650ss Timing

hillbone · Feb 25, 2023

Hi. I bought a beaut 650ss from the UK.
It was featured in Classic Bike mag March 1966 and is a genuine Dunstall delivered new as Dunstall 650 SS.
It will start reluctantly but then misses, backfires and runs like a hairy goat under throttle. So in checking the timing etc Ive found the points would only allow 6 to 8 thou in the gap so I machined the adjusting slot larger to allow the correct 12 to 15 thou. Now Ive discovered the timing dots on the crankshaft to camshaft sprockets are set on 11 rollers not 10. I havent changed it back to 10 but is it possible that the bike was set on 11 by accident and everythings been adjusted to compensate. The Dunstall tuning guide says 10. I am worried that moving it to 10 may bend valves or something.
I,'m surprised its running set on that 11 number instead of 10.
Your thoughts please.
Cheers Hillbone.

texasSlick · Feb 25, 2023

10 is the proper number.
For a complete timing procedure, see

Setting up and Timing a K2F Magneto

It seems like this topic keeps coming up, and I have to write it over and over. Hopefully, one comprehensive discourse will settle it. If anyone finds anything confusing, please let me know so I can revise. The following procedure assumes the magneto armature is properly centered and aligned...

www.accessnorton.com

You should also verify that the dots on the crankshaft pinion and the halftime gear are aligned at TDC.

Slick

Schwany · Feb 26, 2023

I'll skip the part about doing R&R on a cam chain in situ. I'm guessing you know what needs to be done to do it.

Have you had the cam sprocket nut off to check whether or not the key is offset? Somebody could have been attempting to time the cam, which really is a waste of time on a street bike for the most part. Setting the cam timing up as described in the service manuals out there dot to dot at TDC with 10 rollers between the two sprockets works without all the fiddling around with gauges and degree wheels. If it runs as is, it should run a lot better with 10 rollers between the dots.

You may have other problems besides timing with a used bike. If it is a magneto bike the magneto could be going out and/or the carburetion way off. I may be misinterpreting "runs like a hairy goat under throttle" though. I'm reading it as not running well.

acotrel · Feb 26, 2023

I never use timing marks for anything - always a degree disc. The cam timing, ignition timing, compression ratio, exhaust system, fuel type and jetting are all inter-related. I only use one type of fuel, and comp. ratio, exhaust system, and timings remain fixed, while I jet the carburetors to suit them. If the timings are wrong, you are up shit creek.
When you fit a new cam, the other variables must be optimised to suit it.
When I was a kid, I used to hot-up 650 Triumphs by fitting E3134 eace cans and R type followers, but I never knew the significance of ignition advance and jetting and the importance of optimisation. So my 650 Triumphs were always a bit slower than a Bonneville. When you ride motorcycles on public roads, it is difficult to get them really right. You cannot jet carburetors where there are speed limits and traffic.

hillbone · Feb 26, 2023

Thanks for the replies. I havent touched anything yet. I was surprised it could run on 11 rollers and needed to find out if that was possible. I will check the other 2 dots alighning up at top dead centre.
Another question. What is the method of getting the auto advance unit back onto its shaft and tightening?. I can't get the nut,to take up. Cheers everyone.

hillbone · Feb 26, 2023

Schwany said:
I'll skip the part about doing R&R on a cam chain in situ. I'm guessing you know what needs to be done to do it.

Have you had the cam sprocket nut off to check whether or not the key is offset? Somebody could have been attempting to time the cam, which really is a waste of time on a street bike for the most part. Setting the cam timing up as described in the service manuals out there dot to dot at TDC with 10 rollers between the two sprockets works without all the fiddling around with gauges and degree wheels. If it runs as is, it should run a lot better with 10 rollers between the dots.

You may have other problems besides timing with a used bike. If it is a magneto bike the magneto could be going out and/or the carburetion way off. I may be misinterpreting "runs like a hairy goat under throttle" though. I'm reading it as not running well.

hillbone · Feb 26, 2023

Everything is like new. There is no wear as its only done 4000mls.

hillbone · Feb 26, 2023

texasSlick said:
10 is the proper number.
For a complete timing procedure, see

Setting up and Timing a K2F Magneto

It seems like this topic keeps coming up, and I have to write it over and over. Hopefully, one comprehensive discourse will settle it. If anyone finds anything confusing, please let me know so I can revise. The following procedure assumes the magneto armature is properly centered and aligned...

www.accessnorton.com

You should also verify that the dots on the crankshaft pinion and the halftime gear are aligned at TDC.

Slick

Will do. I have that timing article and are following it. Thats when i got to the 11 rollers. Hey Slick, have you ever come across a set of points that needed the kidney shaped slot lengthened to get 15 thou at the points gap?.

texasSlick · Feb 26, 2023

hillbone said:
Will do. I have that timing article and are following it. Thats when i got to the 11 rollers. Hey Slick, have you ever come across a set of points that needed the kidney shaped slot lengthened to get 15 thou at the points gap?.

No

texasSlick · Feb 26, 2023

hillbone said:
Another question. What is the method of getting the auto advance unit back onto its shaft and tightening?. I can't get the nut,to take up. Cheers everyone.

There is nothing special about tightening the AAU bolt, only loosening ! It has an internal LH thread that is supposed to engage and self extract the AAU on loosening. Sounds like the thread is stripped.

Slick

johnm · Feb 26, 2023

On an old K2F mag it is important to check the points open at the same time on both cylinders. Very common to find 3 or 4 and in worse case over 10 degree difference.

hillbone · Feb 26, 2023

texasSlick said:
There is nothing special about tightening the AAU bolt, only loosening ! It has an internal LH thread that is supposed to engage and self extract the AAU on loosening. Sounds like the thread is stripped.

Slick

So, does that mean I start to re engage with a left hand thread?

hillbone · Feb 26, 2023

johnm said:
On an old K2F mag it is important to check the points open at the same time on both cylinders. Very common to find 3 or 4 and in worse case over 10 degree difference.

Mag is like new. Ramps are identical. Points needed maching to get to open to 12thou. Wierd! Thanks for reply.

texasSlick · Feb 26, 2023

hillbone said:
So, does that mean I start to re engage with a left hand thread?

There is a gap between the LH thread on the central fixing bolt and the internal LH thread in the AAU body. The central fixing bolt should be free of that internal LH thread in the body. When the central fixing bolt is in that gap, it functions like any RH bolt.

Slick

hillbone · Feb 26, 2023

So, do I start attaching it when fully off the shaft as a left hand thread or right hand? Apolgies if im not getting your explanation right in my head.

texasSlick · Feb 26, 2023

hillbone said:
So, do I start attaching it when fully off the shaft as a left hand thread or right hand? Apolgies if im not getting your explanation right in my head.

My apologies for not being able to make it plainer.

The central fixing bolt should be fully into the AAU body. Then simply press the AAU onto the magneto shaft taper, and RH tighten the fixing bolt. Easy peasey!

acotrel · Feb 26, 2023

The left hand thread in the centre of the auto advance unit is usually a bigger diameter than that on the magneto shaft. So you might need a bigger LH bolt to remove the unit. If you have already got the unit off the the magneto shaft, forget the left hand thread for the removal tool, it should clear the thread in the advance unit, when you reinstall the unit.
Where do people find 650SS Nortons which have only done 4000 miles ? I might buy a dozen, and save them to sell to enthusiasts when I am 105.

hillbone · Feb 26, 2023

hillbone said:
So, do I start attaching it when fully off the shaft as a left hand thread or right

hillbone said:
hand? Apolgies if im not getting your explanation right in my head.

acotrel said:
The left hand thread in the centre of the auto advance unit is usually a bigger diameter than that on the magneto shaft. So you might need a bigger LH bolt to remove the unit. If you have already got the unit off the the magneto shaft, forget the left hand thread for the removal tool, it should clear the thread in the advance unit, when you reinstall the unit.
Where do people find 650SS Nortons which have only done 4000 miles ? I might buy a dozen, and save them to sell to enthusiasts when I am 105.

hillbone · Feb 26, 2023

The bike was featured in classic bike magazine. Its done very little. All the nuts and bolts have been basically untouched. When it was featured in 1996 in the mag, it only has only another 200 miles or so on it. I purhased it for 16000 pounds which works out at $32000 AUD. You may need to start saving a bit more if you would like to buy a dozen. Cheers.

acotrel · Feb 26, 2023

hillbone said:
The bike was featured in classic bike magazine. Its done very little. All the nuts and bolts have been basically untouched. When it was featured in 1996 in the mag, it only has only another 200 miles or so on it. I purhased it for 16000 pounds which works out at $32000 AUD. You may need to start saving a bit more if you would like to buy a dozen. Cheers.

That sounds like it is a seriously good motorcyclr. It is probably worth the money. I watched Jaco Forrest on a 659SS win an Allpowers A grade race at Bathurst in about 1963. They were probably the best ever Norton road bike. Forrest used to be a works' rider for BMW in Europe. My mate Steve Oszko used to race a Manx in A grade - Steve hated Forrest because he had a big mouth. The troube was Forrst was actually as good as he claimed he was.
It is really strange. I could have bought a new 650 SS back then. But we did not appreciate their true value, so the price was always too high.
Bob Rosenthal bought an Atlas 70 and did well. He got sponsored rides on a TZ700 Yamaha in A grade races

650ss Timing

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