more P-11 stuff

Yesterday we got a P-11 running again after decades of non running. It still has the low compression pistons. I have never worked with the low compression befor so I have questions.
TIMING...what is the timing? degrees please, not fractions of an inch. Any idea of the carb specs for 30mm Amals concentrics? It came with #3 slides, seems to run better with 3.5. Needle position? This weekend the owner is going to put some miles on it on some dirt roads. Has any one here run a single amal on a P-11? Who's got the manifold?

Most of what you want to know is in the Red Maintenance and Instruction manual for the scramblers. The owner should get that book for future reference.

32 degrees fully advanced. 32 degrees works with a 7.5:1 compression ratio using the dished pistons. Well, it did 50 years ago.
Setting the timing is described in the Red book.

Carburetion: Stock as delivered jetting is basically same as a Commando 750 with two Amals on it
Main jet with air cleaner 250
Main jet without air cleaner 270
Pilot 25
Slide #3
Needle jet .107
Needle position center notch

If the owner wants a single carburetor, a Mikuni single setup would be better than an 30mm Amal. Might be difficult to find an OEM Norton single intake manifold for an Amal.

The stock intake manifolds are very short and in my experience with the P11 the old carburetors didn't work long due to not being able to deal with the heat. Slides did stick on more than several occasions due to spirited riding. I think they even stuck after I got the slides re-sleeved. Premiers might be better, but I've never tried them since they did not exist at the time. I switched to twin Mikuni carburetion long ago. I now run the engine with Keihin FCRs. TMI

I agree about using the single Mikuni...heave the Amals into the trash.
I was looking at the steep angle of the carbs and the short manifolds...both spell trouble. I recommended the mikuni set up, I hope he goes for it. Currently it is timed about 25 degrees. We ran out of time for adjusting the timing.
So you ran twin Mikunis. They must have used the turn-out manifolds. #30mm? Did the turn out manifolds cause any problems?

seattle##gs said:

Yesterday we got a P-11 running again after decades of non running. It still has the low compression pistons. I have never worked with the low compression befor so I have questions.
TIMING...what is the timing? degrees please, not fractions of an inch. Any idea of the carb specs for 30mm Amals concentrics? It came with #3 slides, seems to run better with 3.5. Needle position? This weekend the owner is going to put some miles on it on some dirt roads. Has any one here run a single amal on a P-11? Who's got the manifold?

Click to expand...

According to Amal:
MJ 250
NJ 107
Needle Slot Middle
Slide 3

This thread makes me ask myself yet again about the angle of the stock concentrics on an Atlas. Bike came to me with monoblocks but I changed over to early 30mm concentrics as it wouldn't idle on the side stand with monoblocks. Same angle as on a P11. There isn't room for commando manifolds and that would be too much of an angle change anyway. I do have the phenolic heat insulators but it's still hard to start after heat soak in hot weather when I am also soaked w/sweat. It runs fine in all conditions so long as I remember to put gas in it (no trip meter).

Commando head -- 9:1 pistons.
Stock Atlas cam IIRC
#3-1/2 slides (sleeved),
Center notch on needles
0.106 Needle jet (used)
#20 external pilot jets
#240 mains, altitude is 2500'
Factory Atlas mufflers with hole cut in each baffle.
Factory oiled gauze air filter

New pipes are not discolored on first trip; last Sunday's chilly 60 mi. trip up to the snowline and back. Ignition timed per the book for Atlas at whatever inches BTC. (where would I put a degree wheel without pulling the timing cover?) Analog Boyer ignition.

Non-ethanol 92 octane gas out of pump on Sunday but unknown freshness. Seemed slightly down on power after fill up compared to what I had in storage from early last fall with Stabil added.

One one Atlas I took the alu spacer and machined off enough material to make the carbs sit level and still use the Amals. It doesn't look as racy but much more practical.
On the P-11 there was a lot to do and limited time so I did not inspect the carbs other than to see what slide it had, #3. It ran on the bench so-so and ran better with the 3.5 slide. Needle on center notch. Stock pressed in pilot. It started up fairly easily after a little tweaking. A curious thing...Normally I set the slide at .040 measured at the motor side of the carb. This usually gives a slightly high idle which I adjust down. With this motor I am much higher than .040. No idea why except for being 5 degrees retarded and low compression pistons.

Here's another oddball thing. (different P-11) Commando pistons this time. The valve stem rises quite aways beyond the valve collar, I assume this is commando valves. I backed the valve adjusters way off. When I put the head on it dropped right down the cylinder all the way around. This is a first for me, usually it is held off by spring pressure on one valve or two. My first thought is that I had got the wrong pushrods so I found a longer set and tried them. Same thing. Head met cylinder all the way around. I did the usual turning over of the motor slowly and set valve clearances. The adjusters are long on the valve side. It turns over well and looks like it will work but I've never had a head go all the way down to the cylinders before.

seattle##gs said:

I agree about using the single Mikuni...heave the Amals into the trash.
I was looking at the steep angle of the carbs and the short manifolds...both spell trouble. I recommended the mikuni set up, I hope he goes for it. Currently it is timed about 25 degrees. We ran out of time for adjusting the timing.
So you ran twin Mikunis. They must have used the turn-out manifolds. #30mm? Did the turn out manifolds cause any problems?

Click to expand...

My manifolds don't turn out as far as they do on a Commando. Didn't give me any problems.

I bought the MAP Cycle 34mm twin Mikuni carburetor kit for Commandos in the late 80's and modified the intake manifolds to get the carburetors to sit horizontally spigot mounted with 1.5" automotive fuel filler hose. The manifolds are blended from 34mm to 31mm for the mildly ported head I am still using today. All done with hack saw, Dremel, and files. Works great. Only reason I put the Keihin carburetors on is because the P11 is the last motorcycle in my garage and I felt like playing around with it some more.

I still have that Mikuni setup if your customer wants something unique on his P11 that works. In addition to those cone filters, I have velocity stacks for the Mikuni carburetors.



Static timing is not difficult with one of these and a TriSpark ignition:

seattle##gs said:

One one Atlas I took the alu spacer and machined off enough material to make the carbs sit level and still use the Amals. It doesn't look as racy but much more practical.
On the P-11 there was a lot to do and limited time so I did not inspect the carbs other than to see what slide it had, #3. It ran on the bench so-so and ran better with the 3.5 slide. Needle on center notch. Stock pressed in pilot. It started up fairly easily after a little tweaking. A curious thing...Normally I set the slide at .040 measured at the motor side of the carb. This usually gives a slightly high idle which I adjust down. With this motor I am much higher than .040. No idea why except for being 5 degrees retarded and low compression pistons.

Here's another oddball thing. (different P-11) Commando pistons this time. The valve stem rises quite aways beyond the valve collar, I assume this is commando valves. I backed the valve adjusters way off. When I put the head on it dropped right down the cylinder all the way around. This is a first for me, usually it is held off by spring pressure on one valve or two. My first thought is that I had got the wrong pushrods so I found a longer set and tried them. Same thing. Head met cylinder all the way around. I did the usual turning over of the motor slowly and set valve clearances. The adjusters are long on the valve side. It turns over well and looks like it will work but I've never had a head go all the way down to the cylinders before.

Click to expand...

25 degrees advance would make the engine idle lower than 32 degrees with the same lift on the slide settings. It wouldn't kick back starting it up though.

Not sure about the head dropping all the way down on the cylinder's thing. Tappets could be ground unusually short or the push rods are not seated in the rockers or tappet pockets (unlikely), or you have a magic touch and can get the cam in just the right position to let the head drop down. Not sure if that cam in the right position magic is possible either. If I worked on as many bikes as you do, I'd be having nightmares about issues in my sleep.

Thanks for the offer but he wants a single Mikuni.
P-11 #2 fired up in two kicks last night. A few more hours and it is ready for the customer

Thomasa said:

This thread makes me ask myself yet again about the angle of the stock concentrics on an Atlas. Bike came to me with monoblocks but I changed over to early 30mm concentrics as it wouldn't idle on the side stand with monoblocks. Same angle as on a P11. There isn't room for commando manifolds and that would be too much of an angle change anyway. I do have the phenolic heat insulators but it's still hard to start after heat soak in hot weather when I am also soaked w/sweat. It runs fine in all conditions so long as I remember to put gas in it (no trip meter).

Commando head -- 9:1 pistons.
Stock Atlas cam IIRC
#3-1/2 slides (sleeved),
Center notch on needles
0.106 Needle jet (used)
#20 external pilot jets
#240 mains, altitude is 2500'
Factory Atlas mufflers with hole cut in each baffle.
Factory oiled gauze air filter

New pipes are not discolored on first trip; last Sunday's chilly 60 mi. trip up to the snowline and back. Ignition timed per the book for Atlas at whatever inches BTC. (where would I put a degree wheel without pulling the timing cover?) Analog Boyer ignition.

Non-ethanol 92 octane gas out of pump on Sunday but unknown freshness. Seemed slightly down on power after fill up compared to what I had in storage from early last fall with Stabil added.

Click to expand...

There is some poor fuel being sold out there in WA. Got some junk fuel in Marblemount and in Winthrop. I don't search for non-ethanol fuel though. I use premium pump gas with octane booster I carry with me. There is non-ethanol fuel less than a quarter mile from my house, but it is 89 octane and noticeably weaker performing fuel. Also $1 more per gallon.

I static time the P11. Did it with a degree wheel during an engine rebuild and made marks on the rod in the tools I posted a pic of in post #7 in this thread. Now I just screw that tool into the spark plug hole and slide the rod in after the pistons are at TDC and back the crank up with the rear wheel until the upper line marked on the rod is flush with the top of the tool and the light on my TriSpark ignition lights up. Close enough and easy. Never strobe it.

I don't use the P11 spec of 32 degrees BTDC though. I'm at about 29-29.5 degrees BTDC.

Schwany, would that 89 octane fuel come from Spirit?

I used to haul gasoline; from Harbor Island usually or sometimes Anacortes and often Tacoma. I began mixing ethanol in Tacoma about 2008. I had to calculate ten percent and load the 90% and move over the the ethanol rack for the other 10%. What a pain. I don't know where the mixing gets done these days but it seems that non-ethanol has one less chance for error. However....

There are variable number of steps in the distribution of gasoline. Sometimes it is hauled from the Loading Rack like Harbor Island directly to the station. But particularly in rural areas it often goes to a regional jobber's bulk plant and it stored there for local demand. In the case of non-ethanol, there is less demand too. Often it comes from a local bulk plant where it's been sitting and then goes to a low-volume station where it sits some more. There is a bulk plant in Wenatchee, Twisp, Tonasket, used to be one in Chelan, two in Wenatchee, one in Cashmere. Anywhere there's orchards of other ag there will be a bulk plant.

I used to haul into the Methow Valley to Twisp. Most often to a retailer and less often to the Pacific Pride bulk plant. I haven't seen a tanker in Mazama but I ask the drivers in Twisp where they get the fuel when I see them. Sometimes they say Spokane and sometimes Seattle. One time it was Moses Lake where there is a loading rack. Marblemount is the end of the line for tankers coming from the west and that comes out of Anacortes or sometimes Cherry Point north of Bellingham.

I'm sure this is more than anyone wanted to know about gasoline distribution but for those who are making the Cascade Scenic Loop this summer it might be useful information. It's 70 miles from Marblemount to Mazama and another 13 to Winthrop where there is also non ethanol gas. Coming the other way there is Non-ethanol in Carlton but they are very low volume. Twisp Pac Pride has non-ethanol but i don't know if they will sell to the general public, though I've bought off-road dyed diesel retail from them when somebody's there.

I haven't paid attention coming round from the west over I-90 or US2. But all the stations on those routes are high enough volume to get fuel from Harbor Is. (Seattle) or Renton or Tacoma or Anacortes directly so it's likely fresh. Safeway in Cle Elum takes several tankers a day. Costco South Center takes one after the other all day long, hauling off Harbor Island. Sometimes I had to wait till the tanker ahead was done before I could dump. Then the next tanker would pull up behind me just before I was finished. It takes about 45 minutes for 11,500 gallons of a single product to dump. Mixed loads are faster. One time I got held up at the rack and held up in traffic and was an hour late to Safeway and they were out of regular unleaded when I got there. Then the next tanker showed up about 15 minutes later and had to wait.

Schwany said:

25 degrees advance would make the engine idle lower than 32 degrees with the same lift on the slide settings. It wouldn't kick back starting it up though.

Not sure about the head dropping all the way down on the cylinder's thing. Tappets could be ground unusually short or the push rods are not seated in the rockers or tappet pockets (unlikely), or you have a magic touch and can get the cam in just the right position to let the head drop down. Not sure if that cam in the right position magic is possible either. If I worked on as many bikes as you do, I'd be having nightmares about issues in my sleep.

Click to expand...

I do not have the magic touch. I don't know what happened but it runs well. this set up has 3 different lengths of valve stem above the collar but I used a lash cap on the shortest one. Very confusing stuff.

FWIW Atlas pushrods are shorter than Commando ones. Perhaps the valve stems are longer too. I don't have any valves to compare at the moment but I do have a new set of what I believe Atlas pushrods. I'll check the part number if you're interested.

I tried both Atlas and Commando pushrods in this motor and was coming up with the same readings...very confusing. My installation method changed with this bike....my goal was to make certain that the pushrods had located in the lifters. They almost always do but occasionally one doesn't and that can result in a bent valve and MUCH aggravation. So I made two wooden blocks about an inch thick to place under the head so I can get my fingers in and fumble with the pushrods. I dabbed some grease on the pushrod tip so it would stick in the lifter. Being careful I can feel the pushrod and lifter engage then I can drop the head down. I backed off the valve adjusters as far as possible. It worked this time.
Let me know what you want for the Atlas pushrods. I have plenty of commando pushrods.

As it turns out they are 06-7940 and 41 for commando.