New Project(s)

[Taipan]

I hate to say it, but I bet you nipped the tube when refitting the tyre...

[Rockburner]

I hate to say it, but I bet you nipped the tube when refitting the tyre...

I was very careful not to. (but I'll admit I"m well out of practise)

Haven't tried taking the tube back out yet to see where/how the leak has manifested.

[Rockburner]

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I give up. I am officially crap at fitting inner tubes.

Anyone know a good motorcycle tyre fitting shop near Chichester?

[Taipan]

16905683395036758114899450305565.jpg

I give up. I am officially crap at fitting inner tubes.

Anyone know a good motorcycle tyre fitting shop near Chichester?

Dont be too harsh on yourself. Theres not many that fit tyres with inner tubes and dont nip them! I've alwasy fitted my own tyres but with the current bike that has tubes, someone else will be doing them!

[Rockburner]

16905683395036758114899450305565.jpg

I give up. I am officially crap at fitting inner tubes.

Anyone know a good motorcycle tyre fitting shop near Chichester?

Dont be too harsh on yourself. Theres not many that fit tyres with inner tubes and dont nip them! I've alwasy fitted my own tyres but with the current bike that has tubes, someone else will be doing them!

I never really expected to be good at it, but pissed that i damaged 3 in a row.

[Rockburner]

So - while waiting for a tyre fitter who's prepared to have a go at a 12" wheel.......


I tinkered with the JAPton last night.

It's all back together but wasn't running properly - lots of spitting back and backfiring in the exhaust.

Got it running, and spent about an hour going back and forth between the ancient Monobloc "Notes" leaflet (Dad had some photocopies so at least I wasn't getting the original filthy!)* Eventually got my head around it and realised that the damn thing was running "weak" in the mid-range and so pulled the needle up a notch (the first thing I'd done was lower it a notch to the "top" notch, it refused to run on that setting). Now it's in the middle of the needle's range its actually running pretty well (once it's hot). The occasional spit back or backfire, but I think I can live with that for now. (I know that the end-can is a bit loose and that will be contributing to the backfiring in the exhaust).

Happy bunny!

During the course of the session I'd spotted a couple of nuts that had fallen on the floor - one was an engine bolt that (in hindsight) I know was loose - the primary chase mounting lug is held in place by it and I'd simply forgotten it was loose.
The other was the nut off the forward connection for the gear linkage.... it's a nyloc, but I discovered that Dad had cut the bolt for it down so short that the threads aren't actually engaging the nylon locking collar! ( ffs). Couldn't be arsed at that point to root around for a better bolt so I just pushed the nut on upside down. Hardly ideal but it'll do to hold it all together while I figure out another issue.

I was wiping some oil off the top of the crankcase when I discovered something that terrifies me...



That bolt, the one between the push-rod tubes, is loose, and it won't go tight.

It just revolves.

Now - I may be wrong.... but, to me, that indicates that there's a friggin NUT on the other side of the case, that is loose, and is hanging on the threads of the bolt.



I may be wrong, and the loose bolt is caused by the threads on either the bolt or the casing being thoroughly knackered.

But - either way, the mininum work needed before I can do anything with the bike is to strip the entire right side of the engine away to check what's going on in the timing box.

I can't take a chance on the probability of a nut dropping into the timing box.

So - The JAPton is unlikely to see tarmac again this side of Easter, simply because I know that I've never done any of this stuff before and I'll be taking things very slow and thoroughly checking it all, and researching how it all works. Oddly, for all the tinkering I've done over the years, this is the first time I've ever had to actually do the timing on anything.

I also seem to have been thrown off / barred from the JAP Engine Facebook group I was on - so also need to find a J.A.P. specialist source of further information.


Dagnabbit.







* I must get a copy of that leaflet blown up and laminated. I did the same with the exploded diagram for the carb and it's an invaluable reference sheet).

[Rockburner]

Just a quick look at some photos online... and I can't figure out what the hole itself is for... it's NOT the location of the 5th stud on a 5-stud engine (J.A.P. engines came in 4 and 5-stud, and most of the components are interchangable). The 5th stud on the 5-stud engine on the plug side : Here's a photo showing an engine with the 5th stud on the same side as the plug - all the timing gear is on the other side.

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[Rockburner]

oh yeah - there's one other weird thing happening in the JAPton:

On the Monobloc carb, although I've cleaned it all up, when I use the tickler to push the float down, it "works" - but the fuel doesn't overflow through the ticker - it eventually overflows out of the bellmouth! (or possibly a tiny hole in the inlet manifold).

The tickler is simply a metal tube, closed at the top end, but with a small hole on the side about a mm down from the top. The bottom of the tube is squared off, but not closed up, and it's completely clean - it's not blocked in anyway.

The top of the float - which the tickler pushes down on, is rounded, so there's no "flat plane" on which the end of the tickler could possibly "seal".

So I'm highly confused as to why the fuel isn't exiting out of the tickler!

[Taipan]

If its the same as the one below, then it looks like the tickler pushes the float down but the fuel would likely flow out of number 24 as its lower and that would be where you're thinking its coming from? Possibly indicating the needle valve (seal) is worn?

[Rockburner]

If its the same as the one below, then it looks like the tickler pushes the float down but the fuel would likely flow out of number 24 as its lower and that would be where you're thinking its coming from? Possibly indicating the needle valve (seal) is worn?

24 is the feed IN.....


Oh - and the float, float- needle and pretty much everything else replaceable is new.

but - I am now wondering if an internal seal is not in place correctly...

[Taipan]

If its the same as the one below, then it looks like the tickler pushes the float down but the fuel would likely flow out of number 24 as its lower and that would be where you're thinking its coming from? Possibly indicating the needle valve (seal) is worn?

24 is the feed IN.....


Oh - and the float, float- needle and pretty much everything else replaceable is new.

but - I am now wondering if an internal seal is not in place correctly...

I'm not familiar with these carbs, but do have memories of stinking fingers from petrol coming out of ticklers. So it seems odd that its leaking out somewhere before that happens, but as you've just replaced something lower down than the tickler, I guess the golden rule of going back to where you last worked applies then....

[Skub]

I also seem to have been thrown off / barred from the JAP Engine Facebook group I was on - so also need to find a J.A.P. specialist source of further information.

How did you manage that one? Did a rivit counter get offended by a pic of a non stock bike?

[Rockburner]

I also seem to have been thrown off / barred from the JAP Engine Facebook group I was on - so also need to find a J.A.P. specialist source of further information.

How did you manage that one? Did a rivit counter get offended by a pic of a non stock bike?

I have no idea... I've tried to rejoin, but still waiting...

[Rockburner]

Managed to unscrew the bolt this evening.

The threads on both the bolt and the case are "tired". But i found a bolt in my grab bag of Imperial bolts that actually screws in and will go "tight".




Old bolt on left....
So I'm going to cut it a bit shorter (both bolts are twice as long as they need to be), and smother the top end of the threads with silicon and put it in with an ally crush washer (unless i can find a suitable fibre, but i detest fibre washers).

Before that though, I'm going to stuff an endoscope into the hole!

[Rockburner]

Pondering the carb overnight.... I'm wondering if the paper gasket that sits between the jet block and the main body is doing it's job. When I reassembled the carb I nearly made a viton seal for that location, simply because it wouldn't glue itself to the ally like paper gaskets tend to, but now I wonder if it would be worth doing for a better seal. I also realised that I put the gasket in "naked"..... which might have been an error.

Part 32 below:

[Taipan]

As I say, i'm not familiar with these carbs, but if its coming out of the bellmouth then it must be coming up the main jet? Is the needle seating correctly?

[Rockburner]

Managed to unscrew the bolt this evening.

The threads on both the bolt and the case are "tired". But i found a bolt in my grab bag of Imperial bolts that actually screws in and will go "tight".




Old bolt on left....
So I'm going to cut it a bit shorter (both bolts are twice as long as they need to be), and smother the top end of the threads with silicon and put it in with an ally crush washer (unless i can find a suitable fibre, but i detest fibre washers).

Before that though, I'm going to stuff an endoscope into the hole!

oh yeah - just an addendum to this... that old bolt, once I got it out, I discovered that it can be pushed in and out of the hole without rotating it!

The threads on the bolt are rounded off, and the threads on the casing are presumably as rounded that they don't properly engage any more!.

When I put the new bolt in I'm going to have to be very gently with it. Long term the fix will be to strip the head and barrel off, and the timing gear, and re-tap the hole, but for this year I"m just going to try to seal the hole as best I can to get the bike on the road without pissing oil everywhere and see if it will actually go more than a mile!

[Demannu]

16905683395036758114899450305565.jpg

I give up. I am officially crap at fitting inner tubes.

And tightening puch screws!

[Rockburner]

As I say, i'm not familiar with these carbs, but if its coming out of the bellmouth then it must be coming up the main jet? Is the needle seating correctly?

Which needle? the float needle or the jet needle?

As far as I can make out they're both ok. If the float needle wasn't seating correctly then the fuel would continue to pour in from the tank, and overflow everywhere, which doesn't happen.

The jet needle is certainly sitting down the jet tube, but I don't think it would actually prevent fuel flow when it's at the bottom of it's movement (not sure about that tbh), it's on the middle of it's 5 positions.

[Taipan]

I don't know about any float bowl vents within the carb body, but if the fuel isn't coming up and out of the tickler as it should, and is getting into the venturi instead, then there is a limited number of escapes for it with the MJ being the obvious one.