sounds like the resistor mod as thats what it causes to happen above 5500rpm.

mo haggs wrote:bike is still skittish round 5500rpm and7500rpm upwards, plugs are producing a weak yellowish spark - could this be the regulator or (dare i say it) the generator?

If it's speedo related it will cut the spark to 2 cylinders after 5500rpm, check to see that all plugs are firing after this.

A good preliminary check for charging problems is to check battery output at different rev ranges, it should read somewhere between 13.2-13.8V.

Generator is easy to test.

Make sure it's not connected to the RR unit (Remove the plug!)

Put the multimeter on the lowest Ohm setting if it's manual or Ohms in general if it's auto.

Before you test the generator short the two probs of the meter togeather, it should read 0, if it shows a value you'll need to subtract this off the values you get while testing the generator.

Test between each yellow wires in the plug, all the values should be between 0.1 and 1 ohm, anything other than this indicates a faulty generator.

If it passes this test, test each yellow wire to earth, the meter should NOT give a reading, ANY reading here is a knackered generator.

If it passes both these tests leave the generator disconnected and set the meter to AC voltage. Connect the one wire to a yellow wire and the other to earth, start the bike and hold it at 5000rpm, you should have 50v from each wire. (turn off engine between swapping the probes)

If it passes all of these tests it is more than likely working fine.

You can then check the Reg / Rec unit.

With the bike Idling at 5000rpm when the generator is reconnected you should have 13.8v across the battery, with the multimeter set to DC voltage.

Oh and btw it STILL sounds like the resistor mod to me.

before doing any of the above tests, run the bike and see how its running, remove the resisotr and see how its running, if removing the resistor makes no difference then theres your problem ^_^

See my reply in the Technical Tips section.