Topic: New pistons, rings, and fresh bores ... what to lube?!

[iron_worker]

So I'm about to reassemble the top end of my fresh K4 750. It's had the cylinders bored and honed to +.25mm and fresh pistons and rings from Cycle X as well. I'm just wondering about when I go to slide the cylinders onto the pistons what should I have lubed up?

I've heard many versions from only having a light coat of oil on the piston skits to having oil on EVERYTHING.... pistons, rings, cylinders.

So what do you guys do and do you just use engine oil or something else? I just want to give my fresh motor the best chance possible.

Also, if you'd also like to share what your preferred method for breaking in a new cam and new rings is I am all ears.

IW

[Mo]

When I did my top end, I was dumb and didn't lube anything. Luckily, this was before I had really gotten too far into reassembly, but I could notice a squeal when rotating the engine from the crankshaft bolt. When I realized I was a dumbass, I went back and I made sure to lube up the cylinder walls, the pistons and the rings with whatever oil I was planning on filling the engine up with. All seems well so far

[Lostboy Steve]

I used some molly assembly lube. Basically lube everything.

[Dream750]

I use the liquid crane engine assembly lube on all the friction surfaces. It’s a thicker viscosity than engine oil and has a good “cling” factor compared to engine oil. The assembly lube is especially useful if engine start up is delayed as it won’t run off the surfaces.

I’ve had good luck using the 750K owners manual as a break-in guide for stock or nearly stock engines.

Perhaps Cycle-X can offer you specific advice since your using their parts? They would know.    

[iron_worker]

I have some assembly lube. I could use that. There will definitely be a wait before first start up... still have several feet of snow on the ground here. lol

I will give Cycle X a shout as well.

IW

[dave500]

if the engine is going to be started soon after and not shelved for months just use the oil you intend to use in the bike,the pastey assembly type lubes are best used on the cam and rockers.

[iron_worker]

The engine probably won't be ran for a 6 weeks at least. Spring takes a while here.

I've been doing a bit of research and there are varying opinions out there. All the way from bone dry to slathered in oil. Some say that too much lube will cause the cylinders the rings to glaze and cause the engine to burn oil.

Seems like guys have had success either way.

My gut tells me to use a light smear on the skirts front and back and a touch on the cylinder wall. Although when you put the piston in from the bottom it will tend to scape all that lube off.

IW

[dave500]

i assemble the pistons etc with oil,be sure to have plenty in the ring grooves,if the engine is sat for a few weeks before starting drop some oil down the plug holes and rotate it a few cycles,dont let a newly started engine idle or you WILL glaze the bores!!ride and load the engine as you would normally but dont lug or over rev it,it will belch smoke during the first start up for a few minutes.

[Lost and Confused]

I've had luck using Lucas pure synthetic oil additive. A quart is pretty reasonable. Good luck.

[iron_worker]

The cam break in procedure is to allow the bike to "idle" at 2000rpm for 20min I think...

So do you break in the cam or go ride it and break in the rings? ... lol

IW

[dave500]

just ride the bike,dont try any fancy break in procedure.

[iron_worker]

Hop on and giver beans! lol

IW

[Bailgang]

just ride the bike,dont try any fancy break in procedure.

+1,

I use Permatex ultra slick assembly lube or any high moly assembly lube for that matter on all bearing surfaces and cyl walls.

[Stoli]

I have read that assembly lube with moly isn't the best choice for an engine like the CB where the clutch is lubricated by the same oil that passes through the engine. Might be a bunch of BS but for that reason, I went with Redline assembly lube on the friction surfaces when I rebuilt my engine which supposedly doesn't contain any moly. I just used a little engine oil on the cylinder walls.

[iron_worker]

Well I believe you're supposed to change your oil after the first couple hundred miles anyways so probably doesn't much matter to the clutch. All that assembly lube will come out with the oil then.

IW

[CafeDawg]

I'm throwing this in the ring with no hands on experience with the technique described.  Food for thought and figured it would spark a discussion which could lead to edification of all. 
http://www.mototuneusa.com/break_in_secrets.htm
Respect
CD

[Leanier]

I recently went through this with my rebuild.  A guy that restores sandcast 750's and works with them a lot said that you are NOT supposed to lube the cylinder walls at all (or very very lightly) when assembling, due to the rings not seating properly.  - He stated that the chrome type ring tends to have less friction already, and the oil can hinder the initial seating, especially due to the chrome type ring.

Now if its not starting for ~6 weeks, I'd think you would want at least some oil on the cyl walls to prevent rust.

My first rebuild failed to seat the rings properly (I dont know why, but had lubed the walls well)  On the re try I didn't lube the walls at all, and the rings seated great.

Just my experiences, the guy that told me this seems to really know his stuff.

[bwaller]

Around 1990 I rebuilt my 750 and decided to switch to a full synthetic. As per usual I oiled the rings & pistons when I assembled the cylinder. The rings didn't seal and it burnt oil badly.

I read all I could about oils and came to the conclusion breaking in an engine with synthetic probably wasn't wise. I think it's safe to say our oil choices today are better than when our sohc4's were new. This is great for an engine, just creates issues with new ring seal.

This raises eyebrows & I dig that, but my break-in approach now is as follows. One drop of oil on each skirt, rings & bore dry. Cam & followers coated with Redline ass. lube. I start the engine & run it to 50% redline for 30 seconds and shut it off & let it cool. Break-in complete. I usually run it again for a minute or two then change the oil & filter.

I have done this with my race engine several times and see no extra-ordinary wear marks and this engine is torn down often. At the very least breaking in an engine should not include low revs in tall gears. Fooling with jetting while breaking in a new engine will undoubtedly lead to washed down cylinders and comtaminated oil.

End of story....for what it's worth!

[iron_worker]

Seems to be lots of advocates of the "run it hard!" method.

Thanks for all your help guys. I think I have decided that I will give a very light coating of assembly lube on the cylinder walls (mostly to prevent rust over the next few weeks) and a very light coating on the skirts as well. Whatever the rings pick up off the cylinder walls as they are pushed in is probably all they will get.

IW

[PeWe]

If the engine was completely open.....
Assembly lube on the crank bearings or just soak it + conrods lower ends with the oil to be used?

[crazypj]

I'm with Bwaller, piston skirt only, bores dry.
Everything else gets oiled, cam gets assembly lube (the tiny amount of moly paste isn't going to affect clutch)