Went for a quick ride today and during the ride my bike got progressively worse so turned run and limped home.

The problem is that it is losing power through-out the range. It idles fine but as soon as you put any load on it it sounds like it drops one/two cylinders making it sound like a tractor (sounds like being in fifth doing about 1500 revs, very lumpy).

Checked downpipes when I got home and working from left to right when on the bike, 1 & 2 = Very hot as normal, 3 slightly hot and 4 cold.

What puzzles me is that if it is the coil would this not affect 1 & 3 or 2 & 4, not 3 & 4.

How do I test the coil with a volt meter. I dont know anything about how to use it.

or do you have any ideas what else I should check. I have not had the heart to start stripping and checking plugs etc so any advice is appreciated