Can i have your opinion when it is time to change the piston rings? CBR250RR (R) MC22 1994 starts and runs well but I can see some white smoke and it smells like a lawn mower that is well worn. My neighbour says it needs a tune but I think it needs something else. The exhaust is blackened. What is the best place to buy the rings from as well as gaskets?
When your compression test says so. http://2fiftycc.com/index.php?threads/compression-leakdown-tests.3439/
When does it blow white smoke? All the time means headgasket or related issue , If it's only on startup that's normal
Thanks Blair. i do have a compression gauge . What readings are not good ones (what is a low value)? If the reading is adequate, what else could the smokey exhaust be ?
Refer to your service manual for compression test readings. Smokey exhaust can be a few things: Worn piston rings / excess oil burning (check your crankcase breather for oil drops) Head gasket failure from coolant passage to compression chamber (steam out the exhaust, sweet smelling exhaust) There's a couple of DIY tests you can do to check the head gasket. When the bike is cold, take off the radiator cap and start the bike. Bubbles mean an air leak in cooling system or blown gasket. White vapour coming from the radiator cap area is exhaust gasses. Check underside of oil cap for caramel sludge. If there's some there, it means oil in coolant, or someone used the same funnel for coolant and oil. Clean it and check it again the next day. Again when the bike is cold. I made the mistake of taking the cap off when the bike hadn't fully cooled. Due to the blown gasket there was excess pressure in the cooling system. Cap popped off and coolant shot everywhere, burned my left hand rather badly and made a mess. Check your coolant overflow tank for bubbles while the engine is running.
White smoke is oil being burnt. Your service manual should give you the correct compression value and limits. Oil can come from rings or valve guides. There are seals on top of the valve guides and they do not last forever. Most of these four cylinder motorcycles now have wet liners which means the cylinder sleeve, where it seals against the head, is surrounded by water. Oil cannot gain entry into the cylinder via the head gasket. cheers Blair
Found the above somewhere, saves me re-typing it (I'm lazy too which doesn't help). In my old Rodeo (given it's a car, it's the same principle) when the head gasket went it was blowing a heap of white smoke. Also the oil went a milky colour. The second part of that is also important to note. I think to a casual observer it's going to be hard to tell whether or not it's grey/blue or grey/white because honestly it's going to be a bit of a perception, especially at the early stages of the problem. I'd drain your oil and see if it's milky or showing signs of water in it. Also check your coolant to see if it has an oily residue. You could drain both into a clean bucket (different buckets!) and put them back in if there's nothing wrong. If oil is in the coolant or coolant in the oil (the latter would be more likely) you've got a head gasket problem. If not, it's probably you burning oil, which provided it is only on startup (as has been said) it's probably not too much of a concern. It's only when it starts to be consistent during normal running then it would be a problem. Just my 2c.
I get poof of blue smoke on deceleration at high rpm every now and then not stressing she let me know when she ready lol