Replacing piston rings, what else?

[rightious]

Hey guys, it's been a while since i have been on, i am in the process of pulling my motor out to replace my piston rings. I am wondering while i have the motor out and apart, is there anything that i should do while i'm balls deep in this thing? Nothing else is wrong that i know, but i'm pretty new to motorcycles all together. Any help would be VASTLY appreciated. thanks

[Larry D]

De-carbonize, valve stem seals, hone the cylinders, clean off all the grunge and paint.

[chef1366]

Also replace the base gasket.

[Big T]

Okay, bigger question

Why are you replacing the rings?

Poor compression?

Blowing oil?

You say you are new to bikes, are you sure the diagnosis is correct?

Cam chain tensioner guides are mandatory

[rightious]

big t,

yeah, i put a compression tester on all the cylinders, and the one had real weak pressure. So i am going to replace them all.

[tkent02]

big t,

yeah, i put a compression tester on all the cylinders, and the one had real weak pressure. So i am going to replace them all.

#3 ?

[chef1366]

If it was #3 then you probably washed out the cylinder with a leaky petcock. Fix the petcock and the rings will seat.

[rightious]

i believe it was # 4

[mike_of_bbg]

Did a wet compression test help? Checked your valve clearances? How bad off was the compression?

[49er]

You don't need to remove the engine to do the rings. But as others have stated, make sure you have a ring problem before ripping into it.

Has it sat for a very long period. You may have siezed rings in the piston grooves. If so, take it for a hard ride and redo your compression test, while the engine is hot and with the throttle wide open.

You can remove the head and barrels with the engine still in the bike.

[rightious]

yes the wet compression test helped, without oil in the cylinder it was like 20 or so psi. i already have the engine out, i want to go threw it and clean it up any way, and since i live in chicago, it is disgusting outside, so i have a warm basement to do it in.

i do believe it has sat for a while, i just got it in the fall, so i am not sure what happened with the previous owner.

i still have issues with it running on only 2 cylinders, i was one before and everyone told me i need to rebuild the carbs again. i did rebuild them with cheep aftermarket rebuilds, so i might re-do it with oem rebuilds.

[Steve]

Not sure what you are calling "OEM rebuilds", but there are no OEM rebuild kits for the carbs. Your best bet is to get a full set of o-rings from cycleorings.com, dip the carbs in Berryman's Carb Cleaner Dip (overnight for each carb body), use the original jets, put it all back together.

.

[headsbikesmopars]

I believe the vac. port is on the #2 carb.. Use a ball hone on the cylinders and go with new OEM rings if using OEM pistons. Go thru the head with new seals and have the valves re-seated (valve job), have the valves back cut 37 degrees this will pick up low-mid lift flow a bunch. If your machinist doesn't know what a back cut is..get your stuff and run away as fast as you can ! Also, have the deck 'cleaned' up with a .005 surface cut. New base and head gaskets. Use a service manual that explains ring end gap placement (stagger). Work slowly and pay attention to detail and keep a RECORD of what you do. Take a compression test after the first 2000 miles and RECORD that too for future reference. Good luck and keep use informed.

Terry

[Steve]

I believe the vac. port is on the #2 carb...

On the BS series carbs (after 1980 on most models) you are quite correct, however, on the earlier VM series carbs, the vacuum port is on #3.

.

[49er]

I believe the vac. port is on the #2 carb.. Use a ball hone on the cylinders and go with new OEM rings if using OEM pistons. Go thru the head with new seals and have the valves re-seated (valve job), have the valves back cut 37 degrees this will pick up low-mid lift flow a bunch. If your machinist doesn't know what a back cut is..get your stuff and run away as fast as you can ! Also, have the deck 'cleaned' up with a .005 surface cut. New base and head gaskets. Use a service manual that explains ring end gap placement (stagger). Work slowly and pay attention to detail and keep a RECORD of what you do. Take a compression test after the first 2000 miles and RECORD that too for future reference. Good luck and keep use informed.

Terry

Good advise except for two things. As Steve has pointed out, the vacuum port is on #3 carb.
There is little point in staggering ring gaps as mentioned in many service manuals. As soon as the engine is run, the rings move around in the grooves anyway, so occasionally they will all end up in alignment. That won't happen very often. But even when it does, at 7000-9000 rpm, you won't notice the difference in performance anyway.