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acceptable blow by ?

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what's acceptable blow by ? i'm not certain if this is heavy oil blow-by or just some rich jetting... haven't had enough miles on it to know if it's losing oil yet, only 500 or so since the ring job. power is fine, runs great. doesn't run poorly at any rpm, finally !

left and middle spot are 3-4 high revs, left most was way too rich, middle is better, i think it's spot on now, and farthest right is just idling for 10-20 seconds, hard to make out any sploodge at all.

what do the gurus think ?

IMG_20111206_172335.jpg

left most also was already oil soaked from checking oil level... so disregard the obvious large tan oil stain...we're looking at the black here :-)

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My blow by is usually more of a brown color, but I don't keep paper towels is my underwear.

Something is wrong. My exhaust does not do that.

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"Blow-by" does not involve the exhaust. "Blow-by" is compression that goes past the rings into the crankcase.

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I wouldn't stress out about possible oil consumption on your rebuilt engine..

With that mileage anything dark coming out the muffler would be most likely related to jetting than

poor ring seal...

Just keep an eye on your oil level..as you would with post/pre ride checks..

Did you replace the piston?

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You'd think after 500 miles those rings would've seated by now. Did you do any prep on the cylinder walls before installing the new rings?

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You'd think after 500 miles those rings would've seated by now. Did you do any prep on the cylinder walls before installing the new rings? I've seen new rings on smooth unhoned cylinder walls have a hard time sealing.

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"Blow-by" does not involve the exhaust. "Blow-by" is compression that goes past the rings into the crankcase.

OK then, lets just call it oil loss. :lol:

I wouldn't stress out about possible oil consumption on your rebuilt engine..

With that mileage anything dark coming out the muffler would be most likely related to jetting than

poor ring seal...

Just keep an eye on your oil level..as you would with post/pre ride checks..

Did you replace the piston?

yes, i'm checking oil levels pre-post ride. no, i didn't replace the piston, local diesel repair guys said it looked very good, and I mic'd it. the bore was round also, but the nicasil is very slick/smooth. i'm hoping you're right about the jetting.

how did you run it in ?

10 seconds of idling to adjust the timing tensioner, then 20 minutes or hard two-lane on/off throttle through the gears. no steady throttle, no cruising. probably the hardest i've ever ridden it.

You'd think after 500 miles those rings would've seated by now. Did you do any prep on the cylinder walls before installing the new rings? I've seen new rings on smooth unhoned cylinder walls have a hard time sealing.

all i did was clean up the carbon with a dark red scotch-brite pad (by hand) as my understanding is the nikasil is basically sprayed on carbide.... carbide is hard as a preachers... well you know.

everyone i've talked to about nikasil says it's only .002-.003" thick ,so the risk of ruining the cylinder is pretty high if you get aggressive with honing/scrubbing on it.

guess I'll just keep an eye on the oil level and ride. (power is great by the way, for a stock setup) :)

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Prep sounds fine. Break-in sounds fine. I don't see a problem. A little smudge of soot is not a problem. Are you actually getting oil out the exhaust?

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Prep sounds fine. Break-in sounds fine. I don't see a problem. A little smudge of soot is not a problem. Are you actually getting oil out the exhaust?

it's going somewhere, lost 1/4 quart or so since the rebuild. i'm checking it after it's warm at the gas pump, the same gas pump, not screwed in, etc.

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If I went to the trouble to remove the top end ,a new piston would go in with the new rings...if the rings had wear, so would the piston.

i would have, if it hadn't been round. iirc it was within half a thou or so. that was pretty surprising to me, the very unaccomplished wrench. :lol:

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i would have, if it hadn't been round. iirc it was within half a thou or so. that was pretty surprising to me, the very unaccomplished wrench. :lol:

How many miles did you have on it?...were the rings worn?..what oil have you been using and at what replacement intervals?

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How many miles did you have on it?...were the rings worn?..what oil have you been using and at what replacement intervals?

i want to say the milage is 13,000 or so now.

ya, the compression rings were shot, wiped over top and bottom, and seized in the grooves. differing opinions about wether it was crappy gas that made them stick, or high heat, or both. mostly they were stuck with carbon. (i use 87 or 89 octane for the octane junkies)

oil = whatever is handy when the the odo ticks over 1,000 again. it gets 20w50 for HOT months, or rotella for cooler times. or castrol etc

piston pic from the other thread for reference, like i said, it was in very very good shape:

IMG_20111018_112105.jpg

DSC_0276.JPG

how you healing up craigo ?

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How are you determining 1/4 quart? You added 8 oz? Or 1/4 way down the dip stick?

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How are you determining 1/4 quart? You added 8 oz? Or 1/4 way down the dip stick?

it wasn't touching the dipstick, added about a 1/4 quart, went around the block, took the gear off, checked it, back at the top of the hashes.

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I am surprised at the minimal wear on your piston..the bottom of skirts still look in reasonable shape....

The stock piston has a more skirt area on them compared to my stoker piston, so they last longer....

Here is a pic of the stock compared to a 95.5mm 2 ring stroker piston..sorry for the poor pic quality..

Image044.jpg

2 ring stroker piston is shorter with the narrow skirts.

Image045.jpg

And finally out of hospital today...slowly getting better but its gunna take some weeks before I can get back on the bike...It's top end rebuild time for me...at 8,000km the piston looks very average ...will post some piston pics when I can get some decent shots...cheers

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Run it and monitor oil consumption. It might get better, It might get worse. At this point we don't know if oil is getting past the rings, valve stem seals or being recycled thru the breather system.

Rings have to seal not only against the cylinder walls but also the piston ring grooves. Your carbon removal process may have left some imperfections on the ring lands. Run it and see how it goes.

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all i did was clean up the carbon with a dark red scotch-brite pad (by hand) as my understanding is the nikasil is basically sprayed on carbide.... carbide is hard as a preachers... well you know.

everyone i've talked to about nikasil says it's only .002-.003" thick ,so the risk of ruining the cylinder is pretty high if you get aggressive with honing/scrubbing on it.

:

Common cleaning between ring sets is often done with a ball hone. The nikasil plating will not be harmed in any way by the ball hone.. It takes a cutting tool bit or Diamond hone to cut nikasil. Whiter use a scrub pad or ball hone, all your doing is cleaning the nikasil plating.. not cutting into it.

Your break in sounds about as good as it gets other then on a Dyno or track :lol:

Oil has to be going someplace.. Blow by, our burning and out the exhaust, or of course leaking.

If it’s not blow by (wet air filter box and coming out the drain) and not leaking out (kind of obvious) it must be burning… That means past the rings or down the valves past the valve seals which would be very uncommon for this engine.

Sounds like a leak down test is in order..

And a complete drain of oil in to a measuring container to ensure your missing oil observations are correct.

There are so many variables in measuring oil at the dip stick…it really is a crappy way to measure, never mind use as a diagnostic tool.

Run it till warm.. drop the oil from the engine and frame tank, remove the oil pressure plug (below in line with the oil filter) drain the oil from there as well, remove oil filter cover and allow remaining oil to drain down to the pressure port.

Let the whole thing drain for a good 30 min or more… Then measure the drained oil…. You would not be the first to find more the 1800CC due to overfilling. .. even though measurement at the dip stick showed it to be low.

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I save the quart containers from the previous oil change to measure the amount of oil that comes out from the next oil change. It's an extra step to the waste oil container but at least I know exactly how much goes in and how much comes out. Well worth it to me for my peace of mind. Checking for an accurate oil amount in the bike is not easy for me. I usually do it after a gas fill up but it varies so much that if I see oil on the stick, I'm satisfied that as long as no oil leaks have shown themselves to me, there is oil enough to last to the next fill up and so on until I change the oil at 1,000 mile intervals.

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