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Author Topic: Piston/Cylinder diagnosis  (Read 7427 times)

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Offline Stusmoke

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Piston/Cylinder diagnosis
« on: October 25, 2013, 07:59:36 AM »
Did a compression test today, gave me 210 PSI with no air filter, WOT and 10 full kicks. Definitely time for a top end goes I. I bought hte bike from a dealership with a claimed 10 hours on it, I have put on an additional 24 aleast 20 of which are well thrashed hours. I don't trust other people with my motors so I ordered in a full top end from the small end on up with gaskets and will hopefully be here next week. Have to give tomorrows practise a miss though   :'( :'( :( :(

What I need though is some other opinions on my cylinder. I'm fairly certain whats shown below is ring blow by from the excessive hours on the rings because I can't feel any change in teh surface and I ran my cylinder bore gauge over it aswell and it gave no different readings. Theres a little bit of ring blowby on the piston aswell, but no score marks to match the cylinder, hence my conclusion.  But I'm still quite new to this game and don't know very much so any opinions are appreciated.

Wash pattern:


General look:


Close ups:




Cylinder:


Cylinder other side:


Thanks in advance for any advice.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline factoryX

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Piston/Cylinder diagnosis
« Reply #1 on: October 25, 2013, 09:18:15 AM »
210psi? uh...
Hit the walls with a scotch bright pad, it should clean right up. I'm sure you meant 110psi, so my thought is maybe the rings didn't seat correctly?
« Last Edit: December 31, 1969, 04:00:00 PM by ' »


I ride an 03 yz250, wait 04, wait 05, what ever, they're all the same #$@% YOU!

Offline Stusmoke

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Piston/Cylinder diagnosis
« Reply #2 on: October 25, 2013, 10:24:50 AM »
210psi? uh...
Hit the walls with a scotch bright pad, it should clean right up. I'm sure you meant 110psi, so my thought is maybe the rings didn't seat correctly?

Yup my bad 110 lol. 20:1 compression ratio in my 250sx, didn't you hear? I did a diesel conversion  8)
I think the dealership threw in a fresh set of rings for hte purpose of sale before I got it. Thing is, they failed to mention that and I went right into new-bike-glue-the-throttle-the-****-open mode.

Cheers.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline factoryX

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Piston/Cylinder diagnosis
« Reply #3 on: October 25, 2013, 12:57:54 PM »
Even if you had I know people who do this with no problems. See if the shop will hook you up, if not just toss a piston in and be done.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »


I ride an 03 yz250, wait 04, wait 05, what ever, they're all the same #$@% YOU!

Offline _X_

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Piston/Cylinder diagnosis
« Reply #4 on: October 25, 2013, 01:25:52 PM »
buy your self a ball hone stu, http://www.brushresearch.com/flex-hone.php?gclid=CNSq6enBtLoCFc6j4AodpS4AWw, just spray with wd-40 three passes and shes looking good.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline _X_

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« Reply #5 on: October 25, 2013, 01:44:42 PM »
oh yeah....your hands are grubby.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline rlaj1004

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Piston/Cylinder diagnosis
« Reply #6 on: October 25, 2013, 02:30:08 PM »
oh yeah....your hands are grubby.

Ha, at least I have learned to swallow my coffee before I read your posts.  :P
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline Stusmoke

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Piston/Cylinder diagnosis
« Reply #7 on: October 25, 2013, 11:08:38 PM »
oh yeah....your hands are grubby.

That hurts my feelings...  :P ;)
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline Jeram

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Piston/Cylinder diagnosis
« Reply #8 on: October 26, 2013, 07:40:43 AM »
buy your self a ball hone stu, http://www.brushresearch.com/flex-hone.php?gclid=CNSq6enBtLoCFc6j4AodpS4AWw, just spray with wd-40 three passes and shes looking good.

pistons are cheap and disposable, so just pop a new one in!
bore looks ok, just clean it up a little yourself and whack her back together.

PS: your bore might be glazed which is stoppping the new rings from seating, hence the ****ty compressioon
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline evo550

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« Reply #9 on: October 26, 2013, 12:10:05 PM »
It all looks fine to me, tiny bit of blow bye, but that's to be expected, after 30hrs @8000rpm that piston and rings have traveled along that bore 28800000 times, wear is to be expected.
Drop a new slug in and close it up doctor and get back out on the track...
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline rlaj1004

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Piston/Cylinder diagnosis
« Reply #10 on: October 26, 2013, 02:55:47 PM »
buy your self a ball hone stu, http://www.brushresearch.com/flex-hone.php?gclid=CNSq6enBtLoCFc6j4AodpS4AWw, just spray with wd-40 three passes and shes looking good.

Hey Racer, I was looking at the hones on that site. Which one do you use? The aluminum oxide 240?
Do you have to get one to deglaze and one to cross hatch? Never done that to my cylinder.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline Stusmoke

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Piston/Cylinder diagnosis
« Reply #11 on: October 26, 2013, 11:51:42 PM »
It all looks fine to me, tiny bit of blow bye, but that's to be expected, after 30hrs @8000rpm that piston and rings have traveled along that bore 28800000 times, wear is to be expected.
Drop a new slug in and close it up doctor and get back out on the track...

Definitely. Poor little rings  :(

Bye bye vertex! I wish KTM would start putting wossner in their production bikes. They run a forged KONIG in their four strokes I believe. I would have thought it would be easier to buy it all from wossner, I think their factory teams run wossner anyway.

While I've got the majority of the bike down, I'll get a one size bigger and one size smaller main and same for the pilot, just gotta find out what they are the cat chewed up the piece of paper I had it all written down on. ****in cats...
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline _X_

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« Reply #12 on: October 27, 2013, 01:18:23 AM »
buy your self a ball hone stu, http://www.brushresearch.com/flex-hone.php?gclid=CNSq6enBtLoCFc6j4AodpS4AWw, just spray with wd-40 three passes and shes looking good.

Hey Racer, I was looking at the hones on that site. Which one do you use? The aluminum oxide 240?
Do you have to get one to deglaze and one to cross hatch? Never done that to my cylinder.
exactly rlaj, 240AO. i use the one and it does both in three quick passes. i first saturate the hone in wd-40 then get the rpms up on the high speed drill and plung it in and out three times and done. then wash cylinder in soapy water rinse and apply two stroke oil to the sleeve and im done. easy.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline rlaj1004

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Piston/Cylinder diagnosis
« Reply #13 on: October 27, 2013, 02:26:03 PM »
Cool, thanks, you are the man... I think. I saw your other post so......well anyway, hahahaha
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline Stusmoke

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Piston/Cylinder diagnosis
« Reply #14 on: November 01, 2013, 02:29:46 AM »
New top end went in last night. Spent like 3 hours trying to figure out the stupid power valve linkage spring but its all good now. Did my first heat cycle this morning, going to work now and and another one this arvo.

On a side note does anyone know if KTM made some changes to the cylinder head centre o-ring from 2011-2013?

THanks again all.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »