Can someone give me a pointer on how to get the cylinder over the rings etc...

[djmartin]

It sounds like work but I am having a blast doing my own rebuild. Everything has went great but now when I am putting the cylinder back down over the piston I am having a hard time comressing the ring to get the cylinder to slide over.
I have seen people post that they just squeeze the ring with their hand so I must be a puss because It is not working for me that easy haha....
I thought about buying a tool somwhere but wanted to check with you guys first before I drop $30 for a ring compression tool. Any help would be greatly appreciated before I have to load my bike up, head to the dealer so they can smaile and say " Yeah we could have done that for ya for about $300"
I love this site!!!!!!!!!!!!!!!!!!!!!!!

thanks guys!!!!!!

 

[plynn41]

I've never had a problem on a bike. Any that I have ever done have had a bevel on the bottom of the cylinder bore (at least at the stock bore) that makes it easier.

If you're having trouble, before you go to the extreme of getting a sledge hammer, check how the ring fits in the cylinder without the piston. Measure the ring end gap (hope that there is a gap), and make sure it is within the manufacturer's tolerance. If the ring is too tight, you're not going to get the piston in there brother.

Also, especially if you're new to this, make sure when you've got the ring(s) on the piston, that the ring gaps are lined up over the little locating pins that are in the grooves on the piston. If you don't have the ring gap lined up at the right place, it's not going in either.

Good luck!

 

[julien_d]

A ring compressor is absolutely the best way. Some people put one circlip in the piston, then slide the piston into the cylinder on the bench. Then you position the whole shebang over top of the conn rod, slide the wrist pin through, and then install the other circlip.

I did it this way last time, and honestly I didn't think it was any easier OR any harder. I have more problem with the 2nd circlip than with the rings. If getting the rings into the cylinder gives you the most trouble, perhaps for you it would benefit to use the piston in cylinder on the workbench approach. This way you can really see what you're doing.

With the cylinder on your workbench, install one circlip into the piston. Take a look at your bike and determine which clip will be easier to install ON the bike (less stuff in the way, etc), and pre-install the opposite side. With the cylinder either upside down, or on one side, slide the piston into the bottom of the cylinder. Have someone help you support the whole thing (cylinder with piston sticking out the bottom) over the connecting rod, and slide the wrist pin through until it seats against the pre-installed circlip. Install the outside circlip, ease everything down and secure the cylinder to the cases. All done?

 

[2strokerfun]

I use my fingers now, but in the past I used ring compressors. And the absolutely best ring compressor I ever used for small bore engines was simply a strip of 2024 T3 aluminum (aircraft aluminum from a wing or fuselage covering). Cut a strip about 1 1/2" wide, wrapped the ends around a short piece of 3/8" dowel. Place around rings and use pair of open vice grips to pull the wrapped ends toward each other. Oh, coat the inside of whatever ring compressor you end up using with a little premix oil.

 

[rmc_olderthandirt]

I second what Plyn41 said. If you are not aware of it they are easy to miss, but in the grove on the piston where the rings go there is a tiny pin. The gap in the rings MUST be positioned over this pin or the ring will not seat into the ring. It is possible to force the cylinder on even if the rings are not in the right spot but the engine will self destruct if you continue.

On my YZ-125 I could just slide the cylinder down over the piston and the bevel on the bottom of the cylinder compressed the ring (only one ring), no problem. On the 250 I was having difficulty keeping the two rings positioned properly so I used a ring compressor primarily to ensure the rings stayed in position.

The most difficult top end rebuild I have ever done was on a 1200cc three cylinder Jet Ski, with the bottom end still in the boat. There was no way I was going to get three pistons to slide into their respective bores and keep the rings in place without ring compressors so I jury rigged a set using hose clamps. I got really large hose clamps and then bent them to put kinks in the band. These kinks would stick out past the bevel in the bottom of the cylinder to keep the band from getting wedged. Slide the cylinder bank on part way then remove the clamps.

Rod

Also note that some rings have a top and bottom side, and if they are not installed right side up they may not engage with the pin properly.

 

[scottiedawg66]

+1 for hose clamps!

 

[barryadam]

Install one of the circlips in the piston. Put the cylinder upside down on the bench and install the piston compressing the rings by hand, noting the locating pin. Leave the bottom of the piston sticking out from the cylinder so that the piston pin hole is available. Hold the cylinder/piston over the rod sticking out of the bottom end, and install the piston pin. Add the remaining circlip, and lower the cylinder to the base gasket.

 

[RM_guy]

Install one of the circlips in the piston. Put the cylinder upside down on the bench and install the piston compressing the rings by hand, noting the locating pin. Leave the bottom of the piston sticking out from the cylinder so that the piston pin hole is available. Hold the cylinder/piston over the rod sticking out of the bottom end, and install the piston pin. Add the remaining circlip, and lower the cylinder to the base gasket.

:cool: That's how I do it all the time now. Much easier.

 

[whenfoxforks-ruled]

I do not use my fingers to hold the ring in place, but my finger nails I do! Either way works, do not force it, and do not spin the cylinder to align the case studs. If its not aligned take it off and try again. Spinning can collapse the small pins in the piston ring lands. Vintage Bob