My lambretta doesn't work - any ideas?

[Adam_Winstone]

A pal had similar when he assembled and put the needle through the retaining plate, rather than underneath it, allowing the needle to move independently of the slide.

I had a quick skim read and see that you've swapped out various bits of the ignition system but have you tried it with the loom's green off the CDI, so bypassing any failure of ign switch, loom earthing, etc?

To me it does still sound like an ignition issue but could just be carb... the two often feel like each other.

Holed float? Do you have the 200 needle seat and needle to try it with? Changed the fuel out? Blocked exhaust? Fuel pipe being crimped under seated load of rider?

Best of luck.

Adam

[dickie]

A pal had similar when he assembled and put the needle through the retaining plate, rather than underneath it, allowing the needle to move independently of the slide.

I had a quick skim read and see that you've swapped out various bits of the ignition system but have you tried it with the loom's green off the CDI, so bypassing any failure of ign switch, loom earthing, etc?

To me it does still sound like an ignition issue but could just be carb... the two often feel like each other.

Holed float? Do you have the 200 needle seat and needle to try it with? Changed the fuel out? Blocked exhaust? Fuel pipe being crimped under seated load of rider?

Best of luck.

Adam

Good shout on the needle adam, but unfortunately it's correct.
Yes, I've disconnected the green wire.
I submerged the float in hot water and no bubbles so that's ok too.
I don't have a 200 float valve but it ran fine for a year or so on a 400 and I've dropped it to 300 now.
Changed the fuel out last night.
Fuel line is steel reinforced.
I guess it could be a blocked exhaust but it appears fine. How can I tell? Also wouldn't that give consistent symptoms? This isn't consistent at all.
I went from variable ignition to fixed at 18 degrees last night and it was better but still there. Is this a clue or coincidence?

[Adam_Winstone]

The benefit from the change might give an indication of what lines to follow up, however, the relationship of ignition and carburation still exists; a poor ignition will struggle to burn a rich mix, a change to either will have influence.

I'll give it some more thought and come back if anything occurs to me.

Adam

[Warkton Tornado No.1]

I doubt it's your float, but...

As an experiment, I recently tried a heavier float than the lighter type recommended for two strokes & it made an unbelievable difference in becoming rich & boggy so I only say it as something so seemingly insignificant can have an adverse affect.

We're all clutching @ straws for you...

[Feersum Injun]

Is your rubber mount ok? No split?

[dickie]

Is your rubber mount ok? No split?

Thanks. These address all good ideas but unfortunately the rubber is fine too.
I'll bet that one of these ideas turns out to be correct though and I've inspected something badly.

[dickie]

The benefit from the change might give an indication of what lines to follow up, however, the relationship of ignition and carburation still exists; a poor ignition will struggle to burn a rich mix, a change to either will have influence.

I was thinking along those lines but I don't know enough to be able to diagnose properly.

[dickie]

We're all clutching @ straws for you...

And it's appreciated

[Adam_Winstone]

Plug grade and gap?

I know that you say you have changed the carb... was that complete carb or did you swap internals from one to t'other?

Filing element on coil and issue with replacement, i.e. failing LT or pickup on one stator and then replaced with stator that has different pickup height? So swapping one problem for another?

When you say choke opens and closes OK, are you 100% sure that the plunger is seating fully? I like to adjust the cable so that it clears the air intake hole by half, which is enough to operate when ON but ensures that there is play enough in the cable to fully close when OFF.

To check for a blocked pipe, take a wire coat-hanger (or other) and ram it up the tailpipe, give it a good wiggle and then repeat.

Be doing all of these test with the loom's green off the CDI and leave it off until you've resolved the issue(s).

Adam

[dickie]

Plug it's br8es. Gap is 0.6mm

Choke doesn't open until lever is at 45 degrees.

New stator had pick up height adjusted to same as original (both bgm a.c. type).

Your other point is interesting though. The carbs were swapped but my slide and needle as well as choke were not swapped; obviously it's easier that way. I believe the other one was jetted for an avanti.

I'm not sure I've told the whole story here.........

All was fine until the fuel tap was shut to drain the bowl; les mess when adjusting needle. Needle was adjusted. Run up again on dyno; no problems. But while slowing down from this run, it started to play up. I've been mucking around ever since.

Once again thanks for all the helpnn. even if it doesn't fix it helps eliminate.

[Adam_Winstone]

Does the tap flow correctly in both positions? Knowing that you had crap in the tank, has closing the tap off allowed debris to get into the drillings/channels of the carb? If you take the float assembly off and turn the fuel tap on, does it come through at a rate of knots?

Adam

[dscscotty]

Have you done a leak down test?, I'll chuck this into the mix, recently I've seen a few drive side halite washers fail, some of which the gasket had all but disintegrated, some of the scooters, had mis -fires, difficult or unable to start, it was a swine to find, until a leak down picked it up, however it was'nt the problem that I initially thought would cause the symptoms displayed.

[dickie]

Does the tap flow correctly in both positions? Knowing that you had crap in the tank, has closing the tap off allowed debris to get into the drillings/channels of the carb? If you take the float assembly off and turn the fuel tap on, does it come through at a rate of knots?

Adam

The trouble for me with this s the definition of "a rate of knots". Do you think it should be maybe 50 to 75% of the flow rate straight from the fuel tap? That's just a guess based on the fact that it adds further restriction.

[dickie]

Have you done a leak down test?, I'll chuck this into the mix, recently I've seen a few drive side halite washers fail, some of which the gasket had all but disintegrated, some of the scooters, had mis -fires, difficult or unable to start, it was a swine to find, until a leak down picked it up, however it was'nt the problem that I initially thought would cause the symptoms displayed.

Yes Scotty, I did one a couple of nights ago and it held 5psi for the duration of one cup of tea and a couple of biscuits. Do you think it's possible that I could have an intermittent leak? I wouldn't have thought so but...?

And by the way, it's all new seals and gaskets 100ish miles ago as I replaced the crank. But remember that it's done 100 trouble free miles since the crank replacement, so I don't think I've built it badly. The problem only started after the carb was touched.

Also it starts perfectly. First or second kick at worst.

[Steve D]

It sounds like a stator problem. Have you checked the ohms readings. Had a few stators read ok, start ok and breakdown when they start to warm up.

[CHRIS in MARGATE]

I bought a brand new stator last year as a spare; 6 months wrapped in bubble wrap in my toolbox. Needed it and installed it in the garage. Started 1st kick. Strobed it through the revs and fine. Put everything back, cowling, rear runner etc. etc. Would not start !!! Meter.on the ends and everything perfect but wouldn't start. Repaired my original stator and fine.
So.... from experience, more often than not it's electrics that are suspect out of the 3 elements: Compression, fuelling, electrics.
The dodgy stator is sat on the shelf. I will probably send it to Anthony Tambs.

[Steve D]

I had new stators that sparked and readings ok, but the engine would not start or it would run crap in the past. Fitted vartronic and never looked back. You say you fitted new stators have you tried a different flywheel. Antony does talk a lot about pickup heights etc,

[dickie]

It sounds like a stator problem. Have you checked the ohms readings. Had a few stators read ok, start ok and breakdown when they start to warm up.

I can't say no as I haven't fixed it but I did try a brand be stator which made no difference.

[dickie]

Well, I'd never have guessed it; in fact I didn't guess it, but it was the pipe! In desperation I was going to swap it for an ancillotti I have under the bench a coupe of nights ago but I dismissed it as a stupid idea. How could you have an intermittent exhaust problem? Anyway I did. I think it's a loose baffle plate occasionally blocking the exit.

I swapped it for a jl3 curly I had and it's now making just over 20bhp despite a slipping clutch!

Thanks to Darrel Taylor and coaster for the unwitting loan of his bgm silencer (it was only for 5 minutes)

[Adam_Winstone]

Blocked pipe was on my list!