COMMANDER RUNNING FAULT

[banjoman]

My old Boyer ignition box was packing up last summer. I bought a new digital ignition box from Graham at Startright. This caused lumpy running and the tacho needle was going all over the place. He replaced this and I got another which was the same but not quite as bad.Investigated and found ballast resistor had failed due to rotten connections. Got new BR and wired up last week - I had to swap round the pickup connectors after fitting BR (not sure why?) - still have the lumpy running!!I fitted new coils (which I had in the garage) and problem still there.Has anyone encountered this problem and if so what caused it as I am running out of ideas and really need to get the bike running for last weekend in April if possible.StuartCaithness

[W588]

Stuart,Having had some experience of Graham's digital box, I doubt very much if this was the fault. The fluctuating tacho indeed suggests an ignition fault, but a defective ballast would not give such an indication at the tacho.If all the wiring connectors are in good condition, I think it might be an intermittent ignition trigger fault, perhaps a broken wire in the sensing coil, or the air gap is too wide.There is always the possibility of course that the side stand cut-out is only just making contact when the stand is up. With the engine running, move the stand slightly to see if this is the case. If so, adjust the screw out more.Mr Grumpy

[banjoman]

Thanks Mr GrumpyThe ignition trigger resistance is okay but why should the air gap change if it has bever been touched? Maybe it is faulty and I will try to get another. Hopefully it wont be too difficult to change!Sidestand switch was removed just after I bought the bike new in 92.Connectors all look okay and clean!TaStuart

[Joe]

Hello Stuart, Over the years of riding in all weathers I've also experienced similar misfiring which in every case was traced to poor connections though none affected the tacho. Most of my problems were found to be caused by corrosion or verdigris build up which was cured by careful cleaning of the contacts or replacement altogether...... Although you have replaced the ballast resistor and coils It's worth checking very carefully the two spade connections (Brown/White wire) to the resistor and the three ring (Black/White, Black/Yellow & Brown/White) and two spade terminals (Brown/White & Yellow wire) on the coils the Yellow wire being the tacho feed. Mine have all been replaced over the years some several times. Also check the three pin plug and socket (B/W, B/Y & Br/W wires) as this is the feed from the ignition box to the coils. Three other areas are worth checking, the 10A ignition fuse connection (Two spades from underneath the fuse box), the large Lucar connection on the bottom of the starter relay (Two fat Brown/White wires) which is the main feed to the bike, make sure it's a clean and a tight fit and lastly check the Three Nine way connectors (Black, Red & White) recently a broken wire here caused me to stop at the side of the road, sorry can't remember off hand which colour plug or wire it was. Incidentally, I also use a digital box from Graham which I've had for 5 years and have since covered 80,000 miles without any problems. On one occasion when my voltage regulator packed up I even passed about 24 Volts with no ill effect to the box, they are very robust. I have however removed the troublesome ballast resistor and use 12 V coils which I recommend. Good luck, Joe.

[banjoman]

I have given up with trying to repair it as I am totally flummoxed(?).New ign pickup, new coils, cleaned all connectors, new vac line to fuel tap (was broken), plugged LH side vac point as it was missing too. COmmander now mothballed until late 2008 when it will get rebuilt.Have got 2nd hand Guzzi Targa to use in meantime. Thanks to all who suggested remedies to the lumpy running and bouncing tacho problem. I just lost the will to do any more to it and working on the electrics is so damn sore on the hands!Ride safe and smokily!