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New Engine Break In
It really is funny how there are two different ways to break in 2 stroke gas engines. Run it like a 82 year old lady or start it up and run like you stole it. I raced motorcross for 14 years and for the first 5 or so I always broke my engine in as per the book. 15 min, up to 25% throttle, 30 min up to 50% throttle and 45 min up to 75 % throttle and after allowing each session, let the motor cool down. Then you could open the throttle wide open on and off for short burts after that. My friend always bought his bike the same time each year as I did. Year after year, his bike was always much faster than mine, low, midrange and top end. I always thought he was porting his motors. When we would break them down every month to put new rings and or pistons in them, my engine always had blow by past the rings, scuff marks on the piston...ect..ect. His was always perfect looking, we used the same premix oil same everything..but he always snuck off and had his engine hopped up. His secret I found out a few season later was his break in. He started his bike up, let it warm up, and then rode it like he was at the nationals, wide open lap after lap for 45 minutes. This techinque would seat the rings almost right away and allow any other parts to be broken in within a short time. If you ever talk to real engine guys who know what they are talking about they will tell you the same thing. Do you break in your new chain saw or weedwacker like its made of glass or do you start it up and go after it. Then why do we have these procedures???? The manfactures recommend it incase you use cheap or or low octane gas. Do yourself a favor next time and break in in right and you will have the fastest engine around. make sure for the first tank of gas or so to use non synthetic to allow the parts to seat. After that you can go to a quality synthetic like mobil 1 2t. This is without a doubt the BEST 2 stroke oil period!!! A word of advise, they stoped making it Jan 1, 2008 due to EPA crap, it was not profitable for them, so get a bunch while you can....
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RE: New Engine Break In
There are too many variables to consider regarding break-in. Since model engines are hard to burn up, they can be ran at full power with little run time. Some motorcycles can withstand or even benefit from the same treatment, some can't without sticking a piston. Large jetski engines can be raced with little run time if the piston fit is extra loose, otherwise they need a long careful break-in. At the other extreme, an airplane or farm tractor may need to run 100 hours at full power before they settle in.
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RE: New Engine Break In
ORIGINAL: [email protected] It really is funny how there are two different ways to break in 2 stroke gas engines. Run it like a 82 year old lady or start it up and run like you stole it. I raced motorcross for 14 years and for the first 5 or so I always broke my engine in as per the book. 15 min, up to 25% throttle, 30 min up to 50% throttle and 45 min up to 75 % throttle and after allowing each session, let the motor cool down. Then you could open the throttle wide open on and off for short burts after that. My friend always bought his bike the same time each year as I did. Year after year, his bike was always much faster than mine, low, midrange and top end. I always thought he was porting his motors. When we would break them down every month to put new rings and or pistons in them, my engine always had blow by past the rings, scuff marks on the piston...ect..ect. His was always perfect looking, we used the same premix oil same everything..but he always snuck off and had his engine hopped up. His secret I found out a few season later was his break in. He started his bike up, let it warm up, and then rode it like he was at the nationals, wide open lap after lap for 45 minutes. This techinque would seat the rings almost right away and allow any other parts to be broken in within a short time. If you ever talk to real engine guys who know what they are talking about they will tell you the same thing. Do you break in your new chain saw or weedwacker like its made of glass or do you start it up and go after it. Then why do we have these procedures???? The manfactures recommend it incase you use cheap or or low octane gas. Do yourself a favor next time and break in in right and you will have the fastest engine around. make sure for the first tank of gas or so to use non synthetic to allow the parts to seat. After that you can go to a quality synthetic like mobil 1 2t. This is without a doubt the BEST 2 stroke oil period!!! A word of advise, they stoped making it Jan 1, 2008 due to EPA crap, it was not profitable for them, so get a bunch while you can.... This subject has been beat to death. Best way to open a BIG OLE can of worms is to talk about engine break in or different types of oils. It's gone on for hundreds of pages in the past. Over and Over and Over again. If you're curious about the methods other people use, try the search function at the bottom of each forum. There is enough reading to pop your eyes out of your head. |
RE: New Engine Break In
It may be time to go for the popcorn. Just get it started, you couldn't run fast enough to GIVE my any Mobil 1 2T. It builds the hardest carbon I've ever had the unpleasant experience of scraping off. That Crap is like black porcelain. I have a nephew that uses it and I intend to give him mine. I guess to each his own, we all have our favs.
I do agree with his observations on break-in. Some engines just need to have the snot run out of 'em to break-in right. |
RE: New Engine Break In
I never break in my engines, I put em on the planes and runs em. Here's my latest 2 stroke going to work right out of the box on 100:1 full synthetic. I tried to run petroleum based oil to help wear in the piston and cylinder quicker, but it slobbered oil residue on the plane, and that is not acceptable. It loves the 100:1 mix, there's no residue on the plane, and it runs like a watch. I'll break it in next year if I have the time. lol
http://www.youtube.com/watch?v=TbeQKnL0sek |
RE: New Engine Break In
This subject hasn't been beat to death at all, it has not been examined closely enough. Since nobody is having problems, anything special that we do will seem right. Some engines will have measurable benefits from special break-in and others will not.
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RE: New Engine Break In
Kweasel, some academic questions if you don't mind.
Bear in mind the following questions apply only to simple 1 and 2 cylinder, air cooled, two stroke engines. Question 1: Regarding that jet ski engine with the loose piston fit. Please explain and expand on that position. Question 2: Why does an engine with a tighter piston tolerance require a longer break in and how does it benefit from same? Question 3: What specific part of a piston requires a break in? Leave the ring out of it please since it's not part of the piston. Question 4: What part of a piston is intended to make contact with the cylinder wall? Question 5: How long (on average) does it take to break in a piston ring, and which is the harder material, the ring, the cylinder wall, or are they the same? Question 6: What parts of an engine actually get broken in? Question 7: What part of the engine benefits the most from the break in process? |
RE: New Engine Break In
I'll take a shot
1. Water cooled engine should be able to have tighter tolerances due to better cooling but that's a guess seems like aircooled engine would have more metal expansion and contraction due to an unregulated cooling system and would need more clearance 2. it doesn't, It doesn't 3. no part 4. skirt 5.I would guess as long as it takes to for the ring to shave of the high spots on the cylinder left from honing but then that would be the cylinder not the ring breaking in. I'll say the ring is harder since they break if not handle right and I've never seen the ring loose if it breaks and takes a ride on the cylinder wall 6. no parts 7. the cylinder these are just guesses since I don't get paid to fix or build engines I'm not an expert so these are guesses I would think if a engine goes sour early in it's life and it wasen't lean burned or run without oil I would say it had a faulty part from the start be it rare these days with modern machine practices So whats my score ? |
RE: New Engine Break In
In my opinion, before an engine is run, it's the best it will ever be, After it starts getting run, it's starts it's journey towards worn out. The only engines that might possibly benefit from a break is a ringless pinch fit engine. Oh sure, a new ring and cylinder may seal better after it run for a while, but it doesnt require any special break in, it will wear in at it own pace either way. Bearings don't require any breakin, there at their best when there new. I never break engines in, and I have never had a problem. I dont even run em fat when their new anymore.
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RE: New Engine Break In
Pure guess on my part cause I never wanted to be a spurt anyway but I'll say the watercooled needs looser tolerances because the cylinder will not expand but the piston will. #2 For aircooled engine only. The cylinder needs to "learn" how much the piston needs to expand. Not all parts will expand evanly (all you have to really worrry about is not overheating) #3 Havn't a clue. #4 I haven't seen one with a tapered/recessed toplike a large diesel has , so I say all the side surfaces. Allowing for lubricants of course. #5 It doesn't. The ring. Not since about 1930 ad. Unless we're talking about CI sleeve liners. #6 Squish band if present and slicking the cross hatch rough spots.
All surttulation on my part. After rebuilding a dozer/tractor engine I try to push a pile of dirt wide open up hill if there's one close by as soon as possible. Just have to cool it down slowly afterwards and it's good to go. |
RE: New Engine Break In
I think your right ,I bought a skidoo 700 sled from a big shop when I lived out west I loaded in on trailer walked in the shop and asked the top mechanic that did all the race sleds and bikes about breakin is smiled and sad pit 12oz of oil in the gas tank for the first tank only (oil injection)
warm it up for 5 mins and run it as hard as you can the harder the better,I did and never had a lick of trouble the 800cc guys that rode my sled all said it was a hotrod for a 700 It's not like these engine are anything special other the the prophub it just a engine if it was made right it will run just fine I can see a little extra oil for the first run I think it would help carry away any of the material that results from the building process. and if something wasen't machined correctly running it in some breakin ritual isn't going the magicly correct it. |
RE: New Engine Break In
OK OK I want to take the test also
#1--Looser piston fit is needed because the cylinder jacket is cooled by water reducing it's expansion. Our plane engines run hotter and have closer expansion rates between cylinder and piston?? #2--Pistons don't break-in or should not be made too. #3--Refer to #2 #4--In a perfect world only the ring would touch, but the skirt is usually main contact point. #5--A few tanks of fuels will break in the ring. Rings are softer than any chrome or Nikasil coated cylinder we use. Otherwise we would never need to replace the ring by itself as we frequently do. Nikasil is honed with a diamond hone. #6--Rings, but bearing loosen over time too even though I would call that wear because they do not need breaking in. #7--Rings benefit most from breaking in. In the old days of big block engines (cars) as soon as we got it running we would do at least 10 full stop full throttle accelerations to help seat those huge rings in those massive bores. |
RE: New Engine Break In
How did water cooled engines happen to get tossed into this? Air cooled only please. This is kinda fun[8D]
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RE: New Engine Break In
Most jetski engines use iron liners so the piston fit always gets tighter with heat. The pistons have significant shakes machined into them that get flattened over time. It is better to fit the pistons to minimum clearence and put some time on them with reduced combustion temps (careful breakin), you end up with a longer lasting top end. Some racing engines won't last long enough to breakin because of wide exhaust ports. These engines must be fit near the service limit or else they stick. These engines are unique only in that they absolutely WILL stick very quickly if you are not carefull with the setup. Moving on, I have not seen rings harder than the cylinder with the exception of someone installing chrome rings in a Chevy. Whether indended or not, pistons do scuff perpendicular to the wrist pin. How long does it take to seat a ring? That depends a lot on how well it fits the other parts, usually not very long. Our model engines are small enough and turn slow enough to easily dissipate the heat of a hot mixture setting. Plus they use plated aluminum cylinders that do not converge with the piston like an iron cylinder will. In the case of our small aircooled engines there is little that can be done to affect how the ring seats (it will seat) and the piston will never get tight. So there is effectively no breakin for our model engines, just bolt them on an fly.
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RE: New Engine Break In
In respnse to the original post. I'm not an engine guru and I certainly have not read ALL the threads concerning gas engine break in.However, I have never seen a thread on RCU that says to break in a gas engine by running it like an "82 year old lady" or the like. It seems that everybody pretty much agrees, start the engine, set the needles and go fly. The only exception being the type of oil being used EG: non synthetic. Could you please refer us to such a thread?
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RE: New Engine Break In
ORIGINAL: Pat Roy How did water cooled engines happen to get tossed into this? Air cooled only please. This is kinda fun[8D] and on the subject since the cylinder, cylinder head, and exhaust are cooled with water wouldn't the piston run cooler too with less expansion then an aircooled engine water cooled engine even have their own rating of watercooled oil that supports that theroy to a degree. seems like less heat mean less expansion meaning less clearance is needed not to mention a watercooled engine doesn't run to long out of the water question 4. the skirt has to contact the cylinder wall to tranfer the piston heat from the crown the to the cylinder otherwise the piston would soon overheat and fail I do remeber reading a company call pivotal has a 2 stroke water cooled engine that moves coolant through the piston allowing the engine to make much more power for it's size then it's aircooled counter part I guess this also applies to question 1 in that a cooler cylinder can remove more heat from a piston then a hot aircooled one can so the watercooled engines piston would expand less then a it aircooled counter part and require less piston to cylinder clearance |
RE: New Engine Break In
To reply to The mobil 1 racing 2t carbon deposits, I have never had a carbon deposit problem with this oil. You might want to run less oil to lean it out. Mobil one will run as high as 100:1 but I have never run it over 80:1 and I never have had any noticable deposits except slight deposits on the center of the top of the piston. Its the only oil that I ever used that I dont even get shiny spots on the piston skirt let alone scuffing. I have talked to engineers at 4 of the major engine makers and they all say to run a gallon or so of NON synthetic first, before using the good oil. They have refered oil for this as Stil, Husky, or any other quality NON. Like I said in my original post Mobil one has stoped making 2t, so go get some while you can, Auto Zone carries it at most stores.
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RE: New Engine Break In
check out this engine talk about your piston engine advances
http://www.pivotalengine.com/flashversion.html Here's their website very interesting to look at for you engine nuts out there |
RE: New Engine Break In
If the Mobil 2t it was so good I wonder why the quit making it are they replacing it with a better oil ?
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RE: New Engine Break In
I called mobil and they said with the EPA rules and the goverment wants to rid us of 2 stroke motors, for 4 stroke, because of the polution levels of a 2 stroke. Its not worth producing it, and the sales of the oil has declined over the years due to the declining 2 stroke market. Look at the motorcycle market especially the dirt bikes, you cant hardly find any 2 strokes anymore, 5 years ago no one wanted to race a 4 stoke bike, now they are the norm. Sign of the times..............
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RE: New Engine Break In
ORIGINAL: skiman762 question 4. the skirt has to contact the cylinder wall to tranfer the piston heat from the crown the to the cylinder otherwise the piston would soon overheat and fail |
RE: New Engine Break In
My ex boss told me that most of the combustion heat is dissipated out thru the spark plug, and he use to work for Nippon Denso. My guess would have been out thru the cooling fins...
Im just glad that I was a mechanic and not a freakin engineer. Im gettin a headache just thinkin about this stuff, lets go flying and see how the engineers did ! lol |
RE: New Engine Break In
Can't, it's raining and windy[:o]
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RE: New Engine Break In
Same here in Red Bluff... This sucks ! New plane, and new SV26, and now this ! [&o]
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RE: New Engine Break In
OK, Back on topic.
If you want to run your engine like an old lady, run it in like an old lady. If you want a lively engine, learn the engine how to work. Give it full throttle, but for very short bursts. Motocross is excellent for breaking in. So ia working like with a chainsaw. These short power burst are never long enough to cause lots of heat built up, because the surfaces all still have much friction, and contact area to pass the heat on to the outer surfaces is still small. (on micriscopic scale) After a while, the engine limbers up and all parts become real smooth so the coeeficient of friction lowers, and thus the heat generation. This is quite noticeable, and about the time to reduce the oil content to normal running ratio. For running in the content should be high, and forget all the crap of different oil for the first gallons. Use the best oil you can get from the get-go. You do not want to wear an engine, you want smooth surfaces. The second issue is heat cycling. During processing of all the engine parts, stresses have been set up. These stresses can be relieved by aging, but higher temperatures work faster. Because they work so fast, you must be carfull not to relieve it all at once. So stop the engine often to cool down, and then give it the whip again. Like in interval training. Piston fit should still be tight, because the good match between piston and wall is what it needs to transfer heat to the cylinfer wall. Loose fitting pistons tend to sneak up on you and suddenly seize. Tight pistons start lumbering first with ample warning of being maltreated before they lock, often to free themselves after cooling with very litle, or no damage done. |
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