Please help - high oil consumption

[RedRupert]

I wonder if anyone can help diagnose my high(?) oil consumption.

My bike is a 2004 950 with 90,000 km (about 56,000 miles).

During it's early life, oil consumption was acceptable - I mean, it needed topping up with <1 litre between 6-7000 km oil changes. So about 2 litres per 14,000 km (8700 mile) season. (0.14 litres/1000 km).

Over time the oil consumption became worse: 4 litres over 12,000 km, so 1 litre/3000 km (0.34 litres/1000 km).

At 74,000 km, I had to strip the engine in order to replace the selector drum. While the engine was apart I replaced the (serviceable) piston rings and honed the bores lightly. After honing the ring end-gaps were all around <0.32 mm (limit 0.5 mm). I did not have the correct tools to measure the bore and piston accurately.

I also changed the oil seal in the ignition casing (the balancer shaft oil seal).

I ran-in on semi-synthetic oil for over 1500 km on twisty roads not being too gentle - using plenty of acceleration and engine breaking - but oil consumption remains high.

16,000 km after the rebuild, I measured compression and found 16.5 BAR (240 PSI). And carried out a leak-down test and found around 30% leakage, front and rear.

KTM state:
0.3 - 0.6 litres/1000 km: normal.
>1.0 litres/1000 km: there MUST be a serious technical defect!

My bike is ridden hard, but 0.34 litres/1000 km does seem a bit steep! Is it, despite what KTM say?

Looking at the leak-down and compression test results, could it be that the bore/piston/rings are at fault, or should I be look for another reason for the oil loss?

Any info will be gratefully received.

Thank you.

[RedRupert]

[Orangecicle]

Do you have oil in your front carb? The balance shaft seal on the left side if the bike is a known culprit.

[RedRupert]

Originally Posted by Orangecicle

Do you have oil in your front carb? The balance shaft seal on the left side if the bike is a known culprit.

Yes, I did that - see 6th paragraph in my first post.

[azcagiva]

Compression seems ok. Maybe you need some more time with non syn oil to get the oil rings to take a set.

How are the valve seals, any smoke?

You are on the lower end of acceptable oil use. KTM might be using a light tension oil control ring???

-John

[RedRupert]

Originally Posted by azcagiva

Compression seems ok. Maybe you need some more time with non syn oil to get the oil rings to take a set.

How are the valve seals, any smoke?

You are on the lower end of acceptable oil use. KTM might be using a light tension oil control ring???

-John

I've covered a further 12,000-odd km using fully synthetic oil since the post rebuild 1500 on semi synthetic. Maybe it's a bit late to go back to semi or non-synthetic?

I replaced the valve-stem oil seals when I rebuilt the engine.

Sometimes I'm told there's a puff of smoke on overrun. But could that be enough to burn so much oil?

Thanks.

[buzybraza]

In my opinion (I am no expert) you should be looking at valve guides and seats.

[RedRupert]

Originally Posted by buzybraza

In my opinion (I am no expert) you should be looking at valve guides and seats.

I lapped the valves when I rebuilt the engine, also they were not leaking when I carried out the leak-down test.

The valve guides were checked and were OK when I rebuilt the engine.

[Orangecicle]

If you no longer have an oily front carb, you know the valves are good, and she is not leaving a puddle when stopped, you are kind of down to cylinder walls and ring seating in my mind. I know that Pyndon had a delamination of nicacil in a cylinder on his bike that he wrote about in his My KTM 950 Story thread. That's all I can think of. You might PM Pyndon to see if he has any other thoughts.

[RedRupert]

Originally Posted by Orangecicle

If you no longer have an oily front carb, you know the valves are good, and she is not leaving a puddle when stopped, you are kind of down to cylinder walls and ring seating in my mind. I know that Pyndon had a delamination of nicacil in a cylinder on his bike that he wrote about in his My KTM 950 Story thread. That's all I can think of. You might PM Pyndon to see if he has any other thoughts.

When I rebuilt the engine, I checked the Nikasil surface of the cylinders, and found it to be in very good condition.

The breather pipe from the balancer shaft, I have lead into a catch-bottle so that I can monitor oil exhaled. There is nothing to speak of in the bottle.

[Orangecicle]

Originally Posted by RedRupert

When I rebuilt the engine, I checked the Nikasil surface of the cylinders, and found it to be in very good condition.

The breather pipe from the balancer shaft, I have lead into a catch-bottle so that I can monitor oil exhaled. There is nothing to speak of in the bottle.

Well, no valve leak per your thoughts, and no balancer shaft seal issues, and nothing leaking on the ground. I'm assuming it's not pumping oil out of the radiator overflow.

Then you are down to ring seating, right? Maybe your symptoms relate to the honing. Dunno. Here's a related discussion: http://www.thumpertalk.com/topic/294800-honing-nikasil/

[RedRupert]

Originally Posted by Orangecicle

Well, no valve leak per your thoughts, and no balancer shaft seal issues, and nothing leaking on the ground. I'm assuming it's not pumping oil out of the radiator overflow.

Then you are down to ring seating, right? Maybe your symptoms relate to the honing. Dunno. Here's a related discussion: http://www.thumpertalk.com/topic/294800-honing-nikasil/

The coolant is clean and there is no abnormal activity concerning the cooling system.

My symptoms were present before the new rings and honing - it's why I installed new rings and honed.

I can't say that my oil consumption is down to ring seating - it's why I'm posting. To me it looks not, as the leak-down test looks normal.

There may be a cause that is pretty unique to this engine - like the balancer shaft seal, for example.

Thanks for the link.

[pdxmotorhead]

MY humble opinion,, based on my background...

You can't hone Nicasil liners with any tools available to mere mortals.. Usually it ruins the cylinder...

Break in oil should be standard oil, no synthetics at all, preferably a high zinc sulfur break in oil if new cams are involved...

I did the same thing with a motor I built 2 years ago. Started on semi synthetic, and the rings would not seat. I ran straight 30 weight for about 3 days then put the semi back in and voila,, no more oil consumption. (Iron cylinder walls though.. ) But the old Nic barrels on porsches used to wear out two or three sets of pistons and rings before they needed any attention..

Check the vacuum level in the crank case.. It should be close to neutral,, very light suction.

You did valve seals, but how were the guides? Intake valve guides can allow a lot of oil even with a new seal if they are loose.

Just thoughts on it not necessarily answers.. :)

Dave

[RedRupert]

Originally Posted by pdxmotorhead

MY humble opinion,, based on my background...

You can't hone Nicasil liners with any tools available to mere mortals.. Usually it ruins the cylinder...

Break in oil should be standard oil, no synthetics at all, preferably a high zinc sulfur break in oil if new cams are involved...

I did the same thing with a motor I built 2 years ago. Started on semi synthetic, and the rings would not seat. I ran straight 30 weight for about 3 days then put the semi back in and voila,, no more oil consumption. (Iron cylinder walls though.. ) But the old Nic barrels on porsches used to wear out two or three sets of pistons and rings before they needed any attention..

Check the vacuum level in the crank case.. It should be close to neutral,, very light suction.

You did valve seals, but how were the guides? Intake valve guides can allow a lot of oil even with a new seal if they are loose.

Just thoughts on it not necessarily answers.. :)

Dave

Thanks. I will answer so that there is a record of what I've done etc.:

I used a Flex-Hone to hone the bores in accordance with the manufacturer's recommendations and instructions. I used the 240 grade Aluminium Oxide version, which produced a nice light and even cross-hatched surface. I used WD40 to lubricate, and ran the tool through the bore with quick strokes for only 20 seconds. It does not look as if I've ruined the cylinder - remember that it drank oil before I honed, as well as after. Flex-Hones should not be used in two-strokes because of the ports.



This is the result:

[AdvRonski]

Originally Posted by RedRupert

Thanks. I will answer so that there is a record of what I've done etc.:

I used a Flex-Hone to hone the bores in accordance with the manufacturer's recommendations and instructions. I used the 240 grade Aluminium Oxide version, which produced a nice light and even cross-hatched surface. I used WD40 to lubricate, and ran the tool through the bore with quick strokes for only 20 seconds. It does not look as if I've ruined the cylinder - remember that it drank oil before I honed, as well as after. Flex-Hones should not be used in two-strokes because of the ports.



This is the result:

I replaced the rings on my 2004 950, and honed the cylinders with the same type of hone. I also added the crankcase vent valve that did not come on the early bikes. I had no issues with ring seating, and oil consumption is quite low.



However, the picture of your cylinder shows the angle of the cross-hatching is way too shallow. I am a professional auto technician, and have found honing properly takes a while to get the hang of. It appears the you had the hone rpm too high for the frequency of your up and down movement. The ideal angle is 60 degrees between the up and down lines, while yours appears to be about 10 degrees. Hopefully some break-in oil will help seat those rings without another tear-down.