Dry piston install

[slow600]

no oil go boom is not really a strong argument, ive built dozens of engines with no boom yet. i based my opinion off talking to top engine builders, not just average joes (not intended at muleman). granted they were all 4strokes so the kx might be different. manual does state oil on cylinder wall, however if everyone followed the factory manual there would be no performance builders at all. the rings will have immense heat generated as soon as it starts moving from friction so no heat gun needed. what we are talking about is milli-seconds here so i say do whichever you are comfortable with.

[BDI]

The only reason you can get away with installing a piston dry is do to the miracle of ceramic coating. I sure hope no one tries this with a cast iron engine. This is kinda like the brake it in like you drive it deal. An engine that is broke in hard will show more ponies on the dyno right off the bat then an engine that is broken in correctly. The engine that is broken in correctly will show the same horse power further down the road and it will sustaine those levels for a longer time. The brake it in like you drive it thing is what you do to motors in race cars that have a very short life expectancy. I'm sure that a motor with a ceramic bore that is put together dry will seat the rings alot faster but their has to be a trade off. I'm sure that a motor put together correctly and busted in correctly will show more peak ponies and sustaine them longer then one done otherwise. So in other words My engine put together wet and broke in correctly will lose to your engine put together dry and broke in how ever you like on the dyno but after a month of running these engines, the dyno will tell a different story. After a year it will be even more apparent. Just my opinion

[azdirtrider75]

I'm with you BDI - I'll always do my top ends with plenty of oil. Lubrication is the key to a happy engine (and bike for that matter). To all of you that put pistons in dry - clean and dry your bearings; I bet they spin super fast - until they don't.

[slow600]

haha sleeved cylinders get the dry treatment too. like i said earlier, to each his own. voodoo gods say dry engines actually last longer due to less blow-by and oil loss. roller bearings not really a good analogy, kinda like apples and oranges really. i do lube top bearing fyi. im still waiting on proof before i change my mind, i love being proven wrong/learning new things. cheers

[BDI]

So then would you put a small block chevy 350 together this way too??...

[slow600]

cant say for sure, i never got into cars. i would prob say yes, but would research first. all honda motors at dealer i work at get dry. (im not honda tech, service advisor)

edit: after quick phone call, small block wet due to high ring tension. always someone smarter than me out there

[BDI]

Why would you put it together wet do to ring tension? What would happen if you put it together dry?Whats the difference?

[muleman]

I always use a very light coat of oil and do 2-3 heat cycle it let it cool down in between. Never had any problem.

[martinfan30]

With all the engines I have put together, 2T and 4T, I never have had any longevity issues with a decent break in procedure. Including heat/cooling cycles, and most importantly, varying throttle settings.

My break ins will always include light oiling of friction surfaces. I see no reason to worry about gumming up rings when a full dinosaur oil  is used. Synthetic oils after break in.

[KXcam22]

I did a search last nite on dry cylinder rebuilds (car engines) and came up with about 50/50 dry vs lubed.  It would be nice to see some microscope pics of dry/lubed rings after break in to see what the difference in sealing looks like. I couln't find any tech aricles though, only rules of thumb and peoples beliefs, no science. Cam.

[gwcrim]

Stewart, oh STEWART!?!?!?!?

[BDI]

I wonder what the temp of the rings spikes up to when you fire the engine dry. It could go real high and hurt the temper of the rings making them soft but if it got cooled off fast by oil and fuel they could become even harder then they were.

[KXcam22]

I've been doing some thinking and I doubt you would find me doing a dry install.  Firstly, piston acceleration can be upwards of 100,000 ft/sec.sq at which speed I am sure the rings will be cleaning themselves of any surface oil instantly, therefore the lubed bore would be protecting the piston from galling (a good thing) but not preventing the rings from getting full, almost unlubed contact to seat.  Also in a 2-stroke the rings bulge into the ports a tiny bit each stroke.  In a new engine, the cylinder lube would be benefitial in helping the rings slowly wear the correct path without gouging or chattering at the port chamfers.  Just some ideas. Cam.

PS. the one idea that did show up was to never use regular oil as a cylinder lube.  Always use 2-cycle oil.  Non 2-cycle oil doesn't burn properly and leaves carburization (sticky carbon) in the ring grooves which can lead to poor long-term ring perfomance.

[CR480R]

So then would you put a small block chevy 350 together this way too??...

I have once.. The total seal brand rings I used specified using a dry-film lubricant that they sell... It was dry powder like substance, very similar to graphite.. It had no issues with ring seal and is still going strong for its 3rd owner.. I cant say I would recommend it for someone else, but it worked fine for me..  The general concensus is that using oil is the way.. But some engine builders swear by dry assembly and it seems to work for them.. I have put 5 or 6 different 2-strokes together dry or with a light coat of WD-40... right or wrong no issues occured.. I think the roundness and finish of the bore are more important than anything else along with giving the engine ample time to wear in before subjecting the engine to heavy loads or high engine speeds... Idk.. just my thoughts, interesting topic for sure