Installing piston rings help

Waternut

Waternut

Customizing addict
Location
Macon, GA
Ok so exactly how are you supposed to install pistons in a two stroke engine? I understand the concept when the piston is off the crank but not so much when the pistons are still on the crank. I can't install the rings using a ring compressor from the bottom because when I ported the cylinder, the intake side is no longer the same height as the exhaust side.

I actually managed to roll the engine on it's side and manually push the rings in by hand. The problem was, the cylinder got misaligned somehow and it became stuck...oops.

Is it just patience and luck?
 
750SX

750SX

DO IT
Location
Palmyra
You should have a bud help you. One of you holds the rings in and guide the pistons in the bores. Also did you check the ring gap?
 
Waternut

Waternut

Customizing addict
Location
Macon, GA
Although the rings are new, the ring gap is just over the stock limits but under the service limit. Right now the ring gap is 0.52mm.

The only thing I can really think of is that the new rings are a different style from the old rings. The old rings have a notch cut out of the inner side to fit around the notch on the piston. The new rings have a notch cut out of the top side.

Unless the notch is jammed against the pin, I don't understand. The rings aren't hanging on anything but they act like it.
 
750SX

750SX

DO IT
Location
Palmyra
well the narrow end of the taper on the ring should be towards the locating pin. Also has the cylinder been bored?
 
Waternut

Waternut

Customizing addict
Location
Macon, GA
The rings look like they'd sit nicely on the locating pin...I'm wondering if maybe it's too nicely though.

The cylinder has been bored 1mm over but that was quite a few years ago.
 
Waternut

Waternut

Customizing addict
Location
Macon, GA
I'll try the old rings tommorrow and see if it's a ring issue. I don't really understand what the problem is either but I've installed each piston a couple times and both pistons once. Every time the top ring gets almost fully in the cylinder and then it gets stuck and I have to use a good bit of strength to pull the cylinder off the piston.
 
750SX

750SX

DO IT
Location
Palmyra
Also the ring gap required may be considerably different than stock because of your bore size, and piston brand. I found this out this year.
 
keefer

keefer

T1
Location
Tennessee
Arrows on pistons point towards the exhaust. The numbers on the rings should be facing up. Just have a helper hold the cyl while you position one piston slightly more in the up position than the other. Hold the rings closed by hand and ease the cyl down around the piston. Roll the crank a little to let the other piston come up while letting the cyl move with the already instlalled piston. This one is a little tricky but you can do it with a helper. I have done it solo but it is a biatch. Good luck. It usually helps if you get mad as hell a couple of times and cuss a lot. Just walk away and come back in a few and it will pop right on there.:smashfreakB:
 
Waternut

Waternut

Customizing addict
Location
Macon, GA
Ok so the rings are turning out to be the problem here.

Here is rough sketch of the ring style differences.
picture.php


Do you think I could take off some of the taper or hollow out some of the inner side of the ring without destroying it?
 
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#ZERO

#ZERO

Beach Bum
Location
Florida - U.S.A.
jfw432 said:
picture.php


Do you think I could take off some of the taper or hollow out some of the inner side of the ring without destroying it?
Click to expand...

STOP !!!

That's the difference illustrated in your diagram between the Wiseco old and new style pistons.

You won't be able to install those new style rings on your old pistons because not only are the ends different they're also thicker on the newer version pistons.

Just send them back and read the part number from the top of your piston to get the right rings sent.
 
Waternut

Waternut

Customizing addict
Location
Macon, GA
Actually found them at atlanticjetsports.com...They're a little closer to me than Michigan. Part numbers on my piston are matching the rings I'm ordering of 3189TD... 1mm over is 81mm. Wish me luck that they'll be here by this weekend!!

Thanks for all your help. I'm glad you were here... I was seriously considering grinding those rings from SBT to make them work.

Almost forgot... the old rings are ok but they're 11 years old and I just ported the motor and put a fresh hone on it. I didn't think it'd be a good idea to put the old rings back in....especially since they've been mixed up now.
 
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