Fitting new piston rings

[the_admiral]

Hi all i am just waiting for my new piston rings and top end gasket seal kit to arrive from motorbins,i have stripped the left hand head and cylinder off and removed the piston,just wanted to know if any members have found it easier to fitt rings this way and then to slide the barrell back on with the piston pushed in and the connect the gudgeon pin.also should i use any kind of sealer with the new gaskets,rubber seals and pushrod boots
thanks in advance
1981 r65 85000 miles

[Crossrodes]

I had the barrels off my '79 about 2 years ago.  I used some hi temp sealant around the base of the barrel (not directly on the O ring) and as I recall I also put some sealant on the seals for the push rod tubes.  I had no leakage.  Hope this helps.

[montmil]

"...and as I recall I also put some sealant on the seals for the push rod tubes."

And the view from the other side of the aisle... The push rod seals must be allowed to expand and contract with the engine-generated heat and cool cycles.

An article, many years ago, in BMWON dealt with this question. Being discussed by some long-time Airhead techs, the short answer is that sealants should not be used. Lube both the interior of the grommet -so that the pushrod tube and grommet can move with the "expansion-contraction cycles" plus lube the exterior of the grommet prior to seating the grommet in the engine case.

I can provide the month and year of the ON article if anyone keeps issues for 15-20 years.

Monte

[Crossrodes]

Monte you may be correct but I got that advice from a retired BMW mechanic.

[nhmaf]

I know of a couple people who put rings on piston -> piston into cylinder-> slid cylinder onto engine studs and reattached connecting rod/wrist pin.  If you have a helper (I think it is a bit of a 3-handed job) it would be good to enlist one, but I suspect that it may be easier this way than to reattach the piston with the rings on it, and then try to compress the rings and feed it into the cylinder at the same time.

On the non-base gasket machines, BMW says to use Hylomar (VERY thin) sealant on the engine case/cylinder base.  I suspect that it might be OK to use this on yours, but you would not want to get it into the oil passage holes near the upper studs. I haven't had to test this out myself yet.

[benlawlor85]

on my old R80 i just put the rings on with piston etc still attached and then slid the pot back on.

also try http://www.james-sherlock.co.uk for your spares, they are the smallest of the big three UK BM parts suppliers but so much more helpful and delivery is almost always next day! The price list on their site is out of date but they are almost always the cheapest of the three.

[bruce_launceston]

I didn't remove the pistons, I cleaned the piston crown and ring grooves, installed new rings and pushed the barrels on. It is easier with a third hand but it can be done with 2 hands and a knee.
I used a silicone spray lube on the pushrod seals and no sealant on the base. I just relied on the 'o' rings. The original ones worked for 25 years without any additional sealant.

[Rob Valdez 79 R65]

I have always reinstalled the cylinder with the piston attached to the con-rod.  You simply compress each ring in turn.  NBD.

I use a light coating of axle grease on the push-rod tube seals.  Nothing on the cylinder base.  I always replace all 3 O-rings when I have a cylinder off.

[the_admiral]

Hi all i have fitted my new piston rings both sides and it has made a big difference to starting,smoothness and acceleration,very pleased.i removed the pistons and found it easier this way,the gudgeon pin came out easy with a little heat from the wifes hair dryer,although i did manage to slice my finger tips fitting the rings,ouch.new head gasket,o rings and pushrod seals fitted and no leaks yet.will check after a few hundred miles
thanks all
pete