... cont.
Got into the workshop this afternoon, and took the decision to just fuggin do it.
Timing chain cam off easily enough, the two sprockets were well jammed on, but I eventually got them off with the bearing puller.
There's no keyway or anything on these, so the ignition timing needs to be done by "eye"...
The platform the mag sits in is pretty mullered....
Probably why it wasn't exactly firmly located....
It was also only held on by 2 studs.
Here's the Mag drive shaft - note complete lack of keyways...
But nice modern seal.
The foam on the Mag is to stop oil flying about from the timing case, because the hole the mag shaft pushes through is about an inch square....
This frigging engine mount bolt was the main reason I was swearing all afternoon....
The nut on the end was tight as hell and so I couldn't pull the stud out of the plates on the other side.
When I was talking to the guru the other day: he mentioned the "bible" for JAP speedway engines is the "Greenwood" manual.
So - I popped a search into ebay, and one came up! Score! It turned up today, and as I was reading it (it's only about 8 pages), I was thinking.... this is all very familiar.....
Checked the books/manuals in the workshop and ....
ffs.
Dad had a photocopy of the damn thing. :roll:
The interior of the timing chest:
Note shonky paper gasket and crap.
See if you can spot the wtf...
Inlet cam roller
Exhaust cam roller
WTAF?
No - I could NOT figure out what that was.... took me an hour.
This is the inside of the timing chest cover - with the exhaust valve lifter gubbins:
This is the cam-shaft in place in the timing chest cover
Close up of the cams:
I was looking at the valve-lifter assembly above, and comparing it the position of the valves... and I couldn't for the life of me figure out how on earth it was meant to do anything. The lifter assembly is the same "thickness" as the cam-shaft gear, and the exhaust roller is tucked away behind that gear when the chest is assembled ... so ... what did it "act" on??
I eventually worked it out when I got to pulling out the rollers :
That little stub of metal "was" a pin that had been driven through the exhaust roller arm, and which would then stick past the cam-shaft-gear and the valve lifter could act on that pin to lift the exhaust valve. But: the pin has obviously snapped at some point in the past: no wonder the valve lifter was utterly useless!!
TBH I'm probably going to just strip the lifter mechanism out completely, rather than try to get a new pin driven into the roller. It's only 9:1....
Inlet, and exhaust rollers:
However... I think a new inlet roller may be in order, not sure, but I think they come as a pre-assembled part. :
EVENTUALLY.. after quite a bit of twisting, looking, perusing, swearing and general $%^&&ery....
IT'S OUT!
And that was about all I really had time for. Next jobs are to continue stripping down the cases to check the crank bearings are still in good shape. Ideally I'd split the crank.... but I'm REALLY sure not sure I'm brave enough for that....
This frame really has been bodged about.
This is the hole we were talking about... all the way back on page 1...
Hadn't noticed this nick on the conrod before.
I'm thinking this conrod is likely to be second hand, so the nick is likely old too. I hope...
Some carbon on the piston.
From the pile of tools I brought back from Dad's workshop I eventually unearthed this, among the 5 or 6 other "pullers". Put a new bolt in it, for some totally unknown reason he had a carriage bolt in it.. :wtf:.
I had to file it down a touch, but it worked perfectly.
One of the other pullers to remove the crank sprocket from the timing side.
This plate needs to come off, but I've no idea what it's been such on with, or what's behind it that I don't want to damage while removing the plate.
Timing side of the crankshaft
Piston is cleaning up nicely, but I'll keep at it.
Bit more progress on the JAPton strip down yesterday:
Stripped off the oil seal plate on the crank output shaft :
I wonder if that's a modern update. I don't remember seeing anything about it on any of the diagrams or books, and the thing is held on with metric cap-screws... (well, I didn't check the threads, but they take a 3mm metric Allen key, and none of my Imperial Allen keys would fit....)
While I was fiddling with the output side.... I heard a "clonk" from the other side of the cases....
The oil drain box cover fell off.
I'd already removed the screws last time, but it had appeared to have been solidly glued down with silicon sealant... Apparently not so solidly!
Kellogg's still make the best gasket paper.
The gunk inside the oil drain chest.
This is the underside of the oil drain chest - it's a one-way valve of some sort - I'm going to clean up the mating edges for the outer covers, but otherwise leave this alone.
