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Discussion Starter #1
So today I was looking at each one of the cylinders while rotating the motor. Some of them have vertical marks not bad but there is some there. I ran my finger across them and you cant feel them. Is it normal to have a few marks or not? Only 10k miles on the motor.
 

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I would not call it normal,but what you gonna do? Spend thousands and watch them come back? What air filter do you run? How often do you change it?
 

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I know nothing about that level of engines, but I would think that if you can't feel it....it's not that bad. But my ignorance might be showing... heh.
 

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I guess the question is; are you seeing scratches,or just vertical rub marks where the ring end gaps meet the wall surface. if they are scratches,your engine has injested dirt particles. If they are just "witness" marks from the rings running up and down then they are "normal". I would'nt sweat it as long as the compression,leak down,and oil consumption are normal.
 

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Discussion Starter #5
Tunersricebowl said:
I guess the question is; are you seeing scratches,or just vertical rub marks where the ring end gaps meet the wall surface. if they are scratches,your engine has injested dirt particles. If they are just "witness" marks from the rings running up and down then they are "normal". I would'nt sweat it as long as the compression,leak down,and oil consumption are normal.
I thought it could of been from the endgaps on the rings but wasnt sure. Now that you say it is a possibility I am not worried as I think it is that.
 

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If you feel no groves........should be O.K. I have seen this alot mmostly from the rings. proably dark grey in color.
 

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Discussion Starter #7
slutty22 said:
If you feel no groves........should be O.K. I have seen this alot mmostly from the rings. proably dark grey in color.
Dark grey in color and a perfectely straight line up the cylinder. All of them have them, but I cant feel it when I rub my finger over it.
 

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Ya, those are from the rings.. however if they overconcern you, do as mentioned earlier and compressin test after fully assembled
 

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Discussion Starter #9
slutty22 said:
Ya, those are from the rings.. however if they overconcern you, do as mentioned earlier and compressin test after fully assembled
Thats what I plan on doing. And if they are bad or what not, can the cylinder be hoaned? Because yamaha doesnt sell the cylinder seperate, have to buy the whole case, retails at 1200. If thatt is the case I will buy a new motor. But I am sure that I am ok and they are just ring marks.
 

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depends on If they truly are stress groves and how deep they are however a good honeing is typically ment for a couple of things. first after youve bored out a cylinder it leaves for a smother finish and a fresh surface for rings to seal upon.....second if the cylinder walls are shiney and mirror like and has very minimal scarring. Honeing is similiar to wetsanding a paintjob before you buff it. However I will recomend if you plan on going this far if after you do the compression test and all cylinders are within minimal specs. you replace the rings as well as hone the cylinders......This sounds like alot of unnecessary work though for an engine with only 10k on it unless you know that a majority of the miles where HARD.
 

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how hard those miles were r a big factor i feel....
Scarcely! I have never seen damage to a cylinder due to hard miles within the rev band) but rather due to using bad oil/filters, bad air filters or most often pushing it hard while still cold.
My old FZ has some 60'000 miles on the odo, first pistons, first cylinder.
Still pretty good compression. And she was run hard for a good part of those 60'000 miles.
I wouldn't talk of damage in this case, most likely compression is fine here.
 

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Get on it, ride it and if one day it blows up then you know it was a problem, until then quit worrying...

These bikes are made of hard stuff, it's not like flower arranging....

If you have to put your mind at rest then buy a compression tester and check 'em....

I'd say a few lines were normal, especially if you can't feel them....

Think about how many times that piston goes up and down in that cylinder......................LOTS !
 

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Vertical scuff marks on the exhaust side of the cylinder at the top are normal, it is due to uneven expansion of the piston and the cylinder wall as the engine warms up, the piston expanding slightly quicker than the bore at that point. Nothing to be worried about.
If you do a piston/ring replacement you will need to hone the ceramic composite plating, a Flexhone #240 grit in aluminum oxide or #320 grit in silicon carbide will do the trick. You can buy them from Brush Research out of L.A..
BTW, compression testing on these high perf. engines is not a good way to test a motor's condition, the inlet cam is so far advanced to make good power up top that static compression is usually very low, in the 160-180psi range. If you had say 225 your engine would not tolerate the pressure and blow for sure.
 

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Discussion Starter #17
yamaguy said:
Vertical scuff marks on the exhaust side of the cylinder at the top are normal, it is due to uneven expansion of the piston and the cylinder wall as the engine warms up, the piston expanding slightly quicker than the bore at that point. Nothing to be worried about.
If you do a piston/ring replacement you will need to hone the ceramic composite plating, a Flexhone #240 grit in aluminum oxide or #320 grit in silicon carbide will do the trick. You can buy them from Brush Research out of L.A..
BTW, compression testing on these high perf. engines is not a good way to test a motor's condition, the inlet cam is so far advanced to make good power up top that static compression is usually very low, in the 160-180psi range. If you had say 225 your engine would not tolerate the pressure and blow for sure.
Thanks bro.
 

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Discussion Starter #18
And how hard would it be to hoan them yourself, and what else would I need for the job?
 

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I built my 91' Toyota MR2 engine. I know its not exactly a motorcycle engine. But from the factory, there is always 1 or 2 vertical scuff marks placed there by a PERSON. I don't know what the tool is called, but it looks like a center punch. They will scrape the cylinder walls either once or twice so there is one line or 2 going vertical. This is so SOME oil can drip through that scratch for break in.

Remember, the kind of mark/scuff/scratch im talking about is a SCRATCH. It is not wide and probably the width less than a human hair. As if you scratched aluminum with a blade or something. That is all that is needed to get enough oil to lubricate the cylinder during break-in and maybe even normal useage.
 
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