P11 gets the JSM treatment

elefantrider said:

Nice upgrade. What will you be running for a clutch? Planning for any improvement in that area?

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Maybe a 5 spring N.E.B. of mostly alloy construction. No cush though, so I'm on the fence about it today. I guess if the AMC clutch can't take it, I'll end up with the N.E.B. sooner than later.

It would be nice to put a belt drive on it and have a 2-finger diaphragm sprung clutch, but I'd miss that Matchless/Norton primary cover, and have to figure out how to mount the stator. As you know the stator is in the primary cover and there is no "native" support for hanging the stator off the drive side case.

Schwany said:

This explains the breathing issue for the 2S. https://andover-norton.co.uk/en/sicombatcrankcase/

I actually built the P11 back then (1990's) to chase modern motorcycles from Alice's Restaurant on Skyline out to the coast in California. You have to know where that is. It was a popular gathering spot. I thought I could save some money by making the P11 sort of quick for the twisties. Didn't turn out that way. I ended up with 5 modern bikes in the garage and the P11 parked in the corner. Now of course it's kind of cool, cuz I don't have the testosterone level I had back then and hauling ass on the street is not that intelligent.

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I get all the 2S cam etc.

Was jus’ wonderin’ why the Commando timing cover ?

So you could run an EI in the points housing I guess ?

Fast Eddie said:

I get all the 2S cam etc.

Was jus’ wonderin’ why the Commando timing cover ?

So you could run an EI in the points housing I guess ?

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Explained further back, but yes at the time I did the Commando timing cover for dual points and later ended up installing EI.

Just got my barrels out of machinist jail. Need to clean those up and found something I need to fix that may or may not be important. More on that later.

So I fooled around with the timing side case a little yesterday by adding another small hole further down in the case, opening up the two holes that were there previously, and opening up the port for the cNw breather I'm leaving on the timing case. Leaving it on the timing case may prevent me from breaking a land speed record. However, these days 90-95mph is frantic enough on an old antique motorcycle.

Some boring pics



This is the Commando timing cover I'm using for ignition support off the end of the cam.


Has anyone with a pre-Commando ever sanded or ground the Norton off so that the cover looked more like it was period correct instead of running uphill once mounted on a straight up motor?

Schwany said:

Just got my barrels out of machinist jail. Need to clean those up and found something I need to fix that may or may not be important. More on that later.

So I fooled around with the timing side case a little yesterday by adding another small hole further down in the case, opening up the two holes that were there previously, and opening up the port for the cNw breather I'm leaving on the timing case. Leaving it on the timing case may prevent me from breaking a land speed record. However, these days 90-95mph is frantic enough on an old antique motorcycle.

Some boring pics

This is the Commando timing cover I'm using for ignition support off the end of the cam.

Has anyone with a pre-Commando ever sanded or ground the Norton off so that the cover looked more like it was period correct instead of running uphill once mounted on a straight up motor?

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I have a timing cover that has been welded up and polished
If you check out Ludwig's one he has a timing cover that has the cover welded up and the logo reinstated level

baz said:

I have a timing cover that has been welded up and polished
If you check out Ludwig's one he has a timing cover that has the cover welded up and the logo reinstated level

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Thanks baz

Weld and polish would make a lot more sense with a Norton casting. I'd probably uncover air pockets reducing the surface that much.

I knew of Ludwig's timing cover mod and chopped Commando primary for use on a pre-Commando with a belt clutch, but wasn't sure how he did the timing cover. He's very creative and talented.

Finding a skilled welder will be the challenge. Not a job for the muffler shop. he he

"Just got my barrels out of machinist jail. Need to clean those up and found something I need to fix that may or may not be important. More on that later."

The "something" I refer to above had nothing to do with the work John Maloney did. It is a Norton factory mistake I hadn't noticed in 49 years. One of the pushrod tunnels is too close to one of the small stud holes and cuts through into the bottom 1/4 inch of the threads in the stud hole. I can see a couple of threads at the bottom of the stud looking into the tunnel. After thinking about it I don't think it's a big issue. A good thread sealer would probably do the job of preventing any air pressure going anywhere, if it could go anywhere past the threads.

Plodding along. I'm fixing things I should have taken care of a long time ago that are not engine related. For example, cleaned out my oil tank.



Was thinking of taking my barrels to a machinist to get the JS lifter block set screw holes drilled and tapped, but I have an old cheapo drill press and know which end the drill bits go it. I was concerned initially that the cast iron would be hard and would require professional help, but that cast iron is not that tough to drill. Tapping it takes some serious patience though. Would be easy to snap off a tap in it if in a hurry. Oh I also remembered I was a master mechanic in my own mind, so went for it.



Set screws in



Probably have the motor together by the end of the week, if I don't get caught in an over thinking it vortex.

outawack said:

The JS2 cam is a fair bit of cam, but it sounds like you have done the research. Building a performance commando engine is like being married, lots of frustration combined with moments of pure joy. Like Fast Eddie said, be prepared to assemble and disassemble a few times. I had a laugh at the memory thing, i have just pulled my head back off because i couldn't remember if i torqued the through bolts down HAHA.

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This is the first race motor I've built while over thinking everything. When I was younger I didn't think much about it, and just threw things together.

Doing it over and over again is an understatement. Setting up the lifter blocks has taken about 3 times longer than I thought it would and I'm still not done. I had to lightly file and scotch brite fit the lifter blocks in the lifter bores. They bound up in the lifter bores the last 8th inch. The base diameter was a little wider in the front to back dimension than the rest of the block body that went in smooth as silk. Then I made a set of tappet locking plates out of 1/8th" aluminum flat stock instead of butchering up the stock plates. Set screw detents are marked, but not drilled into the blocks yet.

Another push on my schedule. Doesn't matter though. I'm my own client.

Schwany said:

That would get the job done, but I have so many other things to do I'm taking the lazy route and using one from Andover. I doubt the pinion will be difficult to pull. My motor is clean and slippery on the inside.

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I have a factory puller ... somewhere - you know. After I looked for it for two weeks and let my open-mouth crankcases sit there with con rods hanging out of them, I said "I'll order one from Andover". Then, "I don't remember it being really tight" before. So, with adequate self-scolding about overthinking and trying to be too smart, I found a pair of small "L"-shaped bars in my toolbox (I think I'd used them 50 years ago on my Maico road racer clutch) and said "No levering on the timing case, no scratching anything up -- just see what an easy pull will do". So I hooked up, wishing I had three (to match the spacer plate behind it), and - just holding the bars in my hand, gave it a pull. Nothing. But I wasn't too disappointed, I didn't expect it to work. But in for a penny, I tried it again and low and behold, it moved about a 1/16" of an inch. After another self-lecture about getting too excited, I hooked the levers back under the pinion, gave it a slightly stouter pull and it slid off.

Considering Wolverhampton (Edit - apologies, if it's a P11 engine, they should be Plumstead, not that I have a lot of confidence that it makes a lot of difference) tolerances, I'm sure that not all of them will be that way, but -- my suggestion -- get something that will safely hook up and give it a try. HTH, BH.

Blewdy Yaink said:

I have a factory puller ... somewhere - you know. After I looked for it for two weeks and let my open-mouth crankcases sit there with con rods hanging out of them, I said "I'll order one from Andover". Then, "I don't remember it being really tight" before. So, with adequate self-scolding about overthinking and trying to be too smart, I found a pair of small "L"-shaped bars in my toolbox (I think I'd used them 50 years ago on my Maico road racer clutch) and said "No levering on the timing case, no scratching anything up -- just see what an easy pull will do". So I hooked up, wishing I had three (to match the spacer plate behind it), and - just holding the bars in my hand, gave it a pull. Nothing. But I wasn't too disappointed, I didn't expect it to work. But in for a penny, I tried it again and low and behold, it moved about a 1/16" of an inch. After another self-lecture about getting too excited, I hooked the levers back under the pinion, gave it a slightly stouter pull and it slid off.

Considering Wolverhampton (Edit - apologies, if it's a P11 engine, they should be Plumstead, not that I have a lot of confidence that it makes a lot of difference) tolerances, I'm sure that not all of them will be that way, but -- my suggestion -- get something that will safely hook up and give it a try. HTH, BH.

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Good story. I can relate.

It wasn't real tight, but took some effort and I did have to enhance the puller design to get the thing behind the gear. The puller Andover sells appears to me like it was made in the far east, but not labeled for manufacturer. Same with the clutch operating body lock ring tool for the gearbox. Looks to me like all the shiny tools Andover is selling were made where the best price for manufacturing the tool was found. Can't fault them for that. The tools do work and it's a business.

The old man overthinking and looking for stuff I know I have somewhere is slowing the process. I miss being younger and having a memory for where I put tools down. Anywho, I should at least get the pistons on the rods and the barrels on by the weekend. I hope to be done in May at the rate I'm going.

Far as I got plus the BSA lifter stuff finished in the barrels. Tomorrow the jugs go on and I'll set up the cam. If I get lucky on the time maybe get around to doing the valve spring coil bind setup and get the head ready. Lots of this and that before putting the gearbox and motor back in. Head goes on after the motor is in the frame. Can't get the engine in the frame with the head on it according to the P11 manual. Also what I remember from doing this the last time I did it.

I fought like heck with the wrist pin clips until I got the that last one and figured out what I was doing wrong. That last one took about 2 minutes. I like the other style clip more though. I've never had one come loose.

Schwany said:

Far as I got plus the BSA lifter stuff finished in the barrels. Tomorrow the jugs go on and I'll set up the cam. If I get lucky on the time maybe get around to doing the valve spring coil bind setup and get the head ready. Lots of this and that before putting the gearbox and motor back in. Head goes on after the motor is in the frame. Can't get the engine in the frame with the head on it according to the P11 manual. Also what I remember from doing this the last time I did it.

I fought like heck with the wrist pin clips until I got the that last one and figured out what I was doing wrong. That last one took about 2 minutes. I like the other style clip more though. I've never had one come loose.

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This is a good build-up with pretty components! Did you get Jim's hard-coated wrist pins? What was the technique you used for the clips? (I'm a little behind you -- I'm still waiting for my billet crankshaft, never a delivery date promised but "I'm working on it so it should be soon". I have all my other parts so I think if I don't get the crank soon, I'll assemble with my stock crank and do all the tolerance and clearance checking then do a final bottom end with the new crankshaft and complete final assembly. I sure wish that I could do it all now but, hey, you're at the mercy of your suppliers.)

I agree with your comment about Jim's helpfulness through all the processes of getting a custom engine built up. He has been endlessly patient with me as I've been obtaining -- and waiting for -- components from other suppliers. If only the supplier of the crank would come through.

Oh, one other question, did you have to drill the lifter block as well as the cylinder lifter area? Are both tapped or just the cylinder? Thanks, BH

Blewdy Yaink said:

This is a good build-up with pretty components! Did you get Jim's hard-coated wrist pins? What was the technique you used for the clips? (I'm a little behind you -- I'm still waiting for my billet crankshaft, never a delivery date promised but "I'm working on it so it should be soon". I have all my other parts so I think if I don't get the crank soon, I'll assemble with my stock crank and do all the tolerance and clearance checking then do a final bottom end with the new crankshaft and complete final assembly. I sure wish that I could do it all now but, hey, you're at the mercy of your suppliers.)

I agree with your comment about Jim's helpfulness through all the processes of getting a custom engine built up. He has been endlessly patient with me as I've been obtaining -- and waiting for -- components from other suppliers. If only the supplier of the crank would come through.

Oh, one other question, did you have to drill the lifter block as well as the cylinder lifter area? Are both tapped or just the cylinder? Thanks, BH

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You asked, so here's the shade tree engineering babble:

I got all the JSM bits and pieces for the build. Yes on the slick wrist pins. They do slide in nicely. I should have done the pistons on a lower height table. I'm definitely going to drop the barrels on from a lower position where I have more control.

The wrist pin clips go on easy if you set one end of the clip in low and start pushing the clip in around at the top where a beveled edge is for just that purpose. I was doing it sort of backwards trying to start it all low and it was redamdickulous. Once I figured it out they went right in more or less compared to doing it wrong. I think Jim's engine build video shows how to do it the right way, but I was not paying enough attention when watching it.

You have to drill and thread the holes in the cylinder barrels. The barrel metal is not particularly hard, but it is brittle and not like anything I am that familiar with not being an engineer. It is sort of like drilling and tapping hard sand. Very granular and it gets stuck in the tap quickly. Lots of in and out with the tap compared with working with alloy. I have a tap snapped off in my rear fender loop. You really don't want to snap a tap off, because they can be impossible to get out due to how hard they are.

The lifter blocks only need to be drilled, and not threaded. I probably watched the part of the video where Jim talks about lifter block setup 10 times. At least 3 hours of over thinking with no progress occurred. I really did not want to get that wrong. I'm still a little worried that I set them too high. His paper instructions said between .040 - .060 and I set them about .049. The video said .050. Unfortunately, I did not account for the base gasket. I just hope I'm not over .070 when bolted up. Wouldn't want the lifters to drop past the bottom of the lifter blocks. Mock up did not show it as a problem, but who knows when I really get out there and goose it.

Note: Do not drill the lifter block more than 3/16" deep and do not over tighten the set screw. I over tightened the set screw on the side I over drilled by 1/32" and it pushed down enough on the lifter block to bind the lifter. I had to back off on the set screw.

Keep a good selection of cuss words handy. You may need them.

I like the idea of a new crank. I should have gotten my old crank rebalanced using Jim's numbers but will see how it goes. His marketing blurb says the crank does not need to be rebalanced to use his pistons and rods. I took that route. The pistons and rods show up with information on balancing. His marketing also says the parts are "drop in". Probably true if you build race motors all day long. Not so much for a guy that prefers to bolt stuff up. All this thinking is foreign. I thought I got away from thinking when I retired.

On another why am I doing this note: The cNw bolt kits are pretty, but you end up with a bunch of SAE nuts. This is supposed to be a benefit, but I don't see it exactly that way considering I have the right tools for tightening up the motor with the Whitworth nuts and no thin wall tools for SAE nuts. More time on the grinder messing up some tools.

The 3 cNw studs that go into the head are too long for my P11 barrels. The 3/8 inserts I have in my head are shallow. I had to cut .25" off the course thread end. Hope they all stay in there. I also don't have a clue how I am going to get the two 12 point 7/16" headed long cNw nuts on the front two studs out of the head without holding the head up. Never have liked those two studs and nuts.

I'm starting to remember why I put this rebuild it for no good reason stuff off for so long.

Couple of quick snaps of progress.

High rise flat tops. These pistons stand about +.057 above the deck. With a .021 base gasket and a .040 head gasket I still have .038 of squish band on paper. Once I get the head on, I'll check the valve clearance, but it's all looking good to me.

Should run on local premium pump gas with the mild TriSpark ignition curve.





The lump is getting a little heavy with those iron barrels on there.

Schwany said:

I like the idea of a new crank. I should have gotten my old crank rebalanced using Jim's numbers but will see how it goes. His marketing blurb says the crank does not need to be rebalanced to use his pistons and rods. I took that route.

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I strongly advise on getting the crank balanced, particularly when fitted in a P11 chassis. The rationale has been explained before.

- Knut

mdt-son said:

I strongly advise on getting the crank balanced, particularly when fitted in a P11 chassis. The rationale has been explained before.

- Knut

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Thanks for your concern.

I was expecting this comment. If you read everything in this thread, you might know that the crank was already lightened and balanced long ago by people that knew what they were doing. It's probably fine.

I've had this bike for 50 years. It's not typical or owned by somebody not familiar with the P11. I appreciate the thoughts, but I even know what I'm doing a lot of the time.

Schwany said:

His marketing blurb says the crank does not need to be rebalanced to use his pistons and rods. I took that route.

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It's up to you. Please note the "no need to rebalance" applies to the Commando only, because the calculated counter weights are approximately equal. That's when using the 63% dry vs. 65% dry BF. The Atlas engine had a higher BF originally - 84% (dry) - some prefer 70% only (dry) - and the counter weights when using JS parts do not match anymore.

Jim specifes 50 grams of oil in the crankshaft while Jim Comstock uses a figure of 2x75=150 grams. This will make a difference to the crankshaft counterweights as well. I wonder who is right?

Anyway, Jim advises builders of Atlas engines to check crankshafts for proper balance.

If I can find a genuine dished piston in my parts bin, I will make a comparison of the counter weights (stock vs. engine with JS parts). This is of interest to me as I plan to rebuild an engine similar to yours for my '66 N15CS.

- Knut

The crank has 62% scribed on it. It was done about 30 years ago. I have no idea what that number represents dry versus wet. I did not ask when it was done. I just said lighten it and balance it. I guess I'll find out if it works with Jim's parts. If it doesn't, lesson learned, and I get to do it all over again. However, I'll probably wait another year.

Schwany said:

On another why am I doing this note: The cNw bolt kits are pretty, but you end up with a bunch of SAE nuts. This is supposed to be a benefit, but I don't see it exactly that way considering I have the right tools for tightening up the motor with the Whitworth nuts and no thin wall tools for SAE nuts. More time on the grinder messing up some tools.

The 3 cNw studs that go into the head are too long for my P11 barrels. The 3/8 inserts I have in my head are shallow. I had to cut .25" off the course thread end. Hope they all stay in there. I also don't have a clue how I am going to get the two 12 point 7/16" headed long cNw nuts on the front two studs out of the head without holding the head up. Never have liked those two studs and nuts.

I'm starting to remember why I put this rebuild it for no good reason stuff off for so long.

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Nothing wrong at all with the cNw bolt kits. User error. The 3/8ths inserts in my head had an allen set screw down inside them to hold my old set of slightly short studs up. I thought the allen head was part of the insert. I pulled the set screws out after I cut the cNw studs for no good reason. The cNw 3/8ths studs would have been perfect if left alone. Now they are 1/4" shorter going into the head, but will still hold and work. All of it including using SAE nuts bolts and wrenches was much easier to deal with than I had anticipated. I can be a real idiot at times. You all knew that though. (Insert cuss words here)