Super Jet Stiff Piston...what could it be?

[superjet90]

I just installed my cylinder and i used plenty of lubricant and i can see the pistin rings through the exhuast ports and all went on correct. My question is it normal for one of the cylinders to be abnormally stiff when turning by hand. the front piston moves almost effortlessly up and down like i would think it would. the rear piston gets stuck towards the top of the sleeve and you really have to lean into it to get it to ccomplete its stroke. i honed the sleeves and put in new rings. is this normal?​

 

[glennbbautomachine]

I just installed my cylinder and i used plenty of lubricant and i can see the pistin rings through the exhuast ports and all went on correct. My question is it normal for one of the cylinders to be abnormally stiff when turning by hand. the front piston moves almost effortlessly up and down like i would think it would. the rear piston gets stuck towards the top of the sleeve and you really have to lean into it to get it to ccomplete its stroke. i honed the sleeves and put in new rings. is this normal?​

Sounds like rings aren't sitting in piston correctly.remove and inspect before damage.

 

[badvinny]

Wrong size rings or the ring isnt positioned over the anti rotation pin correctly, third thing to ccheck is for correct ring end gap.

 

[superjet90]

how would i check the ring end gap?

 

[jaxrider]

remove ring from piston, put ring into cylinder 1/2 " down, measure the gap with gauge. You should check all rings and both cylinders

 

[superjet90]

better question how big should the gap be?

 

[Matt_E]

The box that the piston came in should tell you.

 

[badvinny]

.012-.015" ring gap

 

[zach613]

Use the piston up side down to make sure ring is square to cylinder before mesuring.