Topic: Pulled head off cb350f today need your thoughts...

[andrew.bator]

Bike ran fine but would blow white smoke on acceleration and idle
Any ideas why the exhaust valves are different colors



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[750goes]

two of them are running lean by the look of the valves - and one of those looks like it may not be seating properly.

while you have the head off - new valve guides if required, new valve stem seals a definite, and relap the valves in.

have you checked for any leakage
tip the head right side up and pour some kerosene down the valve guides  then wait a minute - if it leaks through to the valves - they need to be re-lapped or ground...

[crazypj]

That's some serious oil burning. #2 cyl is the only one which is running even close to temp, darker the valve, colder its running (its not lean, if it was pistons wouldn't have a #$%*load of carbon on them)
You need to have bores checked, rings are either fitted wrong or just worn out.
 All the exhaust valves should be that lighter colour

[andrew.bator]

what would be a good way to remove the carbon from the pistons

[Hasenkopf]

yeah..... looks like one was burning oil....

[crazypj]

what would be a good way to remove the carbon from the pistons

 carbon remover 


 Take a look in local supermarket for something to clean deep fat fryer or similar, as long as it's suitable for aluminium you good to go.
 There used to be a couple of oven cleaners that were non-caustic (caustic soda will 'eat' aluminium)

[faux fiddy]

what would be a good way to remove the carbon from the pistons

Vinegar is good when the  coffee pot gets scorched, maybe use that  as a soak. I  just  used a  triangle file  to scratch  stuff off. Maybe it was  a   special bent one. Scratch and   scuff, better clean when it goes back together. 

[camelman]

Sea Foam does amazing work on carbon buildup.  It will make spark plug ends look like brand new with just a little soak.

I agree about checking your bores/rings.  It might be time for new rings and a hone job on the cylinders.  Depending on how things measure up, you might even need new pistons.  Can you post pics of your cylinders and take some measurements?

Camelman

[andrew.bator]

To me it looks like the rings are fine... Cyl 1 and 4 exhaust valve seals are leaking oil
One of the cyl 3 wall has a little scratch in it

Here are pics of the pistons and rings
To me it looks like they were replaced b4, what do you think




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[crazypj]

You still need to measure ring end gaps, would suck to put it back together and still be smoking
How it looks is totally worthless without measurements.
Are there vertical scuff marks on ring or just weird reflections? (looks like scuffing in first pic)

PJ

[andrew.bator]

thos are reflections the rings look really clean all way round... when i get some measurements i will post them up