Can you tell the difference on which one is the front rotor and which is the rear rotor in the engine?

What can one look for that can help determine this. I've done some research and the only thing I can come across is that you should mark them as you pull them out.

There are some minor differences in the rotors but I cant tell which is which.

Please advise... or point me to the right direction. Thanks alot guys!

Luis

Here are some pictures:
<img src="http://img.photobucket.com/albums/v283/310_Oqi/Misc%20and%20Art/0704081450aSmall.jpg" border="0" alt="2 hearts for Zenki 2">

<img src="http://img.photobucket.com/albums/v283/310_Oqi/Misc%20and%20Art/0704081450Small.jpg" border="0" alt="2 Hearts for Zenki">

 

I'll put it this way: when you go to buy a rotor for an engine, you don't ask for a front rotor or a rear rotor. You ask for a rotor for that series engine.

I'ts best if you had marked them as the came out. Don't know which is which now? Does not matter. Pick one of the two for the front and that's the one for the front.

 

The trailing edge of the apex seal groove was slightly flared back on the used rotors I've seen. You'll notice a little lip on one of the edges of the apex seal groove.

Lay the rotors like you have them in that pic (gears on the outside, facing away from eachother) and figure out which side of the grooves has a lip. Then, you can visualize the rotation (just imagine them rotating on a non-eccentric shaft, which rotates from the intake port all the way around to the exhaust) and figure it out from there.

For instance, say the two rotors are in front of you, each with a corner facing up, gears on the outside. If the lip is on the side of the apex seal groove closest to you, then the right hand rotor will be the front and the left hand will be the rear.

If they are the same weight stamp it's not going to matter, but if they are from a factory balanced set and the stamps are different, I'd try to figure out which one is front and rear.

 

The above sounds good.

You also might try to activate your memory. Such as when were dismantling the engine, you might have looked at the bearing surface of the rotors and noticed one bearing surface had more *copper* showing thru the bearing than the other, and figure it out that way.

 

I see, well thanks guys! Ya my memory is a little blurry right now because I sat down and just started to clean them.

Ill take that advice and look into it some more. I appreciate the input and the time taking to respond.

I have a couple of other questions and I may end up bringing back an old thread I believe I made a while back with my build.

Luis