Vertex Ring-Gap; Does coating tighten?

[vznx1w]

I have noted that my new Vertex piston has a ring end-gap of only 0.007"--much tighter than the 0.016"-0.026" specified in the Honda service manual ('98 CR125).

It appears that the rings may have a friction-reducing coating (similar to the piston skirt). I'm wondering if this may cause the rings to be tight initially, but ok as soon as the coating wears off.

Bottom-Line: Should I file the rings to increase the gap?

I hate to loosen the rings up, but I don't want them to seize!

Thanks,

Steve

 

[elf]

My new weisco ring has some coating on it too. I gapped mine about 0.003 less than I usualy do but I am wondering about this too.The instructions say about 0.012 or 0.013 for a 125. Anyone else know what we should do?

 

[Rcannon]

I just wanted to join the "my rings measured too tight and I did nothing" club.

Yes, I changed mine this weekend in my YZ 250. I used weisco. They measured a bit tight, but I left them alone. Did I screw up?

 

[Rich Rohrich]

Running too little end-gap on the rings can cause the rings to get hung up in the ports. If the rings are too tight you have to file them to the proper spec.

 

[elf]

Running too little end-gap on the rings can cause the rings to get hung up in the ports. If the rings are too tight you have to file them to the proper spec.

I think we all understand that Rich. We are wondering if the ring gap will increase after the coating wears off the rings.
In other words gap it less and when the coating wears off the gap will be where it should be. Does that make any sense?

 

[Rich Rohrich]

The moly facing on the rings is only a couple of microns thick, so no it won't chnge anything.

 

[Jman271]

On most of the Wiseco stuff I have used, it says .04" gap per inch of bore, in my 125's I run about .08"-.010".

 

[marcusgunby]

I wouldnt worry too much-the honda SRS setup reccomends a ring gap half as big as the vertex.

Ive ran the vertex as is with no problems-the honda gaps are on the large side.

 

[elf]

The moly facing on the rings is only a couple of microns thick, so no it won't chnge anything.

Alright just gap it same as usual, thank guys.

 

[vznx1w]

Thanks for the input. 'm gonna set the gap at 0.16"--the tight side of the Honda spec. :thumb: