Ignition timing 125H?????? Assistance please!

[themoudie]

Good evening,

Having removed the flywheel and stator plate to renew the cam belt and put it altogether, I thought that I might have the timing incorrectly set and that this would account for the lack of performance above 60Kph in 6th gear, as described in my previous opening message thread. I invested in an Acuspark timing strobe and following the instructions had it fitted up to the 125H after warming the engine through and the results have mired me further.

With no mechanical tacho working, I used the inbuilt tacho in the strobe and at a steady 'fast idle' of ~1,500rpm the ANT mark on the flywheel is ~3° to the left of the central 'dot' on the top edge of the crankcase. I increased the rpm to ~6,000 and the ANT mark remained in the same position, neither moving to the right or left of the upper crankcase mark in the strobe light? I thought from reading the 'blue' manual that I should see the ANT mark re-align itself to the upper crankcase mark before reaching~6,000rpm.

Mystified, I spoke with Stuart at NLM, who was courteous and helpful, but suggested that I might have more experience than he with the 125H! "If only!", was my retort. Stuart suggested that I check that when the BMS mark on the flywheel aligned with the upper crankcase mark, the engine was indeed at TDC, as he thought that the valve timing might be 'out' by either a "half" to "full" tooth, rather than the ignition timing. However, when the BMS marked is aligned with the upper crankcase mark, I indeed have TDC. I suggested that maybe a transducer was not working, but Stuart thought this "unlikely".

I intend to move the stator plate anti-clockwise, slightly, so that the ATM mark aligns itself with the upper crancase mark, rather than appearing to be ~3° retarded before TDC when running at ~1,500rpm. But I still can't get my head round the lack of variability in the timing of the spark. With this strobe I can set an advance value to a tenth of a degree when viewing the marks, but I'm not sure how this helps when setting the ignition timing. As you have guessed 'electrickery' is not my forte.

Thank you for taking your time to read another tale of woe.

My regards, Bill

[EVguru]

I think that the absence of any change in timing does indicate a faultytransducer or pickup.

If you send me your address I'll see if I have a good spare transducer to lend you. If it's the pickup, I'll first have to actually go and look at one of my 125's to see exactly what setup they use!

[themoudie]

Aye Paul,
Thank you for your very generous offer of assistance, I have PM'd you.

My regards, Bill

[125H]

Hello Bill,

I wondered if you still had your 'Minx' or if you had given up on it, I nearly gave up on mine but found a cure from Anthony Tams who runs Scootronics in Stafford.

He suggested that at first I should align the pick - up with two magnetic triggers inside the flywheel, this is done with shims, if the triggers and the two contacts on the top of the pick - up do not align, then the engine will not run correctly, mine where out of line by about 2 mm. However the ignition still did not advance. So off came the flywheel and stator and all of the ignition parts, I then had a trip over to Stafford and it was all put n his test rig. Looking at his oscilloscope it was plain to see that there was no advance spike occurring, there was some head scratching but he then decided to reverse the polarity and 'eureka' the ignition advances. I can only think that over the years a wrong pick - up was fitted or it was wired in wrongly when I had the stator rewound, but its now working as it should. Now I do not know if this will cure your problem, but if Anthony cannot find it then I doubt anyone can. Have a look at his website Scootronics in Stafford, you could always post your ignition to him for test if you live too far away.

He also producers his own line of transducers and pick - ups so a compatible match can be made and he can test the correct polarity on his test rig.
I have made several attempts to resolve this problem and with many so called 'experts' and spent quite a bit of money with them with no result, so it is refreshing to find someone who knows what he is talking about.

Regards
Leonard.

[julianharty]

Leonard,
what excellent news, I'm so pleased for you. I hope we'll meet on our respective 125's soon (mine needs rebuilding after being dismantled by the previous owner and then registering in the UK, etc).