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Piston damage?

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Long story short: I had a bottom end failure and decided to go for a full rebuild so I recently rebuilt my 2006 200 exc engine - After some 10-15hrs I took the exhaust out and had a look inside the bore and found some marks on the piston. What is this coming from? 

Piston was brand new (vertex) as well as the bore was sent for nikasil plating,

Conrod is new as well (OEM) and crank was given to a local guy who seems to know what he's doing to dismantle and assemble following with balancing of the webs.

Air filter is brand new, was sprayed with oil and is still clean.

Oil I'm using for premix is exol - on paper it seems to be a good oil however I'm not sure. I mix at 50:1 and when I stop at a fuel pump while I'm out riding I tend to go a bit richer on oil in the mix (as for precaution)

Here under please find the marks found on the piston in such short hours,

Many Thanks,
Ross

 

 

IMG_20170504_141541.jpg

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50:1 may not be enough oil. Never heard of oil you're useing tho . You ride it wide open down the road?  Sry but alot do that come on here asking.  No offense to you 

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The guy I bought it from said he used the 60:1 ratio so I guess 50:1 should be good? Exol 2T fully synthetic oil is JASO approved and everyone seems to be using it on the uk ktm forum without complaints. 

Now regarding me riding it wide open, I don't really use it on the roads however when I'm on the road I usually give it short bursts till I'm in the last gear but it is close to never that I'm wide open in the last gear. 

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55 minutes ago, lukeross94 said:

The guy I bought it from said he used the 60:1 ratio so I guess 50:1 should be good? Exol 2T fully synthetic oil is JASO approved and everyone seems to be using it on the uk ktm forum without complaints. 

Now regarding me riding it wide open, I don't really use it on the roads however when I'm on the road I usually give it short bursts till I'm in the last gear but it is close to never that I'm wide open in the last gear. 

What does the manufacturer suggests to run for that bike? Has it been jetted to run 50:1-60:1? Just curious.  Less oil makes engine run leaner is why I ask. I run 50:1 in my chainsaw and 32:1 in my twostrokes bikes. But don't use synthetic oils 

Edited by Motox367

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Just the black coating wearing off the piston. Normal IMO but let the smart guys weigh in.

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I managed to take some more pictures, I don't really think this is normal? I mean the vertical lines mean that the piston itself is making contact with the bore?

 

1st image: piston upper part

2nd image:  piston bottom part

3rd image: Bore itself 

IMG_20170504_165330.jpg

IMG_20170504_165420.jpg

IMG_20170504_165630.jpg

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50:1 is plenty oil. 

Did you wipe down/clean the cylinder at all before you put it together? Piston coating wearing off is normal but it looks like some contaminants were in there. 

Who did the plating? Their cross hatching looks kind of rough IMO. 

You'll be fine, any debris would have moved along by now. I'd run it. 

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Yes I can imagine that it's enough oil just didn't imagine this would come up within the first few hours,

Plating was done by MEC Racing in Germany which as from their reputation german labour works are usually good as one can pretend as they are quite expensive - I paid some 260 euros for a full replate and a fix in the intake port ( they could of invented the fix as I don't have any proof of that )

However as one can imagine after works have been done I sanded and filed down the sharp edges the plating leaves on the ports and cleaned quite well with brake cleaner followed by compressed air to get rid of any debris, so again it should not be the case.

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An old timer told me to blast air first then use wd40 to clean the cylinder until the shop towel comes out clean. It's surprising how much dirt/debris it picks up.

brake clean might dry too fast :excuseme:

Edited by Casing-daily

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You should wash your cylinder anytime it comes back from being plated or bored with warm water and I use blue dawn dishsoap. Then imidently spray with lubrication oil like wd40 and let sit for little while . But I don't believe that's your problem here you got 4 hours on it. I say oil,or lean air leak,didn't let it warm up enough, or something like that.  Just alitte bit of rub could run long time or not. One below I did because bike was super rich and powervalve stuck on one side so got cleaned.  Usually do this with every engine I do

20170426_152547.jpg

20170426_152941.jpg

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I didn't do the washup/soap thing so could be it? But I'm used to cleaning cylinder heads after they had engineering works and usually it is washed up by diesel followed by compressed air followed by brake cleaner and as this is small I did use plenty of brake cleaner and quite sure that I cleaned well, so I'm not really sure on that. Maybe debris stick a lot more to nikasil? 

Oil should not be it as mentioned above a lot of people are using it and it is JASO approved as well. 

Airbox seems to be quite clean as well so don't really know what could be the reason. What I'll do is run it again for some more hours and keep an eye on it making sure it's not getting worse.

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4 hours ago, lukeross94 said:

I didn't do the washup/soap thing so could be it? But I'm used to cleaning cylinder heads after they had engineering works and usually it is washed up by diesel followed by compressed air followed by brake cleaner and as this is small I did use plenty of brake cleaner and quite sure that I cleaned well, so I'm not really sure on that. Maybe debris stick a lot more to nikasil? 

Oil should not be it as mentioned above a lot of people are using it and it is JASO approved as well. 

Airbox seems to be quite clean as well so don't really know what could be the reason. What I'll do is run it again for some more hours and keep an eye on it making sure it's not getting worse.

I know you were saying that you were sanding on the ports. Slavens says nikasil is porous and grit can impregnate the pores of the cylinder.

 

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I personally use wiseco pistons (recently switched to single ring) and mix 40:1 with castor 927 for about a year now and am really happy with it, If i was you i'd run 40:1 just to be safe but that's your call. And yea you should have washed the cylinder when it came back because when they replete it, it will leave a lot of crap in there. But regardless it looks fine and i'd still run it, if you pull it apart put some new rings on it. 

 

 

cheers 

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You are good man. Everything looks fine. 50:1 is fine. Whats all this about wide open down a road? What does your jetting look like?

Edited by theBIGnaud
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10 hours ago, Casing-daily said:

I know you were saying that you were sanding on the ports. Slavens says nikasil is porous and grit can impregnate the pores of the cylinder.

 

2

An emery cloth was used and what I did was to avoid the ports eating the rings with the sharp edges the coating has done.

Still I didn't know nikasil was so porous so thanks for that!

7 hours ago, theBIGnaud said:

You are good man. Everything looks fine. 50:1 is fine. Whats all this about wide open down a road? What does your jetting look like?

Not really into jetting yet but at 50:1 the bike runs slightly rich but still strong - I mean some spooge is coming out from the exhaust but not much

 

7 hours ago, TomTopDog12 said:

Another thing to consider is always pull the clutch in, never let a two stroke engine break :(

Whats the reason for this? Sometimes it cant be avoided but didn't imagine it would do harm to the engine 

 

Many thanks guys appreciate all your help!

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Run some oil in your mix.  You bottom end will last longer than you'll ever keep a bike, and the top end will last longer too.  I like 32:1 myself for any bike under 250cc.  If you like replacing bearings every 200-300 hours, then run 50 or 60:1.  If you want it to last, run some oil.

From the pictures it seems clear that you have managed to get some kind of grit in your engine.  That's what you need to focus on.  My guess is that the guy above is right--debris left behind from the shop service is the culprit.  As noted above, you really need to clean the cylinder completely in the sink before oiling and assembly.  

Edited by rpt50
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2 hours ago, rpt50 said:

Run some oil in your mix.  You bottom end will last longer than you'll ever keep a bike, and the top end will last longer too.  I like 32:1 myself for any bike under 250cc.  If you like replacing bearings every 200-300 hours, then run 50 or 60:1.  If you want it to last, run some oil.

From the pictures it seems clear that you have managed to get some kind of grit in your engine.  That's what you need to focus on.  My guess is that the guy above is right--debris left behind from the shop service is the culprit.  As noted above, you really need to clean the cylinder completely in the sink before oiling and assembly.  

screw it, run 16:1 ..more must be better? it worked in the 1920's...idk why they ever changed.

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3 hours ago, rpt50 said:

Run some oil in your mix.  You bottom end will last longer than you'll ever keep a bike, and the top end will last longer too.  I like 32:1 myself for any bike under 250cc.  If you like replacing bearings every 200-300 hours, then run 50 or 60:1.  If you want it to last, run some oil.

From the pictures it seems clear that you have managed to get some kind of grit in your engine.  That's what you need to focus on.  My guess is that the guy above is right--debris left behind from the shop service is the culprit.  As noted above, you really need to clean the cylinder completely in the sink before oiling and assembly.  

Crazy how my crank has lasted over 800 hours on 50:1 mix.

You must not mind cleaning the powervalve...

Edited by Casing-daily

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Just remember the faster you are the harder you are on engine :thumbsup: back when I raced 125B class mx, Kawasakis , would be lucky to get a season out of a crank. oem. At 32:1 :ride:

Edited by Motox367

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