J.A.P. 4/3

Got the barrel off yesterday. Piston a tad grubby but rings all intact and free.

Taking the cylinder off revealed some numbers:  4/3 / B / P  and 92330/30.

Best info I have is that the B maybe indicates 1961. Any better ideas?

Woodsman wrote:Taking the cylinder off revealed some numbers:  4/3 / B / P  and 92330/30.

Best info I have is that the B maybe indicates 1961. Any better ideas?

My interpretation would be:

Your engine is  JAP 4/3B, and the date code is P = 1940.
The B might indicate the higher/lower speed/hp version of the 4/3 engine.
30 is the makers code for the deviations from the standard specification (unknown).

I don't think this model survived as long as 1961, but I might be wrong.

There should be a date code on the Wipac CJ magneto as well, but of course it might be a replacement for the original Wico A magneto.

Thanks for the info blue cat.

Nice little touch I've not seen before (first J.A.P) - Valve clearances on inside of valve box cover.

As you say nice touch although my 4/2 doesn't have it!

Alan

So I got the cylinder off and started to clean it up but got diverted to domestic duties followed by a few beers in the garden. When I returned to the shed the following day I noticed this little tinker sitting on the top of the crankcase.
 



A quick check and it fits perfectly on the the valve stem. Panic attack ensues - where is it's twin!   Best scenario, it's dropped inside and is now sitting in the sump. Worst case, it's among all the gunge and detritus on the bench. Once I'd calmed down I carefully ran a magnet over said muck and was relieved to hear a little 'clink' The twins are now reunited and carefully bagged up.

Note to self. Have exploded diagram to hand when dismantling!

It also occurred to me that, had it dropped inside, I would have probably forgotten by the time I got to the sump. I think I'm going to get a little whiteboard for the shed where I can write notes like 'The carb is in the paraffin bucket' Spent half a hour this afternoon wondering where it was.

Next question.  What does this lever do?



In the manual it's referred to as  'Lever - Starting and Running'  Something to stop the governor operating ?

So, having got the barrel off I decided to take the valves out.  Following my own advice (see previous) I consulted the exploded diagram before starting.  Not too difficult to compress springs but when I took them out the split collets fell out. According to the diagram they are retained by a cotter pin.  On closer examination it turns out that, unlike Villiers which have stepped valve stems, JAP used in tiny circlip. It was a right faff getting those out.  However, valves look in decent condition once cleaned up . As expected, the exhaust valve seat was rather pitted so I introduced it to the valve seat cutter. Once I've cleaned up the outside of the cylinder I'll reassemble.

Question: Anyone know why the valve guides are different patterns?

blue cat wrote:
Your engine is  JAP 4/3B, and the date code is P = 1940.
The B might indicate the higher/lower speed/hp version of the 4/3 engine.
30 is the makers code for the deviations from the standard specification (unknown).

I don't think this model survived as long as 1961, but I might be wrong.

There should be a date code on the Wipac CJ magneto as well, but of course it might be a replacement for the original Wico A magneto.

Took to mag off yesterday and found the code  - CJ 936 5 63 so I guess you are correct about replacement on or around 1963. Cheers

Well, I've spent several days trying to chase down a welder - all I get is a sharp intake of breath followed by some variation on 'not really..' I did get one 'Yes', sent some pics and was quoted £210!

Re-reading I found Stuarts suggestion so have emailed John. If that proves too expensive then I'll probably break it for parts on ebay - unless anybody wants to take it on.

Woodsman wrote:Well, I've spent several days trying to chase down a welder - all I get is a sharp intake of breath followed by some variation on 'not really..' I did get one 'Yes', sent some pics and was quoted £210!

Re-reading I found Stuarts suggestion so have emailed John. If that proves too expensive then I'll probably break it for parts on ebay - unless anybody wants to take it on.

It will be interesting to see if John quotes a figure, he normally says something like "send me what you think the job's worth"

Well - big kudos to FedEx!
Dropped off 5kgs of cast iron at local newsagent 11:30 yesterday. Delivered to John already! Price £6.52 inc VAT.

Sounds like a bargain!

Alan

Woodsman wrote:Well - big kudos to FedEx!
Dropped off 5kgs of cast iron at local newsagent 11:30 yesterday. Delivered to John already! Price £6.52 inc VAT.

I wonder if it will make it onto his Sunday night nightcap video?.

Robotstar5 wrote:
I wonder if it will make it onto his Sunday night nightcap video?.

Watched 'Baked "Tetty" Potato. Doubleboost Style'  Brilliant !!

He may be a while getting round to it as he's single handed at the moment due to a little accident.

Tig welding electrode through his right wrist

I watch him regularly, he was very lucky.

Robotstar5 wrote:Tig welding electrode through his right wrist

Ouch - I bet that smarted!

It's a star of the small screen now

Beat me to it!
Just watched video. Excellent job. Looking forward to getting my hands on it.
Big thanks to John.

Woodsman wrote:Beat me to it!  
Just  watched video.  Excellent job.  Looking forward to getting my hands on it.
Big thanks to John.

I like the comment after he'd ground it out with the die grinder "well I've got to fix the b*****d thing now"

I also loved the previous episode - SNNC 468 P1 Steam Waggon Regulator - Drilling Broken stud.  I thought "Yup been there done/said that !" 
I was sitting around yesterday waiting for Open Reach to turn up, so watched several hours - might have to get a lathe!!

Been watching him for a couple of years, some of his repairs help me find ways around some of mine, I now know how to repair the exhaust flange on my 1919 Lister M.

Maryalice

Cylinder arrive back, courtesy of DHL this time. Well pleased - big thanks to John again

Before:


After:


Now I have a quandary- park up the Clinton and back to the J.A.P, or finish the Clinton?
Decisions, decisions.

Well, prompted by Colin's enquiry, I've extracted my digit and done a bit more.



Seems a shame to paint it when it's nice and shiny.