Compressing piston ring

I'm trying to put my new piston back into the cylinder jug and I can't seem to compress the oiler ring. I can get the first two by hand, but there is nothing I can do about the third ring. Anybody got any tips?

I'm doing this all by hand like the Yamaha factory manual suggests (it's a wr400 btw).

I know what you mean, I just put in a new vertex piston in my 01 wr426 I had to use a piston ring compression wrench, you can buy them at almost any auto parts store. Spending the money is worth it than spending the time and effort struggling and getting pissed off at something you think you should be able to do with out a tool.

Did you hone (i think i spelled that right) out the cylinder walls first?

use a small flat blade screwdriver to push a section of the ring in, then lower that section of the sleeve over it. Work you way around the piston and she just falls in.If you got yoiur barrel bored and they didnt put a good taper on it, it can be difficult. but it can be done. DIY honing of a nikalsil barrel isnt recomended :banghead:

Get a wide heavy duty zip-ty and use it to compress the rings. Once the rings start into the cylinder bore the zip-ty will fall down where you can cut it with a pair of dykes. What ever you do be careful about using a screwdriver near that aluminum piston, one decent scratch and your hosed. :banghead:

Joe

All good suggestions. What does make it a whole lot easier is to put the piston into the cylinder while it is off the bike. Then push it down so the wrist pin holes just clear the lower part of the cylinder wall and then place it over the connecting rod and push the pin through. You have just enough clearance to keep the oil rings in the cylinder and still push the pin through.

It seems the oiler rings are not able to compress completely. It compresses completely about 90% around the piston, but the other 10% does not want to go in at all. Does this mean I have to file down the 3 oiler rings? Or is it that I just don't have the rings installed correctly? What order do you put them in? I have to put the center oil extender ring in and then the 2 oil rails, is this correct?

where you can cut it with a pair of dykes.

:applause: I wouldn't mind cutting it with a pair of dykes! :banghead:

It seems the oiler rings are not able to compress completely. It compresses completely about 90% around the piston, but the other 10% does not want to go in at all. Does this mean I have to file down the 3 oiler rings? Or is it that I just don't have the rings installed correctly? What order do you put them in? I have to put the center oil extender ring in and then the 2 oil rails, is this correct?

If you have your manual handy it helps.

The ring order from top to bottom:

1st) The top ring is bright (shiny) and should have a "T" next to the opening of the ring, make sure the "T" is facing up.

2nd) The second ring is sometimes darker than the top ring, looks more like a brass color, if this one has a mark on the opened end of the ring make sure it is also facing up.

3rd) The third one is the oil ring.

Make sure that all rings are fully seated in their grooves and should easily move around on the piston. Also place the openings in 3 different locations on the piston Example: 1st at 2:00 0'clock

2nd at 6:00 0'clock

3rd at 10:00 0'clock

This helps in compression and in the breaking-in of the piston and rings evenly.

make sure the oil ring is not overlapping in self install the love first the the wafer ring then the upper ring rnsure the wafer ring is not over lapped and that just the ends are touching

you should have checked your ring end gap of ALL your rings before you started assembly. Check the manual for specs. slide a rind into the barrel, push it down about 1" using the piston to keep it square and check the end gap using a feeler guage

thanks for the tips guys, I'll be back at it again tonight.

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