Another 650 SS thread !

[worntorn]

Alp used nitromethane fuel with the Vincent 666, which used original 45 hp cases.
The amount of power available with that fuel is insane, provided the engine can hold together for a few seconds.
He is using new strengthened cases and crank on his current Vincent build.

I am relieved.

Glen

 

[worntorn]

A Manx prepared today with aftermarket parts would be hard to beat.

The power potential of a 650 being within factory parts, I have never considered aftermarket barrels or cases for a 650. The small bore diameter of 68mm is probably going to be a handicap as it likely restricts breathing of a good head, IMHO. The small valves also.

Would be good to see more information and internals of the Works 650.

I have done JS rods and JE mid-dome pistons in mine. The next parts i’d consider changing is a billet, lighter flywheel and higher dome 4032 pistons and a radius cam to run the lighter-weight lifters.

Did the rod and piston change have any effect on vibration levels?
My 650 ss is decently smooth to about 65 mph then gets a bit buzzy above that. I have considered changing to lightweight pistons and the longer rods.
Ideally though, I would prefer to keep the stock rods as they are very light and strong enough for road use. I suspect that there aren't any lightweight pistons available to fit the stock rods.

I should probably just be happy with a smooth 65mph cruise, that will cover a lot of ground in a day. The vibes above that speed aren't terrible so passing isn't a problem.


Glen

 

[acotrel]

Frequent rebuilding of motors using expensive parts does not contribute much to development, unless blow-ups become less frequent.

 

[acotrel]

Did the rod and piston change have any effect on vibration levels?
My 650 ss is decently smooth to about 65 mph then gets a bit buzzy above that. I have considered changing to lightweight pistons and the longer rods.
Ideally though, I would prefer to keep the stock rods as they are very light and strong enough for road use. I suspect that there aren't any lightweight pistons available to fit the stock rods.

I should probably just be happy with a smooth 65mph cruise, that will cover a lot of ground in a day. The vibes above that speed aren't terrible so passing isn't a problem.


Glen

A lot depends on what you are trying to achieve. Enjoyment in any form is worth having. My bike is a developed shit heap. A 650SS is worth preserving. My memory of them is they were a very sound motorcycle. I liked Triumph Bonnevilles, but the 650SS was probably better. My mate had a Manxman. I wish I had bought one.

 

[worntorn]

I have never warmed to the Manxman styling. I'm not sure where the styling ideas came from. The bike was intended for Export only, primarily for the US market. Perhaps it was the British idea of styling that might sell well in the US. With the red seat and baby blue paint job it was very flamboyant and flamboyant was big in America at that time.
I don't think Norton quite got it with that design, it didn't sell very well in America.
Flamboyant BSA Super Rockets all gleaming chrome and bright colors with big Rocket decals on the tank sold well. Export Triumphs were also pretty flashy and they did very well.
The 650ss styling is quite conservative but it also looks right. A fair bit of chrome, polished alloy, black frame and the Dove grey tank is a very nice colour scheme. I'm glad they didn't use a red seat!
Interesting that the Manxman claimed 52 bhp with just 8.3 to 1 cr whereas the 650ss claimed 49 with 8.9 to 1. I suspect the BHP number for the Manxman is just a bit more puffed up than the 650ss number.

Glen

 

[elefantrider]

Did the rod and piston change have any effect on vibration levels?
My 650 ss is decently smooth to about 65 mph then gets a bit buzzy above that. I have considered changing to lightweight pistons and the longer rods.
Ideally though, I would prefer to keep the stock rods as they are very light and strong enough for road use. I suspect that there aren't any lightweight pistons available to fit the stock rods.

I should probably just be happy with a smooth 65mph cruise, that will cover a lot of ground in a day. The vibes above that speed aren't terrible so passing isn't a problem.


Glen

My motor is still on the bench so any improvement is yet to be determined. I mostly wanted them for higher compression pistons because I couldn't find any good off-the-shelf ones to use.

Since then, I have learned -much to my amazement- about a record-setting land speed bike (another Triumph) running old NOS long skirt high compression pistons so that would have been OK too, if I could have found some in time!

Lightweight is good but reducing the chances of piston rock due to a longer skirt is good also, IMHO.

 

[worntorn]

I should probably leave my 650ss together, it runs very well and is all new internally. The compression is about 9.5 to 1, close to ideal for road use.
There is that saying I must remind myself of now and then-
" Never dismantle a properly functioning unit"
If for some reason disaster struck and a rebuild was needed I would definitely look at lightweight piston options.

Glen

 

[Schwany]

I should probably leave my 650ss together, it runs very well and is all new internally. The compression is about 9.5 to 1, close to ideal for road use.
There is that saying I must remind myself of now and then-
" Never dismantle a properly functioning unit"
If for some reason disaster struck and a rebuild was needed I would definitely look at lightweight piston options.

Glen

The short skirt pistons don't make much difference performance wise on the street riding near the legal speed limits with a well-balanced crank. The real benefit is in the higher RPM range where a speeding ticket may be waiting with your name on it. That said they could smooth out your 65mph vibration. I don't know how they work with stock profile Norton cams though. Could be a very nice street ride. Is the cam in a 650SS a racey profile SS cam or more docile like a stock Atlas or Commando profile?

JSM has lighter pistons for the 650 that will work on stock rods. Might be in stock right now. That said, if it aint broke.....

 

[worntorn]

The 650 cam was called the ss cam but it is not the 2s Combat profile. It the same profile as all of the standard issue non Combat Commandos. It is considered to be a fairly hot cam for a 650, less so for 750 and 850.
The 650ss has a definite powerband that hits at 4200 and goes to nearly 7000 rpm. This bike was ported by Herb Becker, so it might run a bit differently than other 650ss bikes.
The 650ss road testers back in 1962 did note the extra pull that came in at 4200 +-.

With the 850 and the same profile, I cannot sense any powerband. The pull feels constant from 3000 rpm on up.

Glen

 

[elefantrider]

JSM has lighter pistons for the 650 that will work on stock rods. Might be in stock right now. That said, if it aint broke.....

My guess is they are custom-made JE pistons with the stock pin height. Flat top or dome?

Would be interested to see the weight difference.

My JS mid-domes pistons are pretty lightweight:

213 grams with pin
163 grams piston only

If I build another 650, I'd like to try 4032 material.

 

[Schwany]

The 650 cam was called the ss cam but it is not the 2s Combat profile. It the same profile as all of the standard issue non Combat Commandos. It is considered to be a fairly hot cam for a 650, less so for 750 and 850.
The 650ss has a definite powerband that hits at 4200 and goes to nearly 7000 rpm. This bike was ported by Herb Becker, so it might run a bit differently than other 650ss bikes.
The 650ss road testers back in 1962 did note the extra pull that came in at 4200 +-.

With the 850 and the same profile, I cannot sense any powerband. The pull feels constant from 3000 rpm on up.

Glen

That sounds like a really nice motorcycle as is.

Mr Becker's port work might have something (or a lot) to do with how the engine responds to the cam in the 650 when compared to the 850.

 

[Schwany]

My guess is they are custom-made JE pistons with the stock pin height. Flat top or dome?

Would be interested to see the weight difference.

My JS mid-domes pistons are pretty lightweight:

213 grams with pin
163 grams piston only

If I build another 650, I'd like to try 4032 material.

Yes you are right. Kind of hard to tell the type or weight of the stock rod pistons from Jim's info page description, since most of the rod references are for his rods. Maybe 170 grams. Also what is in stock probably is not the pistons for stock rods. Special order. My misinterpretation.

 

[elefantrider]

What he's got left in stock is probably the matched set to mine, .030 over mid-level, backcut domes for his long Carrillos.
(The piston manufacturer makes it uninteresting to make just 2.)

For weight comparison:

JE std (73mm) 750 flat top pistons with pin weigh 319 grams, slightly taller than stock. (piston courtesy of @lcrken )
JCC Triumph std (71mm) 650 with pin weight 293 grams (piston courtesy of FAG Engine)

 

[worntorn]

That sounds like a really nice motorcycle as is.

Mr Becker's port work might have something (or a lot) to do with how the engine responds to the cam in the 650 when compared to the 850.

I think the port work did help.
Herb told me that the stock clutch held just fine before the port reshaping. After the port reshaping the clutch would break loose at about 4500 rpm.
This was still happening when I bought the bike. I tried new plates, new springs but it wouldn't hold.
Finally I fitted a Bob Newby clutch and belt drive. That slipped as well until I really cinched the springs down.
It holds now but the clutch is a bit heavy. A Venhills cable installed recently has helped with that. It's still a fairly stiff clutch but at least it holds.
And no more primary leakage!

Glen

 

[elefantrider]

I wonder if he used the stock size 1.406 intake valve or put in Commando size 1.5.

 

[hybridracer]

I believe Doug Hele reduced the inlet ports to 1" to get a much more tractable motor.

Torque on the clutch can be reduced by fitting a larger engine sprocket and a smaller g/b sprocket.

I found that the 4s cam worked extremely well in my 88ss so there is no reason why a 2, 3, 4s etc wouldn't be good in a 650.

 

[worntorn]

This one has 30 mm carbs and ports. I'm not sure about the inlet valve size. Herb might well have changed those for the 750 size in search of performance.
The earlier bikes had a sleeve to reduce the port size and they had smaller carbs as well. The late bikes got 30mm Concentrics but I'm not sure about the sleeves.
If there were sleeves in there I'm sure Herb would have removed them to go along with his reshaped ports.
Whatever he did seems to be right as the engine runs well at low speed and has adequate power then really hops from 4200 on to 7000.
Interesting that the ss cam in the 650 peaks in bhp at 6800 , in the 750 at 6500 and in the 850 it peaks at 5900.
That is from Norton Literature and I sometimes wonder if they clipped the 850 max bhp rpm number just a little to keep things safe.
The Combat went the other way on the rpm scale and that didn't work out very well.



Glen

 

[worntorn]

As others have stated, a 650ss from the 60s isn't ever going to compare with today's Manx on a racetrack. But then I suppose today's Manx racebike is pretty anemic compared with a modern 600cc racebike.
It is of historical interest only that the early 60s 650ss in racing form did well when raced against the early 60s Manx.

Converted for road use though , I imagine a Manx is going to be pretty sluggish getting going.

The 650ss isn't!
This is a fairly relaxed roll on thru first and second to 75 mph. It can be shifted much faster when under duress!
Still, the timer shows the roll on at 8 seconds and off at 14. That is 6 seconds to go from 15 mph to 75 mph. I'm not sure the 850 Commando will do any better, nor will the Rapide 1000. The Rapide might even be slower at this. It's a slow shifting gearbox.
The BSA Super Rocket takes more like 12 or 14 seconds to manage this.

 

[baz]

I think the port work did help.
Herb told me that the stock clutch held just fine before the port reshaping. After the port reshaping the clutch would break loose at about 4500 rpm.
This was still happening when I bought the bike. I tried new plates, new springs but it wouldn't hold.
Finally I fitted a Bob Newby clutch and belt drive. That slipped as well until I really cinched the springs down.
It holds now but the clutch is a bit heavy. A Venhills cable installed recently has helped with that. It's still a fairly stiff clutch but at least it holds.
And no more primary leakage!

Glen

Not sure if it'd be relevant but the only way I managed to stop my b50 and my B44 clutches from slipping was to hand deck every plate (friction and plain)both sides
This was after trying new plates and heavy duty springs etc etc

 

[worntorn]

I tried roughing the plates up with stick on emery on the milling table. Is that the same as decking?
When run dry that fix held for a few goes then the slipping started again.
I tried quite a few different things with that clutch before giving in to the BNR plan . The final straw was the continued primary cover leakage after trying all the known remedies.

The BNR kit killed both birds plus it's very light rotating weight seems a good thing.

Glen