Series 3 TV175 - ignition…?

[greenfingers]

Hi……please bear with me on this. Fairly new to all this.
I have a series 3 TV175 which I got from Cambridge a couple of years ago. 186 kit, Dellorto PHBH 26 car with remote filter. I think Ancilotti exhaust. Variatroinc ignition.
Its ran like a dream for a couple of years - in fact like a little rocket and no problems until last summer when she started to 'cough' a bit when she got warm. To be honest I didn't take too much notice until it worsened recently when it started to run like it had square wheels. Things I've tried:
1. I've checked an I'm happy with the fuel/oil ratio
2. I found a small tear in the rubber Mallossi inlet manifold so i replaced it - secured on nicely.
3. I've took the carb off more times than i can remember and removed and cleaned out all the jets with compressed air. I'm happy they are clear.
4. I've always got the fuel from the same garage and there are no signs of the float being distorted
5. Numerous new plugs
6. I've re torqued the head and checked for and re tightened the outlet manifold. Happy no air leaks there.
Although the wiring is a bit patchy - it all looks as though its in good order.
7. No excessive amounts of smoke and no signs of burning oil. Exhaust off and no signs of blockage…
8. I've drained the fuel tank, cleaned it out as best i can and replaced the fast flow fuel tape and fuel line. Fuel poring through at the correct rate.
…..But there bugger just will not start…..I have to be honest…..I'm not happy with the spark i'm getting. Its not the brightest I've seen and unless I'm not earthing the spark plug sufficiently when i try and kick it over (by hand) and hold the plug on the side of the frame or engine….I think that's where the problems lie.
Ive took the head set off and disconnected the ignition switch feed and guess what…..patchy spark from there to earth too…

i have rung cambridge and too be fair could simply run it up and write out a cheque but i'm determined to sort this myself….
If i remove the fly wheel and take off the stator plate - is there a way of testing that independently of the scooter…?
Does anyone think I'm looking in the right area….? or have any ideas. Do we get a poor spark when your trying to do all this single handedly holding the plug on, kicking her over in the garage…?

When all this started it felt a lot like fuel starvation but that simply cannot be the case now. i have a glass 'bubble filter' in the middle of the fuel line which i felt contained fair too many air bubbles for my liking so that's gone too.

Any ideas or suggestions would be massively appreciated…

Martin (NE London)

[CHRIS in MARGATE]

Sounds like Low Tension (LT) coil. Somebody will be along with the resistance value in a minute.

[Wack]

http://www.lambretta.co.uk/downloads/vari1.jpg All the info on here, but check you have a good earth between the CDI, reg and engine case. Cut a small bit off the HT lead and hold this a 1/4 " from the engine mount to check for a spark. If weak it maybe the CDI has gone although the stators do play up. It would be easier to borrow another CDI to try rather than buy one then find its not at fault.

[Callummal]

hi the piston rings could be warn

[torquewrench]

Since you said it felt like fuel starvation…..
Have you checked that the breather in your petrol filler cap is working properly ?
Try starting or running with the filler cap either off or loose.

I had a similar problem on my Indian GP, which I cured by drilling a one mil hole through the petrol cap.
Sometimes, but not always, the cheapest and simplest solutions are the right ones.

[greenfingers]

Thank you I appreciate the thoughts/suggestions. I was under the impression that by taking the live off of the stator and brushing it against the frames list turning thee fine over I should get a fairly strong spark but I didn't - which, as it wasn't particular strong or consistent - made me think it was a fault from the stator end rather than the CDi......
Genuine question..... I am in the right line aren't I...???

[CHRIS in MARGATE]

I absolutely hate testing for a spark on my own!
Get a big crocodile clip similar to jump start leads and earth plug body ( not centre electrode) via a length of wire to GOOD earth. Or wrap several turns of stripped wire around plug and secure with elastic band. Then kick (preferrably in the dark !!) and check for spark. Work backwards and try HT Lead.
To test stator use a multimeter set to ohms and should read between green from stator and earth approx 290 ohms.
Fuel filters cause problems !

[greenfingers]

Brilliant suggestion re testing the plug. On it tonight!!! Thank you

[CHRIS in MARGATE]

Wait till midnight !

[greenfingers]

Right. I bought a multimeter today and switched it to 2000 ohms as instructed. I have 2 wires that come away from the magneto that are in use….a blue and a black/red. Both white/red and white/yellow are terminated. I have no battery on this scooter and the lights run purely with the ignition.

The blue goes directly to terminal 2 on the reg and from there off to terminal 2 on the CDi. The black/red goes directly to terminal 1 on the CDi with a a think green tagged into it run off to the ignition system.

The readings on the multimeter were very jumpy…is this normal…? Blue = about 4 ohms (but hovered all over the place) and the black/red 200 ohms…and fairly stable.

Do these readings take a while to settle down…? our is this a clear indication of a fault with the stator…..?? thanks for everyone so far…

Re previous suggestions……fuel cap is fine by the way and re piston rings…I'm sort of hoping its electrical first to be honest.

Martin

[CHRIS in MARGATE]

Measuring continuity through a straight or coiled wire should be a stable reading although digital multimeters can flicker for a second or so by very small amounts before settling down. It can be similar to standing on digital scales and hoping it wil settle as it moves up and down by 0.1 or 0.2 Kg.
What does the meter do if you short its 2 leads out? I expect that may take a second or two.