RD250 Engine leaking, where is it coming from and what is it?

[JiveTalkinRobot]

Hi all,

Well I've finally got her started up and running.  However, overnight the engine seems to leak, not sure what it is and how to solve it.

I have an RD250 (with rebuilt 350 top) and use premix, not the Yamalube.

Here are some pics of where the puddles are if it's helpful.




And for safe measure, this is the off position for the petcock right?  I had a hard time understanding the diagram in the service manual because it looked different and was inverted.  I'm looking really mentally challenged right now....I realize this.




Thanks in advance.

[Sonreir]

Off position on the petcock is almost always in the middle.  Check under your crank cases for leaks.  Any leaks there and you're getting robbed of power as well as leaking fluids.

[VonYinzer]

Off position on the petcock is always always in the middle.  Check under your crank cases for leaks.  Any leaks there and you're getting robbed of power as well as leaking fluids.

Not always true. My petcock points forward for OFF. So does this one. You have it in the RESERVE position, which will allow fuel to flow. Look very closely at the petcock. The positiongs are stamped into the plate that holds the lever on.

As far as the leak, its certainly oil. Where its coming from is whats important though. If its a bad seal, you likely need to rebuild the motor. If its just a cover gasket or drain plug seal, youre lucky. Honestly though, between this and your other thread on this bike (why two threads by the way?) I have a feeling that you have some real work ahead of you.

[JiveTalkinRobot]

Not always true. My petcock points forward for OFF. So does this one. You have it in the RESERVE position, which will allow fuel to flow. Look very closely at the petcock. The positiongs are stamped into the plate that holds the lever on.

As far as the leak, its certainly oil. Where its coming from is whats important though. If its a bad seal, you likely need to rebuild the motor. If its just a cover gasket or drain plug seal, youre lucky. Honestly though, between this and your other thread on this bike (why two threads by the way?) I have a feeling that you have some real work ahead of you.

New to forums, I figured this was the "I need help on a specific topic" area...and then the other one was more for providing updates about your build.

[VonYinzer]

Gotcha... All good man, just wondering. Where are you located? Id see if there was a more experienced member local to you that would swing by and take a look.

[JiveTalkinRobot]

Yeah I might do that, I'm in Southern California.  Seems to be a few members here.

[Sonreir]

As far as the leak, its certainly oil. Where its coming from is whats important though. If its a bad seal, you likely need to rebuild the motor. If its just a cover gasket or drain plug seal, youre lucky. Honestly though, between this and your other thread on this bike (why two threads by the way?) I have a feeling that you have some real work ahead of you.

Ooops.  Sorry... that was a typo... I meant to write "almost always" but accidentally wrote "always always".

[Redbird]

My DS7 had the same issue...
Take a dry rag and wipe the bottom of the shift lever shaft first, and then the bottom seam of the side cover (where it bolts to the case). If you get oil in one location but not the other, it's either the shifter shaft seal or the neutral indicator switch o-ring that's bad. If you get oil in both locations, it's probably just the shift shaft seal and it's leaking all over both locations. Either way, both the seal and o-ring aren't that expensive and relatively easy to change. They're right next to each other behind that cover, so change them both while you have it apart. That'll save you from pulling it all apart again in a month or so when the "other one" goes bad.

[Spoonz]

Did you put a new gasket on the drain plug? Even if you think yours is good, if its been tightend down then removed you need to replace it. It is a one time use gasket. A copper gasket will work and you can reuse it a few times. Shift shaft seals go often too.

[JiveTalkinRobot]

I think I will buy all the gaskets and seals mentioned and also this: http://www.economycycle.com/servlet/the-50/Vesrah-Complete-Gasket-Set/Detail

and just replace everything.

[Swapmeet Louie]

ya, thats a shaft shaft seal.....

[Spoonz]

Off position on the petcock is almost always in the middle.

Not true... My RD off is back, run is down, and reserve is forward. My Honda is off forward, reserve down, and run back

[JiveTalkinRobot]

engine gaskets replaced, shift shaft seal replaced, neutral indicator o-ring replaced....

...still leaks.

Not sure what it could be at this point.  I guess the final remaining thing is the drain plug gasket.