First Two Stroke Top End Replacement

[suzukipride]

I will be performing a top end rebuild on my 2007 RM125. Runs fine, just wanting to freshen it up. Bike has a full fmf exhaust and jetting for mods.

I ordered the OEM Suzuki Top End kit (includes all necessary gaskets/seals for job). I also have the factory service manual.

I have rebuilt many four strokes including bottom ends/splitting of the cases with success each time (RMZ250 and YZ250F), so I'm not really new to this, just wanting to know any tricks or heads up for the 125.

I was told I should also clean the power valve assembly?

[Fixxxer22]

I just went through a older KX and yes, I would recommend removing and cleaning all of the power valve components.  The valve portion located in the combustion chamber had so much ashy buildup that was baked on.  Also the movement of the system was rough before I cleaned it all up. 

[evo550]

Only thing you'll need to consider is what to do with all the extra time you have on your hands....guess you could go riding, while all your mates are still working on their 4ts 

[eprovenzano]

Amen Evo...

Since you are comfortable getting your hands dirty, you will love the simplicity of a modern smoker.  My only piece of advice is to take pics or notes of the power valve setting before you disassemble.  Other than that you will spend more time cleaning up the bits and pieces than the actual rebuild. 

Welcome to the smoking section... 

[suzukipride]

Ok, started the tear-down of the top end on the 07 RM125.

A few things I was disappointed with regarding the Suzuki "top end kit" 12100-36871:

1. Does not contain a new Wrist Pin
2. Does not contain a new piston/rod bearing
3. Does not contain new power valve cover gaskets

I am going to assume here that the wrist pin and piston rod bearing are items that really should be replaced during a top end rebuild? I included a pic of the wrist pin I have. As you can see, shows signs of some wear.

How much side-side play is allowed on the connecting rod with the head off? Mine has quite a bit!

As I stated before, I never did a two stroke top end, I have done my fair share of modern 4stroke rebuilds. I was expecting to see carbon buildup all inside the powervalve assembly and a bunch of gunk. Not so here, besides the I guess normal oil/premix. Nothing was carboned up here. I was unable to remove the two 4mm allen head screws (you can see them in my pics). They are super tight and I ended up bending my allen wrench trying to get them off. I will have to buy a allen socket for this but I'm wondering if it's even necessary (there is no binding or obvious signs of issues within the movement of the valve).

I included a pic of the powervalve shaft. There is some wear from where the two springs rest on it.... should this be replaced?

Cylinder looks great.

Any other tips are greatly appreciated! Here are the pics:

Before a simple Cleaning:


After a simple Cleaning:


The grooves on powervalve shaft I was referring to from where the two springs rest on it:


Wrist Pin:

[2T Institute]

Tip No1 is forget 4T's.
No 2 is jetting and ignition fix carbon build up.
No3 Rod should have at least 1.5mm side clearence when rod bearing and thrust washer pushed tp one side.
PV shaft is fine

[suzukipride]

I ordered a wristpin, piston bearing, and powervalve gaskets.

[rlaj1004]

  My only piece of advice is to take pics or notes of the power valve setting before you disassemble. 

I second that, walked my son through his first top end, forgot to tell him to make sure the PV goes back the same way,
Funny thing it ran anyway but wouldn't make power, kinda like he detuned it. As soon as he set it right it was fine.