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how do my piston & cylinder wall look?

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it needs a top end.

 

piston has a few score lines and on the left there is a good one.

 

also it seems that the cylinder is kinda worn out as you look across the piston at the inlet side, big fat line across the stroke length - surface seems worn/rusted?

mine had almost the same surface texture but mine is sleeved, easy fix with cylinder honing -assuming that the cylinder is round and within spec!

 

what year cr250 is this?

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Just for future reference you can borrow a compression test tool from a auto parts store. Most of the big chains have them.

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That cylinder needs attention as well.

Installing new piston in a worn out  / damaged cylinder will not fix anything.

 

If you have trouble having access to a simple compression tester,

I can imagine having the cylinder replated will be next to impossible in your area. (profile says you are in Lebanon ?)

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i know a place that does engine boring and it seems they service ktm two strokes so i imagine they can get my cylinder replated. they might have compression test tools too, but its a hassle since my bike is in one location and they are in another, and i have no pickup. would be easier to just bring them my cylinder.

 

thanks

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it seems mlatour you are right, i cannot find a place to put a new coat inside the cylinder. im thinking of ordering an LA sleeve and having the cylinder bored to fit it. from reading other threads it seems this is an unpopular option because people say there is the danger of not lining it up perfectly with the port holes. but i think this shouldn't be a problem if i took it to an experienced engine guy.

 

any other reason why i shouldn't go with the sleeve, keeping in mind i cannot replate it?

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it seems mlatour you are right, i cannot find a place to put a new coat inside the cylinder. im thinking of ordering an LA sleeve and having the cylinder bored to fit it. from reading other threads it seems this is an unpopular option because people say there is the danger of not lining it up perfectly with the port holes. but i think this shouldn't be a problem if i took it to an experienced engine guy.

 

any other reason why i shouldn't go with the sleeve, keeping in mind i cannot replate it?

 

Mail your cylinder to la sleeve, tell them you want a matching piston and ring combo to go with your rebuild, they do work in-house.

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To me, the cylinder wall doesn't look terrible. It definitely looks like its glazed and has some time on it. Before you get started on talking about a sleeve, start by taking the intake side apart, and pull out the reeds. Then inspect the intake side of the piston near the bottom for cracks in the skirt. Usually you will see it right at the point where that little spot that doesn't wear because of the port shape..

 

I would have the cylinder cleaned up with a ball hone to refresh the wall, then have it measured to see if it's in spec. I also think pro-X pistons are made in oversize so you could try to run an oversize if it's close to the service limit. http://www.pro-x.com/search/?search-brand=6&search-model=7186&search-year=2001&search-submit=SHOW+RESULTS

 

It almost looks like the cylinder wall at the back has glazed air filter oil or maybe a dirty air filter seeped dirt through and melted to the wall.

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Mail your cylinder to la sleeve, tell them you want a matching piston and ring combo to go with your rebuild, they do work in-house.

should be a ton of places in Europe that can re plate, no need to ship overseas when they do the same work over there.

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if i'm correct and you're still in Lebanon (your location in your profile) then there is a company in UK that does plating at an affordable price, in the end you might find that the difference in cost between re-plating and sleeving is very close.

 

i've heard these guys are good,

http://www.poetonaptec.co.uk/cylinder-repair.htm

 

or these

http://www.langcourt.com/page27.html

 

contact them and see if they can help you out, just make sure you send them your cylinder bare (remove all Power Valve components, head studs etc) and send them your new piston (stock dimension) and rings to get you the right clearances.

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It almost looks like the cylinder wall at the back has glazed air filter oil or maybe a dirty air filter seeped dirt through and melted to the wall.

 

If that's really all it is, could it be scrubbed off with some gasoline and scotch brite pad? ill tear into it soon to see what's really going on, but I'm waiting on oil seals first to see if those solve my spooge and suspected air leak problems.

 

shipping the cylinder out of Lebanon, even if just across the sea to Europe, is really a complicated thing because of customs, time and costs. labor is cheap here and if sleeving is a safe option as long as the mechanic knows what he's doing then is a way more realistic option.

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sleeving is a safe option, just need proper installation by a good mechanic who knows what he is doing, first off disassemble the cylinder and measure it, if it is out of round at that point of those marks then you have to repair it.

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Take the cylinder in to the place that you mentioned who does KTM 2 stroke work. He will have access to a deglazing ball style hone. Let him lightly clean up the cylinder with the proper tool. Make sure he doesn't use a 3 finger style hone, and If he says he can do it with a 3 finger one, grab your cyl and run.. he doesn't know what hes' doing.

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I tore into the top end today. first surprise: the cylinder is sleeved!  😏

 

IMG_20160311_000521_zpswpmsnrky.jpg

 

i scrubbed it with a scotch pad and that streak down the cylinder you see in the video is mostly gone. the cylinder looks to be in pretty decent shape from what i can tell except for one scratch under the exhaust port hole.

 

IMG_20160310_235845_zpsmvy8m1t7.jpg

 

IMG_20160310_235718_zpsdxl5a641.jpg

 

IMG_20160310_235703_zpsk6uhf1hi.jpg

 

IMG_20160310_235645_zpsozixrrhf.jpg

 

IMG_20160310_235520_zpsrwtcql2p.jpg

 

here is the scratch. it's deep enough i can catch my fingernail on it.

 

IMG_20160310_235151_zpskqve3vs5.jpg

 

IMG_20160310_234558_zps7nt2r9gr.jpg

 

 

What should I do about it? sand it? leave it? is this what is causing the blow by on the piston that you see in the video?

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Knowing that you have a liner in it, this is my take on it.. The cast iron sleeve is much softer material than the super hard plating that comes on the factory surface.. That will cause it to wear comparatively quickly and it will need to be measured to see if it is still round and not tapered. It could be oval and even though it looks clean, it won't be good to put a new piston in and just run it. The excessive clearance will hammer the piston skirts and eventually break it..

That being said, the sleeve can be bored out relatively cheap many times over, and fitted with a proper fitting piston.. So take it to a machine shop, and get it measured properly before you move forward with the next decision

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