OutdoorKing Repair Forum Forums Restoring, Customising and Modifying Engines J.A.P. Model 2a Restoration

Anyone seen one of these before??

This is a pulley on the crankshaft of a J.A.P. 2a that Im restoring at the moment.

I'll be buggered if I can get it off!

You can see there are two holes in the outside pulley that line up exactly with the holes on the inner bit - I have stuck a screwdriver through them all to show it goes all the way through - there doesn't seem to be anything in there that undoes, or pushes or anything...

There are three circular things on the front of the inner section of the pulley - one in particular looks like it might move - ie: screw out? Push in? or something.

Any suggestions??






I suspect it will be a trivial exercise for someone who knows how they work


Cheers

Still stuck!!

I've figured out that one of the round things on the inner section - the most silver coloured one, is actually the bottom of a screw/bolt - I can see its head sitting between the pulley and the crankcase. It has a slot for a flat blade screw driver - but there is no way in the world to get to it until the pulley comes off.

I'm considering CEMTEX!

Polybus

Hello Polybus,

I take it that this pulley arrangement is not a JAP part,
and would not be covered in the 2A manual?

Is it possible the whole thing unscrews?
Is the threaded bit part of the crankshaft, or an overlay?

All very interesting.
---------------------------------
JACK.

Hi Guys - after a long absence I'm back - and now living in Port Douglas, Queensland, formerly in Sydney.

My Triplets - the 3 Victa 18s I was restoring - couldn't make the trip with me and they are safely stored away in Sydney awaiting my return.

I'm now holed up in a one bedroom unit with no garage, no workshop and not much room to do anything - however, on the plus side is its quite rural up here and there is lots of old outdoor machinery to be had.

I couldn't help myself, so I got a pair of J.A.P.s - christened "The Twins" - a J.A.P. Model 2a and a matching J.A.P. Model 2s. They are pretty much the same engine with the 2s being the more industrial of the two - with a bigger sump and better governor mechanism.

I'm restoring the 2a first, on my dining room table - I hope the landlord doesn't read this.

The J.A.P. Model 2 was made in the 40's thru the 60s, with this particular engine dating from 1949.

They are very small, only standing about 15 inches high (without the fuel tank) and with a footprint of about 6 inches x 8 inches. They were often used with generators, battery chargers and water pumps - but as you can imagine got put to use doing pretty much anything on a farm.

I'm not an expert by any stretch of the imagination - but for what it's worth I will document anything of interest I discover as I restore it.

If you know about J.A.P.s - please don't hesitate to correct anything I may post that is incorrect - this is all about getting the correct details of the little Model 2a recorded on this forum - not about me pretending I know it all.....so.....

J.A.P. Model 2s - Specifications:

Engine Type: 4S
Displacement: 98cc
Bore: 52mm
Stroke: 48mm
Type: 4 Stroke - Side Valve
Power: 1.2hp at 2800rpm
Fuel: Petrol
Spark Plug: L-10 - Champion N-8
Points: 0.018 - 0.020
Magneto: Wico Flywheel Type - FW880 (but varied through the model life)
Carburetor: Zenith Type 13T


And here are some pictures of it as I picked it up.















Early observations - it has no spark - which from what I gather is a bit unusual for these things - apparently the Wico Flywheel Magnetos were really good and reliable.

If anybody is interested (granted, this is not a mower - but it was used outdoors!) I'll post progress photos as I go.

Polybus

Hi Jack - thanks for taking the time to respond with help

I'm pretty sure the threaded bit is just an overlay - I can just see down between the crankcase and the pulley, and it looks like the actual crank is about 2/3 the diameter of the the big threaded shaft on the pulley.

I have considered whether or not it just unscrews, and even had a half hearted attempt to unscrew it - but of course I couldn't really secure the crank, so it wasn't a serious effort.

And no - I don't think its an original J.A.P. part - I don't have a manual for it - but I'm hunting around for one.

Thanks heaps for the thought - I might have to try and lock the crank, or do some research and see if this end of the crank even has a thread on it.

Thanks again

I have just posted a new Thread about the restoration - so you can see more complete photos of the whole engine there.

Polybus

Hello Polybus,

I've just merged both of your topics.

Manuals for the 2A seem readily available.
A reliable Vic. company has an 81 page manual for a reasonable price.
[just let me know if you would like the details].

Cheers
-----------------------
JACK.

Who are they?

I'll order one now.

Hello Polybus,

Covers Engines: Model O, Model 2A, Model 2S, Model 4F, Model 4/2, Model 4/3, Model 5, Model 6 & Model 55
Available: HERE.



Hope this helps.
--------------------------------
JACK.

Thanks heaps!!!

I'm sure it will be a huge help And I've got a Model 6 stashed away in storage in Sydney (pictures elsewhere on this site) so it will help with that restoration too.

Cheers Jack

Your welcome Polybus

Please keep us posted as the resto progresses.
I'm keen to get more JAP info. on this wonderful site -
because JAP engines featured so much in our, and imported, vintage lawnmowers.
There has been less-than-ideal recording of their contribution to lawnmower history.

Cheers
------------------------
JACK.

For chainsaws there is a gadget for locking the piston that screws in place of the spark.plug and basically is just an extended long piece of rod with a spark plug thread. You could try something similar to lock the J.A.P. and put your screwdriver through all those holes and give it a sharp tap with a hammer. Make sure the piston is hard up against the rod before you do though. Probably be good to hit it with heaps of penetrating oil overnight first as well.

Those chain saw 'piston stops' often won't work on sidevalve 4-stroke engines, due to the plug hole being positioned away from the bore.

The other old piston stop lurk; that of feeding a soft [e.g. cotton] cord into the combustion chamber via the spark plug hole, can work OK on these, though.

Polybus I hope this may help, sorry I can not post a PDF so I just took photos of my monitor but you should be able to make most of it out. 20 photo's so two posts.

Thanks to Jonesy for posting the Manual.
These are now available as PDFs [see posts below.

Well, it may only be trivial if it hasn't all become rust-bound. That notch in the disc does look like it's intended to be used with a drift and hammer, to unscrew a left hand thread.

The cross-holes could be intended to take a rod to lock some part of the assembly, while the drift is used.

You may need to use a small inspection mirror, to see which inner bit would be held stationary by an inserted rod, here.

And a good soak with a quality penetrating lubricant [Penetrene, CRC 5-56, Inox etc.] is an essential preliminary step.

Hiya Jonesy - Thanks so much for the manual pages - they are gonna be a huge help.

And Gadge - thank you too for the suggestions on the Pulley - cause I'm still stuck on it - I'll have a go at spinning it in the reverse direction.

And guess what!??!?!

Hey - check this out.



Check out the little button he presses at about 0:50 seconds.

I reckon that might be my Mystery Item - I'm off to check it out.....

Polybus

Yep - the item in question is the Kill Switch - it attaches to the Magneto backing plate, just below the carby.

Obviously, you press it - something gets shorted out, and the engine stops - so - mystery solved.

I can't see how it attaches - or how it shorts out the ignition, but I'll figure it out.

Polybus.

YAY!!!

I took the engine - with pulley attached over to a mate's place - he's got one of the best setups you'll ever see - plus a wealth of knowledge and experience.

We considered all the responses I've had and ended up assuming the pulley was just slid on to the original JAP crank. So we ended up hammering (and hammering....and hammering) a couple of chisels down in between the pulley and the crank case and got not movement

Applied some heat - heard a bit of a "crack" - more hammering and it began to move ever so slightly.

Of course once is started moving it wasn't so tough to get off.

Then it was easy to get the valve gear, the valves and the crank out - the bearing was a little difficult, but came out eventually.

Cleaned everything in my mates 53 litre Ultrasonic Cleaner!!

And now this is where I'm at.....completely apart.









The bore looks OK - but I'll give it a hone anyway - new rings and new bearings - new gaskets - and the carby is going to need some sorting out I'm sure - hopefully I can get a carby kit for it.

But as for now - bead blasting for the cowl and crankcase and start the prep for painting.

I've uncovered quite a few spots of the original paint colour - a kind of pale/steel blue - a metallic shade - I am thinking of doing it with GALMET Hammer Finish Reef Blue - seems a reasonably close match to the original - but how will it handle the heat?

I will probably do the crank case and cowl the Hammer Finish Reef Blue, but the barrel heat proof matt/satin black and leave the head polished alloy.

Now - just to get it done.

Very happy!!!

Polybus

Hello Polybus and ODK viewers

What a great story so far! And excellent 'exploded' pics of the engine.
These are very well made engines for sure.

I wish the maker of the pulley had just put a tapped hole on the end of the
false crankshaft. Just put a bolt in and tighten, automatically releasing
the pulley from the engine crank.

I guess you won't be re-installing that pulley-thing!

All very interesting.
--------------------------------
JACK.

That's a great outcome there, the reef blue is a nice paint. Jonesy, that must have taken you a lot of time to upload all those pages ! Thanks, it makes interesting reading as a small Jap and a BSA are on my wish list.

Good show!


I'd consider soda blasting for the crankcase, too. The problem with glass beads is that they get stuck in all sorts of nooks and crannies, especially tapped holes. And they're buggers to get out of there!

If you aren't extremely thorough in cleaning them out, it only takes a couple of them to get into a bearing or such, to wreck it.

For de-rusting, if you're the patient [as in a couple of weeks to complete a job] type, there's an extremely simple, cheap, effective and environmentally friendly DIY rust-removing bath solution recipe about.

It's just stock feed grade Molasses [a byproduct of sugar refining], mixed with tap water in the range 1+5 to ~1+10 dilution. I've got one of these baths going at the moment, to de-rust some old tools and such. It cost me $11 for 5L of black molasses, and I've used 1.5kg of it in ~12L of water. One bucketful of hot water to dissolve the stuff, and a top-up from the garden hose. The bath does need to be set up out of doors, though [edit: it does stink a bit, once it starts to ferment]. And kept covered.
Wouldn't expect it to have any problems on a cooling cowl. The crankcase does need to be done in 'engine paint', which is a bit more heat-tolerant, I'd say.