1962 650ss Build

seanalex

VIP MEMBER
Joined
Dec 30, 2018
Messages
122
Country flag
Haha. Of course.

New carbs fitted. Cables run. Fuel on. Small leak on the bottom of the chopped carb, but I think its coming from the banjo and could just be a hair tighter. I'll pull these, as I want to shorten the fuel line between the two banjos anyway.

tickle carbs. many kicks. nada. one pop. tickle again. flooded. gonna let it dry out, and will approach tomorrow. Noticed again a bit of fuel in that balance tube, so, pretty confident its just flooded. Will let it dry out overnight and retry tomorrow.



I've been thinking back other adjustments that I've made between when it was starting easily, and where it is now.

1. I lowered the top yoke approx 1.5". I did this because I felt the front end was a bit too high, and the center stand not really taking on the weight of the bike. Would there be an instance in doing this where the inlet tract of the manifold is now pitched too far forwards? And fuel is rolling into the manifolds and or the balance tubes?

2. I removed the screens that I had fitted onto the velocity stacks. I did this when I was thinking that it was too restricted by the screens. I'm going to experiment tomorrow or the next few days with refitting the screens to see if it makes any difference.

3. Lastly, is there an instance where the clutch plate would be too tight or too loose? Would this have any effect at all on starting? With the bike in gear I cannot roll the bike forwards or backwards. So I'm confident that the clutch plates are of good tightness. As a side, this bike has the Newby belt drive, and I'm setting the springs to the suggested turn level in the "instructions." I've also balanced the plate with dial indicator so that it's run true.
 
Joined
Nov 11, 2012
Messages
345
Country flag
1. The way the carbs are mounted on the down-draught head, excess fuel is going to drain into the inlet track.

2. Don’t think this would be a big factor, but could be missing something?

3. Not familiar with the Newby belt drive. If you can pull the clutch and kick through free and the way you describe not being able to push the bike over compression with belt tension as prescribed I would say you’re good.


Are you setting up the carbs as recommended by Amal (air screw 1.5 turns out, etc.)? Haven’t had a bike fail to start without something else the cause.

I’d be tempted to relook at timing/spark, valve clearance.

How much gas is in the crankcase?
 
Last edited:

Fast Eddie

VIP MEMBER
Joined
Oct 4, 2013
Messages
18,141
Country flag
Sounds like the flooding you describe is simply that, ‘normal’ flooding rather than faulty carbs.

As mentioned above, with carbs mounted in a downdraught fashion, and manual float bowl flooding, it is going to lead to fuel making its way into the engine.

Maybe it’s your flooding technique? Maybe flooding too much?

You need to be careful as fuel entering the engine in this way can cause ‘petrol wash’ whereby the pistons and bores get washed clean of oil, leading to obvious issues… I know cuz I dunnit.
 
Joined
Dec 14, 2013
Messages
374
Country flag
Hi
You mentioned you lowered the top fork yokes 1.5" why? If the original stanchions were the correct ones than you have just increased the angle the Monoblocs are set at, increasing flooding issues?
1.5" lower screams out to me that something is wrong or was not right with the original stanchions on the bike?
In lowering the front by 1.5" it would seem to me that riding the bike you would feel like you would be falling over the front wheel?
Get back to the to the original Norton specs, set up as per the manual. I did this with my 1963 650 SS and it is first kick every time, although I have a Pazon CDI ignition system fitted to the crankshaft, rather than run the magneto, just because it was cheaper than rebuilding the magneto, I left the shell of the magneto in place for originality.
Only problem with the Amals was the float levels, no flooding but rich running at idle.
Burgs
 

seanalex

VIP MEMBER
Joined
Dec 30, 2018
Messages
122
Country flag
Hi
You mentioned you lowered the top fork yokes 1.5" why? If the original stanchions were the correct ones than you have just increased the angle the Monoblocs are set at, increasing flooding issues?
1.5" lower screams out to me that something is wrong or was not right with the original stanchions on the bike?
In lowering the front by 1.5" it would seem to me that riding the bike you would feel like you would be falling over the front wheel?
Get back to the to the original Norton specs, set up as per the manual. I did this with my 1963 650 SS and it is first kick every time, although I have a Pazon CDI ignition system fitted to the crankshaft, rather than run the magneto, just because it was cheaper than rebuilding the magneto, I left the shell of the magneto in place for originality.
Only problem with the Amals was the float levels, no flooding but rich running at idle.
Burgs

They're not the original stanchions. They're 35mm Ceriani GP forks with the Minnovation Racing triples.

@FastEddie - I think you're right in that I'm flooding too much with the tickler. Also, well said about washing the bores. Makes sense that this would happen. I'm going to drain the sump today and see how much oil is in there as well. Plugs didn't smell of gas, and or weren't wet last night when I pulled them. And I only had the fuel on for a little bit.

@kernel65 Yes, carbs were checked and set to the recommended spec before fitting. Also blew out all the jets with compressed air, and checked to make sure that everything was correct size wise, and that was sufficiently tight. I've checked the points gap on the mag and looks to be in order. Also
checked to make sure that I have decent spark.

1962 650ss Build
 
Last edited:
Joined
Apr 22, 2020
Messages
1,560
Country flag
Dropping the yokes down 1.5" on the stanchion tubes won't make any difference with the carburetion. If the floats are set to spec it won't flood anymore than it would riding downhill, which is not at all. Your geometry will change and the handling may be a little bit twitchier.

I would use the Norton stock spec for jetting initially. If using a racer's spec out of a 3rd party book for what should be done for racing, you may end up chasing your tail for a while.

It takes a lot of fuel to wash the cylinders entirely of oil. Fuel has to get past the compression rings and wash out the oil rings. Otherwise, every time the piston rises and falls the oil rings will leave some oil behind in the bore. More than likely all that is happening is you are fuel fouling the plugs. Washing the cylinders to the point of engine destruction is certainly possible just not that common.

I know putting the balance tube on the bottom of the intake manifolds is what Norton did with all the straight up motors. My guess is they did that so that users would have easy access to the intake valve cover, but it is better to put the balance tube on top of the manifolds. Particularly if it is a clear tube and you don't want to see any fuel in it. I also think it performs better on top, because it stays clear of fuel.
 

Fast Eddie

VIP MEMBER
Joined
Oct 4, 2013
Messages
18,141
Country flag
Petrol wash doesn’t mean ‘Washing the cylinders entirely of oil’.

See piston below, front face is perfect, rear face looks like it’s seized solid !

Consensus of opinion on this was petrol wash. A hypothesis supported by the fact that I later found the float needle housing leaking on this side only.

So petrol wash can happen, and this is what it can look like:
 

Attachments

  • 1962 650ss Build
    468F5EDF-E3B9-485F-B4B5-C53340AD7596.jpeg
    81.3 KB · Views: 18
  • 1962 650ss Build
    81154093-C187-4454-B530-117A58CC6120.jpeg
    83.7 KB · Views: 19
Joined
Apr 22, 2020
Messages
1,560
Country flag
So petrol wash can happen, and this is what it can look like:
Guess I misunderstood. I believe it happens although I had a drastic cylinder wash image in my head when I read that. Fuel in the sump and all that jazz. Looks very unfriendly to the piston.

I've never had it happen on any motor I've built, or if I have had it happen it was not severe enough to tear down a motor. I only tear them down when the bottom end takes a poop or I want to try a different engine configuration. Well, that's not true. I did have an out of round overbore done by some genius and that seized a piston, but that was a 2 stroke and a million years ago.

I was trying to be less gloom and doom about the situation, and I didn't think Sean was having float needle issues with the new carburetors. I suppose I could be wrong about that, but it seems less likely than it was with the older carburetors.

Kind of surprised it did not start right up.
 

Chris

VIP MEMBER
Joined
Jan 21, 2008
Messages
1,430
Country flag
I've told this story before lol. I parked my Rickman Trident on the slope at Cadwell Park holding area, waiting to be called up for my race. Bump started the bike down the hill as the previous race ended. Small home made tank, did my sighting lap, it was a 6 lap race & the bike cut out at the end of the back straight on the final lap!
Gutted! Quick trip in the van. I found I had no fuel! Next race I was greeted by the marshals with " again? Did you miss us!"
I had done the MV owners club track day, loads of laps & no problems. Serviced the bike ready for Croft (& purchased an alloy TZ tank) & found nearly as much fuel as oil in the sump. Proper washed bores lol
Never understood why petrol taps on race bikes are impossible to find with gloves on.
 

seanalex

VIP MEMBER
Joined
Dec 30, 2018
Messages
122
Country flag
The saga continues, and possibly onto a better path.

So, new updates. The new carbs are nice, and look nice. I do not think I am having a flooding issue anymore so thats great. I was still having a lot of problems with starting the bike. I would get a few pops here and there, or it would turn over maybe 10-15 revolutions then kind of die off.

Tightening up the clutch springs did help with the starting issue. But looking at the plugs, they didn't smell of fuel.

Other thought I had was that the Rotor was not centered within the Stator, and it might be rubbing, and preventing the engine from freely revolving, causing it to stall. This was a problem when I first put the motor into the bike, and I could not kick it over. Taking it apart this evening the rotor definitely has some mildly deep grooves cut into it. So it definitely was not square with the stator, and not at the proper gapping. I also noticed that the stator housing was a bit loose. I'm getting nervous about properly tightening this housing down, I really don't want to strip out the threads in the cases. Not sure what I can do to lock these screws up. Kind of sucks that they're just flathead screws, and shallow ones at that.

Under the urging of a friend, the timing at this point should be double checked. Just to rule it out as the last possible fault of why this bike is not running as it should. Especially given the fresh carbs.

This time around I'm using a much better degree wheel. When I first build the motor I used the Andover one, and it's kind of a POS. This wheel locked onto the rotor nut is much much more accurate looking. I used the spark plug ruler thing just to make sure that I was on the compression stroke. Used a long thin screwdriver to find the proper TDC.

Using the cigarette paper I found that the mag was firing at 27deg Before TDC. So clearly that's out about 3deg.

Standing over the bike, and kicking it through slowly I looked down at the timing side. I noticed that the AAU seemed to be on a slight wobble. Rotating through slowly with the kickstarter I was able to see that the chain tension on the Magneto chain is all over the place. It's clearly not lined up, and the chain goes from about 1/2" slack to pretty much dead tight.

Looking back through some other posts here and the NOC forums, I've ordered the chain tensioner tool from Andover. So I'm thinking that I have to advance the timing a few deg, but also readjust the mounting of the magneto to make sure that the chain runs true. This is bringing me back to my initial issue a few months back when I had the bike out for its first run. Makes sense now if that chain is not running true, that the firing of the Mag would be all over the place once the bike is at running speed.

So guess that my initial issue from all that time ago wasn't fueling after all, and was instead a timing issue. At least, I hope thats the current issue and solution.

Does anyone have any better ideas if I should be looking to just replace the AAU? It returns freely from the advanced position, but it is or does appear to be original, and I'm getting a little ahead of myself suspecting the possibility that the unit is warped or damaged in some way.

the other slight annoyance is that one of the new carbs has a slight fuel leak. Through the bottom where the banjo connects the carbs. I've tightened it up to what feels like a lot, and I'm reluctant to tighten it further. The leak is either from the small cap that houses the main jet, or the joint where the jet holder threads in.

Is it possible that I just need to put fresh washers on? Like if the washers have been over tightened and have failed?
1962 650ss Build
 

texasSlick

VIP MEMBER
Joined
Jan 2, 2013
Messages
3,542
Country flag
Now that`s a degree wheel!

Be sure to check timing on both ramps.

Your description of chain tension reminds me of a post by robs ss. Ultimately, he found his magneto armature was off center, causing the chain tension to vary as the engine was rotated by hand. See https://www.accessnorton.com/NortonCommando/dommie-magneto-chain-tension.22207/

Slick

EDIT: A simple check for a centered armature is to check point gap on both ramps. If the gaps are not equal, something is wrong. The armature must be centered before trying to correct any gap difference.
 
Last edited:
Joined
Apr 22, 2020
Messages
1,560
Country flag
That is a colorful degree wheel. :cool:

I used to think timing wasn't that big a deal on an old Norton until I set it 6 degrees retarded by mistake. Really not a good thing.

My manual says 32 degrees BTDC fully advanced for the 650ss. If nothing else it should start easier, idle and run better set for 32 degrees all in as long as you use good fuel and kick hard on cold starts. I do think you are on the right path correcting the timing. I should have and may have mentioned getting timing right with that old magneto is a PITA. I definitely thought it, but if I didn't mention it, it was because I didn't want to defend my simple man thoughts to the "test don't guess" police. he he

I don't know your carburetors well enough to say what would stop the leak.
 

Bodger

VIP MEMBER
Joined
May 9, 2017
Messages
412
Country flag
Now that`s a degree wheel!

Be sure to check timing on both ramps.

Your description of chain tension reminds me of a post by robs ss. Ultimately, he found his magneto armature was off center, causing the chain tension to vary as the engine was rotated by hand. See https://www.accessnorton.com/NortonCommando/dommie-magneto-chain-tension.22207/

Slick

EDIT: A simple check for a centered armature is to check point gap on both ramps. If the gaps are not equal, something is wrong. The armature must be centered before trying to correct any gap difference.
If the ramps are off (ring needs to be "stoned" or shimmed, won't that also show as unequal point gaps? And if the that's the problem, while the fix is a PIA, it's nowhere as serious as an off center armature. Also, sounds to me like, for some reason, the magneto sprocket and/or AAU might not be sitting properly on the magneto shaft taper?
 

seanalex

VIP MEMBER
Joined
Dec 30, 2018
Messages
122
Country flag
Looking at it for a few hours this morning . . .

Points gaps have been measured and adjusted to 0.012". They are now the same on both ramps. Having the AAU on and off a few times, it was not sitting proper on the taper, I will play with this a few more times to make sure it is square before fitting the cover.

I feel like I had read in a few places that the timing should be closer to 30deg with modern fuel.

As for the carb leak, going to replace the washers and see if that helps.
 

texasSlick

VIP MEMBER
Joined
Jan 2, 2013
Messages
3,542
Country flag
Bodger is correct in that cam ring can result in unequal point gaps. Unequal gaps is due to either poorly machined cam ring or off center cam ring, or off center armature shaft.

Seanalex now reports both gaps are equal which is a very good sign.

Except for assembly with a bit of crud in the AAU female tapere, it is a mystery to me how the AAU can fit poorly on the magneto shaft taper, but that would cause the chain tension problems he reported.

@seanalex: now is the time to rigorously set up and time your magneto. A how to guide is here: https://www.accessnorton.com/NortonCommando/setting-up-and-timing-a-k2f-magneto.19685/

I agree .... with modern fuels, I have set my timing to 30 degree.

Slick
 
Joined
Apr 22, 2020
Messages
1,560
Country flag
I feel like I had read in a few places that the timing should be closer to 30deg with modern fuel.
29 degrees is safer yet.

For some reason (lack of rational thought probably) was thinking an older ignition with an AAU and K2f magneto might work better at 32 degrees BTDC with a lower compression motor and milder cam like yours has.

Definitely go with 30 degrees BTDC if that is what others with the same build are doing. In my experience, the engine build components dictate tuning parameters as much or more than anything else.
 

seanalex

VIP MEMBER
Joined
Dec 30, 2018
Messages
122
Country flag
Bodger is correct in that cam ring can result in unequal point gaps. Unequal gaps is due to either poorly machined cam ring or off center cam ring, or off center armature shaft.

Seanalex now reports both gaps are equal which is a very good sign.

Except for assembly with a bit of crud in the AAU female tapere, it is a mystery to me how the AAU can fit poorly on the magneto shaft taper, but that would cause the chain tension problems he reported.

@seanalex: now is the time to rigorously set up and time your magneto. A how to guide is here: https://www.accessnorton.com/NortonCommando/setting-up-and-timing-a-k2f-magneto.19685/


Slick


I won't be able to get back into it until tomorrow night at best, for some reason work keeps getting in the way. I've consulted that thread about the Mag rebuild about 50times. Actually have it saved as a tab on my phone, so I can reference the sequence.
 

seanalex

VIP MEMBER
Joined
Dec 30, 2018
Messages
122
Country flag
Still waiting on delivery from Andover for the timing support tool. For some reason takes me about 2 weeks to get Andover deliveries. RGM and Norvil seem to ship overnight, should have ordered from them.
 
Top