Piston circlip and piston ring, 125cc

[Noobi06]

1. Today I installed the piston and it's circlips. The first one, I just slide in and push from the other sides with my finger, no big deal.
The second one, I can't push from the other side obviously since it is on the crank. After having a very rough time installing it, I got it in.
Both Circlips are sitting in their groves and are very snug, however I did notice that the open end (mouth or what to call it, gap?) is different on both circlips after installation. Even though both are in their groves as they should, one gap is bigger than the other. Is this normal or is it a problem? One is very tight and has a small gap, while one is bigger.
2. I measured the piston ring gap. (125cc, 54mm bore). 0.25mm feeler gauge went in easy, 0.3mm and 0.35mm also goes in but they are very very snug. However isnt 0.35mm too big? Im pretty sure it is supposed to be 0.21mm.
Note! Piston is a new 53.95mm wiesco. Piston ring aswell.
Cylinder is replated and is at 54.05mm, meaning it is 0.05mm larger than normal, also meaning that piston-cylinder clearance is 0.05mm bigger than normal.
This makes piston ring gap even larger.
We did this because according to the guy who replated, it is way better for road riding since the piston won't pinch as easily.

 

[Noobi06]

Just read that KTM 125 SX manuals says ring end gap should be 0.4mm which makes me believe that the ring end gap isn't a problem.
Though the circlip is scary

 

[Anders]

Can you post a couple of images of the circlips?

 

[Noobi06]

Pics

I already closed up the cylinder, but I took a picture from google and edited it to explain better.
On the following picture, the pink pencil is the circlip and the circlip is sitting perfectly in the groove. However the gap as you can see with the arrow, is smaller on one side than the other. Even though the circlips are the same size and both are located in the groove perfectly.
Even though it is concerning, for me, it is impossible to understand how this would make a difference since it sits perfectly in the groove.
The one that has a smaller gap I had trouble installing since that one was installed on the crank. Maybe it got more compressed with more attempts resulting in less gap?

 

[(F5)]

I just don't see how that is possible. If the circlips were the same length the only conclusion is that the small gap one is hung up, perhaps on the piston cut out so not fully in the groove, at least on one side.

How else aside from magic, could the gap be smaller?

Wiseco piston yeah? QC should be good enough that grooves are machined properly. Both circlips from same packet.

I usually rotate the clips with a scribe to get the closed end over the gap but also to ensure fully seated.

You've been getting a hiding with this thing, bit if there is a doubt you need to check it again. The piston going up and down will dislodge a circlip that is misplaced. Maybe not the first time you ride it. And the pin will walk sideways to dig a trench in about 200 milliseconds.

 

[Zman]

Did the clips look the same before you installed them?

 

[Noobi06]

Yes, clips looked the same before I installed them.
I tried to move the clips when they were in the groove with the screwdriver but I couldnt get them to move at all.

 

[Anders]

Yes, clips looked the same before I installed them.
I tried to move the clips when they were in the groove with the screwdriver but I couldnt get them to move at all.

In that case I would reccomend that you take off the cylinder and do another check. Something must be wrong.

If you start the engine like this, the chance of ruining your newly coated cylinder is very high.

 

[Noobi06]

Im so glad I listened to yall. I took a 10mm socket and I was able to pop in the clip in the right position aswell as turning the clip to the right position. Thanks so much!
However Ive got one more problem.
I installed the power valve assembly and it works perfectly but the power valve arm is moving not so freely. When I go to connect the arm and the rest of the power valve, I need to use a lot of force with my finger to get it up and down. If I screw the nut that holds them together more than hand tight, it barely moves. Something for sure has to be wrong with the power valve arm assembly, but what?

 

[(F5)]

Good on you for listening rather than just closing your eyes and hoping. Life is too short not to learn from others mistakes.
I'll tell you about the time I put a 50cc piston in backwards some day

Powervalve is different on the 125s I think, can you post a picture or diagram.

 

[Noobi06]

Power valve ass

Ye backwards pistons im familiar with. this gasgas came with the piston backwards, yet it ran. I have another 50cc that also had it backwards.
Here is the power valve diagram for 125cc
The bearing is new, and is sitting as it should. I also just rebuild the power valve assembly and everything is installed correctly.
Im starting to think that maybe it should be rough? To be fair, the engine is much stronger than me.