JAPton blog

[mangocrazy]

It looks like you have what are known as 'full complement' needle roller bearings as opposed to the far more common caged needle rollers. The early RSV Mille/Falco/Tuono had the same type of bearings (Torrington HK1812V) in the swingarm linkages and it was a common mistake for people to over-pack the races with needles. There needs to be almost space for another roller when populating the bearing. If you squeeze another one in they will fail early doors...

[Rockburner]

It looks like you have what are known as 'full complement' needle roller bearings as opposed to the far more common caged needle rollers. The early RSV Mille/Falco/Tuono had the same type of bearings (Torrington HK1812V) in the swingarm linkages and it was a common mistake for people to over-pack the races with needles. There needs to be almost space for another roller when populating the bearing. If you squeeze another one in they will fail early doors...

That's what confused me - all 4 bearing liners DID have the gap when fully loaded with all the pins. I haven't tried to take measurements of diameters or anything to see what the differences might be.

It's quite possible that they're just slightly different (at least each bearing on a specific rocker arm has the same number of pins. Otherwise I'd be REALLY worried that there's a pin rattling about in the timing chest..... )

[mangocrazy]

If there's a gap roughly equivalent to one roller in each race, then I'd say you're good to go. I take it you're aware of the trick to defying gravity when inserting the rollers into the race? It's called grease, thick stuff and lots of it...

[Lutin]

This is not immediately helpful but might bear fruit later on.

I know that people don't appear to buy or read magazines anymore, but Classic Bike Magazine's Rick Partington seems to have an incredibly extensive knowledge of vintage machines. You could contact him through the magazine or even via his own website - https://rickparkington.co.uk/. You never know you might be able to gain his interest enough for it to be material for the mag.

I have no connection to the man but have enjoyed his exploits and articles in Classic Bike.

[Rockburner]

This is not immediately helpful but might bear fruit later on.

I know that people don't appear to buy or read magazines anymore, but Classic Bike Magazine's Rick Partington seems to have an incredibly extensive knowledge of vintage machines. You could contact him through the magazine or even via his own website - https://rickparkington.co.uk/. You never know you might be able to gain his interest enough for it to be material for the mag.

I have no connection to the man but have enjoyed his exploits and articles in Classic Bike.

Worth a try.

The bike has been in print already, "The Classic Motorcycle", Feb 2003. It's where I've got some of my information about the bike from! (Cos Dad never wrote anything down!)

[Rockburner]

Pulled a few more bits off tonight.

When you think you have a large spanner....


But you still end up needing something larger!


That nut came undone far more easily then I was expecting, but the threads cleaned up nicely. The exhaust is nicely patinated with spilt Castrol R, so I'm not going to polish it, just clean it up.

Next job is either to get the head off, or pull the engine out of the bike, just not sure which to do first.

[Skub]

Good thread RB. Sadly I've nothing of practical use to offer.

[ZRX61]

But you still end up needing something larger!

That's exactly how I pulled the exhaust on my Hagon/JAP 500 grass tracker.

[Rockburner]

Sooo.. pulled the head off this evening.









This was most of the oil that had overflowed into the fins on the head.






These scores look nasty, but tbh, I think they're actually just superficial.


So i thought I'd pull the barrel as well.


Nice polished con rod there...


Nasty lump taken out of the barrel skirt though.
Funnily enough, I have the oddest feeling I've seen this before... Maybe in a photo or something. I need to see if there's any photos of this in the paperwork I have.




Next job is to fit a plug, or bolt into the head, then fill it with water to check the valve seals.

Oh, and see if that barrel is useable....

[Rockburner]

Oh yeah - I took a quick video of the movement on the big-end.



Not the steadiest of shots I'll admit - but hopefully you can see the movement left to right of the conrod.

This seems a lot to me..... but is it a lot for a an engine designed in the 1930s?

[Lutin]

Wow, those are some impressive valve cut-outs in the piston top and domed as well!

What's the clearance between valves and the top of the piston if the cut-outs are shaped like that?

[Rockburner]

Wow, those are some impressive valve cut-outs in the piston top and domed as well!

What's the clearance between valves and the top of the piston if the cut-outs are shaped like that?

a lot.

I've no idea, but I'm guessing the piston is a fancy race item (and the conrod), but the crank is 350, and the rest of the engine is a 500cc - so the compression ratio is roughly 9:1 - not huge (racing engines, running dope as they were designed, run at over 13:1 )

See the amount of carbon deposit on the barrel - the piston isn't travelling anything like as far as it could.

[Count Steer]

Q? When this Heinz 57 Varieties bike was fettled and running well etc was it actually any good RB? Did it win races? Struggling to see a consistent design in it all. It looks a bit more 'Frankenstein' with each post! (Stick assorted bits together, slap a bolt through the lot and wait for lightning to strike ).

[Rockburner]

Q? When this Heinz 57 Varieties bike was fettled and running well etc was it actually any good RB? Did it win races? Struggling to see a consistent design in it all. It looks a bit more 'Frankenstein' with each post! (Stick assorted bits together, slap a bolt through the lot and wait for lightning to strike ).

Errr no, although it's been built as a race-bike, it's not really anything more than a product of my Dad's 50 year fever dream since he saw something similar on the circuits in the 1950s.

It's utterly unique, and was built up by him over about 30 years from found parts.

It HAS run well in the past, so it "works", but it's only ever been a road bike special.

[Lutin]

See the amount of carbon deposit on the barrel - the piston isn't travelling anything like as far as it could.

Ah, I see what you mean about the carbon deposits. I'm sure there were an almost infinite number of configurations for those engines.

[Rockburner]

Concerning this damage to the barrel skirt.....

I've chatted to one or two mates of my Dad today, and although no-one remembers anything about this.... we sort of agree that:

a) IF this damage had happened during the current "build" of the engine... then that damage would be apparent elsewhere: ie, the conrod would be dis-attached to the piston and in several pieces itself: it's not. and;

b) Using this barrel would be exactly the sort of thing my Dad would do, if he considered that the piston is unlikely to be affected and the barrel wasn't going to start cracking up any further.

I've got a boroscope (ish) somewhere around, so I'll have a poke around in the cases, but I think that the barrel will be useable, and the damage was from a previous useage: ie some racer (possible a Formula 500 car) blew the engine, caused the damage, but then discarded the barrel to scrap/sale. The damage is likely 50 years old.....


any road - next jobs are to continue stripping the engine, and figuring out how the hell to mount the timing disc onto the drive-side of the crankshaft so I can attempt to check the timing on the thing. I also want to get the drive sprocket off - but can't figure out how to lock the crank in one position (tbh - I'm not even sure if the drive-sprocket nut is right- or left-hand threaded....)

[Rockburner]

See the amount of carbon deposit on the barrel - the piston isn't travelling anything like as far as it could.

Ah, I see what you mean about the carbon deposits. I'm sure there were an almost infinite number of configurations for those engines.

Speaking about those... what's the best way to get rid??

I can probably dig up a honing tool from somewhere, but wouldn't mind cleaning up that shite. (similarly, the head & valves are covered in it)

[Rockburner]

I figured out how to get the nut off the engine sprocket...





The jaws on this clamp fitted into the sprocket carrier splines perfectly.


The nut came off with a LOT of torque required... because the fucker was loc-tited.

Tidied up the edge on that barrel liner skirt. It's usable because the piston is on a short stroke length.



I also had a long call with a lovely old feller who is a bit of a guru with these engine, and he definitely have me some good advice and warned me about some things I wasn't aware of.
It turns out the conrod in the engine is most likely an aluminium one, which is not as strong as the steel ones (obviously), and they haven't been made since the '70s, however, given that the engine is setup as a 400cc, running 9:1, on regular petrol, instead of 15:1 on meth... We reckon it should be okay for road use.

He also gave me some directions on the rocker box rebuild, and described how to do the valve timing using "split timing". Apparently he's never seen a JAP cam that was actually manufactured to the exact correct shape!

[Rockburner]

Oh yeah, and the valves need lapping...



Especially the exhaust!

[Rockburner]

Stripped the valves out of the head tonight.







The inlet valve had a good seal. You can see the shiny ring around the head of the valve, that's indicative of a clean seal to the seat.
The odd broken/tired rings are the mica washer(s) that sit under the spring cup. I'm not sure about these. I don't know if this is multiple washers, or one washer that has delaminated. I know nothing about the material mica.



The exhaust needed a little... "persuasion" ... to separate the collets from the spring cap.



You can see that the exhaust seat isn't shiny like the inlet.



Lots of crud around the valve stem tube fitting on the exhaust side



Needs a clean



And, guess what.....

There's a video too!