yesterday, and I'm looking forwards to seeing if there's a noticeable difference.

The headsteady is almost certainly going to be the rose-jointed Dave Taylor number marketed by RGM - not sure if I need the spring to go with it or not though...again, advice welcome!

 

[batrider]

There are some differences of opinion on the head steadies. All I will say is I use a Dave Taylor with no spring and I'm happy with it. It transformed my '72 Combat. There are a number of other variants popping out everywhere now.

 

[B+Bogus]

There are some differences of opinion on the head steadies. All I will say is I use a Dave Taylor with no spring and I'm happy with it. It transformed my '72 Combat. There are a number of other variants popping out everywhere now.

Russ,

I've been reading some of the posts regarding the headsteady, and the Dave Taylor job looks right to my way of thinking (i.e. it positively controls the direction of motion), and they're made just up the road in the next County to me :wink:
It's also cheaper than the alternatives....

On a more general theme, I got the rods off the crank last night, and the journals look very good. Even the shells look OK, but I'll get new. The part number of the old ones (Vandervell) is 25384. I'm guessing thet in the absence of any marking to the contrary, they're standard?

To remove the mains, The workshop manual recommends heating the drive side case and smacking it onto a big plank (did I make that sound grim enough?)
Is this still the preferred method? Curiously, I heated the timing side case and drove the crank out using a sleeve butting onto the bearing inner, and the bearing came out complete......then the outer race fell off the crank! What's all that about??? :?
happy but confused!

 

[bigstu]

I put my cases in the oven and the bearings fall out on their own if you have them the right way up. A sharp 'tap' would help but should not be required.
I think the outer race is not 'tied' to the rest of the bearing on the timing side, but I could be wrong...can't remember...know it wasn't on the Triumph. It was lipped.
You need to replace the mains with superblend bearings. Don't use anything else. Do a search on superblend...get the right ones. Watch out here...make sure you get the right ones, with the right cage material, as well.
I used the standard headsteady but modified it myself by making 5mm thick aluminium triangular plates instead of the original bits of tin. It seems to work...
Stu.

 

[B+Bogus]

I put my cases in the oven and the bearings fall out on their own if you have them the right way up. A sharp 'tap' would help but should not be required.
I think the outer race is not 'tied' to the rest of the bearing on the timing side, but I could be wrong...can't remember...know it wasn't on the Triumph. It was lipped.
You need to replace the mains with superblend bearings. Don't use anything else. Do a search on superblend...get the right ones. Watch out here...make sure you get the right ones, with the right cage material, as well.
I used the standard headsteady but modified it myself by making 5mm thick aluminium triangular plates instead of the original bits of tin. It seems to work...
Stu.

Good info! I just need to get the Wife out of the house for a couple of hours.

I'd assumed the timing side was tied, but clearly isn't, so all the more suprising that I managed to drive it out with no lip on the outer race.
On my Triumph I replaced the ballrace witha double-lipped roller on the timing side, and that had a seperate inner flange - seems to work well, and maintains positive location.

RGM sell brass caged superblends FAG NJ306E - I'm guessing these are the right stuff?
I think the old ones (FAG) have phenolic cages, but I'm stuck at work and can't check :cry:

The old headsteady is missing a few bits and is in a pretty sorry state, and having seen the endorsements of the Dave Taylor job, I'm more or less convinced it's the way to go.

It brought it home to me how important the yaw control of the head is when a mate's 750 was being MOt'd years ago - any latitude at the head is amplified at the back wheel; I was a bit suprised to put it mildly!

 

[grandpaul]

Howdy, B+, welcome.

 

[Cookie]

That just made me remember the first time I heated a case in the oven, the bearing fell out with a clang leaving me with "What the %#$@ was that?". It was kind of a relief that was all it was.

 

[B+Bogus]

Howdy, B+, welcome.

Thanks GP - I visited Texas once and just couldn't believe how big it all was!
Glad to be on board :wink:

 

[B+Bogus]

That just made me remember the first time I heated a case in the oven, the bearing fell out with a clang leaving me with "What the %#$@ was that?". It was kind of a relief that was all it was.

Looks like Wifey's out on Saturday, so I'll let you know how I get on.

 

[Cookie]

That was while I was in college, I don't think I'd get away with it now. If I was going to do that now I'd put a little oven in the garage. I have a hot plate for boiling carbs and it could go right next to that.

 

[Rich_j]

Welcome aboard.

As far as mods are concerned I would do the absolute minimum to start with.

By 74 the Commando was pretty sorted so I would get the bike up and running with the minimum cost and get some miles under your belt.
Changing too many things at one time usually results in a lot of wasted time and head scratching.
The mains will be superblends so if they're not worn re-use them.

Assuming you've got a runner -
If you find the brakes are a bit weak (and most people do) I'd go for taking any chrome off the disk and sleeving the master cylinder down to 13mm. It keeps the brakes looking original and that caliper looks pretty good polished up.
If you find clutch drag/slip problems, and you should have the bronze plates, the dyno dave clutch rod seal gets good recommendations . I wouldn't bother with belt drives or alternative plates, they're expensive and bring a whole load of their own problems with them.
Fit a PCV, they keep crankcase pressure down which helps keep the oil inside the engine where it should be. There are lots of flavours out there, Krankvent, Motormite, Bunn XS650.. they all work.

After that if you feel you want to go further
3 phase alternators/solid regulator
electronic ignition
18" rear rim for better choice of rubber
Carb mods are personal choice. The original twin MK1's can be improved, the single conversions of whatever type save all the balancing effort but cut some performance or you can hold out for fuel injection.

all good stuff

 

[B+Bogus]

Andy
I bought the RGM belt drive 'kit' with sureflex plates, clutch pushrod seal and thicker pressure plate (steel, don't get the alluminium one). They use a better quality belt than others, in my opinion. They are also cheaper. I have had no problems....oh, and I fitted my own double sided gearbox adjuster...this is important, alignment issues are the common problems encountered with belt drives.

Remember, with brakes, it is the ratio of master cylinder piston diameter to caliper piston area that counts. I have the RGM 12 " disc and Grimeca caliper with a AJP 11mm piston master cylinder off a GAS gAS bike. It works great. JimC also has the same setup on the wheel and also an 11mm piston up top. He advised me after consultaion with 'vintage brake'. The only thing I need now is a fork brace! Maybe twin discs would help here but you will be into some serious cash. You may also find the piston diameter would be different if you used twin discs....not sure here....My setup is 11mmm to 2 x 42mm below...giving a ratio of about 27:1 (area ratio)......follow this link....http://www.vintagebrake.com/mastercylinder.htm

Also think about Amals....I have chosen this route, I bought a new pair from RGM. Many folk tell me they will not idle for long. Got 2500miles on so far no probs...Many folk go the Mikui route.

I lowered my bike, front and rear, by 34mm......I did this in consultation with CNW....Matt....great guy. At the back I put Progressive Hagons with adjustable damping, slightly shorter than standard......but to me they are under damped even on the max setting....dunno about progressive springs on the front, but I think you can get them.

One more thing Andy, don't just ask questions here. You can use this site I believe to do searches on different topics, like belt drives, carbs etc....You will find this usefull. Study, think, consult and then buy once.

Stu.

Stu,

I missed this one!
I'll check out the original Amals, but I'm not expecting any miracles.
Regardless of how good or bad they are, I'm a bit nervous about fitting a J*p*nese carb......No problems with using their spark plugs of course, but there is a limit :wink:
I'd rather keep the acceleration and sacrifice a little smoothness - I don't do many long journeys, and most of my riding is on country lanes (occasionally with grass down the middle...)
I do have a set of pumper Dell'ortos lurking somewhere...
The RGM master cylinder sleeve is on the shopping ling list before I mess with calipers and discs. I've been discovering that pad compound can make a massive difference, but I don't know what's on the market for the standard Norton caliper. I have original Lockheed Racing calipers on the Bonnie and they're a bit too good if anything.
I'm not too concerned about lowering the bike - I've got a 40" inside leg to accomodate, so I'll keep it stock. The Ikons on my Duke were *ahem* shockingly expensive, but definitely worth it - the difference has to be experienced.