Hi everyone 

I have a question to ask ? Are there different size magneto,flywheels ( internal),I ordered an electronic ignition system from in motion to replace my FEMSA  ignition system,I have not been able to ride for 5 years now and wanted to upgrade to make starting easier. On receiving the parts I set about removing and replacing ignition system as directed only to find on trying to start no spark, checked wiring,plug  etc,no spark .on removing everything again I looked at the original fitment to flywheel/ magneto to find the electronic system doesn’t fit anywhere near as snugly hence no electrical connection so no spark 

 

Mickeyg - 

Not entirely sure what your problem may be but you may have introduced some confusion in the title of your query, and possibly the details you supplied to In.motion ;-

model 91 is a 250 Sherpa, 350 would be a model 92 (for bikes of same age and model range.)

Femsa original equipment for the two bikes used different weight flywheels, although I had always thought they were similar (identical?) internal diameters.

More detail required - pics. possibly ?

Ah, I see you refer to Model 92 350 in your very first post...............   so which is it ?

Edited May 10May 10 by lorenzo

The ID of the flywheels for Sherpa Ts with original points FEMSA ignitions are all the same.

The flywheels on different Sherpa Ts are different weights and this is achieved by using different materials for the body of the flywheels. Light ones are cast aluminium and heavy ones are cast zinc. 

There are quite a few different modern electronic ignitions available to suit the Bultaco Femsa flwheel and some have the stator coil position adjustable to minimise the magnet/winding gap. However I have recently fitted two ignitions from In Motion on Bultacos and neither required any sort of adjustment to work well. i did not measure the magnet to stator coil gap on either.

It would help you work out what is going on if you post up the flywheel markings or even a photo of the flywheel. Maybe yours had a different type of flywheel fitted before you got it.