TY250 A - what is the correct amount of gearcase oil?

[Tillerman6]

At the risk of kicking this subject to death-   If I put in a full liter of gearcase oil after draining it all out, the dipstick shows an overfull condition- even after running the bike for hours.  The oil is about an inch above the top mark on the dipstick even with my modified drain plug which allows oil to level between both sides of the clutch wall.   So I am wondering - this is probably soaking up horsepower that could be useful at the back wheel, engine responsiveness and easier engine starts if the clutch was not half immersed in oil.   So to me- I've got conflicting information- the book and the marks on the case say to put in 1 liter, but the dipstick says that's too much- even with the modified drain plug that allows self leveling.  What could it hurt to bring the levels down to the upper line on the dip stick?  Opinions? 

[feetupfun]

If the reason for your conundrum is that the gasket is acting as a weir then you can test for this by draining the gearbox and seeing if the dipstick is still showing a level

[Tillerman6]

Feetupfun,

   it's possible that the gasket is the problem- I noticed that the gasket appeared to be a non- Yamaha part because there is a sort of watermark name printed into the paper that did not say Yamaha or anything close to that. It's also almost a black color rather than the greenish paper that the Yamaha gaskets are usually made from.  And yes- and just going from memory here the dipstick still shows a higher than normal oil level after the oil is drained- not for long, but for a few minutes anyway.   Since then I have switched oils to something called "clutch saver" 10W30 and now the oil level is barely above the top mark.  ???  Unfortunately, my camera memory stick is no longer functional and I lost the photos of the gasket when the clutch cover was off.   The modified drain plug is still doing service in the bike now too, so that is still a factor in this mystery.  If I get a chance, I will take the cover off again and have another look- the problem could cause severe damage if the dip level was high only because of the gasket.

 

[Tillerman6]

Update- I did a little more investigating today- I checked the level with the dip stick sitting on the threads - still had about 5MM above the top line on the stick- 

I then drained the oil and re- checked the stick- it was now dry to the tip.

I then measured the quantity that was drained- 0.8 Liters.

I took a flashlight and can see the inside of the bottom of the clutch compartment including the gasket at the bottom- there is no obstruction or gasket sticking up into the clutch compartment anywhere near the dipstick.

So I think with the modified drain plug installed, it should be safe enough to operate with 0.8 Liters on board.  The dipstick is happy anyway.

I will keep an eye on the oil level and report any news I come across, but since the dipstick goes dry when the oil is drained, I feel pretty confident that the dipstick is giving a valid reading.