Bonneville America Forums Forums Technical Forums Performance Mods What oil after a big bore?

Hmm, I got to thinking that maybe I might want to use regular old petroleum oil for my breakin after the big bore mod.
Did you guys that did it already do this or just stay with the synthetic?
Inquiring minds want to know.

Dinqua,
did you do the big bore yet?
Joker

Mine is at the shop right now. I told them to use the Triumph Running-in Oil. I think it's just Mobil 4t? semi synthetic.

joker,
Naw, not yet. I figured I would wait until February when winter really hits. Oh wait, that's tomorrow isn't it? I guess I gotta get off my lazy butt this weekend (wed/thur for me) and get going on the job.

I am in the compressor business and not sure if this applies. But we never run a synthetic after a piston compressor rebuild. We found that the rings never seated well and started passing oil prematurely. I for one will stick with a petroleul base for break in.
Jango

The break-in oil Triumph uses in our bikes from the factory is a 10W-40 semi-synthetic oil. I would say you probably want to use the same type oil for at least the first 500 miles and then change over to a full synthetic.

Tom

TCV,
I was thinking on the same lines after a big bore. Treatr it like a new engine and change after 500 mi. makes good sense to me.
Jango

Tom,
Ah, but the new cylinder walls will be iron now, a significant difference there. I was thinking along the lines of straight petro based for this reason alone. There will probably be more iron micro shavings than from a nickasel lined cylinder.
Just thinking out loud. Or maybe talking out my butt.

Interesting ? When breaking in a fresh/new motor what are we actually breaking in? Do crankshaft bearings need breaking in? Camshaft bearings? Valves & valve guides? Piston/rings & bores(cylinders) Do roller bearings need a break in period like big end & main bearings in 427 chev? If not are we actually doing any harm to the rest of the motor while breaking in a new set of pistons/rings and bores.I would be interested to know/debate anyones thoughts.
Cheers from Muzza in OZ

Well that is a interesting question. A new engine can be broken in using Synthetic oil. All oils allow some level of friction to occur. So with a synthetic oil the engine will break-in. It might take 5 to 10 times long, but eventually it will happen.

Another thing to remember is todays engines are not the same as the engines being producted 10 or 20 years ago. A new engine today right out of the factory has tighter tolerances than a engine 20 years ago after it has been perfectly broken-in. Typically when breaking in a engine all you are really doing is seating the rings.

Some of this improvement is due to better quality control, some due to foreign competition, but primarily due to the EPA placing more restrictions on the amount of pollutants a engine can produce.

Tom