Engine overhaul

[Onne]

How much should an average 1098 cost to revise? elisabeths piston rings seems to have lost the will to live, she barks out black smoke when pulling away, and blue when going off the throttle.

What is you opinion on valve cleaners? Maybe the rings are just stuck with carbon residu

[Alec]

Hello Onne,

black smoke is due to too rich a mixture, either the choke is stuck or the carburettor wants adjusting. Blue smoke on the overun is oil being drawn down the valves. From your post on compression,the engine doesn;'t sound too bad. How much oil does it use?

Alec

[Onne]

It uses half a liter every 65 miles, when driving in the city that is, on the long run about a liter to 300 miles

[Alec]

Hello Onne,
that's a little high really. I take it that it is not leaking a lot?
If you see a lot of blue smoke when you accelerate after lifting off the throttle, then it is likely that the valves need attention. If it is generally smokey then perhaps the whole engine needs looking at.

Alec

[Onne]

its only smoky when lifting of the throttle, the blue smoke that is, and only black smoke when full on throttle. She does leak a bit, about 5 or 6 drops overnight
I use her every day, so I can see. She still very happily revs though, no strange noises at all

[Kevin]

It as Alec says sounds like you need new valve guides which are around £15 - £20 a set, but you will need to check the condition of the valves as well and check the valve seats, as you are in the trade I would have a compression test done to see what that reveals as well before you start.

[Onne]

ve the compression stuff at home, Got 145 psi on all four, no oil applied, which is good for a low compression engine. don't really want to take the head off though... she runs beautifully

[Kevin]

don't really want to take the head off though... she runs beautifully

Apart from the smoke and oil consumtion, it sounds like valve guides and valve stem seals will need to be done sometime in the future.

[Alec]

Hello Onne,
if you are happy using the oil and it runs fine then, that's up to you. I would suggest getting a spare head prepared as it is a small job to do a head swop. However, have a look at the carburettor with regards to the black smoke, (not forgetting to ensure the air cleaner is clean) as it is much too rich. The extra fuel could make your oil consumption worse than it should be.

Alec

Alec

[Onne]

The carb does indeed need checking. I have had her gas tested, the CO is now 4,5. How much should it be?