JAP 4/2 (Engine no. P15904UVX)

Just a suggestion as I have some in the shed. If you know a bricky,. an offcut of damp proof membrane might be good (polythene approx 1.5mm thick) or better still flat roof membrane (EPDM 1.0mm and upwards)

Obviously you will need to ensure that whatever you use is ethanol resistant. I bought some rubber sheet from an internet site and even though it suggested it was petrol proof it did not survive modern petrol with ethanol in it. The description was technically correct, as it did not specify what type of petrol it was resistant against. Buyer beware!

Neil.

Thanks for your replies, I think it's a bit of a minefield when it comes to ethanol resistance. Had a quote for a kit of seals (no mention of ethanol) for £21!
Have ordered some suitably (sized) ones off the bay so fingers crossed.

Alan

If you've bought a set, it might be worth soaking one in a jar of E5 or E10 petrol, if you can get some, to test it. I found they will either curl up, swell or go spongy, if they are not resistant.

Neil.

Thanks Neil, will have a 'soak' test

Alan

Woodsman wrote:Just a suggestion as I have some in the shed. If you know a bricky,. an offcut of damp proof membrane might be good (polythene approx 1.5mm thick) or better still flat roof membrane (EPDM 1.0mm and upwards)

I have some flat roof membrane (not sure of thickness without checking), happy to send you a piece if you want to experiment.

Thanks Matt lack, I have some O rings on the way if it doesn't work out I'll bear your offer in mind, thanks.

Alan

O ring turned up fitted and appears ok, time will tell!
First run today, sounds a lot nicer in the flesh! Bit slow on throttle take up as I think it's running a bit weak although the carb screws have been replaced exactly as they came out.
https://www.youtube.com/shorts/gxn0PCiZyaw?feature=share

Second run with belt fitted to drive the alternator setup.
https://youtu.be/YREUbiV9Unw

Really impressed with how steady it runs the governor giving precise control.
On the second start up the handle didn't come out cleanly giving a wack on the wrist, thought I'd broke it in the split second it happened.
Think the problem is I have made the handle too good a fit in the starter boss I believe the originals to be quite a 'loose' although as I haven't experienced the correct handle I am going to make a removable rope starting pulley to avoid a repitition of the event!

Alan

They say there is no gain without the pain but I think you took that too literally. I hope you don't suffer any painful bruising.

The end result looks really good and it runs as good as it looks, you can't do any better than that!

Well done,

Neil.

Running lovely that, well done.
If in doubt get the wrist checked out, I broke mine and didn't release it. Nothing worse than an engine kicking back on it now....

Thanks for the compliments!
Don't think it's broke, swelling has gone down a lot - but bloody hurt at the time!

Alan

Fantastic result!

(The engine that is, not the wrist... )

It's a vampire engine !!! Sweet runner. All the hard work has paid off.
What's your next engine.
Andrew

Next engine! Need to finish the trolley/mounting then I was considering using a couple of pieces of angle iron as sort of railway lines to wheel it in and out of the estate.
So my next engine will be to finish the Villiers generator before the JAP jumped the queue!

Alan

Ouch - I bet that smarts!

Well one - a very nice job.

Need some help here guys!
Been making a 'load' unit for the JAP consisting of 20 H7 headlight bulbs. These can be switched in banks of 5 giving a variable load, not quite finished but good enough to have a trial this afternoon!
Engine started first pull and after a minute or so with some choke was allowed to warm up, governor adjusted to give about 1800 rpm first bank switched on and governor responds immediately with a full throttle but mixture is now very rich with black smoke and will not pick up.
Tried all sorts of mixture and air screw settings but threw the towel in.
Initially carb was very dirty but spindle wear negligible and it all looked good. Measured the settings before it was dismantled so was confident it went back as it was but moving the screws appears to make little or no difference!
Going to remove the Zenith 24-T carb to check petrol level as it's the only thing I can think of.
Ticks over lovely but will show same richness problem when revved which prevents it being revved?
Am I barking up the right tree with float level - or just barking!
I need to get to the bottom of the problem.

Alan

What size is your generator?

Nice load bank

What is the output current of your generator? as each "bank" is dropping 20 odd amps onto it, can you monitor output voltage with it?

He has over 1 Kw with twenty lamps at 55 watts per bulb

Yes, lots of amps involved.
The engine is driving a Bosch alternator rated at 100 amps at 14.3 volts.
My load board incorporates a meter (LCD) which displays volts, amps, Watts and energy but so far with one band switched on (with relays) I measured 14.4 volts but only about 185 watts. So I think the H7 bulbs, which were cheap off the bay, aren't drawing the full current.
The engine is rated at 2 1/2hp and with the lights drawing 1100 watts (746 watts to a horse power)  an allowance for inefficiency and the H7's not drawing what they should - it is capable.
But that's not the problem I can't find a recommended starting point for jet setting?
I shall pull it all apart hoping to find a problem.

Alan

Alan, I've just done a reply, but as it didn't get through, assumed it was because you were posting at the same time. But I now realize that I clicked on POSTREPLY instead of Send doh!
I just wanted to say that as well as the float setting, I think that if the air cleaner is not standard; you should check that the air filter element is not restricting the air flow. Also maybe check that the air cleaner can has a big enough inlet area on the dirty side.

Yes I think the load unit is brilliant (or, should be).

George.

George thanks for your comments. Filter strangulation sounds likely cause.
I do believe the majority of these didn't have air filters but as I wanted to fit one I contacted one of the usual suspects (could be meetens?) and was supplied with what can be seen in my photos.
Fitted as though it was made for it but never having seen a 'real' one I'm not how similar it could be.
I shall give it close scrutiny during the post mortem and perhaps on a rerun leave it off.

Alan

My Villiers MK25HS had Zenith carb with dirty great oil filler air cleaner.

Thanks woodsman my 25HS has the same oil filled filter.
Removed canister air filter from the JAP today and blew/sucked at it's attachment port expecting (hoping!) to be met with resistance but no. It seems to have a convoluted paper element inside and is non restrictive at all! So I don't think the filter is affecting it's running condition, although I will try it without.
Next I removed and dismantled carb which all looked fine.
I have a JAP engines part numbers and reference book (pdf) which suggests the 4/2 engine is fitted with a '13' choke tube - mines 16? and the air jet is a 1.75 - mines 1.5?
Not sure how this variance would affect it's running but I can only assume that it had been performing with these discrepancies.
Anyway washed all parts again and have assembled it and replaced it on the engine ready for tomorrows trials.

Alan

Not sure if I've offered before (senility !) but I have some info on Zenith 24-T. PM me if you would like a copy.