Backwards

[Nigel. S]

Hi
I have recently experienced, for the first time, reverse gear on a Lambretta

I was just out and about on a long evening trip and stopped for a break. On restarting the engine felt like it was struggling to pick up properly, a bit like if it is flooded and you think it will clear up. Don't know if that is relevant after all piston goes up/down regardless of direction of crank. Maybe un-natural rotation of sprockets chain gearbox made it feel odd. Then into 1st, clutch out and.... wtf!!! It went backwards. It is actually the 2nd time it has done it, I should have remembered the way the engine started the 1st time and known what was going to happen the 2nd time it did it. There was a few good miles between occurrences. Separate trips. On stopping and restarting it to get it going in the right direction it ran fine, a good 40-50 miles home.
My immediate thought was timing. I've had a look through some posts here and elsewhere to read up.

So far... I have had the flywheel off and checked woodruff key = OK.
Stator plate hasn't moved, but then it's running an external pick up so wouldn't affect it anyway.
External pick up hasn't moved. Trigger on flywheel is OK.
Spark plug gap was a bit big if I'm being really fussy. 0.48mm gauge was a bit loose so I closed it up so tight.
Reassembled and strobed it and timing is still where I set it when I built it about 2,000 miles ago. 17deg.

RT195, scootronics stator, external pick up.

Any thoughts? Was it a case of things just being so aligned that it was going to happen? Twice?
Thanks. Nigel.

[Andy B.L.C.]

Probably not that useful, but perhaps worth sharing...

In 1991, when I'd given up on Britain after the introduction of the poll tax, I was working at the San Francisco Scooter Center (& doing spanner work for Team Lucky-7 race team, a real underdog D.I.Y. outfit compared to the behemoth West Coast Lambretta Works team that we were racing against - the Fri night pre race tequila fueled push races around the go-cart race circuit were hilarious, & leveling, in so many ways mind - big up to Fat City S.C.! If you're thinking name dropping w*nker. fair nuff ) but I digress...

An LI 150 that we had in for a service manifested the same symptoms,but only once while we had it. It was beyond surreal, riding circles, backwards...! Now I don't know whether this was the prognosis then, or my rationalizing now but might it be if the piston is within 2 Park Drive packets of TDC & the crank, for whatever reasons, goes backwards...?

[dickie]

Which CDI are you using?

[Nigel. S]

Thanks Andy. My thinking also

[Nigel. S]

Dickie... scootronics high powered cdi (the one with two diagnostic leds)

[dickie]

Dickie... scootronics high powered cdi (the one with two diagnostic leds)

The reason I ask is that I have a bike with scootronics CDI, but not the same as yours; mine is the DC type without diagnostics. Although it seems likely that much of their circuitry is shared.

Mine is static at 18 degrees. However, often when starting, it kicks back, as if I have the ignition timing set stupidly early. It has never actually run backwards though.

My suspicion is that before it is running properly, it is prone to sparking at the wrong moment. One spark would be enough.

[Nigel. S]

Thanks, Dickie.
Funnily enough it did kick back, should've mentioned that. One to monitor I think.

[Nigel. S]

(& doing spanner work for Team Lucky-7 race team, a real underdog D.I.Y. outfit...

I like underdog D.I.Y. outfits. Especially with a 7.

[Fast n Furious]

This is why really good programabale electronic ignitions (mainly for race cars & bikes) have a software option, so you can disable the spark for the first rotation or two to ensure the processor has confirmed it is triggering at the right point so as to prevent potential counter rotation ignition, which can lead to severe engine and transmission damage with some motors if allowed to happen.
If you have enough slack in your chain on a lammy, then there is the potential for the chain to bunch up and jam between the bottom of the front sprocket and the lower chain guide if it gets started in reverse, which can make a right mess.
So beware.

[lofty]

no help, but maybe amusing..

it happened to a friend of mine on the grid at 3 sisters a good few years ago... flag dropped, throttle pinned, clutch dropped, he shot back as fast as the rest shot forward.. much hilarity was had by all

[Nigel. S]

Thanks, F&F.
The chain slack was ok last time I was in there. Not to say nothing has moved though. I'll be keeping an eye on this. A few strokes of the chin and 'hmmmm' noises too prob.

[Nigel. S]

no help, but maybe amusing..

it happened to a friend of mine on the grid at 3 sisters a good few years ago... flag dropped, throttle pinned, clutch dropped, he shot back as fast as the rest shot forward.. much hilarity was had by all

To be honest I just thought I hope nobody saw that

[bsso78]

This is usually caused by too much advance on your ignition timing. It can happen occasionally when kicking it over with the throttle open and it tries to fire after TDC because the cylinder is full of fuel.

[Nigel. S]

Thanks all for taking the time to reply.

Given that the kickstart can only send 1st gear one direction and so sprocket/chain/sprocket/crank, I always imagine a violent change of direction when this happens.

[bsso78]

Thanks all for taking the time to reply.

Given that the kickstart can only send 1st gear one direction and so sprocket/chain/sprocket/crank, I always imagine a violent change of direction when this happens.

The kickstart pedal will kick back at you when it fires but it’s not as violent as you’d think

[Warkton Tornado No.1]

Thanks all for taking the time to reply.

Given that the kickstart can only send 1st gear one direction and so sprocket/chain/sprocket/crank, I always imagine a violent change of direction when this happens.

Precisely the way that a ratchet works in one direction, the kickstart engagement teeth will be pushed out of the way, avoiding the likelihood of a broken leg. Not all powered two wheelers were as sophisticated, apparently.

Running in reverse is down to ignition timing.

You can 'rely' upon it as that is the principle by which early electric starters functioned I.e. two sets of points. The 'secondary' set could also be selected for deliberately reversing the engine in order to have reverse in certain three wheelers powered by two strokes.

Wildly advanced ignition timing results in the likelihood of the engine running in reverse & this used to occur @ race meetings. Riders could have sat with engines running on the start line, only to discover the engine had changed direction when the clutch was released, full bore in first gear. Dead funny if you saw it in sidecar racing.

I feel compelled to say that the phenomenon was due to human errors in timing of the engine, not an issue of any kind to do with ignition contract breakers!

It really has become a myth that aftermarket electronic ignitions make for a more reliable Lambretta.

[Swat]

I've had this happen to me on a few occaisions, last time at a toll both on the way to Zakopane for the Euro - caused some consternation with the lady in the toll booth as I apparently reversed !
I too have a Tambsy external pickup & mentioned it to him - he did explain, but in 'electronics speak' - any of you who have had cause to chat with him regarding his excellent kit will understand. It's something to do with the external pickup triggering early at very low rpm (or something like that)