Oil burning after laid up
 

I have a curvy which has a big bore kit to take it to 700cc.

It's a track bike so doesn't get used much, especially after some little people made an appearance. :)

Anyway, after being laid up for 2 years it started to burn oil going through a reasonable amount in two days track use. Another lay up for 6 years this time and the oil use is now impressively bad. As in I used a litre in a morning and two of the sessions were red flagged and ended early!

My thoughts are it's likely to be one of two things.

1) Rings have "stuck" (maybe due to slight rust in the bore) and oil is either being sucked past or the crankcase is being pressurised and it's blowing oil into the airbox.
2) Valve stem seals have perished, cracked and it's sucking/leaking oil past.

Any other options it might be?

Equally are there any tests I can do to indicate which it is likely to be?

While I don't really want to open it up as the oversize head gaskets are rather pricey it's got beyond the "just keep topping it up" stage, more to the point I don't want to just do a top-end rebuild if there is something likely to be contributing down below.

Re: Oil burning after laid up
 

hmm I think you're onto the usual suspects - easy to check the airbox. Valve stem seals usually smoke on overrun as the vacuum is high - can you see anything?

Re: Oil burning after laid up
 

If it's burning a litre in what, 60 miles on the track, it should be smoking like a bonfire, unless it's pumping the oil out of the breather.

A compression test will tell you if the rings are stuck.

Re: Oil burning after laid up
 

You would have thought so but it's not noticeably smoky. I would have expected it to be laying down a smokescreen worthy of the rolling coal boys but nothing to be seen.

A bit less than a litre thinking about it as that was to top it back up up to full and then I didn't ride it again. Not sure what the difference is between full and empty on the sight glass however.

Suppose I'd better fire up the lathe and make an adaptor for the SV plugs then.

Re: Oil burning after laid up
 

For closure... I ended up getting a "new" set of barrels bored out and new rings as well as new valve stem seals.

Seems to have cured it of its oil drinking excess.

Re: Oil burning after laid up
 

Did the old barrels / pistons show any signs of stuck rings, scoring etc?

Re: Oil burning after laid up
 

Yep, rear was pitted.
https://lh3.googleusercontent.com/_q...=w1263-h947-no


Front was oddly worn.

https://lh3.googleusercontent.com/Ee...=w1263-h947-no

I asked the engine place if it could be saved but he said the bore was all over the place.

Looks like it was a bit of a shoddy job in the first place tbh...It's noticeably faster now. I should probably put it on a dyno again and see what it's making.

Re: Oil burning after laid up
 

try these people to sort the old bores http://www.poetonaptec.co.uk/cylinder-repair.htm

Re: Oil burning after laid up
 

No point, I picked up a pair of barrels off ebay for £20 and got a fresh rebore on them. I've no use for a spare set and if required I'd just do the same again. Especially as I have an a engine just for spares (£50 for a non-running engine) *and* what was a running engine as well.

Re: Oil burning after laid up
 

Interesting wear patterns there, looks like it's been bored out-of-round like your engine guy suggested ....