[gino]

Day after riding on the motorway for about 40 miles at max speed (never done this before...but was in a rush), went out for a short ride around town, but after about a mile, the engine started to cut out (jerky) at low rpms

Kept it going at high revs, but once turned off, could not restart; pressing the starter button could hear a click (just one), then nothing. Managed to push start-it and get home. The next day after topping up the battery fluid, thought I'd go around a bit to let the alternator recharge the battery. Had to push start it to get going.

After about 30mins stopped and tried to restart ...but again one click, then nothing ...so I assumed it had to be a problem with the battery

Replaced it (as it was getting old) and it started immediately; At this point I thought to myself great, problem solved! ...but as it turns out, not :

After one week (bike left idle), tried starting and to my horror ...one click, then guess what?...nothing. Tried to push start it down a very steep hill (practically a cliff), but wouldn't have any of it.

At this point thought the battery was flat, and assumed that this could have happend because of two things: a charging problem or a static discharge

Decided to get myself a volt/ohm/amp meter and a manual. Proceeded to check the battery, expecting it would be flat, ...but it wasn't ..it was fully charged (doh!).

So at least, I can probably rule out the above assumptions.

Anyhow, checked the stator with ohm meter ...and is ok.

Not sure how to check Voltage Regulator/ Rectifier ...or if i need to since it doesn't have to be charging problem, right?

Starting to think it's the ignition...now

unplugged the spark plugs and pressed start button, but couldn't see any sparks... apart from the ones flying off the battery's negative pole

Can someone please explain why this is happening?

Thanks

[DaveFxst]

Had a '91 Sporty, nice ride, pretty much identical problem. Couldn't have described it better than you did. Turns out one of the wires from the rectifier (that little square gizmo at the bottom of the downtubes) got pinched under the seat. The insulation was intact but the wire was broken inside. I had to take it to a shop to find out because the defect was invisible, but once they located it the fix was a simple wire splice that added about 4 inches and a reroute job. The leading indicator was when I took the plugs out and the electrodes looked absolutely furry from soot buildup. It cost $40 to locate and $5 to fix. Hope this helps.

[chucktx]

you have a good starting point....as the neg cable should never spark!!!!!! make sure it is good and clean.....also do the same with the pos cable and post. when cleaning they should end up being bright and shiney....a lot of folks clean the posts and wires but dont get the "black crust" off the wires and posts....the easiest way to test the charging system is to get the bike running, then use the volt meter on the battery and see if it is charging.....should be up around 14.5 or a bit better.....then turn on all the electrical....it should drop a bit but come back in a bit. it is hard to tell the condition of a battery with a volt meter....it will give you voltage but not "capacity"....or how much power is in the battery....the best way to tell this is with a load meter....there are cheap ones and expensive ones....the cheap ones work ok for casual use.....such as what you are doing...and will last a long time if used casually. once you confirm that the charging system is ok it is time to move to the starting system.....you can bypass your button and soloniod by jumping the 2 big posts on the solinoid....if the starter turns then the starter is probably ok. next is to check the solinoid engagment....take a jumper and go from the battery side of the solinoid to the post that the starter button attaches to.....remove the starter button wire first..if the bike turns over, you have proved the starting system is aparently ok.....one thing...do this with the plugs removed. im not sure, but you may have a starter relay in the system that might need attention..sorry this is so long.....just trying to help a bit and keep ya from throwing a bunch of money at a problem that might be pennies to fix......hope this helps...
chucktx

[gino]

Thank you all for your advice - I appreciate your help very much.

Only not sure about one thing from chucktx about testing the starter: ...when you say remove the plugs, do you mean remove the caps from the spark plugs or remove the spark plugs but ground them with the caps on ?

[chucktx]

remove the spark plugs....it will prevent the engine from starting, and let the enging turn over easier. with the plugs out, you may also check the spark by grounding the plugs. it should be a blueish spark, not yellow. test each plug. this should prove the ignition system to be sound. hope this helped........let us know what ya find........
chucktx