P11 gets the JSM treatment

Schwany said:

Funny looking thing is all dressed up, sans foot pegs and shifter, and no place to go.

I won't be starting it. Although I must admit the urge is strong to do just do it. Unfortunately, a couple of days ago about 4 hours after torquing the head down I realized I screwed the engine build up. I got ahead of myself and forgot to safety wire those 4 damned screws for the lifter tabs. A check list might have been handy is an understatement. I went ahead with the bike assembly anyway because I had a few things I wanted to plumb around and rewire. The screws might hold with the little dab of locktite they got, but having them fall out would be a bad day, and possibly my last day on earth if leaned over in a favorite 80 mph sweeper when they fall onto the cam and jam up the works.

Anywho, going to have to pull the head and barrels and do that part of the build over again. Should not be a big deal. I'm just a bit disappointed that I didn't realize I had reached my level of incompetence earlier like when I was holding the barrels over the crank case and about to install them.

Not sure when I'll get around to tearing it down. I've got some catching up to do around the house.

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I like those pipes, where can I get a set? I have a trackmaster project and the pipes are the biggest hurdle to overcome.

Fast Eddie said:

Glen why not put inserts in so you can use the off the shelf wasted fasteners from cNw or JSM? They are a known quantity, the working out has already been done !

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I've got some grade 12.9 metric bolts here that I can machine into waisted bolts.
Grade 12.9 metric is a bit above Grade 8 SAE.
Going to give that a try before disassembly.
The maker of the cylinder likely used 10mm size for the additional thread strength vs 3/8". That part is good!

worntorn said:

I've got some grade 12.9 metric bolts here that I can machine into waisted bolts.
Grade 12.9 metric is a bit above Grade 8 SAE.
Going to give that a try before disassembly.
The maker of the cylinder likely used 10mm size for the additional thread strength vs 3/8". That part is good!

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Probably, the choice of thread pattern in an alloy cylinder is more important for strength versus the ~ .015" difference in diameter. Which has the coarser thread (or maybe specification for radial measurement of thread engagement)? Metric 10MM/Coarse, 3/8" UNC, or 3/8" BSW???

(This is more of a question than advice. I'd appreciate discussion. Thanks.)

seattle##gs said:

I like those pipes, where can I get a set? I have a trackmaster project and the pipes are the biggest hurdle to overcome.

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You can buy my bike and they're all yours.

It's a Bub Enterprises pipe built last century when he was building pipes in a small shop. Not sure if Bub Enterprises is still at it. I doubt they would do a one off these days if they were.

Most of the custom pipe builders are apparently exceedingly busy. I have yet to get a response from the two I tried getting in touch with via email last year. I did not try the phone though.

Schwany said:

Most of the custom pipe builders are apparently exceedingly busy. I have yet to get a response from the two I tried getting in touch with via email last year.

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I got response and promises, promises that were ultimately unfulfilled.

Farts!! Right hole sounds bad up top. Might have run out of squish on that side when fully heated up. Why only on the right side? Uneven excessive torque technique, or maybe it's a rod bearing? I could not hear it until I started letting the motor idle. Time to park it and forget about it for a while.

Also it did the same thing it did yesterday farted and spit when cold, then got a little better and would idle, but did not like small opening steady throttle and a blip. Anyway, even if I could address the spitting through the carburetion when cold, it sounds like it's considering breaking.

Good lesson in leaving things alone. By the way, not pissed about it. I'd thrown in the towel when I forgot to safety wire the little lifter guide screws. Forgetting too many small details is a good way to screw up anything.

Time for me to get off this site and do some gardening. Gardening I think I can handle.

Schwany said:

Farts!! Right hole sounds bad up top. Might have run out of squish on that side when fully heated up. Why only on the right side? Uneven excessive torque technique, or maybe it's a rod bearing? I could not hear it until I started letting the motor idle. Time to park it and forget about it for a while.

Also it did the same thing it did yesterday farted and spit when cold, then got a little better and would idle, but did not like small opening steady throttle and a blip. Anyway, even if I could address the spitting through the carburetion when cold, it sounds like it's considering breaking.

Good lesson in leaving things alone. By the way, not pissed about it. I'd thrown in the towel when I forgot to safety wire the little lifter guide screws. Forgetting too many small details is a good way to screw up anything.

Time for me to get off this site and do some gardening. Gardening I think I can handle.

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Well, damn. Good luck, Schwany. Take a break, forget about it for a while, and come back refreshed when you're ready. Best wishes, man, you're really close.

Blewdy Yaink said:

Well, damn. Good luck, Schwany. Take a break, forget about it for a while, and come back refreshed when you're ready. Best wishes, man, you're really close.

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I agree take a break and come back to it

worntorn said:

.Right now those 10mm bolts are stainless Allen head. I could make some waisted SS bolts or I could go the other way and try high tensile.
I'm not sure if the bolts are stretching too much or not enough!

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Glen,

I am sceptical to the usefulness of waisted head bolts, as they are rather short. Waisted bolts are beneficial for long bolts as the variation in elongation will drop. For short bolts the variation in elongation will be less affected.
However, bolt material is an important issue, and if you don't know origin of the bolts, try to get ARP bolts or another renowned brand. Don't use bolts off some obscure back yard business.

I seem to remember your 920 engine has a fairly high C.R. Recently I proposed use of spigotted cylinders, and I still think it may cure some leakage problems accuring with these hc motors.
BTW, check your head and cylinder decks for flatness.

- Knut

Yes, it is fairly high in CR.
Both sealing surfaces were milled flat before assembly.
I'm going to try the waisted bolts as they are easy to make.
The supplier is Fastenal, a large industrial supplier.

Glen

Schwany said:

Farts!! Right hole sounds bad up top. Might have run out of squish on that side when fully heated up. Why only on the right side? Uneven excessive torque technique, or maybe it's a rod bearing? I could not hear it until I started letting the motor idle.

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Not sure I understand. Do you suspect a valve clash? Plasticine test performed? Was your barrel bored prior to fitting new pistons?

- Knut

mdt-son said:

Not sure I understand. Do you suspect a valve clash? Plasticine test performed? Was your barrel bored prior to fitting new pistons?

- Knut

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Right you are Knut.

What I said did not make a lot of sense.

Fortunately I don't suspect anything anymore. Read on, or not.

Regarding your question: I torqued down the barrels over the pistons rods crank and crank cases and put the pistons at TDC. I used squish band remainder after subtracting how far the piston topped out at TDC would penetrate beyond the copper head gasket into the squish band to determine if everything would work when the motor was fully assembled. The head was on the bench. On paper all the numbers worked without squeezing plastic or clay. Yes the barrels were bored pistons fitted and rings checked for the proper gap. After complete assembly I also kicked the motor over many times before I ever fired it and nothing was clanging or banging. Very detached garage mechanic like. I also installed the cam straight up dot to dot and didn't screw around with the opening and closing valve/cam timing numbers.

I was tired and not in the right frame of mind when I wrote that previous post. I was done thinking about the motor. But being the hypocrite that I am and not walking away like I said I would, I took one more stab at it. How could I make so many mistakes? I said to myself.

I installed some older colder plugs I wanted to try, and performed a professional session of blank staring... Then fired it off and it was redamndiculously loud. I was confused, so started looking around the head a little more carefully. Also changed the timing a little. As it turns out the bad noise I heard previously was the right header starting to come loose and moving on every exhaust stroke. When I later started the engine and it was really loud, the header was barely hanging on and clanging and banging every time the right cylinder blew exhaust. I have a spigot style exhaust like old Triumphs and must not have tightened the right side header good enough for how much punch this motor is putting out. I banged the header back into position and tightened up the clamp. Fired it up and it sounded like a normal Norton engine albeit a lot quieter than my older build. I plan to lift the needles up one notch (dropping the clip one notch to position 3) to test for a bit of a soft spot off idle. I should be able to go back to my previous carburetor tune which was a shim under the clip at position 2. Won't know the particulars until I put a load on it out on the street. Can I tell the difference between a shimmed half clip position and a full clip position? I sure tell myself I can.

Anywho my previous post was a dumb and dumber moment and the loose header explains a lot about how the motor was responding to throttle.

I will cold start test tomorrow to see how it goes. I'm feeling positive about it. The old let off high rev exhaust note I like is back. Things are looking up.

Sure hope I don't get on here tomorrow and start whining again. That is even annoying to me.

Your not alone on this.
After working on income tax forms all day (wife's & mine) I wanted to do something interesting this evening.
I have fairly new a rule that says do not work on any motorcycle after 5 pm. I used to go out in the shop for hours after dinner and things generally went ok.
In the last couple of years several silly mistakes were made during this evening work and damage resulted.
So the evening is for sweeping the floor and not much else.
Breaking the rule today I decided to move the Vincent Special off the lift to run the 920 up there for a gander at the head leakage problem.
The Vincent is a light bike and is normally a treat to move around but it was balking a bit as the rear wheel hit the floor.
I gave a big shove and heard a metal crunching noise.
Then the light came on.
Years ago I made a wide rear mudguard for this bike. It's in 5052 which is a bitch to form, but is very resistant to cracking. The UK equivalent was called Birmabright. Land Rover bodies are made of this.
The mudguard is 8" wide for the 180 tire. Wide mudguards are very difficult to form, narrow are quite easy.
It took about 2 days to form and at least a day to polish.
I removed it a couple of years ago as the spindly lightweight mount I dreamt up was inadequate.
A couple of days ago I decided to figure out a new mount and placed the mudguard back on the tire , leaving it loose on there.
The crunch was the tire rolling over it on the concrete floor.
Some time spent with the English wheel and polishing equipment should fix it to about 99%
Good thing it is polished alloy rather than painted.
Nonetheless, a morning of frustrating work was created in just a couple of seconds of evening ineptitude.

Glen

We’ve all done it!

The ‘walk away and come back to it later’ thing has to be balanced in my opinion.

Sometimes it’s DEFINITELY the right thing to do. I have often downed tools for the night when fighting something (and losing) only to come back a day or two later and it’s easy, or that illusive solution now suddenly seems blindingly obvious!

But if left too long, it doesn’t seem to happen.

I think what’s really going on is the sub conscious mind is at work. And a small break allows it to come to the fore. But if left too long, the sub conscious mind forgets as well, then you’re just left with a big problem !!

That's true, a big gap in time makes it really difficult to pick up from the stopping point.
In this case I'll leave the 920 alone for a few days then get at it, daytime work only this time!

Glen

Well, fired it up cold and it farted a little and then started idling and taking throttle. No excessive noise to report.

I don't have enough fingers to count all the dumb assed stuff I have done. I thought it made me wiser and experienced. Sometimes it seems so, but for the most part it just gives me a very large compendium of mansplaining content, which drives my wife nuts.

Going for a very short non-violent ride. Checking plugs when I get back.

I do not have a YouTube account, so maybe none of this really happened. I'll see if my son has one, and maybe post a video one day.

Thanks for the support. Much appreciated.

Running well enough. Some carburetor tuning will be done, but nothing dramatic. I richened up the low speed fuel mixture and it started running a little better off idle with light throttle input. Still need to raise the needles and see what happens. Plugs look clean and the right color everywhere but they are used. Need some new plugs to verify what I see.

Rotating assembly balance does not seem to be an issue at low speed. I doubt I went over 40mph though. Stayed in 2nd gear most of the time. I have not been on the HWY with it to test 70-90mph or long drone cruising. Next week if weather holds. Overall I think the motor is a lot smoother. Could be placebo.

I like the cam. Mellow with a feeling of better torque than the 2S and some go when the throttle is twisted. I have not stayed on the gas WOT to see if it has a "now it's working" RPM range. Have not used WOT period on the street yet. Once I really let it rip I'll know if the lighter pistons and shorter stroke are a wild and crazy improvement.

Rebuilt the gearbox before doing the engine, since the machinist had the barrels. Gearbox works just like it did before I took it apart. However, it does not leak anymore.

Primary leaks. I think it is part of the P11 charm and DNA. Just going to top it off until I get around to doing something about it. Might put a N.E.B wet clutch in it when I open it up next time.

I guess it's louder. Kids heading home from school were covering their ears when I went past.

Schwany said:

Running well enough. Some carburetor tuning will be done, but nothing dramatic. I richened up the low speed fuel mixture and it started running a little better off idle with light throttle input. Still need to raise the needles and see what happens. Plugs look clean and the right color everywhere but they are used. Need some new plugs to verify what I see.

Rotating assembly balance does not seem to be an issue at low speed. I doubt I went over 40mph though. Stayed in 2nd gear most of the time. I have not been on the HWY with it to test 70-90mph or long drone cruising. Next week if weather holds. Overall I think the motor is a lot smoother. Could be placebo.

I like the cam. Mellow with a feeling of better torque than the 2S and some go when the throttle is twisted. I have not stayed on the gas WOT to see if it has a "now it's working" RPM range. Have not used WOT period on the street yet. Once I really let it rip I'll know if the lighter pistons and shorter stroke are a wild and crazy improvement.

Rebuilt the gearbox before doing the engine, since the machinist had the barrels. Gearbox works just like it did before I took it apart. However, it does not leak anymore.

Primary leaks. I think it is part of the P11 charm and DNA. Just going to top it off until I get around to doing something about it. Might put a N.E.B wet clutch in it when I open it up next time.

I guess it's louder. Kids heading home from school were covering their ears when I went past.

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The kids holding their ears is a recent thing
Years ago I would run with just the downpipes or a set of drag pipes and I never saw kids holding their ears
Nowadays I see it a lot and that's with stock peashooters and balanced downpipes
It must be the way they are taught to hate fossil burners I guess?

Schwany said:

Once I really let it rip I'll know if the lighter pistons and shorter stroke are a wild and crazy improvement.

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Have you changed the stroke?

Glen

worntorn said:

Have you changed the stroke?

Glen

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The rods are longer than stock and the wrist pin locations are moved up in the pistons. Is that a fake short stroke, or just a way to increase dwell time at the top of the stroke and reduce the violence of the piston changing direction from going up to going down in the bore?

Gotta make the answer simple for me. If it's overly technical I won't remember after five minutes passes. Seriously I've hit my head too many times off roading.