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Author Topic: What are those black lines inside the cyliner?  (Read 7406 times)

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Offline cnrcpla

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What are those black lines inside the cyliner?
« on: May 29, 2012, 06:51:24 PM »
I opened up my top end today to make sure everything was alright, and I have been noticing this one prominent black mark, very skinny, almost looks like a scratch in the bore, but it is smooth. Is it ring blow by? I hope not because I only have like 3 or 4 hours on a brand new top end... Any thing I can do to stop it?
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline cnrcpla

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What are those black lines inside the cyliner?
« Reply #1 on: May 29, 2012, 07:10:12 PM »
I kind of answered my own question. I am pretty sure coolant is getting in the cylinder on the down stroke. The O rings seem fine so that points to only one thing... A warped head. How can I be sure the head is warped, are there any tests I can do to make sure the head is or isn't warped?
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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What are those black lines inside the cyliner?
« Reply #2 on: May 29, 2012, 09:14:20 PM »
take your head to a machine shop they would be able to clamp it down level and then mich it or anybody in your area that builds any kind of race engines would be able to check it out for you
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline cnrcpla

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What are those black lines inside the cyliner?
« Reply #3 on: May 29, 2012, 10:22:11 PM »
Thanks man, I just took it to me neighbor who owns his own machine shop. He can do it for me, he said he could see the warp just by looking at it  :o With a planed head, am I going to have more compression? And with more compression, it is to my understanding more power?  ;) ;D
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Offline SachsGS

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What are those black lines inside the cyliner?
« Reply #4 on: May 29, 2012, 11:57:08 PM »
Heads often "collapse" in the exhaust area rather then warp.I made a fixture that clamps to the cylinder head and then mount it in my lathe and use a dial indicator to determine the damage.
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Offline cnrcpla

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What are those black lines inside the cyliner?
« Reply #5 on: May 30, 2012, 12:07:23 AM »
Oh, that's cool. It was warped on the ends of the head from the port sides. I knew it was warped when I put a straight edge on it and I could see sunlight...
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Offline scotty dog

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What are those black lines inside the cyliner?
« Reply #6 on: May 30, 2012, 02:29:39 AM »
you can also get a plate of glass, stick some sandpaper to it and do figure 8 movements on it with the head that will show up any warpage and  you can get it flat again. Obviously you dont need to seeing as your getting yours machined though, just a handy thing to know if ya need to do it quick
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline cnrcpla

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What are those black lines inside the cyliner?
« Reply #7 on: May 30, 2012, 02:57:32 AM »
I actually did try that, but I only had really fine emery paper on me at the time, so that didn't show up to well.
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Offline scotty dog

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What are those black lines inside the cyliner?
« Reply #8 on: May 30, 2012, 03:20:49 AM »
haha yeah that would take a while  :D
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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F**K THE WHALES......................SAVE THE 2 STROKE!!!!

The hardest part about riding a 4 stroke is telling your parents your Gay!!

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Offline cnrcpla

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What are those black lines inside the cyliner?
« Reply #9 on: May 30, 2012, 02:46:22 PM »
So am I right?  ;D Planing the head would give me more compression and more compression means more power, right? hahaha  ;D
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Offline riffraff

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What are those black lines inside the cyliner?
« Reply #10 on: May 30, 2012, 02:58:28 PM »
Quote from: cnrcpla on May 30, 2012, 09:46:22 PM
So am I right?  ;D Planing the head would give me more compression and more compression means more power, right? hahaha  ;D

you want to take off the least amount as possible, taking off too much could give you clearance/squish issues and higher compression would require higher octane fuel possibly
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Offline cnrcpla

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What are those black lines inside the cyliner?
« Reply #11 on: May 30, 2012, 03:23:04 PM »
Yeah, I just want enough taken off to get the warp out and make it flat again. The lines I am referring to are apparently light seizure marks, which is a direct result from coolant leaking into the engine in the down stroke. That is also where the little dingers in the top of my piston have been coming from.
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Offline cnrcpla

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What are those black lines inside the cyliner?
« Reply #12 on: June 01, 2012, 01:19:53 AM »
Update:  I got the head back today, he had to take off .004 to make it all flat again. I put it all back together and turned the gas on, then it started pissing gas all over the floor out of a vent hose. Apparently the raised tube inside the carburetor was bent ever so slightly (I have no idea how) but I put it straight and it stopped. I finally went to kick it over, and the first kick it almost started, the second kick the starter fell OFF because the compression DENTED the roll pin...
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Offline Jeram

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What are those black lines inside the cyliner?
« Reply #13 on: June 01, 2012, 02:04:36 PM »
Quote from: cnrcpla on May 30, 2012, 09:46:22 PM
So am I right?  ;D Planing the head would give me more compression and more compression means more power, right? hahaha  ;D

not always,

higher compression = cooler exhaust gases (T1/P1=T2/P2 and cooler exhaust gases mean the pressure waves in the pipe move slower, meaning the pipe is more efficient at lower revs.
which is why there is also a general misconception about high compression heads being for bottom end power gain. Because thats what it does when you keep the same pipe.

If your someone who likes to use the bottom end and midrange of your bike, you should like the subtle change it will make.
such a small change shouldnt change your comp ratio by much tho, So I doubt it will be very noticable.

be sure to plug chop and check jetting tho :)
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Offline cnrcpla

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What are those black lines inside the cyliner?
« Reply #14 on: June 02, 2012, 02:07:10 AM »
Oh ok, I see what your saying. I do use bottom and mid a lot pulling out of turns on the track, so it should come in handy.
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