Question on 850 Pistons

As some of you probably know I am doing a frame up restoration on my Mk2 Commando. I have purchased a lot of stainless parts, new centre stand, new gearbox cradle with double cotter pins for swing arm attachment.

I am now in the process of stripping the engine and have the head and barrels removed as well as the timing cover and all the bits in there. Had a hell of time removing the woodruff key from the camshaft. Still have to work out how to remove the half time pinion. It won't budge at the moment and of course I don't have the factory puller for it.

Anyway here are some pics of the disassembly so far. The bottom end around the crank looks clean which is a good start.









In the picture above it shows the STD piston tops with an A on the piston top as well.

Does anyone know what these letterings mean please.

Also any hints on removing the half time pinion without the use of the puller.

Thanks
Don

thunderbolt said:

In the picture above it shows the STD piston tops with an A on the piston top as well.

Does anyone know what these letterings mean please.

Click to expand...

It's the bore size grade (normally 'A' or 'B') so 'A' should also be stamped on the top of the barrels?).

See factory manual, Technical Data section, "Cylinder block" (pdf p.21):

http://www.classicbike.biz/Norton/Repai ... mmando.pdf

Interested in this myself since I don't have that tool, either. Might have to take the bottom end to a local shop I know has the tool.

I'd be polishing the minor scratches and nicks out of the conrods and protecting them from further damage.

I would read this article on oils by Castrol. http://www.castrol.com/en_gb/united-kin ... -oils.html

You can avoid most of that build up on the pistons and junk with classic motor oils with phosphorous and zinc. I use Valvoline VR1 40 weight racing oil.

Do any of the modern oils affect the conical seal in the Commando engine ? - I use a fat neoprene O-ring in there. Is that seal commonly available from bearing suppliers ?

Thanks guys for the comments. Appreciated. I will press on.

Cheers Don

Here is a picture that should please some!!!



Danno:

I read a fair bit on how to remove the half time pinion from the crank and none of the ideas worked for me. There were ideas on grinding down roofing screw heads and getting them behind the pinion and using finger pressure to release the pinion. I am afraid my pinion was held on much tighter than this.

The solution I used might be common knowledge to some, but no one had mentioned it. So here it is for what it is worth.

I separated the crank cases so the crank was left in the timing side half. Everything else was removed from the timing chest except the pinion including the oil pump. I removed the two oil pump bolts. I then used a propane torch to heat around the area of the oil pump and the other surrounding areas of the main bearing until my spittle would just sizzle off the case on immediate contact. At this temperature the FAG bearing, sealing tin washer, triangular washer and pinion pulled through the hole in the crank case. So the crank and pinion was now separated from the case. I then mounted the crankshaft in the soft jaws and with a couple of stout screw drivers was able to move the pinion about ⅛" now that the crankcase was out of the way. I then used two LARGE tire levers to lever the pinion the rest of the way off. BUT it was not easy - it took all my strength (at 68) and using the very ends of the levers to gain most leverage advantage possible.

No finger pressure was going to move this pinion. I doubt the special tool would have worked, but never having used one I cannot vouch for that.

This may be of use to someone and might even be common knowledge amongst the Norton fraternity. But I could find no reference to it on the internet.

Thanks
Don

Thanks, Don. I was wondering about splitting the cases with the pinion still fixed to the crank. I'm currently having issues with the gearbox sprocket, which should be a snap. Not sure how large a puller the half-time pinion may take, but the one I have isn't large enough for the g/b sprocket. It may work for the half-time pinion. If not, I have to split the cases anyway, so your methodology might be the way to go.

Danno a normal puller with either two or three legs will not fit, it needs a specialised puller.

https://andover-norton.co.uk/en/shop-de ... nmet-2003-

thanks les and T-bolt for the info. Judging by what I found today, I will likely just be popping off the driveside case to inspect and replace the seal.

Buy the right tools, so simple and you will have them forever, it just make things a lot easier, I use to do it the hard ways but now I have the pinion puller, some come off easy but others need that puller to brake its grip on the shaft, for other things that need pullers I have made a few special tools as well using 2 and 3 jaw pullers, I have a good collection now, well worth the investment having every tool for thr job.

Ashley

ashman said:

Buy the right tools, so simple and you will have them forever, it just make things a lot easier, I use to do it the hard ways but now I have the pinion puller, some come off easy but others need that puller to brake its grip on the shaft, for other things that need pullers I have made a few special tools as well using 2 and 3 jaw pullers, I have a good collection now, well worth the investment having every tool for thr job.

Ashley

Click to expand...

I understand your point of view, but I am not going to buy a puller that I will only use once.

A really easy solution to protect the rods from bouncing off the sharp edges of the crankcase opening, is to slip over the rod the cardboard roll that paper towels come wrapped around. Easy to fit and cheap too. Put a few aside instead of throwing them in the bin and you will have them on hand when required.

thunderbolt said:

ashman said:

Buy the right tools, so simple and you will have them forever, it just make things a lot easier, I use to do it the hard ways but now I have the pinion puller, some come off easy but others need that puller to brake its grip on the shaft, for other things that need pullers I have made a few special tools as well using 2 and 3 jaw pullers, I have a good collection now, well worth the investment having every tool for thr job.

Ashley

Click to expand...

I understand your point of view, but I am not going to buy a puller that I will only use once.

Click to expand...

I'd buy one in a heartbeat if I needed it. Maybe on the next project. Right now I need a larger 2-jaw (or 3 would do) than the one I have to get the stubborn gearbox sprocket off. Replacing the Mickey Mouse layshaft bearing and the driveside seal is a necessity.

Danno said:

I'd buy one in a heartbeat if I needed it. Maybe on the next project. Right now I need a larger 2-jaw (or 3 would do) than the one I have to get the stubborn gearbox sprocket off. Replacing the Mickey Mouse layshaft bearing and the driveside seal is a necessity.

Click to expand...

Purchase the Mick Hemmings layshaft bearing if you want one that will last.

thunderbolt said:

Danno said:

I'd buy one in a heartbeat if I needed it. Maybe on the next project. Right now I need a larger 2-jaw (or 3 would do) than the one I have to get the stubborn gearbox sprocket off. Replacing the Mickey Mouse layshaft bearing and the driveside seal is a necessity.

Click to expand...

Purchase the Mick Hemmings layshaft bearing if you want one that will last.

Click to expand...

I think there's a common Timken bearing available here in the States that will do the job. I did the one in the SS clone many years ago after the original caused second gear to break a tooth.

The Mick Hemmings bearing is not a roller bearing as often used, it is a heavy duty ball bearing. He has never had one fail even on race bikes he has prepared including Wayne Gardner to mention one of them. I can post a pic if you would like.

Cheers
Don