setting the timing and points

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November 10, 2016 at 2:30 pm #1475

oldmgs
Member

OK still hard to start, so taken the head off so I can check the timing. Two questions.

Don’t quite follow the instructions in the manual. Talks about using a thin and thick feeler gauge which comes with the bike to set the points, which I don’t have. Can someone talk me through this please. Should the points be just starting to open at 3.4mm before TDC or fully open at 0.4mm?

Also it says you should wind the piston back from TDC to a depth of 3.4mm. The piston is domed so do you measure at the crown of the piston or the side?

Thanks

Douglas

 

Douglas

November 10, 2016 at 9:40 pm #1477

Gords
Member

Hi Douglas,

I wrote a reply to this earlier and submitted but thing it got lost in the ether! Great to hear that you have the beast up and running. So to your questions;

Firstly set the points gap, this should be done when the piston is at TDC (and the points at their most fully open) and the gap should be set to 12 ‘thou’ or 0.3mm (depending on what sort of feeler gauges you have) use the adjusting screw to achieve this. Might take a couple of goes to nail TDC.

Secondly to set the points opening position. Wind the crankshaft anti-clockwise until the piston is 3.5mm down from TDC (doesn’t matter if you measure this at the crown or at the side – as long as it is the same place that you measured TDC. Here I do it a bit differently to the thin feeler guage or cigarette paper method. I hook up a continuity meter or a test lamp through the points. At 3.5mm before TDC, the points should be just opening so; loosen the 2 screws on the points backing plate just enough to be able to rotate the plate clockwise until the points close and you have continuity/the test lamp lights up. Then turn the plate slowly anti-clockwise until you just lose continuity/the test lamp goes off. Tighten the 2 screws then wind the crankshaft slightly anti-clockwise (you should get continuity/lamp should light) and then slowly turn the crankshaft clockwise until you just lose continuity/lamp goes off – check that you are at 3.5mm before TDC. Repeat if necessary.

Give me a call if you would like to talk it through.

Gordon

November 11, 2016 at 9:15 am #1479

oldmgs
Member

Thanks for both replies Gordon. I have a continuity meter so will give that a go.

 

Cheers

 

Douglas

November 15, 2016 at 10:43 am #1480

Jim
Keymaster

Good stuff Gords,

I’m going to do the timing on my 501 soon so a “timely” topic all round.

Douglas, what was the outcome of the gear selector?

November 15, 2016 at 10:49 am #1481

oldmgs
Member

Gears are OK – because I have a 502 engine in a 501 frame the pedal works back to front due to the way lever is pivoted.

I spent Sunday resetting the timing – the plate did end up in a different position than I had it before. But starting still hard – fuel in the plug hole got it going for a while. I am going to try a different carb at the weekend. Perhaps Gordon is right and there is an air leak somewhere.

November 15, 2016 at 11:17 am #1482

Jim
Keymaster

Douglas,

Just so I can check mine before starting it:

What spark plug are you using and what are the jets in the carburettor?

November 15, 2016 at 1:20 pm #1483

oldmgs
Member

Plug is a Champion L82C – which is the one Motoren supply for the 502. Noit sure about the jet. Carb came with the 502 engine I installed. I’ll be taking the carb off again at the weekend and will get back to you.

For the carb Blair said:

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/

November 15, 2016 at 2:08 pm #1484

Jim
Keymaster

Thanks Douglas

I will check the 501 carby settings in case they are different.

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