Technically what would happen if......

yesterdays oil change(first this year) had me thinking...

Technically what would happen if...... your bike was--

a) had too much oil

:naughty: didnt have enough oil

im talking if it had enough or not enough oil to cause damage, what would that damage be?

too much oil can cause it to foam from the crankshaft beating it up to a good froth and that leads to loss of oil pressure. too little leads to the same thing.

how much is too much

i mean would you have to double up the recommended dosage or cut it in half? just some thoughts thats all

dunno, I run 1.5 liters in ours with no issues.

my dad always says that its better to have to little that put too much in. he explained it to me but i cant remember why. how much oil do 250fs take :naughty:

The '02 and earlier are different from the '03 and later.

The '01/'02 fills from the tank (frame) and calls for 1.7L (1.6 with a filter, 1.5 without)

The '03-'05 fills at the ignition cover, even though the oil is stored in the frame, and calls for 1.2 (1.1 and 1.0)

Except for the location of the filler and dipstick, the frame reservoir is no different in either bike, so you could put up to 1.7 in the later models. It might drool out of the dipstick hole at that point, though.

Say the bike is an '04, and it sat for 2 days, and you didn't start it and warm it before changing oil as the manual states. You then fail to drain the frame, drain only the engine, and throw in your liter of oil. You will now have the liter in the crankcase, and maybe another one in the frame. You start the engine and the oil in the crankcase is pumped up into the frame. Before it all gets there, the system runs out of room in the tank. The return pump is bigger and faster than the feed, so the oil keeps coming, but where does it go? It gets shoved down the vent tube that runs between the tank and the cam box in a steady stream, flooding the area around the valve guides, and running back into the crankcase that the return pump is still trying to empty. The oil splashes around the crank excessively, which causes it to be thrown onto the cylinder walls in much more than the usual quantity, overwhelming the rings. So it smokes, is what it does, and belches slime out of the breather, until it finally burns off enough excess to make it all fit it the tank, or you realize your mistake and drain down the level. Oil foaming from crank splash is nearly impossible in a dry sump, because until it reaches the point I just described, the excess is nowhere near the crank; it's up in the frame with the rest of it.

Too low an oil level is dangerous, but there are degrees of too low. A little too low, and the oil gets hot and dirty quicker. Very low, and all of it gets put into circulation before any gets back to the tank for use by the feed pump. Loss of oil pressure. Bad. Because a YZF concentrates the last pint of oil in the frame in such a small area, it's difficult for the oil to slosh away from the feed pickup as it can in most wet sump engines, so you would have to be nearly out of oil before you actually started starving it.

If you lost oil pressure completely, I would say the part in the most immediate danger would be the cams and the bores in which they ride in the head. After that, probably the piston, then the rolling bearings, most likely the rod first. Momentary losses can cause all sorts of trouble that shows up at some later time. For instance, you could scorch a crankpin one day, and finally blow a rod on another because it took that long for the bearing to finally fail.

So, PLR, what bring you out of OT?

my dad always says that its better to have to little that put too much in. he explained it to me but i cant remember why. how much oil do 250fs take :naughty:
He says that because it's easier to check and add a little than it is to drain a little out. :naughty:
The '02 and earlier are different from the '03 and later.

The '01/'02 fills from the tank (frame) and calls for 1.7L (1.6 with a filter, 1.5 without)

The '03-'05 fills at the ignition cover, even though the oil is stored in the frame, and calls for 1.2 (1.1 and 1.0)

Except for the location of the filler and dipstick, the frame reservoir is no different in either bike, so you could put up to 1.7 in the later models. It might drool out of the dipstick hole at that point, though.

Say the bike is an '04, and it sat for 2 days, and you didn't start it and warm it before changing oil as the manual states. You then fail to drain the frame, drain only the engine, and throw in your liter of oil. You will now have the liter in the crankcase, and maybe another one in the frame. You start the engine and the oil in the crankcase is pumped up into the frame. Before it all gets there, the system runs out of room in the tank. The return pump is bigger and faster than the feed, so the oil keeps coming, but where does it go? It gets shoved down the vent tube that runs between the tank and the cam box in a steady stream, flooding the area around the valve guides, and running back into the crankcase that the return pump is still trying to empty. The oil splashes around the crank excessively, which causes it to be thrown onto the cylinder walls in much more than the usual quantity, overwhelming the rings. So it smokes, is what it does, and belches slime out of the breather, until it finally burns off enough excess to make it all fit it the tank, or you realize your mistake and drain down the level. Oil foaming from crank splash is nearly impossible in a dry sump, because until it reaches the point I just described, the excess is nowhere near the crank; it's up in the frame with the rest of it.

Too low an oil level is dangerous, but there are degrees of too low. A little too low, and the oil gets hot and dirt quicker. Very low, and all of it gets put into circulation before any gets back to the tank for use by the feed pump. Loss of oil pressure. Bad. Because a YZF concentrates the last pint of oil in the frame in such a small area, it's difficult for the oil to slosh away from the feed pickup as it can in most wet sump engines, so you would have to be nearly out of oil before you actually started starving it.

If you lost oil pressure completely, I would say the part in the most immediate danger would be the cams and the bores in which they ride in the head. After that, probably the piston, then the rolling bearings, most likely the rod first. Momentary losses can cause all sorts of trouble that shows up at some later time. For instance, you could scorch a crankpin one day, and finally blow a rod on another because it took that long for the bearing to finally fail.

So, PLR, what bring you out of OT?

Look at the BIG BRAINgrayracer513 :naughty:

very well put :naughty:

greatly put grayracer..that helps me out a bit

what brings me out of tt? im riding my bike now since theres barely any snow..which means more questions in here..so stay tuned and enjoy

i tossed roughly 1.250 or 1.2 in my bike yesterday..1/10 of a liter isnt alot but i wanted to be safe and sure enough i was..btw this was without changing the oil filter

i rode the mx track today and rode harder then ever..im pretty pumped right now!!

anyway thanks again

Oh, no! Please tell me that you were wrong with the amount of oil for the 03-04. I use a shop (huge 500+) manual that says to use 1.7 because it's for a 01-02. I've been adding 1.5 every time I change the oil w/o the filter. It registers a little high on the dipstick, but I figured that wasn't anything wrong and kept it that way for saftey reasons. Could there be anything wrong with my bike or any signs to tell if there was anything wrong? PLEASE REPLY! I'm scared!

No, I'm right. But you're OK. Remember I said that the frame oil tank isn't any different except the fill location? You can, as I do, and as YZ250F_Rider does, run more than the required amount, up to around the original 1.7 liters.

Thanks! What a relief. You had me scared there for a minute. I think I'll run about 1.2-1.3 just to be safe. You have some of the best posts on TT Grayracer. I wish I could nominate you for a "best post" award or something.

Dont worry about it dirt, the bikes will hold a tad over 2 liters before they start biatchin. More oil is a good thing as it takes just that much longer to contaminate it. Clean oil is the secret to low wear.

If you want to help keep the oil clean longer re-reout the vent tube for the cam cover to the airbox like this. This way the engine only pulls clean air in, and it definitely pulls dust in otherwise.

http://www.forumpictureprocessor.com/pictureprocessor/images/IMG_0022_1.jpg

Ditto here.

Since my buddy and I change our oil together, we just use 1.5 quarts per bike and we call it done.

He gets a little oil out the breather every now and then, I don't. He rides harder than I do.

Are there any downsides from running the breather pipe to your air box?? Hot engine oil all melting your air filter if you spray a bit out?

What is the pipe clamped to at the airbox, did you drill the box and poke a bit of pipe through to clamp the hose to??

The hose looks pretty bent at the top of the head, is there any risk of pinching it and if so what would happen then.... :naughty:

Pinching the hose will result in blowing out one of the following:

The decompression plug if you have not installed a TT plug (of course, the stock decomp plug will eventually blow out anyways).

The half-moons covering the cams.

If you refer to the faq and look under "swamp proofing" you'll see some ideas.

I would NOT run the breather into the airbox. It can and does spit oil, and you don't want that in your air filter.

What I would recommend would be two mods.... Put in a "T" fitting and run a second line up high under the fuel tank. This will be 100% effective in preventing the breather from sucking in water if you happen to stall the bike in the water/mud.

If you are worried about dirt, then put a breather filter on both lines. Just be aware that the lower one is going to get oil soaked and will need frequent replacement.

I file this under the "if it ain't broke" category... there are good reasons to mod to prevent water from being drawn in, but if dirt being sucked in was an issue, Yamaha would have designed the breather differently.

One potential problem is if a rock or stump happens to hit the clamp that ties the breather to the frame and pinches it... see above. A full skidplate like the Utah Sport Cycle will also provide full coverage for the breather hose.

I file this under the "if it ain't broke" category... there are good reasons to mod to prevent water from being drawn in, but if dirt being sucked in was an issue, Yamaha would have designed the breather differently.

One potential problem is if a rock or stump happens to hit the clamp that ties the breather to the frame and pinches it... see above. A full skidplate like the Utah Sport Cycle will also provide full coverage for the breather hose.

And if dirt being drawn in was an issue, the interior of the breather hose would be dirty at the upper end. Check it out (it's not). "Back in the day", we used to add rocker box breathers to our Norton and BSA flatrack and TT bikes. We made them of clear hose. Only the lower 4-6'' ever had dirt in it.

After mine pinched one of the metal clamps down on the hose (and blew the plug), I shortened them and rolled them up into a ring I could thread a zip-tie through and hold the hose in place with a nylon tie that won't stay flattened out if hit on a bush.

Good info.

Thanks yet again guys for the arguments for and against :naughty: - I think I'll leave it where it is but check how dirty it is actually getting up top.

Hey Grey, when do you recommend replacing piston and rings on a '01 yz426f. I bought this new and am still running the originals...? :naughty:

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