Perhaps some of the members will consider this a bodge but it has worked for me and only applies to twins efi or carb.It,s an old trick from decades ago to balance or check the balance of carbs or throttle bodies(the bike needs to have a tacho).Increase the tickover speed slightly then pull off a plug lead(rubber gloves or insulated pliers to avoid a shock would be a good idea) and note engine revs,replace the lead,let the engine settle then remove the other.The result should be similar revs on each cylinder and you can adjust the appropriate screw to achieve this but be aware which cylinder you are adjusting and which way the screw needs to be turned. On a Bonneville efi anti clockwise speeds RH cylinder clockwise slows RH cylinder.Reset tickover speed when done.I have checked this method after it being set correctly at a Triumph dealer and it gave the same result but if you do not like the idea of making adjustments then simply use it to see if it is out and then take to a dealer.
