900 Sprint - Long winded!

Hi folks,

During the summer, my other halfs 900 Sprint "broke" it's ignition pickup (cut out when hot, ran when cooled down).

I swapped the sensor over from mine, and all good. Since then, it has had a weird problem.

On idle, the engine will miss a beat and recover or will just cut out. The tacho needle will drop to zero and flick back up if it doesn't cut. Video here:



This is what we have done so far:

New battery, new coil and pluglead (swapped between all 3), new plugs, CDI unit swapped from mine, carbs stripped and properly cleaned, new intake rubbers. All accessible wiring plugs checked and cleaned. Wiring loom "manipulated" to check for breaks. Have ruled out the fuel tap diaphragm.

Any further ideas? Somebody has suggested alternator, with the "low speed coils" acting up. Personally I'm not so sure, but I do have a spare if needed.

Any further ideas? I'm getting grief here - We have a funeral on Wednesday, and the loan bike option is a Suzuki which she is keen to avoid!

Any advice appreciated

J

 

View attachment 13686 View attachment 13686 She still fires up on the button.

Revs cleanly. Nothing different apart from this issue. Occasionally on cranking it will drop down and almost stop (like a car with the distributer set to too much advanced) giving a couple of slow wuh wuhs before picking up again and firing. I put that down to the battery, which was pretty much shagged hence the new jelly. It hasn't quite cured it - It will do that when it's hot after a 20 mile run. Both issues seemed to appear at the same time!

Hopefully the next video will show things a bit better, as soon as YouTube can actually bothered to upload it!

J View attachment 13685 View attachment 13685

 

Here we go. Sometimes it will dip down as in the video, other times it will just cut out, like the kill switch has been pressed. Usually at a junction!

 

Yep, plugs were the first thing to be changed....