'66 N15 coming together

Well, it runs after a long delay. It is very strong. I'm just breaking it in with short rides, probably about 8 so far. It won't idle very well yet and is running rich, but hat's about it. The front disc is very strong with good feel, the gearbox shifts well, and it's charging with the new 3-phase alternator and Podtronics. My garage floor is even free of drips .... for now. Oh, the gearing is very tall and I like it. The clutch is heavy but progressive and working fine. I think they are the original plates, I just cleaned them up with solvent. The video is the 3rd start after firing it up in the garage with the help of some starting fluid.

Looks great and sounds good, Nice job! I'm currently building a G15.

My son, who found the bike, saved a screenshot of the Craigslist ad on his phone.

Hortons Norton said:

Looks great and sounds good, Nice job! I'm currently building a G15.

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If I can make one recommendation, it would be to get a front disc setup. I lucked out on getting a good caliper, fork lowers, and front wheel for $100 and got the aftermarket drilled rotor later. It needed a bit of tweaking with a file on the caliper to work, but the results are fantastic. I have a '22 XR650L and it's just as good as that bike, which stops quite well with a good feel. I was chirping the front doing hard stops from 40MPH today, and the pads are still bedding in.

gpzkat said:

If I can make one recommendation, it would be to get a front disc setup.

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Tom, the build looks good. Which type of master cylinder did you fit, and does it match the caliper area-wise?

Heat shield for the oil tank is/was still available with the club. I wonder why it's missing on a lot of G15/N15 bikes? Unlike the battery box cover, it's not prone to falling off. The latter benefits from an internal strap, preventing loss.

Do you plan to fit a bash plate?

The open space between oil tank and tool box becomes more apparent when not using twin carburetors and the stock wedged air filter. Fitting cover plates off the G12 may be considered. They help keep the bike clean and tidy.

What kind of filler cap / petrol tank did the bike come with? There were two types, the finger type (not sealing well), and the disc type bajonet design (sealing much better). My petrol tank (off a 1965/6 model) has the former design, but I plan brazing pins to the filler neck and fit the later type of winged cap. I believe all P11s had the later design, thus introduced by AMC for 1967 models. (BSA made a similar design change.) One of several unobtrusive improvements on the model.

- Knut

mdt-son said:

Tom, the build looks good. Which type of master cylinder did you fit, and does it match the caliper area-wise?

Heat shield for the oil tank is/was still available with the club. I wonder why it's missing on a lot of G15/N15 bikes? Unlike the battery box cover, it's not prone to falling off. The latter benefits from an internal strap, preventing loss.

Do you plan to fit a bash plate?

The open space between oil tank and tool box becomes more apparent when not using twin carburetors and the stock wedged air filter. Fitting cover plates off the G12 may be considered. They help keep the bike clean and tidy.

What kind of filler cap / petrol tank did the bike come with? There were two types, the finger type (not sealing well), and the disc type bajonet design (sealing much better). My petrol tank (off a 1965/6 model) has the former design, but I plan brazing pins to the filler neck and fit the later type of winged cap. I believe all P11s had the later design, thus introduced by AMC for 1967 models. (BSA made a similar design change.) One of several unobtrusive improvements on the model.

- Knut

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I have no idea about the oil tank shield, it's how I got it. It would cost too much to source and paint one. I can live with it. I am fine with the open space in carb area too, it looks simple and uncluttered. There was no cap, I got the winged/half-twist aluminum type from Walridge which pivots. I just have a cotter pin through the hole for now. The MC is from a Yamaha Vino 125 scooter. It is 12mm bore and works great but there is a bit too much gap in travel before the lever engages. I have a fix for that though. I don't plan to ride off-road and won't fit a bash plate.

On to carburetion. The bike pulls hard through the range but is sooting up the plugs and is sort of 'light switch' like at low RPM. I'm revvving it up and down through the range without caning it to break it in on short rides. A bit of black poof through exhaust but given the plugs that is explainable. Overall quite good.

It hasn't broken in yet and is tight still, so I don't expect it to idle, but I have got it to run half decent with some cable adjustments - the carb adjustments are pretty useless. I am surprised it runs as well as it does, I always expected the VM34 that came with the bike was a stopgap 'who knows' situation. I pulled it today to check the jet sizes as I lost track of my notes. It has a 290 main (!) and indistinguishable pilot and needle. I am looking at the JRC "POWER JET" PWK carbs and like the fact that they can bolt up to my manifold. Having a rubber spigot limits my room for a filter. I don't expect perfect plug-and-play but given the JRC is targeted to Brit twins I am hopeful that they supply something close and 'fiddle-able' without surgery. I have inquired directly with them as they sell a 34mm spigot type setup with manifold (which I don't need - I need a flange mount). I hope to hear back that they have a perfect flange mount setup in proper size for my basically stock N15CS!

I have done a lot of carb rebuilding and tuning on my Japanese 4-cylinder bikes including my GS1100 turbo, so I am up to the task, I just think this single carb should be easy. We'll see. My '66 Bonneville and '66 Hornet did fine on Amals, so there is that option too.

I got the Mikuni set up and it's idling well, the plugs look good, and it pulls well. Not sure I can ask for more, but I will. It had a 290 main and 45 pilot, really big. I put a 230 main and 30 pilot in. My 19 y/o son (who found the bike, and will inherit it) has a very good aptitude for riding, and took to it like a duck to water. I taught him the startup technique and he's able to kick it over first or 2nd try. I trailed him on a 20-minute ride and he said the front brake's very strong, and altogether it rides fine. It's in our DNA, I guess.

Somehow missed the story about the find. I like that $150 original price. Of course, now you have a small fortune in it. Lucky young man your son.

A single Mikuni carburetor on an old Brit bike is going to make your son very happy over the long run. He will get a lot of thumbs up from other motorcyclists with that beauty of a bike. Great conversation starter as well.

That flip fuel cap (same as the one on my N15 tank on my P11) might leak when braking hard if the tank is filled to the top. I fill mine level with the frame tunnel visible through the filler cap opening and ride kind of slow for the first few miles. If I fill it all the way up to an inch below the top, I end up cleaning some residual drying fuel off the tank at the next gas stop. Mine may not be 100% correct though. All it has in it is a rubber gasket that lays on the very top lip of the fuel filler opening.

Schwany said:

That flip fuel cap (same as the one on my N15 tank on my P11) might leak when braking hard if the tank is filled to the top.

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Pre-67 or post-67 filler cap? The later ones are of bayonet locking design, filler neck has two pins welded in. The design was adopted by BSA and AMC.

- Knut

mdt-son said:

Pre-67 or post-67 filler cap? The later ones are of bayonet locking design, filler neck has two pins welded in. The design was adopted by BSA and AMC.

- Knut

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Thanks Knut

Oops, My apology to all concerned.

I can see now that the fuel cap is not like mine. gpzkat's cap is raised in the center and alloy.

I knew about the two cap types but did not know about the dates. My tank doesn't have the pins in the filler neck, so pre-67 tank.

I bought a nice alloy cap that is the later bayonet type. I thought it was the same as what I had. That's when I learned about the two fuel cap types. I still have that nice cap somewhere.

My fuel cap is the crappy aftermarket chromed version as shown below. Almost useless, but reduces fuel odor while riding. Over time the once flat top has become concave from trying to tighten it down enough to prevent it from leaking with a full tank. Gave up on that.

Mine is serial number 119799. I was told it was a '66 but had no papers, just a bill of sale. It could be early '67. I registered it as a '66, and can now sort of say I have owned three '66 British bikes - a BSA Hornet, Triumph Bonneville, and this. I've owned Japanese, German, Italian and British bikes but never American. I need to round out all the major WWII powers. I could go for an XLCR on style but alas, not function.

I have been taking short rides, progressively longer, breaking it in. No smoke, no weird noises.

I'm sticking with the VM34 single Mikuni for now, as it works. I got it running with what I had, way too big of a main jet at 290, and no markings on the pilot. Bought a bunch of jets, and went to a 27.5 pilot and 230 main to start. It idled better (but also has been breaking in and that helps), but the mid-throttle transition brought stumbles. I put 35 pilot in and it is idling well after adjustment, and opening up the throttle hard through the range is fine. But.. a slight opening of the throttle in mid-range brings a stumble. That didn't happen with the original settings. I have been checking the float level carefully and also dropped the needle clip down (to enrichen it). I have a 159 P2 needle. Whether that's good or not, I don't know. But I'm close, and it's fun to ride. But that slight stumble has to go. Thankfully it's about a 15-minute job to make a change - vs the bank of 4 carbs on my other bikes that I'm used to.

It starts 1st or 2nd kick when cold with the enricherner lever pushed down. It's easy to kick for me or my son, but I'm heavy, he's young haha. Once warm, it's one kick every time. I changed fork fluid and the front end is great, like magic with good absorption and a super firm lever. I can chirp that front tire at any legal speed.

The gearbox (which I rebuilt) is not as slick as my old '66 Bonneville, which had easy short throws, but with firm action, it's not a problem. The clutch is really good, and all I did was clean up the original plates which had about 15K miles on them and sat for 50 years haha. I'm still bedding in the rear brake, as I don't use it so much. It is a blast to ride and sounds fantastic and seems to be healthy and holding its fluids inside.

I took a ride to Cook's corner, and through Live Oak Canyon and the surrounding area. Here's a pic, because people like pics....

Idling pretty well

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gpzkat said:

Idling pretty well

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That bike is superb
It's a credit to you mate ,I'd love to own that

I went for a nice 30-minute ride yesterday with my son (on his own bike) and it was fun, but I could tell it was running rich, and the right side lockring loosened up. The bike started surging and he said over the communicator "Hey it sounds like your exhaust is leaking". Kid has good ears. OK, so I smacked that lockring down when hot, put in a #30 pilot jet, lowered the needle clip one positon went for another 30-minute ride today. Wow. I was laughing inside my helmet, it idled, took any throttle input, pulled hard and the plugs look perfect after a high RPM chop. Now I'm OK letting him ride it. He has done neighborhood rides with me following and is fine on it. But as a dad I am sort of protective. Of the bike I mean.