www.ukengineforum.forumotion.com
Please log in , the forum is open to guests who are now able to view most sections, feel free to become a member , you will then be able to post and reply to topics.

Join the forum, it's quick and easy

www.ukengineforum.forumotion.com
Please log in , the forum is open to guests who are now able to view most sections, feel free to become a member , you will then be able to post and reply to topics.

J.A.P. 4/3

+7
Robotstar5
mattblack
Foden
oldgit
neil (LE)
Alanengine
Woodsman
11 posters

Page 1 of 2 1, 2  Next

Go down

J.A.P. 4/3 Empty J.A.P. 4/3

Post by Woodsman Wed Jun 01 2022, 16:35

Picked this up yesterday.  Oh No - it's air cooled  affraid affraid  What was I thinking Wink Wink


J.A.P. 4/3 20220613

J.A.P. 4/3 20220614

J.A.P. 4/3 20220615

Seems to mainly all there. Obvious at first sight are missing magneto points cover and starting handle - anyone got either lurking in spares box? Also as you will see from picture 1 part of the flywheel cover is missing so I'll need to find a local metal basher.

Was seized at first but I whipped off the head and sprayed some GT 87 down the bore and got it moving in a few minutes.
Bore, valves and piston look OK at first sight - it came off a allotment rotovator so probably only did a few hours work a year.
Magneto HT winding reads approx 7K so that's promising.  Removing the tin-work revealed a collection of different nuts,  bolts and studs had been used over it's previous life. Bottom of the cowl is shot so, again, I need to find someone to plate it up.

First job is to clean most of the gunk off and get a spark at the plug.

_________________
Regards Paul
Tha can alus tell a Yorkshireman - but tha can't tell him much.
Woodsman
Woodsman
Admin

Posts : 2819
Join date : 2014-08-24
Age : 73
Location : God's own county

Back to top Go down

J.A.P. 4/3 Empty Re: J.A.P. 4/3

Post by Alanengine Wed Jun 01 2022, 19:26

Can't beat a good old (air cooled!) JAP, especially a larger variant. My 4/2 doesn't have that cowling removable section to access the points - the whole cowling has to come off! It seems quite common I've found to have a variety of fixing types as long as the tapped holes are intact it's easily rectified.
Also found unused magneto points seem to grow a fungus type of deposit, easily cleaned off. I've also found the condensers to be serviceable but worth checking if you still can't get a spark.
A good clean up makes things far more pleasurable!

Alan

Alanengine
A credit to the forum
A credit to the forum

Posts : 461
Join date : 2020-11-21

Back to top Go down

J.A.P. 4/3 Empty Re: J.A.P. 4/3

Post by Woodsman Thu Jun 02 2022, 11:50

What's this little jigger on the inlet manifold do? According the the manual it's a 'Release Tap'
Can't see what it releases. scratch


J.A.P. 4/3 20220616

_________________
Regards Paul
Tha can alus tell a Yorkshireman - but tha can't tell him much.
Woodsman
Woodsman
Admin

Posts : 2819
Join date : 2014-08-24
Age : 73
Location : God's own county

Back to top Go down

J.A.P. 4/3 Empty Re: J.A.P. 4/3

Post by Alanengine Thu Jun 02 2022, 13:37

Not seen one of those before.

Alan

Alanengine
A credit to the forum
A credit to the forum

Posts : 461
Join date : 2020-11-21

Back to top Go down

J.A.P. 4/3 Empty Re: J.A.P. 4/3

Post by Woodsman Fri Jun 03 2022, 10:01

Having removed the tank bracket I found this.  No mention in manual - over engineered breather ? scratch

J.A.P. 4/3 20220617

_________________
Regards Paul
Tha can alus tell a Yorkshireman - but tha can't tell him much.
Woodsman
Woodsman
Admin

Posts : 2819
Join date : 2014-08-24
Age : 73
Location : God's own county

Back to top Go down

J.A.P. 4/3 Empty Re: J.A.P. 4/3

Post by neil (LE) Fri Jun 03 2022, 13:46

Certainly looks like an engine breather. Don't know about over engineered but seems to be in good order with the oil mist keeping any rust at bay. I'm guessing the two slotted screws are holding the disc valves in place, if so it will allow them to be removed for easy cleaning.

Seems to be an interesting engine, I have no idea what the release valve is for, hopefully someone will be able to come up with the answer.

Neil.

neil (LE)
A credit to the forum
A credit to the forum

Posts : 399
Join date : 2012-03-21
Age : 68
Location : N/W Kent

Back to top Go down

J.A.P. 4/3 Empty Re: J.A.P. 4/3

Post by Woodsman Fri Jun 03 2022, 14:52

Well, lack of spark was easily diagnosed - plug lead was open circuit. Took a fly lead from HT and placed near body spun it over and got a big fat spark. Happy bunny.

_________________
Regards Paul
Tha can alus tell a Yorkshireman - but tha can't tell him much.
Woodsman
Woodsman
Admin

Posts : 2819
Join date : 2014-08-24
Age : 73
Location : God's own county

Back to top Go down

J.A.P. 4/3 Empty Re: J.A.P. 4/3

Post by Woodsman Sat Jun 04 2022, 10:16

According to the manual...
 
"No adjustment is provided for timing the magneto, which is unnecessary, as the magneto is correctly set before leaving the works ...."

I can understand that the retarded impulse timing is fixed for starting but surely there should be some adjusting for 'running' timing (25° before TDC). Or am I missing something?

_________________
Regards Paul
Tha can alus tell a Yorkshireman - but tha can't tell him much.
Woodsman
Woodsman
Admin

Posts : 2819
Join date : 2014-08-24
Age : 73
Location : God's own county

Back to top Go down

J.A.P. 4/3 Empty Re: J.A.P. 4/3

Post by Alanengine Sat Jun 04 2022, 10:56

As far as I'm aware the only timing adjustment available is by releasing the 2 screws that locate the 'points plate' which will then give (very) limited adjustment.

Alan
J.A.P. 4/3 Img_2157

Alanengine
A credit to the forum
A credit to the forum

Posts : 461
Join date : 2020-11-21

Back to top Go down

J.A.P. 4/3 Empty Re: J.A.P. 4/3

Post by Woodsman Sun Jun 05 2022, 09:40

I have WIPAC mag and it has 'slotted' mountings so will allow a little adjustment. We shall see.

_________________
Regards Paul
Tha can alus tell a Yorkshireman - but tha can't tell him much.
Woodsman
Woodsman
Admin

Posts : 2819
Join date : 2014-08-24
Age : 73
Location : God's own county

Back to top Go down

J.A.P. 4/3 Empty Re: J.A.P. 4/3

Post by oldgit Sun Jun 05 2022, 23:35

The release tap, may be to allow petrol vapour to be vented.
If petrol lies in the bottom of the induction pipe when the engine is stopped; this will, on a hot engine, vapourise and hang up at the highest point. This vapour lock may make the hot engine very hard to restart.
I think that may be what it is for.

oldgit
A true Stationary engine owner
A true Stationary engine owner

Posts : 168
Join date : 2019-07-07

Back to top Go down

J.A.P. 4/3 Empty Re: J.A.P. 4/3

Post by Foden Mon Jun 06 2022, 10:43

Breather is standard JAP, the 2A/2S models have the same. Tap is to release excess vapour, again a standard JAP fitment, timing will be fixed like many engines with impulse mags such as Coborn, Wisconsin etc.

Pete.

_________________
Too much to do, and so little time!!
Foden
Foden
Life Member
Life Member

Posts : 1411
Join date : 2009-11-04
Age : 73
Location : North Midlands

Back to top Go down

J.A.P. 4/3 Empty Re: J.A.P. 4/3

Post by Woodsman Mon Jun 06 2022, 11:36

Thanks gents.

_________________
Regards Paul
Tha can alus tell a Yorkshireman - but tha can't tell him much.
Woodsman
Woodsman
Admin

Posts : 2819
Join date : 2014-08-24
Age : 73
Location : God's own county

Back to top Go down

J.A.P. 4/3 Empty Re: J.A.P. 4/3

Post by Woodsman Tue Jun 07 2022, 14:21

Looks like the project has hit the buffers. Sad
Took the exhaust off to find that one of the mounting holes was snapped. Breaking for parts I guess.
J.A.P. 4/3 20220619

_________________
Regards Paul
Tha can alus tell a Yorkshireman - but tha can't tell him much.
Woodsman
Woodsman
Admin

Posts : 2819
Join date : 2014-08-24
Age : 73
Location : God's own county

Back to top Go down

J.A.P. 4/3 Empty Re: J.A.P. 4/3

Post by mattblack Tue Jun 07 2022, 21:13

Shame to break it just for that.

If it were mine I think I'd be looking into sleeving the port and exhaust and just using the one stud to locate the exhaust

_________________
Specialist in precision guesswork.
mattblack
mattblack
Life Member
Life Member

Posts : 889
Join date : 2019-06-21
Location : Leicester, me duck...

Back to top Go down

J.A.P. 4/3 Empty Re: J.A.P. 4/3

Post by Robotstar5 Tue Jun 07 2022, 21:28

If you know anyone that does TIG welding they could build that up again for you drill and tap a new hole.

_________________
Stuart
Robotstar5
Robotstar5
Life Member
Life Member

Posts : 1110
Join date : 2018-09-25

Back to top Go down

J.A.P. 4/3 Empty Re: J.A.P. 4/3

Post by Woodsman Wed Jun 08 2022, 10:47

Robotstar5 wrote:If you know anyone that does TIG welding they could build that up again for you drill and tap a new hole.
 Welding cast iron ?? My ignorance astounds me!

As  everyone on the forum is aware my welding and machining skills are nil so I'm happy to take advice. A bit of internet research seem to suggest oxy-acetylene or brazing might be preferable too keep temperature lower. Any thoughts / comments Stuart.

_________________
Regards Paul
Tha can alus tell a Yorkshireman - but tha can't tell him much.
Woodsman
Woodsman
Admin

Posts : 2819
Join date : 2014-08-24
Age : 73
Location : God's own county

Back to top Go down

J.A.P. 4/3 Empty Re: J.A.P. 4/3

Post by Woodsman Wed Jun 08 2022, 16:23

mattblack wrote:Shame to break it just for that.

If it were mine I think I'd be looking into sleeving the port and exhaust and just using the one stud to locate the exhaust

Will have a look into that idea, Cheers.

_________________
Regards Paul
Tha can alus tell a Yorkshireman - but tha can't tell him much.
Woodsman
Woodsman
Admin

Posts : 2819
Join date : 2014-08-24
Age : 73
Location : God's own county

Back to top Go down

J.A.P. 4/3 Empty Re: J.A.P. 4/3

Post by Robotstar5 Wed Jun 08 2022, 22:29

Woodsman wrote:
Robotstar5 wrote:If you know anyone that does TIG welding they could build that up again for you drill and tap a new hole.
 Welding cast iron ?? My ignorance astounds me!

As  everyone on the forum is aware my welding and machining skills are nil so I'm happy to take advice. A bit of internet research seem to suggest oxy-acetylene or brazing might be preferable too keep temperature lower. Any thoughts / comments Stuart.

Send some pics to john@doubleboost.video if anyone can sort it John can, he's Newcastle area so it may need posting?.

_________________
Stuart
Robotstar5
Robotstar5
Life Member
Life Member

Posts : 1110
Join date : 2018-09-25

Back to top Go down

J.A.P. 4/3 Empty Re: J.A.P. 4/3

Post by maryalice Thu Jun 09 2022, 08:23

Paul,

What ever method you use to weld or bronze you need some serious brownie points to accrue with your better half as the item to be welded etc needs to be preheated, usually in the oven Very Happy , as cast iron suffers from stress cracking next to the welded repair.

Maryalice

maryalice
Life Member
Life Member

Posts : 1310
Join date : 2010-01-23
Age : 70
Location : Bedfordshire

Back to top Go down

J.A.P. 4/3 Empty Re: J.A.P. 4/3

Post by Woodsman Thu Jun 09 2022, 17:01

Just picked up my bored out starter boss from David. Works a treat - many thanks to David. Always a pleasure to step into his shed and admire some of the lovely model engines he makes. Note also the magneto cover I got off fleabay - it's the right way round now. Rolling Eyes
Once I've replaced the duff HT lead I'll give it a spin to see if it will fire.

J.A.P. 4/3 20220620

_________________
Regards Paul
Tha can alus tell a Yorkshireman - but tha can't tell him much.
Woodsman
Woodsman
Admin

Posts : 2819
Join date : 2014-08-24
Age : 73
Location : God's own county

Back to top Go down

J.A.P. 4/3 Empty Re: J.A.P. 4/3

Post by Davidlang1947 Fri Jun 10 2022, 11:08

Good to see it back on the engine, only to glad to help, cheers David

Davidlang1947
Born to be wild
Born to be wild

Posts : 22
Join date : 2021-08-21

Back to top Go down

J.A.P. 4/3 Empty Re: J.A.P. 4/3

Post by donp Fri Jun 10 2022, 13:33

Agree what you say about David`s shed when I was at his a while ago collecting an engine it was excellent to look at his workmanship, Hello again David had the model 72 from you if you remember. Don
donp
donp
A credit to the forum
A credit to the forum

Posts : 312
Join date : 2013-09-03
Age : 84
Location : N.East

Back to top Go down

J.A.P. 4/3 Empty Re: J.A.P. 4/3

Post by Woodsman Fri Jun 10 2022, 15:20

Back to the cracked exhaust mounting.  What do we think about a biggish blob of JB Weld reinforced with some steel. Ugly maybe, but would it work?

_________________
Regards Paul
Tha can alus tell a Yorkshireman - but tha can't tell him much.
Woodsman
Woodsman
Admin

Posts : 2819
Join date : 2014-08-24
Age : 73
Location : God's own county

Back to top Go down

J.A.P. 4/3 Empty Re: J.A.P. 4/3

Post by maryalice Fri Jun 10 2022, 15:36

If your going to reinforce it with steel why don't you just use steel, braze in on then re drill the hole, I'm sure somebody local to you can make the repair, another way would be to braze a large blob and re shape it by hand.

Maryalice

maryalice
Life Member
Life Member

Posts : 1310
Join date : 2010-01-23
Age : 70
Location : Bedfordshire

Back to top Go down

J.A.P. 4/3 Empty Re: J.A.P. 4/3

Post by Sponsored content


Sponsored content


Back to top Go down

Page 1 of 2 1, 2  Next

Back to top


 
Permissions in this forum:
You cannot reply to topics in this forum