Project update: very good, then a very bad day

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baz said:
Yep I have 5 old bikes on the road
I try to rotate them as much as possible to avoid wet sumping and jets clogging up etc
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Trade two or three of your old ones for a new one. More riding, less maintenance!
 
Coolhands said:
Trade two or three of your old ones for a new one. More riding, less maintenance!
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What maintenance?
Do you mean riding a bike to stop it wet sumping?
I use my bikes for commuting as well as leisure
 
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baz said:
What maintenance?
Do you mean riding a bike to stop it wet sumping?
I use my bikes for commuting as well as leisure
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Routine maintenance. The magic number of bikes for me is two or three. If I have more I always favor one and the others sit too much.
 
Coolhands said:
Routine maintenance. The magic number of bikes for me is two or three. If I have more I always favor one and the others sit too much.
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I bought a modern bike a 1993 Indian Enfield but it's not quite up to what I need despite slightly tuning it and raising the gearing
My commuting is 3 days a week 18 round trip per day
The Enfield and my A10 are okay for that
But 2 days a week my commuting is 70 miles per day
I use my commando,t160,r100 for those because 50 miles of that is motorway riding
And they are perfect for that
 
Schwany said:
Pistons move up and down. If the cylinders were moving up and down all kinds of hell would break loose. Just giving you some BS.
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On a Norton the cylinders and everything else is moving up/down/forwards/backwards. :D

65% balance factor test

Made a jig with a tiny brass tube superglued & taped to a heavy block, set it on a jack stand next to the Norton 750 motor. Inserted a 1/32 wire sharpened to a needle point. Taped a piece of sheetmetal to the timing cover. My motor is now balanced at 65% wet (72% dry) in solid featherbed...
www.accessnorton.com www.accessnorton.com
 
Update. Timing cover came off today. Still don’t know the extent of the damage but I know the cause!

Oil pump drive shaft has broken.

Engine turns all the way through with a wrench on the crankshaft. Hangs up at one point on each revolution of the crank.

Seized piston do to oil starvation? We will see.
 
Coolhands said:
Update. Timing cover came off today. Still don’t know the extent of the damage but I know the cause!

Oil pump drive shaft has broken.

Engine turns all the way through with a wrench on the crankshaft. Hangs up at one point on each revolution of the crank.

Seized piston do to oil starvation? We will see.
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Has the main bearing collapsed on the timing side?
Try lifting the crank to check, maybe use a block and lever to see if there's movement
 
If you have the cases with no sump screen, I will guess that a chunk of metal got sucked up into the oil pump and stopped it very suddenly.
 
Remove the oil pump and broken shaft and then turn the motor over to see if it moves without sticking in one spot, if the motor was seized motor wouldn't turn over at all, if the oil pump shaft has broken that could be why the motor sticks in one spot as the broken shaft jams, as you have said earlier that there was no metal in the oil.
 
Sorry I should have been clearer. The oil pump caused the problem but wasn’t the symptom.

Looks like a failed wrist pin retaining clip to me. Scored up the barrel pretty good.
 

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Well that wouldn't help, major rebuild, how deep are your pockets in how far you will go, rebore and new pistons to start and everything else, good luck with it, only time and money now.

Ashley
 
Coolhands said:
Update. Timing cover came off today. Still don’t know the extent of the damage but I know the cause!

Oil pump drive shaft has broken.

Engine turns all the way through with a wrench on the crankshaft. Hangs up at one point on each revolution of the crank.

Seized piston do to oil starvation? We will see.
Click to expand...

If you mean the shaft (and gear) snapped off the oil pump which then led to engine seizure, that is exactly what happened to a 1973 750 here last year on a new rebuild.

The pictures posted then showed a Kibblewhite alloy push rod (which seems to be discontinued and enough for me to pull down my new unstarted 850 to replace the ones I had used) that had failed at the upper cup, a camshaft follower cup then got beat up and a portion ended up in the scavenge side of the oil pump (having no filter gauze on that 1972 / 1973 750 engine)
The pump jammed, sheared the shaft and the engine was oil starved resulting in a seizure including split connecting rods.

The piston circlips are a known issue (within the community) which I replaced also on new AE pistons with the next size up.
I was able to find the same clips recommended by Jim Comstock locally (within a 300 kms ride)

That bore picture is sad to see.
 
Coolhands said:
If anyone has a spare barrel laying around…
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There're getting a little hard to find. Have you measured? May only need a bore. Piston sets don't cost very much (unless you go fancy). They are available in +0.020, +0.040, +0.060, and +0.080 but I don't think I would go over +-.060 - the skirt would be too thin for me. Sleeves are also available, but I have no idea who installs them. Of course, you need to be sure the rods and crank are OK before you start spending money IMHO.
 
Unfortunately I don’t think it’s getting the micrometer over from my dads shop. It’s pretty deep.

Was looking at sleeves but it looks like it’s not recommended on the 750. Thoughts?
 
You might want to carefully take the oil pump apart to find whatever jammed it, if that's what happened. At least see if the broken shaft still turns. I have a few used pumps around here if you need parts and want to try and fix it. If it did suck something up, check the passageway to the sump to see if anything else is in there. Flush it out with kero.
Russ
 
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Coolhands said:
Unfortunately I don’t think it’s getting the micrometer over from my dads shop. It’s pretty deep.

Was looking at sleeves but it looks like it’s not recommended on the 750. Thoughts?
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I'll leave the to sleeve or not to sleeve opinions to others - I can get them if you decide you want to. I do have a 750 engine from the barrels down - have no plan to use the barrels or pistons - the top right front fin is missing. I believe that the pistons are +0.40 and what I can see of the bores are OK - it's very hard to get to right now and it's very dirty. Don't really have a plan for the of it other than to take it to a swap meet and sell it.
 
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