Well thanks for the advice folks. I checked the oil when cold and sure enough it was at the full mark, way overfilled by somebody. So I decided to give the bike it's annual service even though it has only done a 1000 miles in my care and since it's last service, that according to the service book was carried out by an independent motorcycle garage in Wales.

To start with I drained 3.8 litres of oil (!) from the bike, changed the filter and have carefully measured and refilled with 2.8 litres as per the book.

Then I found the head of the screw to remove the right side panel had been completely mashed by somebody, so I had to drill it, then remove the remains of the screw with mole grips. My air filter looked like this



Then I removed the spark plug, which I had wanted to do when I bought the bike because I thought it was running a little rough and down on power, but until recently I couldn't get hold of the right size spark plug socket. It looked like this



Note the crush washer is rusted into place half way along the thread and at an angle, the spark plug was not even screwed in properly. No wonder the bike doesn't like river crossings and deep water!

So looks like by bike has been maintained by a complete idiot.

Damn it! The oil pressure check bolt has had it's head mashed by some idiot with a spanner too! As I was doing it back up the thread stripped, it still had a couple of mm to go, was turning quite happily, then just a touch of resistance and before I had a chance to react to it, turns free again. Took the bolt back out again and the thread from the inside of the oil filter cover was wrapped round the screw. So now I have had to drain the oil again so I can take the filter cover off and a friend can drill and re-tap it for me (I've never got round to buying a tap and die kit)!

Arrrgggh! My friends expression was, "Well your bike has obviously been maintained by Stevie Wonder"

So you took out 3.8ltrs AFTER taking out 400ml from before.......... Phew! It had 4.2 ltrs from a recommended 2.8! Jeez, I daresay it wouldn't run well from that amount inside it. Good job you drained it and started again methinks!

The state of the air filter and plug makes me think what else has the previous owner bodged or neglected to do..?

Have fun!

__________________
Geoffshing

'Security is a product of one's own imagination, it does not exist in nature as a rule, life is either a daring adventure or nothing.'

No, I took out 3.4 litres, then add the 400ml, and you get to a total of 3.8. Still it was a litre over!

To be fair, I don't think the previous owner had a clue about bikes, and the bike has a full service history, so it's more like what his garage has neglected to do. I'll stick up the service history shortly.

Does make me wonder though. The bike only has 9000 miles on it, so hopefully nothing really major has been needed (and missed!), but given that I now know I can't trust the service history, I'll be doing the rest of the stuff that should have been done on an 8 year old bike, like changing brake fluid, servicing calipers, etc. Just so that I am happy that the bike is is good condition.

I need to rub down and respray the frame under the seat, and the rear swingarm too as they are showing surface rust in places.

Service History

April 03, 652 miles, Sale Yamaha Centre, Manchester
May 05, 3750 miles, Bill Lomas Motorcycles, Chesterfield
Dec 07, 6829 miles, Jonesies Motorcycles, Conwy, N Wales, Spark plug, oil filter and oil on the invoice
May 09, 8220, Jonesies Motorcycles, Conwy, N Wales, Front pads, Oil filter and oil on the invoice

So the spark plug was probably fitted by Jonesies in 2007, it would seem to have been fitted badly from the start as the crush washer had never been crushed, so it's not like somebody has removed and refitted it since, unless an amateur has changed the whole plug since, but the last owner who used Jonesies said he knew nothing about bikes and had never touched it. And it has probably never had a new air filter since new. The overfill of oil could have been the previous owner.

I misunderstood but here's where I got my math from.....

"Thanks everybody. About removing 400ml, but the dipstick level not dropping, is there a maximum that the dipstick can possibly read, and I still haven't dropped below that, ie: I had more than 3.1 litres of oil in there?"

Added to........


To start with I drained 3.8 litres of oil (!) from the bike, changed the filter and have carefully measured and refilled with 2.8 litres as per the book.

= 4.2ltrs. I had a vision of oil bubbling all over the place..!

Anyhow, subject finished........ you have it done, good on you! It's good to know that when you've done a job yourself that it's done correctly.

__________________
Geoffshing

'Security is a product of one's own imagination, it does not exist in nature as a rule, life is either a daring adventure or nothing.'

Regarding the bleed screw, I wouldn't bother with the whole tapping etc business. The small cover it fits in to (assuming we are talking about the oil filter cover bleed screw) is not expensive and easily obtainable from any yamaha dealer. If you ask me it's better to get a new one and keep it all standard.

Yep, I see where your maths comes from, my posts were misleading. I only actually drained 3.4 litres, but I drained the oil into the same container as I had used to empty the 400ml, so when I measured it at the end I had 3.8l

youll find that if you check the oil, and its too high, check it again and its too high then you need to keep removing oil untill it gets to the correct level because the bike can only put so much oil into the oil tank at any time and the excess is generating pressure somewhere it shouldnt be..... ive always been told you can damage an engine by overfilling, does anyone have a definitave answer on this?

Permanent engine damage on a modern motor is unlikely. In the old days before good crankcase venting, pressure could be put on rubber engine seals, especially in very cold weather.

Nowadays fewer internal/external seals are used and most modern motors (like the XT) have good crankcase pressure venting.

Normally, on most bikes when oil is overfilled, the oil will have to go somewhere. At higher RPM's it can be pumped into the air box on many bikes. Most vent from the crankcase into the air box. Excess oil can then be drained from the air box but often times the air filter will become soaked with oil. A foam filter can simply be washed. A paper filter will have to be replaced.

Too much oil means much more friction or drag on the crank and internal moving parts. Too much oil pressure can also cause oil burning, as the excess oil level and pressure forces it past piston rings.