501 "finished" but with issues

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October 23, 2016 at 3:38 pm #1430


Hi NZETA people

I have “finished” the NZETA (501 with 502 engine) and have been round the block, see video here


Few problems someone might be able to help with.

  1. It is very hard to start (I am using the kick start) and only way I can get it going is to squirt some fuel into the cylinder through the spark plug hole. Once running it pulls well and seems to have plenty of power. I do have a choke fitted. Any suggestions?


  1. The generator does not seem to be charging (ignition light flickers but does not go out) and starter does not work – I fitted new brushes, and had the commutator cleaned up. I do have two other generators to try. I have a new solid state rectifier. The starter does “try” to turn the engine so I think the wiring is good (new loom). I have a new battery.

3      Bigger problem is that the gears are back to front! First is where 4th should be – i.e. you push down on the front of the lever to engage first and on the back to change up. Did not think that was even possible! Not sure if I have all four gears, but certainly 3. Would it be possible to put the gearbox together so that this happens? The gear lever is on the right way i.e. pointing up. Guess I will have to pull the engine but thought I would seek advice first.



October 24, 2016 at 8:39 am #1431


Hi Douglas.


Your Nzeta looks great and teething problems are par for the course. Nothing major by the sounds of it.


Your gears are in the correct order, for first you should be pressing down on the front and the back to change up. Only the poms did it the other way around.


The hard starting could be a number of things, but I’d be starting with ignition timing. On your video your engine the engine seemed fairly flat at low rpm, that would definitely point me in that direction. Failing that I’d go through the carb and make sure there’s nothing blocked.


I had an issue with an Nzeta not charging as it should and found that if the battery is not charged fully before it’s installed it won’t work properly. Also just check all your connections in the wiring loom, especially the ones to and from the battery. Any resistance there will cause grief.  Stating the obvious here but  it’s a positive earth system, make sure it’s connected the right way.


That’s my 2 cents, hopefully it’ll give you somewhere to start. Anyone else have anything to add?



October 24, 2016 at 9:53 am #1432


Thanks Mike, very helpful. Good to know the gears are right – did not fancy taking it to bits again.

I am confused by the manual though – I have an originl 502 one and it says on page 20 “… shift into bottom gear with you left foot by depressing on rear part of the gear change lever” then to change up “… depress the front part of the lever” then …”When changing down depress the rear part of the lever.” Were export ones configured differently?

Timing sounds like a good place to start – I did take out and clean the carb yesterday, but it was all clear. I wonder if I have the needle in the correct position – what level should it be at?

The battery is new and was fully charged. With the solid state rectifier you have to change to negative earth which I did – and “flashed” the generator. But I will check the wiring again to make sure the neg is going to earth.

Anyway I will deal with the sarting issue first.

Best wishes


October 27, 2016 at 11:08 pm #1460


Hi Douglas

Nice vid mate, and great looking scoot!  Nice one.

Oh god, yes the fettling to get these old girls going right… have spent many an hour on this, very frustrating at times huh.

As Mike suggested I’d be checking engine timing, and cleanliness of the carb’s innards, as you have.

502’s have a different gear lever to the 501.  502 has a tab protruding through the floor board, whereas the 501 has a spline on the end of the shaft.  Depending how you configure the rest of the levers off the splines and gear change rod, it will affect how you use your foot.  My 501 and 502 changed gears the opposite way around, very confusing when swapping from one to another.  They do have different gear shafts inside the engine too, so not interchangeable, not that I tried.

My 502 is stripped down, but I remember it was 1 down, 3 up (if using my toe).    The 501 was 1 up 3 down.

You may be kicking it straight into 2nd if you it feels like you only have 3 gears.  Have play around and do some adjusting and see how you go, I found it a bit of a balancing act to get right and affect gear changing smoothly.

I agree about the battery needing to be at optimum charge to dynastart the scoot.  I had a 12 amp hr battery on my 501, but got a 14amp hour for the 502 as 12 I felt was not strong enough.  I use a 12 volt battery, not 2 x 6 volts as they were originally, what are you using?

Dynastarting from cold could be a cow, and I think the manual recommends kicking it over a few times before doing it electronically.  You should be able to kick start it reasonably easily once run in, think about 2 – 3 kicks was the most when running well.

Here is the 502 carb setting from the manual:

2429 S 13 Carburettor on the 502/00 to 01 models
Main Jet 109 to Solex
Idling Jet 40 to Solex
Needle position 2nd notch from the top
Pilot air screw slacken by ½ to 1 turn from tight /anticlockwise/

October 28, 2016 at 8:51 am #1461


Thanks for all that Blair – now I understand the gear issue, of course I have a 502 engine in a 501 frame and I must have been reading the 501 gear change instructions in the manual! That was my main concern – other things I should be able to deal with without taking the engine out.

I have one new 12volt battery under the seat – not sure of the amp hour – I’ll have a look tonight. What I may try is “jumping” it with a 12volt car battery and see if that will turn it over.

I’ll check the carb and timing at the weekend.

Could be worse. When I “finished” my MG TD, I had to remove the engine twice again to fix problems.



October 29, 2016 at 11:35 am #1462


Just had a look at my battery – it is only 4Ah! So a bit light for the job I fear. I shall obtain another one.



November 6, 2016 at 4:14 pm #1474


So, I have bought a nice grunty 14Ah battery, enlarged the hole in the seat box and fitted that. Starter still did not work – then it did! Then it didn’t, then it did again. So sometimes it works and somtimes it doesn’t. But anyway at least I know it works. It could be the ignition switch. I bought a new one from a guy in Oz, but everytime I put it in the panel it blew the fuse. He had no more, but said he would fix it if I sent it back- which I did – and it no longer blows fuses and everything else it is meant to do it does – lights etc. But perhaps a bad contact in there. Anyone know of a suouce of these switches with the starter position?

Anyway, I do have a kick start and bigger issue is that it still almost impossible to start unless I squirt a bit of fuel in the plug hole, but even then it will not run for more that 30 sec or so. I tried moving the timing plate a bit left and right, but did not seem to help. There is a nice fat spark at the plug.

I checked the carb needle was in the right groove. I do have another nice looking carb I could try – but it is a 501 engine carb with no choke, just the float depressor (my engine is a 502). Will that carb work with my engine?

Any JAWA mecahnics in Auckland!



November 10, 2016 at 10:04 pm #1478


Hi again,

Starting issue (petrol through plug hole) makes it sound a bit like inability to suck enough fuel through to the motor so 2 likely causes firstly; choke not operating properly or blocked passage(s) secondly air leak on the intake side – this could (unfortunately) come from a number of places – easy ones would be gaskets between carb / bakelite spacer / motor. Worse ones would be crankcase mating surfaces – between the crankcase halves or even barrel to crankcase joint.

If you can get it running, you could try getting a spray can of CRC ‘Engine Start’ (Bunnings or Repco) and while the motor is running, give a little spray around some of the suspect areas mentioned above – if you notice an increase in engine revs, you may have found the problem. Obviously if you spray it around the air cleaner / intake the revs should increase too but this wont be indicating the problem.

Wouldn’t hurt at all to try the other carb, certainly no short term issues – jetting leading to lean-ness or richness might be longer term.

Good luck

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