Scored cylinders leading to an oil consumption problem

GREAT QUESTION.! OK now I see you have many posts and topic?
you need to have 1 post 1 top, (oil burner) do that use comment to the one post so it all stays as one.

YES ENGINES ARE AN AIR PUMP, HUGE.
EACH CYLINDER IS,
why not lead off with a real problem and all evidence first.
yes compression test can show 200PSI easy with 10:1 CR
both tests only prove the top 2 rings are good and cyl walls not scored hugely.( lead down at TDC)
no engine or maker told at all.

those other questions, about cracks
well gee , depends where the cracks are. and how bad they are.
freeze damaged water jackets? (you do know the machine chip pressure tests the block and head to find cracks not seen
and the cracks in heads can go anywhere wants. port, combustion chambers or water jacket to top if head OIL side. lifter side.

most times the leak-down test finds bad rings and is done at TDC.
so only finds cracks a TDC, unless you do tricky tests just after valves closed.

read the 100 point tests of of engine rebuild. it's huge. CHECK IT OUT FIRST.
oil consumption a question here?
oil control rings bad, or not seated or wallS with scoring
valve seals bad, are first to fail most time.
or valve stems guides so loose it beats the seals to *****.?
clogged PCV , and it burns more oil and leaks out seals.

the compression test is done , at 300RPM starter running.
warm/hot engine, not cold, all sparks out, W.O.T AND FULL BATTERY CHARGE ! factory manuals shows PSI to expect.
and is altitude dependent, (need chart ask)
AT THIS TIME THOSE PISTONS MOVE REAL FAST
AND WiLL IGNORE SOME SCORING AND CRACKS.
Due TO SWEPT SPEED ALONE.
and the test repeated with 1/2 teaspoon of oil, down spark hole if PSI jumps high rings are not seating.(for all the reasons)
SEE WHY LEAKDOWN FINDS MORE LEAKS ,IT'S SLOW

Wish I new what was the problem , at the beginning,
not told. what put you here, with no car stated, engine or size.

you might have damaged the piston cylinder or crank bearing. Put some light weight oil in the cylinder leave the plug out and pull it over a few times to see if it gets easier. If it does, the cylinder may need to be honed, if it doesn't make a difference put enough oil in the cylinder that it will get oil into the crankcase where the bearings are for the piston, pull iy over with plug out and see if it gets easier, if it does the bearing is scored. do it in that order a little to start with to check the cylinder, add more to check the crank. if you can before doing that procedure pull the plug, use a bright small light to look into the cylinder through the spark plug hole and look for score marks, dark areas on the cylinder wall, any kind of deep scratches. if there are any of those things, the cylinder wall is damaged and will need to be hones or bored, depending on the make and modle of the saw it may have a sleeve that is replacable.

You can do that. But it would not run as good or as long as it would buying both the piston and the cylinder housing. You either have to buy both or the try installing a new piston with new rings in it. It should give you enough compression to start it up. But it can't be guaranteed to last too long.

If you are getting oil from the air pump in your hoses and tools your problem is in the cylinder/piston area. The piston on air pumps is very much like a car piston, depending on what model you have it has compression rings and oil scraper rings. If any of these are damaged or if your cylinder(s) is badly scored oil will get by the piston and be forced out with the compressed air to your tools. The only repair is to take the head and valve plate off and find out what parts you need to replace. If the cylinders are lightly scored they can be honed out but you can't machine them out as Campbell Hausfeld doesn't make oversized rings or pistons.

It is possible to hone the cylinders and replace the rings to save the pump but don't remove too much metal as there are no oversized rings available for this type of piston/cylinder set. Also make sure to find out what caused the scoring in the first place and remedy that or you'll be replacing the cylinders and pistons next time.

In all my time rebuilding compressors I have not been able to find an oversized ring set for compressors. If light honing does not remove the scoring you will have to buy a new cylinder (Hitachi part number 885469). Hone only enough to get the scoring out and put in all new rings (Hitachi part number 885465) then give them a couple hours of running time to get fully seated. If you still have a lot of blowby you'll need a new cylinder.

Hi,
Most late modle MX & enduro (from about 1990 on plus some even earlier)
have what is called an electrofusion bore.
This is a very thin plating on the alloy cylinder. They use this so as to allow heat to dissipate quicker & can run tighter piston cylinder tolerances for improved performance.
To answer your questions,
No, they can't be re-bored(like the older style steel sleeved bore bikes could)
Yes, they can be honed but it requires a special type of hone(finger type bottle brush style hone).
Pistons are available increasing in size by much smaller incriments than the old style & are usually marked A,B,C,D(as the coating is much thinner than steel sleeve).
If it is scored very badly & you can see alluminum spots/scores anywhere on the cylinder surface there are several ways to deal with this.
Here in Australia there is a company(electrocill) that can re-cote the cylinder which is much cheaper(plus thicker & stronger) than replacing the barrel
If you have a cylinder re-coated It has to have all studs, seals & power valve assemblys removed.
You would also need to supply(or have them supply) a new piston in order for them to set the correct clearance.
Also here in Australia you can have most of the common models fitted with a sleeve & this gives you the abillity to rebore in the future.
In the U.S this company is known as Wisco(serco in Aust.)
It is worthy of noting that the piston rings are not interchangable between an electrofusion & steel type cylinder.(so if you opt for a re-sleeveing any spare rings from your spares kit ar of no use).
If you need a lead on how & if these services are available in your country(if your not in Australia) I suggest taking a look in the classified section of your local dirt bike magazine.
The trick is to undertake regular srevicing of your air filter(this is A MUST),oiling it properly with propper foam filter oil, useing a top quality 2stroke oil(motul,syn-lube for eg)
& regularly inspect & replace rings/piston as needed to get the best life from electrofusion or steel type bores
Hope this explains it all for you
Regards Andrew Porrelli

There are only four ways for oil to get to the spark plug. Bad head gasket, bad rings on the piston, Cylinder scored or warped, and bad valve seals.

• Start with the most likely, bad head gasket. When they rebuilt the engine they could have left out an oil seal 'O' ring. Check the head bolts. Did they tighten the top end down tight? Are you seeing oil on the outside of the head and cylinder? When the cylinder is firing properly, do you hear any head gasket leakage?
• Do a compression check on both cylinders. This should tell if rings and valves are ok. Does the bike smoke most all the time when running properly? Does it only smoke when first started and when pulling away from a stop light? Bad rings will smoke all the time. Bad valve seals will smoke when starting out.
• Scored cylinders are best checked with the head removed. Warped cylinders can only be checked with the head removed and by using a cylinder hone. The hone will reveal any low areas.

Chances are slim that you can avoid pulling off the cylinder head. Best wishes.
Please rate this solution after the problem is found. Thanks.