Hi I just need a bit of help from anyone,I recently have done the exhaust system,ecu,carby upgrade kit,koso rx1n taco and a few other things,the problem I'm having is prior to doing the carbys my bike idles and ran fine but I have completed them and put the mixture screws to their settings,since fitting the carbys the 2nd cylinder has no spark and the 4th cylinder has a weak spark,1&3 are fine,I have replaced coils,new spark plugs,swapped 2nd cylinder spark lead around to no.3 cylinder with a good plug,leads get strong spark,I have tested the coils for current and there ok,I replaced the original ecu and still the same,I've cleaned all earths,checked all loom clips and all fuses and I took out the loom and made sure that was ok,I just haven't power tested the loom but I have full current to the coils,........HELP PLEASE!
Thanks, Tristan

Hi I just need a bit of help from anyone,I recently have done the exhaust system,ecu,carby upgrade kit,koso rx1n taco and a few other things,the problem I'm having is prior to doing the carbys my bike idles and ran fine but I have completed them and put the mixture screws to their settings,since fitting the carbys the 2nd cylinder has no spark and the 4th cylinder has a weak spark,1&3 are fine,I have replaced coils,new spark plugs,swapped 2nd cylinder spark lead around to no.3 cylinder with a good plug,leads get strong spark,I have tested the coils for current and there ok,I replaced the original ecu and still the same,I've cleaned all earths,checked all loom clips and all fuses and I took out the loom and made sure that was ok,I just haven't power tested the loom but I have full current to the coils,........HELP PLEASE!
Thanks, Tristan

Welcome.

For starters -I would swap the coils and plugs from 1/3 to 2/4 and see if it follows the hardware or not.

I have had issues with my '92 vfr 750. It turned out to be high resistance in the plug caps.....
They are easy stripped, cleaned & rebuilt to correct the resistance - 5k ohm on the 750.

The bike now runs perfectly.

I'm going to check this on any bike over 10yrs from now on.
It's certainly worth checking!

Pip

If you remove the original clocks the bike won't rev over 5500rpm without a delimiter on the bike.

Could this be your issue?

Don't post multiple threads with the same issue either. I've merged these together as you were getting replies in both.

How do you check the coils for current, do you mean resistance? As pip said, check the coil secondary resistance from one plug cap to the other. Should be no more than 25k ohms.