JAP 4/2 (Engine no. P15904UVX)

That's great news Alan, hopefully all will be well with those parts fitted.

George.

Replacement jets and choke tube arrived so dismantled the carb (again!) to fit the new parts. Original choke tube was quite difficult to remove but with the application of plusgas and heat it eventually came out.
Fired up first time as usual and immediately noticed a big difference - it ran properly. Warmed up and set revs to about 1850 as measured with a digital tachometer and switched in my load banks one at a time up to the maximum. Engine speed momentarily dipped as load was applied but responded immediately to the increased throttle - it sounded great!
Full load is 20 H7 headlight bulbs which in theory should use 1100 Watts although only 720 Watts was measured (alternator giving 13.8 v) so I guess my Chinese bulbs aren't quite the ticket but certainly allow the engine to do some work.
Video is at 720 Watts with lights visible in background.

https://youtu.be/0i-IEiQ9WDM

Alan

got it in one or wire a switch in the earth wire, if you look at other pictures of Wico magneto's they have metal tags earthed to the body which you press against the stud to short the magneto.

Maryalice

The mag has the metal tags (I had to make them) which as you say are pressed to stop the engine although I usually turn fuel off and let it use what's in the carb.

Sometime it it's past it has obviously had a carb swap - right type but incorrectly jetted. The Zenith 24T-2 was used on all sorts from tractors, Austin 7's and a variety of stationary applications. Must be many thousands about.

Alan

Yes, that runs nicely now.
Glad you sorted it.

Had a persistent petrol leak from the combined fuel tap/glass bowl.
It would seem that in it's past the bowl clamp has been over tightened distorting the diecast top making a seal difficult/impossible!
I have flattened this before but it appears the original cast material has lost some of it's strength and despite only tightening the clamp moderately it readily distorts.
It really needs replacing but as a temporary get it running fix I have 'repaired' it by sticking the glass bowl into the diecast top using JB Weld!
Trial run proved it successful, videos of it at tickover and generating 13.6v @ 55 amps - sounds much better in the flesh!

Alan
https://youtu.be/vb5pYOrKXtM

https://www.youtube.com/shorts/wTNjDnwC4zg?feature=share

Is it the Wipac type combined unit?, Viliersparts have spares.

Thanks, yes that's the beastie and it seems good value but I wanted to sort it quickly although I will probably order a replacement as obviously I can't now remove the sediment bowl!

Alan

Decided to give the JAP 4/2 a run today. Didn't want to fill the tank with fuel so rigged up a lucozade bottle with petrol tap to supply the Zenith, this was hung from a rack.
Started second pull and gradually eased choke off and it settled to a fast tickover to warm up before I loaded it up with the alternator.
However it didn't play ball, running gutless and stopped! Didn't want to start but eventually did (reluctantly) and ran gutless, stopped again. Checked for spark - ok, so decided it must have debris blocking the carb, decided to run it if it would cooperate until float bowl was empty prior to dismantling.
It was at this point it discovered the cap on my temporary fuel tank was done up and causing a vacuum within preventing petrol flowing - with the cap loosened we were back to normal running!
Ran it under load of 720 watts as measured on my panel meter and while it was running out of interest I marked the level in the bottle and after 10 minutes of 720 watts load remarked the bottle.
At this load it was using 1.2 litres/hour. After a good run (and probably all the neighbours could stand!) I treated it to its first oil change since it's rebuild.
Link of it under load (quite noisy in the garage)
https://www.youtube.com/shorts/cFXI77xJJVc?feature=share

Alan