G15 Questions

File under "For What It's Worth"

Bill, I have just arrived in California for a couple of weeks and have been doing a bit of work on my own G15, could you kindly answer a couple of questions for me regarding engine mounting?

The engine plates from this bike have the various spacers welded to the plates, so it is self-evident where each one goes, however having mounted the rear plates onto the crankcases and fitted the gearbox in situ, I note that the gap between the rear engine plates is 3 5/8" whereas the distance between the forged frame mount is 3 1/2", the right side mounting plate has a couple of thin washers welded to the inside of the plates, but are there 2 loose spacers that go in the gap on the left and how thick are they?

Regarding the front mounts, there is a hollow spacer that goes between the front engine mounts at the top where it goes into the frame lugs, is there an identical spacer for the bottom mounting?

Many thanks

Dave

dave M said:

Bill, I have just arrived in California for a couple of weeks and have been doing a bit of work on my own G15, could you kindly answer a couple of questions for me regarding engine mounting?

The engine plates from this bike have the various spacers welded to the plates, so it is self-evident where each one goes, however having mounted the rear plates onto the crankcases and fitted the gearbox in situ, I note that the gap between the rear engine plates is 3 5/8" whereas the distance between the forged frame mount is 3 1/2", the right side mounting plate has a couple of thin washers welded to the inside of the plates, but are there 2 loose spacers that go in the gap on the left and how thick are they?

Regarding the front mounts, there is a hollow spacer that goes between the front engine mounts at the top where it goes into the frame lugs, is there an identical spacer for the bottom mounting?

Many thanks

Dave

Click to expand...

Hi Dave,

I got my bike in pieces, so much of the way I assembled it was through trial-and-error. The rear engine plates on mine have washers about 1/8" thick welded on the right (timing) side, and the gap between the plates away from these welded washers is 3-5/8. The frame mount is 3-1/2", the same as the top mount on the transmission. On mine, I had a 1/8" spacer for the transmission which I fit between the mount and the plate on the right side (As I recall, no spacer was needed for the bottom tranny mount). There's a sort of J-shaped bracket that holds the front of the rear fender. I found it works best if held in place by one of the studs going through the frame into the rear plates. One of my studs was 1/8" longer than the other, I assume specifically for this purpose.

On the front mount, there is a middle spacer on both the top and bottom stud.

The center stand also has spacers - one in the center, through the coils of the spring, and one on the right, about 1/8". One end of the spring hooks around the cross-brace of the stand, and the other hooks into a hole in the right engine plate. There's a retention clip for the stand that screws to the base of the frame vertical section with two small screws, I think 2BA

For the long, square stud that runs through the frame, engine plates and footrests, there are 3 spacers. The center one is about 3-5/8, the left (primary) side is about 1/4" and the right side is about 3/8".

You need the footrests in place before you can mount the primary, and to install the outer primary, you have to drop the brake pedal as low as it will go, and slide the stator over the rotor with the primary cover almost vertical, then rotate down to horizontal as you slide it in around the footrest perch.

Thank you very much Bill, your measurements and spacers match what I have including gearbox mounting with top I/8th washer, I got mine as a rolling basket case with the engine and gearbox in the frame but not mounted.

Am I correct in assuming that the difference between the width of the rear frame mounting point and the gap between the plates from the thin washer, ie 3 5/8" minus 3 1/2 making 1/8th, needs two 1/8 loose spacers on the left engine plate? If this is the case I am surprised that they are not welded in place as the others are.

dave M said:

Thank you very much Bill, your measurements and spacers match what I have including gearbox mounting with top I/8th washer, I got mine as a rolling basket case with the engine and gearbox in the frame but not mounted.

Am I correct in assuming that the difference between the width of the rear frame mounting point and the gap between the plates from the thin washer, ie 3 5/8" minus 3 1/2 making 1/8th, needs two 1/8 loose spacers on the left engine plate? If this is the case I am surprised that they are not welded in place as the others are.

Click to expand...

Dave, I didn't have to add any washers between the engine plates, crank case and frame. The necessary spacers were pre-welded to the plates. This is the one instance where the G15 is easier than the P11. The only spacers needed were the 3 long sleeves (2 on the front mount between the plates at the top and bottom mounts, one on the stud running through the foot pegs) and three spacers (one on the right side of the upper transmission bolt and two on the footpeg stud between the rear engine plate and the frame, thinner on left and thicker on right). The only spacers I didn't have in the bits were the two outer ones for the long, square stud that runs through the pags.
This is how I got mine, so my assembly was very much a trial-and error fitment.

Sorry Bill, I'm not quite visualising this, Does your primary side engine plate also have spacers welded to the top two mounts where the plate buts up against the frame mount and if so how thick are they. As I said in my previous post, my Timing side rear plate has two 1/8" washers welded to the inside of the plate, but the primary side plate has no washers welded at the top although there are three thick spacers welded to the inside of the plate where it bolts to the crankcase. My problem is that I have a gap because of the difference in thickness between the frame top mounting position and the rear engine plates including the timing side washers. It looks like you measured this same gap in your earlier post ie, 3 1/2" frame lug versus 3 5/8" gap between the two plates including the washers. My assumption is that the assembly either has to but up against the frame lug on the right or left and would need a couple of additional washers of approximately 1/8" on the opposite to whichever side is butted up to the frame. Thanks very much for your patience, I am only here for a short while and if I can solve this problem I am a lot further forward than I was last week.

Dave, the way I see it, the rear of the crankcase where the plates mount is about 3-1/2" wide, as is the top mount on the transmission and the frame lug. The primary side plate has spacers welded to the front holes to shift the engine toward the timing side. The timing side plate has the same thickness spacer welded to the rear holes to match up with the front. Then, you've got the steel spacer between the crank case and the primary to bring it back in line with the transmission. The trans is shimmed tight to the primary side.

The 3-5/8 I measured the other day is between the plates, not between the spacers.

This frame was designed for this transmission, so no shimming of the trans should be needed on the primary side. The engine, on the other hand, was not designed to fit in this frame, and for whatever reason, the engine plates were shimmed to shift the motor a bit to the timing side. Are you sure the plates are flat, and you've got the front plates on the right way? I think the front plates only go on one way, but I kept careful note of which was which anyway. The frame lugs on the front could also have been modified to work better with the Norton motor - I know that was done on the P11 - so I don't think you can draw any conclusions as to spacer location on the front.

Bill, I would agree with you except the rear engine plates I have consist of a left (primary side) plate with three approx 5/16" washers welded to the bottom where it mounts to the crankcase and none on top where it mounts to the frame and a right (timing side) plate with no washers where it mounts to the crankcase but a single 1/8 washer for the bottom gearbox mount and two 1/8" washers at the top where it mounts to the frame. The gearbox adjuster has a loose 1/8" washer to allow for adjustment.

The front and rear of the crankcase mounting lugs are 3 5/16" and the gearbox is about 3 1/2" wide, with these plates the gearbox fits perfectly when the plates are bolted to the crankcase, but there is still about a 1/8" discrepancy between the width of my plates and the frame engine mount. I have another set of engine plates that I bought on E-bay and they are identical and I have been up to Rabers Parts Mart in San Jose this morning and they have a pair which are also identical to what I have. You don't by any chance have an extra mudguard bracket holder or something at the frame lug thus widening it by 1/8" do you?

Dave, I'm sorry I didn't measure everything before I re-assembled. As I stated before, the engine, trans and primary were still all bolted together and with the engine plates on when I got the bike. The head and cylinder were removed to facilitate getting the entire lower assembly out of the frame. I found out during the strip-down that this was probably done because the previous owner couldn't get the primary open (primary had half-filled with water at some point and corrosion fused the screws until the water ate through the case at some point, allowing it to empty).

Yes, my rear plate on the timing side also has the welded spacer at the bottom trans mount. The one bracket that holds the lower front of the rear mudguard is fixed on the outside of the rear plate with one of the studs the goes through the frame lug. Do you have the engine plate cover (030328), that snaps over the top of the rear engine plates? it has a pair of dimples that lock into the little hole on each plate above the upper trans bolt. This piece is a tight fit, and will tell you if you're missing a shim somewhere.

Mine this evening - too late to start it up, but will be running tomorrow if everything's right or close to it

Bill, the problem is solved, the right hand plate had a slight set in it, I removed it and checked it on a flat surface and noted it bent outwards slightly towards the rear mount, having straightened it and bolted it all back together tightly I now have the requisite gap for a perfect fit to the rear of the frame, many thanks for your patience and answering all of my questions. I have already made good progress on this trip and have dropped my cylinder head off at Rabers today for some fins to be welded back on and new valve guides. Thanks again,
Dave

Bill,

After viewing the picture of the primary, I can see why Clive said it was too far gone and you needed a primary. Wow! I'm really impressed with the result. Good to see you at Barber. Hope to see you soon, maybe at Wes'

Thanks for the help, James - you made my weekend!

Now that the bike is essentially done, I posted up a build thread. Learned a lot about this series, and will gladly share what I learned.

Does anyone know where I can get the front fuel tank mounts? i don't even know what they look like as my tank has empty tubes, I assume it is some kind of rubber plug with a thread bonded in, a bit like a long thin exhaust mounting.

AMC Classic Spares, Steven Surbey definitely has the mounts you require.
Telephone: (+44) 01462 811770

Fax: (+44) 01462 851035

spares@amcclassicspares.com

Regards, Paul.

Hi Dave,

The front fixing assembly is available from AMC Classic Spares. There are 5 or 6 pieces for each tube - a rubber disc goes in first, then a 3/8 CEI bolt with special thin head, then the rubber sleeve, which sticks out of the tube about 1/2-3/4 inch, then either one or two washers to sandwich the frame bracket, then a 3/8 CEI nut. I think you would want the kit 027161C, 2 required, which is for '61-on Competition models. As you tighten the nut, the bolt compresses the sleeve, which locks into the tube holding the tank firmly in place. The back is held by the same rubber ring found on Atlas tanks, and a Commando rubber works, too, if you cross the rubber to the opposite buttons. You need a rubber pad on the tank at the back of the tank spine, and again a Commando pad works fine. You don't need anything at the front of the spine, as the rubber sleeves hold the tank above the frame tube.

As I've stated elsewhere on this forum, I've found Mike at Walridge to be a great source for hybrid items, but Steve at AMC Classic Spares is the best source for those items that are unique to AJS/Matchless machines, especially this nut-and-bolt stuff.

Paul answered you while I was writing my rather long-winded reply. I know he's a regular customer of Steve, also :wink:

Thanks Paul and Bill, it is so handy to have others with firsthand G15 knowledge on the forum as my own project continues on at the rather slow pace dictated by living over 6,000 miles from where the bike is actually located!

As I have a few days off for our Thanksgiving holiday, I spent yesterday with the bikes, tweaking and such. Rode the G15 another 20 miles or so, working out the kinks (up to 50 miles now). Bike is settling in, but is still running a bit hot. I may change the drive sprocket, too. 17 teeth just feels a bit too buzzy. The 19 tooth sprocket of the Ranger seems a better size for a bike like this.

I'm going to try to get the bike into the Boca Concours, so need pictures for the application. Rode each hybrid over to a local park and snapped some pics in the afternoon. These are the ones for the G15:





Pics are a little clipped, I guess due to the size of the file. Ranger pics are posted up on the P11 thread

Update on the G15CS

The bike sat for pretty much all of December and part of January, due to work being somewhat chaotic the past several months. Got it up on the table around the 10th of January to address a number of issues

- I didn't like the 17 tooth sprocket the bike came with
- the primary had an annoying leak - went through three gaskets trying to seal it
- I wanted to re-time it with a degree wheel, still running hot and perhaps I was a bit retarded (in my timing, not my mind)
- time to retorque everything and check valve lash

I picked up a really nice-looking 19 tooth sprocket at Wes' shop and tore into the bike. With the primary off, I re-checked the timing. I was 9 degrees retarded, which would help explain less-than-crisp revving and hot running. With the new sprocket, I found my chain one link too short. Ordered a cranked link while doing the rest of the stuff. After two tries, got the primary to 'practically' stop leaking. It is shaking out pretty well, and I've started running on longer rides (1/2 to 1 hour). Got the bike cleaned up and brought it to the Dania show last week.

It took second in its class - English 'Other' 1960-up. Due to the number of Triumphs and Nortons, they were in their own classes, but there were probably 25 bikes in the 'other' class, including Royal Enfield, AJS, BSA, Velocette, Ariel.

The Ranger won in the Norton class, with my Commando coming in a surprising 3rd behind a '39 16H.

Both the G15 and Ranger were invited to the Boca Raton Concours d'Elegance in 3 weeks

Bill, I am back in California and making good progress on my bike, I wanted to ask a couple of questions:

What does the front lower hole in the toolbox inner shell mount to? I have found that there is a hole in the top and one at the back that mounts to corresponding points on the frame, but it looks like the lower hole must mount to a bracket that would in turn be bolted somewhere on the frame.

The inner primary cover has three holes in close proximity to each other, one is for mounting the case to the engine/gearbox plate, the other is for the alternator wires to exit the case and the 3rd I cannot see a function, although I am inclined to seal this up to prevent primary oil going everywhere.

Thank you.

dave M said:

Bill, I am back in California and making good progress on my bike, I wanted to ask a couple of questions:

What does the front lower hole in the toolbox inner shell mount to? I have found that there is a hole in the top and one at the back that mounts to corresponding points on the frame, but it looks like the lower hole must mount to a bracket that would in turn be bolted somewhere on the frame.

The inner primary cover has three holes in close proximity to each other, one is for mounting the case to the engine/gearbox plate, the other is for the alternator wires to exit the case and the 3rd I cannot see a function, although I am inclined to seal this up to prevent primary oil going everywhere.

Thank you.

Click to expand...

Hi Dave,

That bottom hole in the toolbox mounts to a tab on the battery tray. Look at the tray, and you should see a bracket on the front edge that comes down about an inch and a half - that should line up with that hole. Mine is a late G15, and this tab is welded to the tray. Yours may be different, and it may be a bolt-on 'L' bracket.

The third hole is a breather for the primary. I fit a breather pipe I had leftover from a battery, and fit a plastic elbow on the inside to make a sort of trap. If you look at the primary case, you'll see that there's actually an eyebrow over that hole to keep oil from splashing out as it falls off the primary chain.