Tech Tips!

by Jonathan Teraji


 We get tons of phone calls about "My YSR is leaking oil on the left side, what's wrong?"
This one is simple. 99% of the time there are only
TWO reasons for your YSR to leak oil.

 1. Transmission has been over filled

2. Clutch push rod seal is leaking

Why is this? Let's take a quick look.
This is the left side of your YSR Engine


Let's check it out closer


The white arrow on the left side of the picture points to a small hole. This small hole is the vent to atmosphere for the gearbox. The hole goes to a channel cut in the left engine case which acts as a trough for oil to flow. If you have overfilled, i.e., more than 600cc ( 20 ounces for those who are metrically impaired ) this is where the extra oil leaves the sanctity of the gearbox! O.K., I know this sounds stupid not, repeat, do not fill up that hole with expoxy, chewing gum, mud, or any other semi-solid goop! We get engines in all the time where that hole has been blocked off. New seals all around for those!
So the next question becomes, "How do I know when I have enough oil in the gearbox? I can't see it through the filler hole and there is no dipstick!?" All right now, enough whining, no there is no dipstick, yes Yamaha supplied a dipstick originally in their fine "tool" Kit that came with the new YSRs. The dipstick was as useless as, oh well, never mind. Remove the oil drain plug, drain oil. Replace oil drain plug. MEASURE 600CC of oil and pour into oil filler hole on right engine case. Now, if you still leak oil, we will move onto the second problem.
TCR Recommends Castol GTX 20-50W motor oil. (Remember this is a wet two plate clutch which does not like synthetic oil) Drain oil, measure 600cc (20 ounces) and pour into transmission filler.
The white arrow on the right side of the picture points to the clutch push rod seal. If your YSR is an '87 or '88, this seal will leak. Yamaha came out with a factory mod to combat this. In January 2001, they stopped producing it! Guess they figured all the leaks had stopped. Not so. All '87s and most '88s, depending on the manufacture date, will leak oil from this seal. The seal is not defective, the left engine case is. So what do we do now that the modification is no longer available? Put a small amount of silicone around the outside of the seal to keep it in place. Simple fix!

That's it for now. Shoot me some E-mail if you have specific YSR questions and I'll do my best to answer them as time allows, and/or suggestions for topics in "Tech Tips!" Remember this page is for you!
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