For the first time last year I noticed the oil level in the sight window drop during the course of the summer.
It went from completely 'full' (actually overfilled past the sight glass window) to empty, in about four thousand miles.
This year I decided to check the oil usage, and I've worked out that it's using around 175ml per thousand miles.
It doesn't leak, so it's presumably rings/bores or valves/guides, or a combination of both.
I also think, it's down on power, but despite having had the bike from new, I can't say exactly when I first noticed it.
As regards how much power it's lost, my guess (and it truly is a guess) is about 10bhp - 15bhp
It's also noisy when you start it up, the sounds seem to come from the top end (cylinder head/barrel), but it does quieten off a bit when it's warmed up.
However on the plus side, it still starts easily, doesn't misfire, and the exhaust doesn't smoke.
Anyone else had this issue, or something similar to it, and if so, did you isolate the cause?
And if you did isolate the cause, is it worth* trying to fix it?
*worth = cost and piss-malling about.
Basic bike details below:
2001 FZS600
Mileage: 74,000, serviced regularly, and ridden hard regularly, but not deliberately abused..
Engine, gearbox, clutch etc. have never been touched, except for checking the valve shims at 30,000 miles.