Why is my bike using oil???

What does it say on the that cover in the dinky little picture?

Originally Posted by Graham

What does it say on the that cover in the dinky little picture?

Factory Pro

vtour

[embee]

Breathers - the reason V-twins (and big singles, 360deg parallel twins, boxers etc) are significantly different to multi-cyl engines is that the piston motion means that the crankcase volume is cycling up and down greatly as the engine rotates. A 4-cyl inline engine "exchanges" gas between cylinders going up and those going down, as do other multi cyl arrangements (more or less).

This means that there is a lot of bulk flow and reversal in the breather pipes in addition to the actual blowby, which can tend to carry more oil mist. There also tends to be high pressure reversals in the crankcase, which can give more joint leaking problems than in an L-4.

However, oil consumption associated specifically with high speed+load is usually piston ring and bore geometry issues (generally termed "piston/liner interface). Particularly with the short slipper type pistons as in most modern bikes, the piston attitude (tilt) control becomes more tricky, and this can lead to ring lift off from the bore surface, or ring "flutter" in the grooves, which will dramatically (in relative terms) increase oil film thickness and thus oil consumption.

True "ring-flutter" is usually at high speed when you remove all the load (overrun or gear changes) and the gas pressure between the various rings causes the top and second rings to vibrate in the grooves, which drops the gas sealing and allows oil to get round the back of the rings. You often see a little puff of blue smoke when this happens.

Ring design is like most things a compromise of weight, dynamics, wear, friction and cost. The weight issue is a lot bigger than first sight suggests - one mm on the piston crown (ring pack) height means an extra mm on the height of the whole engine.

Farking Hell... Thanx....

Well guys there you have it... Always check your oil level before you start the bike just to make sure.....

[embee]

...........oh and while on the subject, this is why a **proper break-in process is important, so that the surfaces of the piston rings, grooves, and bores are properly bedded together and so work correctly later in the life of the engine.

**proper means a process of progressively increasing speed and load over a reasonable time.......but others know better.

Originally Posted by pridhac

You want one of these you do. There are still a few floating around on eBay I think. No oil leaks out of this puppy!!!

Yeah, i have seen those, but it really ain't worth the outlay (for me) for such a little leak. Does look nice though.

[northwind]

Probably just wants a new seal, not a whole new cover- but any excuse to spend money If anyone ever spots the Yoshi ones, I've got first dibs...

proper means a process of progressively increasing speed and load over a reasonable time.......but others know better.

I'm with you but there's no convincing some people. I don't know whether to laugh or cry when that link to that stupid irresponsible run in your engine by thrashing it website pops up.

Originally Posted by embee

Breathers - the reason V-twins (and big singles, 360deg parallel twins, boxers etc) are significantly different to multi-cyl engines is that the piston motion means that the crankcase volume is cycling up and down greatly as the engine rotates. A 4-cyl inline engine "exchanges" gas between cylinders going up and those going down, as do other multi cyl arrangements (more or less).

This means that there is a lot of bulk flow and reversal in the breather pipes in addition to the actual blowby, which can tend to carry more oil mist. There also tends to be high pressure reversals in the crankcase, which can give more joint leaking problems than in an L-4.

However, oil consumption associated specifically with high speed+load is usually piston ring and bore geometry issues (generally termed "piston/liner interface). Particularly with the short slipper type pistons as in most modern bikes, the piston attitude (tilt) control becomes more tricky, and this can lead to ring lift off from the bore surface, or ring "flutter" in the grooves, which will dramatically (in relative terms) increase oil film thickness and thus oil consumption.

True "ring-flutter" is usually at high speed when you remove all the load (overrun or gear changes) and the gas pressure between the various rings causes the top and second rings to vibrate in the grooves, which drops the gas sealing and allows oil to get round the back of the rings. You often see a little puff of blue smoke when this happens.

Ring design is like most things a compromise of weight, dynamics, wear, friction and cost. The weight issue is a lot bigger than first sight suggests - one mm on the piston crown (ring pack) height means an extra mm on the height of the whole engine.

Crikey! Go Embee!!
Thanks!

I don't know if bikes have the same issue as high performance cars but...

If you have an engine ina car designed for high performance and use it it should use oil. By letting just a little oil though you lubricate the cylinders to prevent excess wear. It wasn't unusual for the MR2 (2.0 Gti) I had to use enough oil for the oil light to come on midway between servicing. Others I know said this is normal for the cars.

My 2.0T Volvo also uses enought to go from Max on the dip stick to min in 15000km's, Volvo have said this is also normal.

Are bike engines designed in a similar way?

Stu

PS My '78 fiesta (first car) used to use an engine of oil every 50 miles, but that was a dead engine