Problem I Haven't Seen Before

marshg246

marshg246

VIP MEMBER
Joined
Jul 12, 2015
Messages
4,917
Country flag
I'm about finished with a 69S and ran into a problem. For a change, I didn't do this engine - supposedly "Ready to Ride". Was getting ready to set the static timing and as always checked the timing marks. Thought I was crazy - 22 degree off! Tried a new rotor - 22 degrees off. Switched from the AN timing marks checking tool to a degree wheel - 22 degrees off. When the engine is put at TDC (used piston stop method) the 40-degree mark on the AN tool aligns with 18 degrees. When the engine is put on 30 degrees using a degree wheel, it is off the scale on the timing marks.

I tried both sides to be sure the crank wasn't somehow twisted - both 22 degrees off. I can't see anything wrong with the rotor portion of the crank, but the keyway for the front sprocket was re-cut on the other side of the crank so it went through some issue at some point.

Question: Is there a crank for a different Norton that fits a 71 750 and has the rotor slot in a different place?
 
Sounds like a Norton atlas crank
Hopefully someone will correct me if wrong
 
I never use timing marks for anything. I set the timing with a degree disc, then jet to it. If the timing is out, it has a similar effect as changing the fuel/air ratio, or changing the compression ratio.
 
acotrel said:
I never use timing marks for anything. I set the timing with a degree disc, then jet to it. If the timing is out, it has a similar effect as changing the fuel/air ratio, or changing the compression ratio.
Click to expand...
That would be fine if I were keeping the bike - I'm not.

What is "jet to it"?
 
baz said:
Sounds like a Norton atlas crank
Hopefully someone will correct me if wrong
Click to expand...
Searching the web I found a 2016 thread here that talks about this subject, but it says that the Atlas rotor keyway is 90 degrees out from the Commando rotor keyway.
 
Figured it out.

Took a known correct crank half and used a degree wheel to determine where the rotor keyway is. It's at 200 degrees from TDC best I can measure. The keyway in the problem crank is at 340 degrees from TDC best I can measure. I put the rotor on with no key but turned to where the keyway should be and the 30-degree mark lines up but with the other rotor mark. So, this crank, whatever it is, has the rotor keyway about 140 degrees from where it should be on a Commando.

This is a beautiful bike that I was supposed to only need to service - so far, EVERY component has had a problem. For instance, no 4th gear - off a tooth and bad timing side main shaft bearing, Fork springs new, but different lengths, missing on rear hub bearing, and so on.

This bike only needed static timed and a tank to start. Now I have to take the engine out and my helper left for college - o'well, I can do it.
 
With the exception of a few electrical upgrades, Premier carbs, and better fasteners, I build stock bikes and I don't do the kinds of things that I would be ashamed of. I have no idea if the crankshaft in that engine is properly balanced or even decent. The engine was supposedly built by a "famous Norton engine builder", now I'm thinking infamous. Every other bike I've rebuilt for someone was stripped down to empty cases to start. In hindsight, that would have been easier and faster.

Yes, if it were my rider I might paint a mark on the rotor and stator and get rid of the degree indicator and see how it runs - I'm not doing that to a customer - and especially not to a patient man who hasn't even asked what the two bikes will cost him, he's just asked that they be right.

This is the Combat and towards the end the 69S I'm building for him: https://www.gregmarsh.com/MC/Norton/CustomerCombatBuild.aspx
 
marshg246 said:
Searching the web I found a 2016 thread here that talks about this subject, but it says that the Atlas rotor keyway is 90 degrees out from the Commando rotor keyway.
Click to expand...


www.accessnorton.com

ignition timing

Taking a second look at commando cranks.:(
www.accessnorton.com www.accessnorton.com

dynodave said:
ATLAS crank
At piston TDC
Atlas keyway is around 11 oclock
Commando keyway is around 6:30 oclock
there fore NOT 180 degrees
Click to expand...

...and not 90°.
 
marshg246 said:
With the exception of a few electrical upgrades, Premier carbs, and better fasteners, I build stock bikes and I don't do the kinds of things that I would be ashamed of. I have no idea if the crankshaft in that engine is properly balanced or even decent. The engine was supposedly built by a "famous Norton engine builder", now I'm thinking infamous. Every other bike I've rebuilt for someone was stripped down to empty cases to start. In hindsight, that would have been easier and faster.

Yes, if it were my rider I might paint a mark on the rotor and stator and get rid of the degree indicator and see how it runs - I'm not doing that to a customer - and especially not to a patient man who hasn't even asked what the two bikes will cost him, he's just asked that they be right.

This is the Combat and towards the end the 69S I'm building for him: https://www.gregmarsh.com/MC/Norton/CustomerCombatBuild.aspx
Click to expand...
I guess it's different if it's for a customer
Have you informed the owner about the extra work? I doubt he was expecting something like this to happen
 
baz said:
I guess it's different if it's for a customer
Have you informed the owner about the extra work? I doubt he was expecting something like this to happen
Click to expand...
Everything about both builds is documented in the link I gave.
 
L.A.B. said:
www.accessnorton.com

ignition timing

Taking a second look at commando cranks.:(
www.accessnorton.com www.accessnorton.com



...and not 90°.
Click to expand...
This is pretty funny. I kept thinking you mentioned at some point that that the keyway should be down and the timing mark was opposite it. Then, you provide the link above and I look at my post #27 there. I wish I had remembered that picture - would have let me know right away that this crank was wrong and that you may have said it, but I proved it!

I keep trying to find old threads on various subjects and often don't. I found the 2016 thread searching outside Access Norton. In this case I searched for crank issues in every way I could think of - didn't think to search for ignition timing :(
 
Please stainless lovers, use anti-seize!

Got all rigged to pull the engine. - ready to remove 4 bolts, jack it up, and it's out, NOT! The big bolt through the front iso was beautifully polished stainless installed without anti-seize. The nut unscrewed about two turns and stuck. I used bigger wrenches and got it a little farther until I pulled a muscle in my arm. The I tried my 600 ft. lb. capable impact - just rounded the head of the bolt. OK, angle grinder time. Hate using them inside the shop so put towels everywhere in the area to catch the mess and started at it. Very difficult place to do that without hurting anything else but I finally got the nut split down the middle and off. The other three stainless bolts were not seized - because they were barely more than finger tight!

At any rate, the plate on top of the cylinders has many purposes. It is just a 1/4" square of aluminum with holes drilled as needed and some tapped for various pulling, case splitting, lifting, etc. purposes.

Now I can take apart another engine, to get a crank. I have two "on the shelf" but the timing side of both is with Jim Comstock to have the seal surface de-gorrilla'ed. Of course, first I have to get the glued-on timing cover off. Hopefully easier out of the bike - tried a longtime in the bike - gave up.

Problem I Haven't Seen Before
 
Interesting engine support method.
The timing cover I would use a heat gun and perhaps acetone and a rubber persuader mallet .
 
Torontonian said:
The timing cover I would use a heat gun and perhaps acetone and a rubber persuader mallet .
Click to expand...
If the stuff he used is the same as the gearbox, it's not affected by acetone or alcohol, and I'll spend a great deal of time with a single-edge razor blade once I get it off. Now that the engine is out, there are spots where a soft drift and hammer can be used. Failing that, heat. If that doesn't work, I'll have to split the gasket with razor blades.
 
marshg246 said:
Please stainless lovers, use anti-seize!

Got all rigged to pull the engine. - ready to remove 4 bolts, jack it up, and it's out, NOT! The big bolt through the front iso was beautifully polished stainless installed without anti-seize. The nut unscrewed about two turns and stuck.
Click to expand...
Stainless pipe has a similar issue with galling. Unless tape or dope that contains teflon is used the galling will cause leaks. Even then, one has to be careful to not over tighten the joints.
 
Back
Top