Tank of premix after rebuild?

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skidoodoug

Member
Guys, I know that this has been discussed before, but I just can not find any old threads. I just had my engine rebuilt from bottom to top...new crank, new bearings, pistons, the whole thing. Should I be running a tank or so of premix thru it? What is happening by doing this? I do not excpect this as it did not have one before, but wouldn't this mask a carb mixture problem if one exsisted?

Thanks
 
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rp7x

Well-known member
what did the guy say that rebuilt it ? if it blew did he find the problem or just put a bandaid on it
 
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tyeeman

New member
Typical mix ratio on a new or rebuilt motor is 40:1 gas oil in the tankd PLUS your oil injection oil. Your doing a couple things. A) just in cast your oil lines have a little air bubble in them you are making sure you are still geting lubrication to the engine. B) your making the the whole enigine run "wetter" so the little tiny wear metals that are generated upon break in are flushed out of the engine via the exhaust.

Also, remember to baby it for the first tank of gas. The first 1/4 tank, warm up the engine really well, go easy, no full throttle at all and vary your speed. 3/4 tank up to 1/2 tank- increase your speed a little, short bursts of speed not to exceed 3/4 throttle. 1/2 to 1/4 tank- short burst of full throttle, increase your speed while varying your speed. The last 1/4 tank- longer bursts of wide open throttle, vary your speed, and that should about do it, she should be broke in. Pesonally i'd still take it a little easy for some or most of the second tank but thats just me. I mean hey, rebuilds aren't exactly cheap.
 
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skidoodoug

Member
tyeeman said:
Typical mix ratio on a new or rebuilt motor is 40:1 gas oil in the tankd PLUS your oil injection oil. Your doing a couple things. A) just in cast your oil lines have a little air bubble in them you are making sure you are still geting lubrication to the engine. B) your making the the whole enigine run "wetter" so the little tiny wear metals that are generated upon break in are flushed out of the engine via the exhaust.

Also, remember to baby it for the first tank of gas. The first 1/4 tank, warm up the engine really well, go easy, no full throttle at all and vary your speed. 3/4 tank up to 1/2 tank- increase your speed a little, short bursts of speed not to exceed 3/4 throttle. 1/2 to 1/4 tank- short burst of full throttle, increase your speed while varying your speed. The last 1/4 tank- longer bursts of wide open throttle, vary your speed, and that should about do it, she should be broke in. Pesonally i'd still take it a little easy for some or most of the second tank but thats just me. I mean hey, rebuilds aren't exactly cheap.
Click to expand...

Thanks Tyeeman
 
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mikedrh

Member
If your oil injection is working properly (something you should check before you ever start it, including checking for air bubbles) there is no need to add any oil to the gas.

Rings WILL NOT seat if you throw a ton of oil at them. Short bursts of wide open throttle, right from the start, creates high cylinder pressures and is good for the ring seat.
 
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whitedust

Well-known member
Me I would run premix just plain 2s oil NOT syn for 1 tank vary speed not pin it for 1st tank. My buddy would ride like he was running for his life flat out redline the thing. Who has had better 2s luck?...... My bud ....I can still smell the paint burning off his new 2s engines but his engines lasted far longer than any of mine.
 
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thebreeze

Member
I would premix the first tank closer to 100:1. It is mainly insurance against air bubbles in your oil lines until they have a chance to work their way through. Everyone seems to actually handle the break in procedure differently. Some take take it easy, others just tape it to the bars.

I take it easy, but give it a lot of very short WOT bursts. I delete the oil injection from my sleds, so I run the same premix ratio I intend to run for the life of the motor.

I don't think it would be masking any jetting issues. The premix will lean the fuel mixture out slightly, but not enough to make any difference. Even at 32:1 premix, you are only leaning out the fuel mixture by appx. 3%.
 
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snocrazy

Active member
I bought a used sled. The guy told me it had one fresh cylinder in it.
I fix a bunch of suspension-track issues with the thing and get it all polished up.
I take it on a trip as a backup.
My sled breaks down. - electrical
I break out the backup.
My friend with me tells me I should put oil in the gas to make sure all is good.
I say nah. Every thing is fine.
It runs for 50 miles of deep snow hammering on throttle.
MELTDOWN
Turns out the oil pump was not working at all. Must have been why the thing melted down on the last guy I bought it from.
Unless you have a way to test the oil pump and know it is delivering sufficient oil to your motor, I would put oil in the gas.
Lose a cylin
 
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snoluver1

Active member
Most reputable PERFORMANCE engine builders will tell you to never go more than 40:1 ratio. Anyone that tells you different is just trying to cover their arss, and that includes the factory. DO NOT break in on synthetic oil, PERIOD. Your rings will never seat correctly. DO NOT baby it! Beat the tar out of it, as long as it is quick short bursts, and not held wot for more than a few seconds at a time. You'll get a thousands different opinions on this, but in my personal experience, this has provided the most positive ring seal. As long as it was built with the correct tolerances, and you have gone over everything a thousand time over(oil lines bled, pump set correctly, etc.)you should have no problem.
 
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frnash

Active member
Re: snoluver1's post:

Correct me if I'm wrong, but for those that may be wondering why that is:

As I understand it (from an aircraft engine overhaul some years ago) the reason for this, including the "DO NOT break in on synthetic oil, PERIOD." rule is that you do in fact want some friction during break in, to essentially hone the cylinder walls/rings to a perfect fit. Plain ol' dinosaur squeezin's will work quite fine for this, but it just won't happen with full synthetic oil, 'cuz it lubricates too well, and doesn't allow that "honing" to occur. (!)
 
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snoluver1

Active member
Nash nails it again! You also want your rings to be seated within the first twenty miles or so. You have a very short period of run time in which the cylinder walls and piston rings have enough friction to properly "wear in" or "seat" the rings. Once you pass that point, and the rings are not fully seated, your done. If you baby it for 100 miles it ain't going to happen! Hence the "beat the tar out of it". Get those rings seated as quickly as possible! You can baby it if you want, and you will have no problems, but your engine will not run at its full potential.
 
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snoluver1

Active member
...and trust me when I say I have learned these lessons the "hard way"! I also have gotten most of this information from the aircraft industry,(thems is sum smart fellars) but the concepts apply to any motor. 2 stroke, 4 stroke, plains, trains and automobiles!
 
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snow_monkey

New member
frnash said:
Re: snoluver1's post:

Correct me if I'm wrong, but for those that may be wondering why that is:

As I understand it (from an aircraft engine overhaul some years ago) the reason for this, including the "DO NOT break in on synthetic oil, PERIOD." rule is that you do in fact want some friction during break in, to essentially hone the cylinder walls/rings to a perfect fit. Plain ol' dinosaur squeezin's will work quite fine for this, but it just won't happen with full synthetic oil, 'cuz it lubricates too well, and doesn't allow that "honing" to occur. (!)
Click to expand...

Just curious. My dealer told me my doo and everyone built after was shipped with full synthetic?
 
indy_500

indy_500

Well-known member
last sled i rebuilt, 50:1, lots of short WOT bursts, don't hold it to the bar more than 3 seconds or so. Let it warm up LONG and go to town. Just put Vforce Reeds in this friends sled the other day, pistons look BRAND NEW from both the intake and exhaust.
 
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thebreeze

Member
Arctic Cat literauture has you running full synthetic on fresh powervalve motors as well. I sure read a lot about running non synthetic for break in but it seems like a question where there is no for sure answer for. For the average rider, it is MOST important that your rebuilt motor is ACTUALLY GETTING OIL upon startup, and for the first few miles. Be it dinosaur oil or synthetic.
 
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