Low Oil Causing Loss of Power

[Valkyrie]

Now I have searched this in multiple different wordings and key phrases, can't find anyone who has managed to f*** up like I did.

I was riding my bike when the oil light flicked on. At the time I was accelerating onto the highway so I got up to 70 mph when the bike wouldn't go any faster. It started to slow down before stalling all together. Started right back up no problem, with a bit of a strange noise that I still can't place. Accelerated fine, shifted to second and again with almost no power. Parked it, checked the usual suspects. Apparently oil is something to check religiously and I feel dumb for having not done that. I assume it ran low and messed something up internally.

Anyways, fast forward till I get it home. Add some oil, start it up, and its fine. Let it idle and listen for noises, nothing. Both exhaust pipes are spitting, no weird smells from them. Rev it up and it redlines like a champ. So I drop it into gear and start riding, again at the top of first it starts to lose power, shift into second and very little get up and go.

The only things I have seen so far say to check the airbox. There is a strong smell of gasoline, I presume due to the carbs, a bit of oil on the inside, and a bit of oil on the outside going down under the carbs. Drained oil and checked for metal shavings, only found reallllllllly fine shavings inside of the filter and they were few and far between. I don't want to tear the engine apart if I don't have to, anyone have any ideas of what to check next?

[dcj13]

Is your fuel running into the crankcase (when bike is parked) because you have a bad fuel petcock?

[Swann]

If you hear a loud TAK TAK TAK TAK TAK.

Those are called bearings. crankshaft or conrod bearings.

[Ghostt]

Check oil level, check oil pressure sending unit for lose wire.

As far as the stalling goes, could be you tank vent. Next time it happens, open your gas cap, then close it, and see if that helps.


If is does, sounds like it could be a venting issue, no worries it's a free and easy fix,

You need you to disassemble the gas cap and remove the two small red diaphragms, assuming this is your only problem.

The diaphragm gets hard and losses it's flexibility and gets stuck, and doesn't allow proper venting.

IMHO this modification should be done regardless to prevent future problems whatsoever.

They are ment to vent the tank, but in the case of an accident not allow gas to leak out, but more often cause problems then they fix.

Here are some pictures to help you.

The plastic piece houses the two small red diaphragm pieces, this one being mine, they are already gone, and you can leave the plastic piece out all together, as I'm going to do now.

Some things to watch out for are, there are 5 small springs under the round collar, and a small round collar as well on the locking mechanism, don't lose any of them.

Good luck.

PETCOCK TEST
install a fuel hose from the petcock fuel outlet into a catch can. Pull the vacuum hose from the engine side. Leave it connected to the petcock.

Now...petcock set to on or res.... fuel should NOT be flowing. Apply suction to the vacuum hose (which is connected to the petcock ONLY) ...fuel should now flow.

Make sure the vacuum line doesn't have any pinholes or cracks!

[jkv45]

Based on what happened (oil light coming on at speed), I think you make have done some engine damage.

To know, you will need to get a compression test. That will tell you if the cylinder walls were damaged from a lack of oil. Knocking noises will tell you the bearings were damaged.

As a refresher for any new Ninja owner -

The oil level needs to be checked often. During high RPM running (highway) the Ninja 250 will pump oil from the crankcase breather into the airbox. Eventually the oil level will drop to an unsafe level. Once the oil light comes on it's too late. That tells you there is not adequate oil pressure. If it comes on when you are riding you need to pull over and shut it off immediately, and not restart it until there is adequate oil in the sump.

[Valkyrie]

Sorry for the delayed response, been working like crazy. There is/was no knocking sounds, I figured I probably did some internal damage. Will probably have to wait a week or two to get around to checking compression sadly. Don't believe that fuel is running into the crankcase. Will check into testing the petcock when I get a chance.

Gas cap may have caused the stalling because right after I stopped I popped the lid and then it started right back up. It was exceptionally hot out. Again I will check this and get back on it as soon as I can.

Thanks for the ideas so far by the way~

[alex.s]

it's pretty obvious when there's enough damage to reduce engine performance. it makes sounds well before it really does enough damage to reduce power.

[quarterliter]

Originally Posted by Valkyrie

Rev it up and it redlines like a champ.

Make sure to be nice to your engine before it is warm!

[dcj13]

How much oil did you have to add?

[Valkyrie]

Originally Posted by quarterliter

Make sure to be nice to your engine before it is warm!

I swear she was was warm! I let it idle for a bit.

And dcj, less than a quart, not sure exact number though.

[jkv45]

Originally Posted by Valkyrie

I swear she was was warm! I let it idle for a bit.

And dcj, less than a quart, not sure exact number though.

Warm or not, it's best not to rev to that range (redline) if you are not under load (riding/on a dyno).

It really tells you nothing if you are having problems, as the fuel and ignition requirements are significantly different from no-load to load.

[Valkyrie]

Finally got a little time to work on it this morning and I think there may be a problem.

http://i.imgur.com/CRIikMB.jpg
http://i.imgur.com/tSThp8r.jpg

Apparently there is a crazy thing that stops major debris from being cycled back in. So it caught the metal chunks. First one was what was stuck to the screen, second is what I found by running around the inside. Its all really thin but I am going to bet she'll need a lower end rebuild.

[Alex]

[choneofakind]

Holy mother of...

Just for future reference, if the oil light comes on during normal operation (not massive braking...) consider shutting her off ASAP and getting a ride home.

[Valkyrie]

Originally Posted by choneofakind

Holy mother of...

Just for future reference, if the oil light comes on during normal operation (not massive braking...) consider shutting her off ASAP and getting a ride home.

To be fair it actually didn't. Only came on during hard braking. And I did get a ride home right after she sputtered down.

Oh well, live and learn. Will probably end up pulling the engine Friday and post more pictures of bike brutality.

[choneofakind]

Well if the oil light turns on under braking, you're a hair low and/or the oil has lost some viscosity and should be changed.

But your first post said you were accelerating when it turned on. That's s bigger issue and means you're lower.

Anyhow, I'm sub'd to see how it goes for you.

[quarterliter]

Originally Posted by choneofakind

Well if the oil light turns on under braking, you're a hair low and/or the oil has lost some viscosity and should be changed.

But your first post said you were accelerating when it turned on. That's s bigger issue and means you're lower.

Anyhow, I'm sub'd to see how it goes for you.

Ive had, to my surprise, the oil light come on during fairly hard braking with fresh oil that is at the correct level. So its not out of the question.

[choneofakind]

Originally Posted by quarterliter

Ive had, to my surprise, the oil light come on during fairly hard braking with fresh oil that is at the correct level. So its not out of the question.

I'd bet you were low. Only ever had it come on when I was low. Never came on at the track...

But it definitely shouldn't come on during acceleration as above in the OP

[Valkyrie]

Engine is out and on the workbench. I think Japanese hulk put my cylinder head on, those bolts will not budge...

[dcj13]

Originally Posted by Valkyrie

Engine is out and on the workbench. I think Japanese hulk put my cylinder head on, those bolts will not budge...

[Valkyrie]

Alright got them off finally. Breaker bar and penetration oil. cylinders looks good, valves look good, pistons look good, huge build up of carbon but that an easy enough fix. Rings look alright on both sides. working towards the crankshaft now I guess.

http://i.imgur.com/AQ7LoCr.jpg
http://i.imgur.com/wqG1Fbh.jpg

What would probably be the easiest way to get to the bottom end?

[Valkyrie]

Doctor Doctor, gimme the news, I've got a bad caseeeeeee of rod bearings.
Finally had time to work on it and surprise surprise.

http://i.imgur.com/k5991ZX.jpg
http://i.imgur.com/EC8hV6X.jpg
http://i.imgur.com/Rxb2EpP.jpg

Everything else is looking okay, going to check tolerances and what not just to be on the safe side.

[Jrp]

Was your crankshaft was alright?

[Valkyrie]

Crank has some very light grooving that I'm concerned about, otherwise it was totally fine.

[Jrp]

I see... How are you going to determine if it is salvageable? Do you have any pics of the wear?

[ninjunk]

light grooving should be recoverable, i'd reckon any decent auto machine shop will be able to hone that. I don't know where you'd buy oversize bearings but as popular as these bikes are, I'd imagine they are out there.

On the SOHC hondas, its really common to smear your cam journals when you run low on oil, be sure to check them.


My bike pops the oil light on a lot, always when it is at idle and i'm turning hard or braking or both. I've got the idle down around 500-600 rpm, that probably has more to do with it than anything.


I noticed that when its running it sucks the sump down (since all that oil is pumping around in the engine) so I don't worry too much about leaving it a bit on the over-full side. I fill it up all the way to to top of the sight glass, and add oil about once a month, its just getting low now and i changed it 3 weeks ago, i'll add a pint or so tonight. All my miles are highway and I do 30-40 miles a day, sooo in 500-600 miles i burn between a cup and a pint of oil... how's that for science?

[quarterliter]

Originally Posted by ninjunk

light grooving should be recoverable, i'd reckon any decent auto machine shop will be able to hone that. I don't know where you'd buy oversize bearings but as popular as these bikes are, I'd imagine they are out there.

On the SOHC hondas, its really common to smear your cam journals when you run low on oil, be sure to check them.


My bike pops the oil light on a lot, always when it is at idle and i'm turning hard or braking or both. I've got the idle down around 500-600 rpm, that probably has more to do with it than anything.


I noticed that when its running it sucks the sump down (since all that oil is pumping around in the engine) so I don't worry too much about leaving it a bit on the over-full side. I fill it up all the way to to top of the sight glass, and add oil about once a month, its just getting low now and i changed it 3 weeks ago, i'll add a pint or so tonight. All my miles are highway and I do 30-40 miles a day, sooo in 500-600 miles i burn between a cup and a pint of oil... how's that for science?

Why on earth would you have the idle that low? Especially if the oil light is coming on!?

[choneofakind]

Lol, don't think my bike will even idle that slow. 1000 rpm and she starts missing. Happy as a clam at 1400-1500, OEM recommendation is 1200-1400.

Bearings do come in different sizes. Google "RC Cramer ninja 250 rebuild". I think that's right. Lost my computer, lost all my book marks with helpful information otherwise I'd link you the article with a complete list of parts needed for a rebuild. Iirc there is 3 sizes to choose from on crank bearings, all denoted by different colors.

[Valkyrie]

Originally Posted by choneofakind

Lol, don't think my bike will even idle that slow. 1000 rpm and she starts missing. Happy as a clam at 1400-1500, OEM recommendation is 1200-1400.

Bearings do come in different sizes. Google "RC Cramer ninja 250 rebuild". I think that's right. Lost my computer, lost all my book marks with helpful information otherwise I'd link you the article with a complete list of parts needed for a rebuild. Iirc there is 3 sizes to choose from on crank bearings, all denoted by different colors.

Well my concern is getting the crank machined. That would be just as costly as buying a used engine wouldn't it?

[choneofakind]

Here's the link I was thinking about.

http://www.rcramer.com/bikes/ex250/rebuild_notes.html

You're going to have to get measurements of the shaft, determine how much bearing clearance you need (confirm proper clearance with plastigauge on assembly) and then deal with the shaft. Hopefully you just need to dress the shaft a little and get new bearings. If it's bad, I'm sure someone local can weld repair and then re-machine it, but I'd guess that the cost would be more than just buying a new crank...

Theoretically, babit is soft enough that if your crank touches off, it should damage the babbit and not the shaft. Buuuuut if you had dirty lube oil, then you have cutting fluid that will damage the shaft.