Oil disappearing on a 4 stroke??

[Dannyyankel94]

Hi,
Recently my engine oil has been disappearing on me. I have a 4 stroke, liquid cooled, originally 125cc, bored up to 150cc, done some work on the cylinder head, put in a performance camshaft etc, stock exhaust by the way. When I change my oil after 1000km, it seems like my oil has somehow disappeared. I know it's not a broken piston ring or leaking valves because there is no sign of oil burning that I know of. There is no white smoke coming out of my muffler, the cooling system seems to be fine and the engine operates in the right temperature, because my "your coolant is turning into steam" alarm has not blinked yet.
So what can be the problem. The oil capacity is about 800ml. It drops about 200ml after every 1000km. There is no white smoke. None whatsoever. Do I need to use better oil, any suggestions would be great.
Thank you

 

[donnyj08]

Combustion engines consume some oil by nature. Just keep it topped off.

 

[Dannyyankel94]

I know that even a 4 stroke can consume oil, but at this rate is it a little too much? 800 ml to 600ml after 1000km may be a bit hard.

 

[WobblyElvis]

From what I have seen, I would say it's more likely the oil is leaving due to a valve seals/guide problem. When oil is consumed because of worn/bad rings it's usually quite visible.

 

[Dannyyankel94]

Thank you. So I need to check my valves now?

 

[bmwpowere36m3]

Its either leaking or burning it... 200 ml per 1000kms seems a little excessive. Are you checking the oil level properly?

Besides leaks, which should be apparent, it could be worn rings, worn valve stems, worn valve stem seals and/or a bad PCV.

 

[Dannyyankel94]

Well I drained the oil out and use a special tool to measure it.
It does not leak. I leave it in my garage for one night, next morning, no oil on the floor.
Maybe it's the valves then. A worn ring is probably unlikely, as there are no visible white smoke.
As for PCV, I would have to check with my mechanic then..
Thank you.

 

[Quest]

Originally Posted By: bmwpowere36m3
Its either leaking or burning it... 200 ml per 1000kms seems a little excessive. Are you checking the oil level properly?

Besides leaks, which should be apparent, it could be worn rings, worn valve stems, worn valve stem seals and/or a bad PCV.


OP is talking about motorcycles, not emissions-controlled NA automobiles.

PCV does not apply in most cases of motorcycle engines, for they traditionally uses a vinyl tubing as a form of a crankcase breather typically into the air filter box.

Q.

 

[bmwpowere36m3]

Originally Posted By: Quest
Originally Posted By: bmwpowere36m3
Its either leaking or burning it... 200 ml per 1000kms seems a little excessive. Are you checking the oil level properly?

Besides leaks, which should be apparent, it could be worn rings, worn valve stems, worn valve stem seals and/or a bad PCV.


OP is talking about motorcycles, not emissions-controlled NA automobiles.

PCV does not apply in most cases of motorcycle engines, for they traditionally uses a vinyl tubing as a form of a crankcase breather typically into the air filter box.

Q.



I know, some bikes simply have a "breather" hose... others more elaborate breather, catch can, recovery setups... i.e., "PCV". Two of three bikes I own have it and one is a "simple" dual-sport. It's something if plugged or not hooked up correctly can lead to excessive oil consumption.

OP did state what bike he referring to.

*edit* maybe I miss worded it, I didn't mean a PCV in the sense of the valve found on typical American cars... I meant the breather system as a whole.

 

[Dannyyankel94]

Just to clarify, I have a scooter which has a dry CVT clutch. Will check the valves and try to update. Thanks for all your help.

 

[tomcat27]

how many miles are on it? what oil are you using? did the increase in consumption coincide with boring the cylinder? if so, perhaps you now have looser tolerances than before. with my Buell, I had to add a 200-400ml every 1000 miles. of course, my consumption dropped significantly and consistently just switching brands of oil. I was previously using M1 and switched to Valvoline VR1 synthetic. 20W-50 in both cases.

 

[Dannyyankel94]

About 5000 miles since the boring up. The excessive oil consumption started when I did some work on the cylinder head to insert bigger valves.
I'm using Motul. But it's the type of oil that Motul outsourced to a local company to manufacture under Motul's permission.
Honda recommends to use 10w30 in my scooter. I'll try to change my oil brand.
Technically I did not bore up my cylinder, I replaced it with a bigger one.

 

[Dannyyankel94]

I did check my valves. They seem to be fine.
Can it be that the stock exhaust cannot handle the new 150cc displacement and a racing camshaft with increased lift and duration? By using a racing cam and a larger displacement, the amount of air flow increased and the stock muffler is too restrictive, causing the hot exhaust air to bounce back towards the cylinder head, overheating it and vaporizing oil as a result?

 

[Atesz792]

Nope. Probably it's just that the aftermarket piston-cylinder clearance is that much bigger, or the oil control ring is of lower quality than stock. Then again, you mention work on the cylinder head, if your valve seals don't seal perfectly, that could be the cause too.
Also bigger displacement generates more power and heat, and I'm assuming your cooling system is stock. If it was marginal in the first place, it may be a little bit overheating, but if not, oil temperature will still be higher than stock. That means it is thinner while at operating temp, so you could go up a grade.
So close to the Equator you could even run a monograde SAE 40 oil year round without problems, I think. Something dual rated, like API SJ/CF, or the like.

 

[bmwpowere36m3]

Usually if its the valves (either the clearance between the stem/guide is too large or worn stem seals, if it has them) you'll see BLUE (not white) smoke during hard deceleration and cold start-up. That might be difficult to test on a scooter with CVT, because you can't decelerate and load up the engine (the clutch simply disengages).

It's also possible the cylinder is glazed... how did you break-in the engine?

Besides opening up the engine and checking valve stem clearances, replacing stem seals (if applicable), de-glazing the cylinder wall, replacing rings.... your probably only option is to try a different brand of oil, heavier weight and/or living with it.

Valve stem clearance:

NOT valve/tappet clearance:

 

[Dannyyankel94]

Where I live the ambient temperature is always above 80. I am running a 5W40 though. Might try some other brands to see if it helps.
It may be overheating a little bit, with the stock exhaust. But the coolant alarm does not blink yet so I think it's still in the acceptable range.

 

[Doog]

With the engine completely cold after siting for at least 8 hours. Start the engine in the dark with someone shining a flashlight on your muffler tips. If you are leaking oil by valve seals you will see the blue start up smoke.

 

[Dannyyankel94]

Well I have done some checks.
I check my engine oil level everyday using a dip stick as guided by Honda.
1/ Cold start my scooter on a center stand
2/ let it idle for 3 to 5 minutes
3/ turn off the engine and let it cool for 3 to 5 minutes
4/ get the dip stick out, clean it and put it back in but do not screw it in
5/ get the dip stick out and check.
Over 2 weeks, my oil consumption seems to be fine, almost no consumption except for the amount of oil that I clean off every time I check the dip stick.

After 2 weeks, I decided to mod my stock exhaust to allow my engine to breath a little more freely.
Saw off the muffler tip, get the core out, replace it with a drilled core, wrap it in fiberglass and put it back in.

Suddenly, when I drive back from the shop, I noticed some white smoke that dissipated very quickly coming out of my muffler. After maybe 30 seconds, the smoke cleared, and I drive home.

Put my scooter on the center stand again. Rev the engine a couple time. No smoke or anything. Check my engine oil level (remember this is with the engine recently riding 40km), it's about halfway between minimum and maximum. I'll check my engine oil level again after I let it cool down a bit.

I also checked my coolant level. Still the same.

What can be the origin of this white smoke?
Normally, if there's a broken ring, broken valve seals, etc the smoke would continue to come out of the muffler but in this situation, nothing after about 30s of white smoke that quickly disappears. Can it be the fiberglass setting in with the heat from the exhaust gas or anything?

I'm having my engine rebuilt in about 1 month, hope I can get out of this headache of a situation..

Thank you.

 

[Garman]

That white smoke is probably the new fiberglass "burning in". when ever I repack my silencer I get white smoke for about 10 mins