S1 Publishing(Oxford)©20-07

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S1 Publishing(Oxford)© 1999-07
 Maintenance - Engines
Bores & Barrels

This is just a general guide.
If you are about to do your own maintenance, using these pages, I take no responsibility if you get things wrong!

What do I look for when checking the bore?:
When the running and you see white smoke it is possible that oil is getting into the combustion chamber and is burning in there. If you see oily or carbonized  deposits on the spark plugs, this usually confirms it. If you've already checked your valves you'll need to investigate further.
1, Check the sides on the bore, you should find a smooth surface. You can check this with the with the piston in the bore, just turn push the piston (or turn the crank) to top bottom center
2,  Check the diameter of the bore, you'll find the measurements in your manual.
 If it's smooth and within it's limits, remove the barrels and check the piston rings.
3. If you see small scores in the bore it might be possible to have them honed. I usually run my fingernail across them to feel how bad they are.
4.  If the scratches are too deep it might, then it's possible the rings have broken. The pistons will be have also been damaged if this is the case. There are two choices:

Here there are two deep grooves. This is what happens if the circlips fail, or you forget them, the wrist pin rubs against the walls of the sleeve
Choice 1
 An oversize bore. 
 You will also need over sized piston & rings, these usually come in a kit. Check with you engineer and local parts supplier for the re-bore.
 You will have to this for all barrels.
Choice 2
 You could replace the sleeves / piston and rings, either using used parts or new. Most barrels can be heated and the sleeves knocked out & replaced when they are hot.
 Click here for more info.
 If buying second hand, make sure you get the piston(s) &  barrel(s) as a pair(s). 
Modified for 2009
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