JAP Engine

Hi,

I have recently purchased a JAP engine.  I have never owned a stationery engine before so I am after some advice please.

The engine was sold to me as a JAP 2A engine but I'd like to know how to tell for definite what model and year it is?

I have attached some photos with comments on them pointing to various parts I am unsure of what they do. If anyone can let me know it would be much appreciated.





It came with a carb but is missing a fuel tank and exhaust.

To start these engines, does I matter which way you turn the engine? Looking at where you wind the pull cord, it looks to me that it should be turned clockwise?

Thanks in advance,

Pete

Hi Pete and a warm welcome to the forum.
As a new member you will not be able to post links/images for a few days - forumotion rules not mine.
Once you are able please study these instructions for adding images.

https://ukengineforum.forumotion.com/t9665-how-to-upload-images

Swinp22 wrote:Hi,

To start these engines, does I matter which way you turn the engine? Looking at where you wind the pull cord, it looks to me that it should be turned clockwise?

Thanks in advance,

Pete

You will need need to work out which way the engine runs, as the JAP 2A was made in both clock- and anti-clockwise versions. It will only start and run in one direction.

Ive just seen a message stating I cannot upload photos in the first 7 days of joining the forum - opps!

In the meantime, I am not getting spark at the spark plug. If I remove the plug from the HT lead and press the HT lead against the engine casing I get a tiny tiny spark jump across. What would be the reason be for the small spark and also for the no spark at the spark plug?

Thanks,

Pete

No spark at the plug could be a duff plug or plug gap too wide. I would clean the contact breaker points and set the gap and take it from there. If that doesn't improve the spark It would suggest to me coil/condenser issues.

Ok thanks.

What plug is best to use?

What should the points gap be?

Thanks,

Pete

You may find it useful  to get a copy of The JAP Engine  book which is available from Kelsey publishing and covers models up to 8hp, including the 2A, with instructions on running and repair.
The points gap should be 0.018 to 0.020 ins  and they were designed to run on a Champion L10 orLodge B14 plug but you may need to access modern equivalents.

Thanks. I am looking to purchase a manual once I have managed to get confirmation on what model JAP engine I have.

Not familiar with these engines, but:

In the first picture, the arm on the right looks like it's on a spindle so I suspect it's the governor arm, the arm on the left looks to be adjustable so maybe there should be a spring between them, altering the spring tension could alter the governed speed.

Threaded bit is the end of the crankshaft by the look of it, looking at the flange bolted to the engine I wonder if it's an engine off a pump and there was an impeller screwed on. Looks a bit short for anything else?

Googling 'Jap 2A' shows some engines with an open pipe coming from that 'box', maybe the crankcase breather?

That is one of the earlier 2A models, there would have been a spring between the two levers and the tension was adjusted by moving the 'fixed' lever which would alter the engine speed. That is the crankcase breather, the later ones had a pipe leading across to an elbow on the carb inlet to recycle the fumes back into the engine, the earlier ones like yours were just open to atmosphere.

Pete.

Brilliant thanks guys.

How can I work out what year it was produced?

Does the elbow section between the carb and the cylinder look correct?

Swinp22 wrote:Brilliant thanks guys.

How can I work out what year it was produced?

Does the elbow section between the carb and the cylinder look correct?

Well I have had lots of those engines and still have a few dotted around but have never seen that set-up on one. Usually the carb on the early ones is one of JAP's own manufacture and they screwed directly into the cylinder, these proved troublesome on horticultural machinery as they cut out when the machine wasn't level so the Zenith carb was used with an adapter that screwed into the cylinder but had a flange on it for the carb to bolt to.

For dating there should be some numbers stamped into a flat piece on the top of the crankcase just below the cylinder on the exhaust side and near the front of the crankcase, they should read '2A' and then various numbers/letters. They will be covered by that layer of paint though so will need unearthing!

Pete.

Ok thanks.

I don't suppose you know the bolt type/ thread for the 3 flywheel magneto puller bolts.

Thanks,

Pete

Swinp22 wrote:Ok thanks.

I don't suppose you know the bolt type/ thread for the 3 flywheel magneto puller bolts.

Thanks,

Pete

I've never had one that didn't pull off by hand as they are a parallel shaft. However from memory they are 1/4" BSF thread. The very early ones did have a tapered shaft but I have never encountered one that old.

Pete.

I have an issue with the keyway key - its been damaged. Im hoping to fabricate a puller to ease it off the shaft.

I ordered some 1/4 bsf bolts for the flywheel puller and they do not fit.

How can I find out what bolts sizes are used as I also need some for the outer casing as well. Does the manual provide this information ?

Thanks,

Pete

Swinp22 wrote:I ordered some 1/4 bsf bolts for the flywheel puller and they do not fit.

How can I find out what bolts sizes are used as I also need some for the outer casing as well. Does the manual provide this information ?

Thanks,

Pete

Time for some detective work, you need a vernier or digital caliper, a set of thread gauges and a Zeus reference book

https://www.ebay.co.uk/itm/A-Practical-Guide-Covering-The-Maintenance-Overhaul-of-J-A-P-Stationary-Engine/133438471207?hash=item1f118d7c27:g:h9sAAOSwHWJe5jg7