"Test Mule" '74 850 Monoshock build

Jeandr · Jan 19, 2010

Some people seem to think that the products issued by a know company are better than what can be done at home, sometimes that is true and sometimes it is not. A case in point is the way the first Commando frames were made, they were even dubbed the "widow-maker" and just look at what the chopper guys run with their absurd long forks, raked front ends and rigid rear ends, those are accepted even by engineers otherwise they would be outlawed. Even the ISOs on the Commando, I was told the early ones were very much different from the later ones, the earlier ones were much sturdier probably because the bean counters had a bigger say than the engineers. Many bikes of the same era have rubber mounted engines, the Norton is AFAIK the only one with the swing arm mounted to the engine yet it does not handle any worse than the others, did the Norton factory do it right or did the others do it right? The single most important factor may be to have both wheels aligned.

I am not worried at all by backyard engineers, usually, if it looks good, it most likely is.

Keep at it Paul

Jean

splatt · Jan 19, 2010

Apoligy due regarding remounting swing arm, while at work today the elevator went to the top floor and the light came on :idea:

:idea: , the primary is in the way isnt it :!: :!:

.I still feel if it could be done it would make a huge improvement, this is what happens when you think aloud on the w.w.w . :lol:

grandpaul · Jan 19, 2010

I don't doubt that there is SOME way to engineer a workable solution wherein the swingarm pivot would directly mount to the frame, I'm just not the guy that's going to do it (this year, at least).

My cup runneth over at the moment.

davamb · Jan 20, 2010

Jeandr said:
...the Norton is AFAIK the only one with the swing arm mounted to the engine yet it does not handle any worse than the others...

My Pantah has the swingarm bearing (bushing) in the gearbox, not the frame. (Bitch of a thing to repair when worn.) Of course the engine's not rubber mounted like the Norton. Think it's done that way because there's only a trellis frame and no frame as such where necessary to hold the swingarm axle.

splatt · Jan 20, 2010

davamb said:
My Pantah has the swingarm bearing (bushing) in the gearbox, not the frame. (Bitch of a thing to repair when worn.) Of course the engine's not rubber mounted like the Norton. Think it's done that way because there's only a trellis frame and no frame as such where necessary to hold the swingarm axle.

Also to get the pivot point as close to the sprocket centre as posible

grandpaul · Jan 22, 2010

To allay any doubts some folks might have regarding the gearbox, the bearings & bushings were perfect, so were not replaced.

swooshdave · Jan 22, 2010

grandpaul said:
To allay any doubts some folks might have regarding the gearbox, the bearings & bushings were perfect, so were not replaced.

I sure assumed that since you cleaned all the parts you probably took the gears out and checked the parts. Just because a process as exciting as cleaning gearbox parts (DAMHIK) isn't documented in pictures that it wasn't done. :roll:

Looking good, keep up the work. It's fun to see someone else get something done.

grandpaul · Jan 27, 2010

Cam followers safety wired in place-

Pistons installed after a bit more cleanup-

Cylinders slipped on with the typical bit of fiddle. I almost like installing them using my fingers to work the rings better than using the confounded ring compressors, as the space between cylinders make for a real hassle-

grandpaul · Jan 27, 2010

Cam drive / timing / twirly bits & oil pump all done and nipped up-

ML · Jan 27, 2010

I remember seeing somewhere that someone had fitted needle roller bearings to his Commando swing arm. He found It did not last, the pivot pin surface was badly grooved by the harder steel needle bearings causing all sorts of roughness and slop. Possibly this is caused by the lateral forces when the swing arm wants to tilt over under heavy corner loads. I guess the only solution is a inner race bearing that then may be far too large to fit within the swing arm bearing ends?

Mick

grandpaul · Jan 27, 2010

Okey-dokey. Dropped the little lump into it's cradle this afternoon-

I used the two-strips-of-cloth method to hold the pushrods in place while lowering the head into position, then pulled them out with needlenose pliers. Too easy.

Still have to lube and cap the swingarm, but went ahead and shimmed up the inner primary cover. It's amazing how many cracked cases I've found due to folks leaving out a washer or two back here...

grandpaul · Jan 28, 2010

Megacycle identified it as a mild street grind; I thought I posted a copy of thier analysis? They advised it should be run with flat cam followers and re-ground them accordingly. (The cam is a re-grind of a factory "S" part)

As it is a relatively mild cam, it doesn't require special timing. I set it all up dry and carefully checked the working fit, no issues whatsoever at decreasing valve lash settings right up to zero. Rocker geometry looks spot-on as well. The head hasn't been cut down, and I'm using a "thick" paper base gasket with a flame-ring (eyeletted) head gasket, so there's no effort to increase the compression ratio. I think that's a good combination with flat-topped standard style pistons and just a mild cam grind. More of a reliable work horse than an all-out race horse living on the edge.

grandpaul · Jan 28, 2010

Clutch plain plates (before)-

Plates after swirling them on the concrete shop floor to remove the glaze, then washing them off-

Pressure plate & diaphragm before & after cleanup-

grandpaul · Jan 28, 2010

I installed the swingarm spindle cap setup and filled it with 140wt oil (easy, just assemble the caps loosely, remove the lube fitting, stick the nose of the tranny oil jug in the hole and squeeze till it runs out the far side). As usual, the previous owner had stuffed it full of grease which is useless; it's also got new swingarm bushings. The cradle and spindle are in perfect shape, ZERO slop.

Clutch basket, engine sprocket & primary chain in place with the appropriate shimming behind the basket to get good chain alignment, square with the inside cover-

4 SureFlex (thick) friction plates and 1 Barnett (thin) plate added up to a nice stack height for easy lever pull and good engagement-

Clutch all done-

grandpaul · Jan 28, 2010

I'm not too keen on re-using the alternator rotor that came with the engine, it was an explosion waiting for the worst moment to happen-

Had a nice rotor on the shelf and used that one instead. Also had a better stator with a longer pigtail-

The little lump is starting to take shape-

jaymorgan · Jan 28, 2010

Very Interesting

grandpaul · Feb 2, 2010

Hmmmmmm...

Going back over the original post, it looks like I'll only be using the frame, swingarm, tranny cradle, meters, headlight shell and sidecovers from this lot-

Wheels should arrive tomorrow, forks are done, so should have most of a bike by the weekend.

splatt · Feb 2, 2010

grandpaul said:
and I'm using a "thick" paper base gasket

Thats cleaver

Keith1069 · Feb 3, 2010

A thick paper base gasket is not so clever.
GP : surflex plates are nice with a belt drive

I was thinking that also. How thick is 'thick' ? For 7 years have used a 0.030" steel base spacer to reduce compression, metal to metal is good.
Yep, discovered that in my early days, needed lots of cleaning every thousand miles. BD now and the latest Surflex haven't worn their teeth to points like the originals did and these have a lot more harder miles on them. Maybe they changed the core material?

grandpaul · Feb 3, 2010

It is as easy as a Dyno Dave clutch seal, and NOT OVERFILLING the primary chaincase, to keep the clutch working well for a long time.

Everything on the engine that is not OEM is only moderately high performance. It will have higher compression from some skimming, but shouldn't be in the 10s. Cam is a mild grind, and the intakes will be modified from 32 upstream to 30 downstream, no port mods on the head. OEM jugs, +.020 flat-tops. Factory crank balance factor and very nice aftermarket isolastics with "rose" joint top & front steadies.

It should outperform a standard 850, but not by a lot. Enough to make it a fun bike.