Squirt some WD40 or a drop of oil onto each one of your exhaust header pipes just where they exit the cylinder head. Now run the bike around the block and have another look at the header pipes.

Some of the pipes will have burned the oil off themselves while others will have not. This can tell you lots about each cylinder in relation to the rest.

For example three pipes are clean; Well, we already know which cylinder the fault is on then don't we? First check the plug cap on that cylinder for disconnection from the lead. No?

Well as long as the plug is clean, the fault is probably carburation. Suspect your carb diaphragm on that cylinder (a cracked plug cap will probably affect a pair).

Two pipes clean? Well, are the two a pair (1 & 4 or 2 & 3)? Each pair runs of the same ignition coil so one pair not burning probably means an ignition fault on that coil (or a cracked plug cap).

Two on the same side? Oh dear!Definitely not ignition now, so that's eliminated on that one! This is serious carburation possibly mechanical. First take out the plugs and check for compression (if you don't have a gauge stick your finger over the plug hole and hit the starter button, as long as the motor's not too hot it should push your finger off the hole, if it is it'll burn your finger). Got compression on both? Then you probably have a fault on two carbs! Possibly float heights.

Only one pipe clean? I don't know how it got you round the block but it might be time to start thinking about trading it in for something a bit more reliable.

Ride safe!

First published in Streetbiker Feb/Mar 99. Dennis aka Mr Loobman is the inventor of the Loobman Motorcycle Chain Oiler