P11sed myself

[DazzerLancs]

Was out today with my mate and his newly built rapido 225 classic. Done about 100 trouble free miles so far and all is good. Stopped at traffic lights, he put it into first to set off and scooter went into reverse!!!!! no word of a lie, never seen anything like it. What could cause this? it was fine after he put it into neutral and tried again. Nearly fell of mine laughing.

[jimmers]

did it cut out and he restart it before he went in the correct direction?

[sean brady scooters]

its possible that the timing is way out...............
too close to tdc..........
thats all i can think would cause this...............

[Mick Abbey]

its possible that the timing is way out...............
too close to tdc..........
thats all i can think would cause this...............

Sean is rite tell your mate to check his timing I have seen this before and yes it is bloody funny when you see it

Mick

[bsso78]

Ive seen that happen twice,both at Blackpool sprint years ago on engines built by the same people.....keen as mustard but as reliable as the weather!
One was in a sidecar the other a solo,the solo went backwards about a foot before it stopped.
The look on the blokes face was priceless and we had only just stopped giggling when the outfit lined up......throttle to the stop clutch dumped and the passenger promptly did a complete somersault and landed on his arse in front of the rapidly reversing outfit,the driver meanwhile was vertical hanging on to the bars as he sped up Bispham Prom the wrong way screaming like a banshee
I can see it now,it was one of the funniest things ive ever seen,names witheld to protect the guilty
Anyway the timing was so far out the engine had fired the wrong way (as Sean said)........
Later in the season the same people spent all day at a 3 Sisters endurance race trying to get their scoot to start but thats another story

[firekdp]

I would say the timing was too advanced, not too close to TDC.

[sean brady scooters]

you may well be right...........but i beg to differ..........surely the closer to TDC the spark occurs the more chance it has of running backwards.........
if for eg your timing was at say 30 degrees BTC..........it may kick back......but not actually run backwards cos in that direction the spark would occur at 30 deg after TDC..........
on the other hand..........if your timing was say 5 degrees BTDC it would then fire at 5 degrees after TDC and then stand more chance of running.................

[DazzerLancs]

Just told him about the timing, supposed to have been done, wont mention the shop but he is gonna ring you sean tomorrow and book it in for dyno and setting up. Wish I'd had me video camera, mega

[rog60]

This has happened before and was diagnosed as the engine firing on the secondary ignition pulse from the magneto. (there are two pulses, I believe, and the second is a weaker one 180 dgress after the first).

I am sure that on the graphs of an electronic ignition readout there is a small spike(pulse) 180 degrees from the main one.

[firekdp]

This has happened before and was diagnosed as the engine firing on the secondary ignition pulse from the magneto. (there are two pulses, I believe, and the second is a weaker one 180 dgress after the first).

I am sure that on the graphs of an electronic ignition readout there is a small spike(pulse) 180 degrees from the main one.

On a standard electronic there should only be one trigger pulse per revolution, although as seen on an oscilliscope some flywheels will cause a small extra pulse causing a misfire but this only normally happens at higher revs. It is the varitronic that fires every 180 degrees because this system doesn't use a pick up pulse to fire the ignition.
I'm still sure only too far advanced timing will cause this problem.