Lammy starts but dis and backfires!

[Livi- Graeme]

Had similar problem on my mates lammie today. Would tick over but flip the throttle and it would splutter and backfire. Turned out to be the connections on the red wire at the cdi unit was dodgy. Was a nightmare to suss out cause at first the multi meter was giving the correct ohms reading and then when I checked a while later it didn't. No wonder I drink

[alanscottj]

Had similar problem on my mates lammie today. Would tick over but flip the throttle and it would splutter and backfire. Turned out to be the connections on the red wire at the cdi unit was dodgy. Was a nightmare to suss out cause at first the multi meter was giving the correct ohms reading and then when I checked a while later it didn't. No wonder I drink

I can't actually find anything wrong with mine! Just been for a spin and she's running great,I haven't touched anything but I am going to check the timing tomorrow just to be on the safe side and change the plug.

[yozzer]

maybe backfires when reaches temperature

[alanscottj]

maybe backfires when reaches temperature

Not sure mate, when I rode it yesterday I was proper thrashing her around the back lanes and she ran great. I have a feeling it might be the set up - it doesn't like 'tootling' around as I was doing when it broke down. She doesn't like going slow!

[coaster]

..............I have a feeling it might be the set up - it doesn't like 'tootling' around as I was doing when it broke down. She doesn't like going slow!

If it was just boggy or not revving I might agree with you but back firing indicates that you have a definite fault somewhere. As mentioned, the stator is a likely suspect and needs carefull inspection of all the connections including the earth tag which is often loose and will need peening over. The plug is also a VERY likely suspect, I had similar issues with an LML engine recently which was due to a faulty NEW plug

[alanscottj]

Finally got around to checking out the stator, scoot has been running but not great, sound like misfiring. Took flywheel off and the stator looks fine, no obvious damage at all. I did notice though that there are two timing marks and whe I lined up the White line with the marks on flywheel, the arrow at the top isn't anywhere near either of the marks made to set timing. So I can assume that the timing may be out. Would that account for the poor running?

[storkfoot]

Yes. You can't really on those marks. You need to use a strobe at around 3000 revs on static timing

[alanscottj]

Yes. You can't really on those marks. You need to use a strobe at around 3000 revs on static timing

I've borrowed a strobe light but forgot to ask how to use it!!!!

[storkfoot]

Trust me, they are simple. I think this is the type I have:

http://scoot.net/gallery/bbs/LL1503.JPG

I have an old car battery which I charge up first. I then attach the connectors to the battery, the big red part to the HT lead, start the engine and then point the light at the tippexed marks on the flywheel and mag.

Do it in a darker garage if possible. Don't do it just at tickover, give it some revs, say 3000.

Let us know how you get on.

[ArmandTanzarian]

Mine did exactly the same. Slowly got worse until it died completely and I had to wait 8 hours for the AA. The stator was slowly dying. New stator, problem solved.