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Don't use namura piston kits

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I just put a namura piston kit in my ktm150sx 2010 and blew a ring. Piece of the ring chipped off.1/2 inch piece. It scarred the top of the piston and bottom of the head. THANK GOODNESS my jug was clean! I had it replated uhhhhhh 4 hours ago! Piston blew the ring at 4 hours.... Don't use namura. Ima go with vertex since that is the stock piston for this bike. Gotta flush out the cases wih diesel as well for any

Metal

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Most namura failure I've read about are actual piston failures, like the skirt breaking off etc. Needless to say they never have seemed worth the small savings.

I have been using vertex in everything for years. Only other piston I'll use is OEM.

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Did you spec the ring end gap? And put the ring(s) in the right side up?

 

 

Bingo.

 

These threads are no different than the "I hate Wiseco" threads.

 

Failures of this sort are almost without exception the fault of the person that did the work. Broken piston skirts are almost always the fault of the rider that ran the piston past its service limits, or installed it with too much clearance to begin with.

 

Is it possible to get a bad part? Sure, mass production will always have a few bad eggs in the batch. But one bad experience is not a reason to disparage an entire brand, especially when the likelihood of the cause of the problem being the rider is high.

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Bingo.

 

These threads are no different than the "I hate Wiseco" threads.

 

Failures of this sort are almost without exception the fault of the person that did the work. Broken piston skirts are almost always the fault of the rider that ran the piston past its service limits, or installed it with too much clearance to begin with.

 

Is it possible to get a bad part? Sure, mass production will always have a few bad eggs in the batch. But one bad experience is not a reason to disparage an entire brand, especially when the likelihood of the cause of the problem being the rider is high.

I installed a Namura top end in my recent cr250 , Runs like a champ . Ring gap set at .008 . A lot of manufacturers will leave the ring gap at 0 so you can properly set it . Easier to file some off than add to it.  :lol:  It takes less than 3 minutes to set ring gap and why people won't take advice and follow instruction is beyond me  :facepalm:

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I just put a namura piston kit in my ktm150sx 2010 and blew a ring. Piece of the ring chipped off.1/2 inch piece. It scarred the top of the piston and bottom of the head. THANK GOODNESS my jug was clean! I had it replated uhhhhhh 4 hours ago! Piston blew the ring at 4 hours.... Don't use namura. Ima go with vertex since that is the stock piston for this bike. Gotta flush out the cases wih diesel as well for any

Metal

This could also happen if your ports aren't chamfered correctly . Worth a check if the cylinder was a fresh bore and ring gap to spec. 

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Also i wouldn't wash out cases EVER with diesel this washes oil out of the bearings , you say that at the dealership they will laugh and hand you a crankshaft. If you can't find that ring piece it's probably in the pipe . If you think it's in the cases use a magnet to fish around. I have washed cases out with cheap motor oil before but the engine was off the bike and i just flipped it upside down to drain overnight. 

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Also i wouldn't wash out cases EVER with diesel this washes oil out of the bearings , you say that at the dealership they will laugh and hand you a crankshaft. If you can't find that ring piece it's probably in the pipe . If you think it's in the cases use a magnet to fish around. I have washed cases out with cheap motor oil before but the engine was off the bike and i just flipped it upside down to drain overnight. 

 

diesel actually has pretty good lucrative qualitys, wont hurt a thing if he puts a couple drops of premix on the main rod bearing and down the main bearing lube holes when he is done.

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Also i wouldn't wash out cases EVER with diesel this washes oil out of the bearings , you say that at the dealership they will laugh and hand you a crankshaft. If you can't find that ring piece it's probably in the pipe . If you think it's in the cases use a magnet to fish around. I have washed cases out with cheap motor oil before but the engine was off the bike and i just flipped it upside down to drain overnight.

I've washed a motor out with diesel, bike still runs strong...

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Also, the OP said he just had the jug replated, wonder if the jug was spec'ed too?

Kinda what i was thinking about the chamfers , if it was done at Joe's cylinder re-plating where they paint the inside of the bore with a brush to put hone marks in it. :lol:  

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I previously rebuilt my CR125 with one of their pistons. Never had it go wrong except I never checked the head to make sure it was alright and it blew a head gasket. Flushed everything out, planed the head, and it ran awesome til the day I sold it! A solid 30 hours on it with no piston related issue.

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I've used namura piston kits for years... never had one fail yet. It's not the brand. The most likely cause is something the mechanic/builder did wrong.  

 

Just my 2 cents.. 

 

 

 

 

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Didn't they have a issue with the last generation 150sx and piston/rings? It may not have been the piston although namura piston are the cheapest pistons you can buy I believe. I've never seen them in tucker/parts/western. When it comes to engine components I always roll with the ART/oem/pro x or vertex pistons. That's just me though. I'm sure there's a bunch of dudes who run pep boys pistons or something and swear buy them. I spend the extra 30 or so dollars for peace of mind.

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Replating was done at POWERSEAL in Pennsylvania USA. And uhhh how could it be my fault? I ran 40:1 ratio with the piston in the right was. The piston was even sent with jug to be replated so it'd be a perfect fit. The ring snapped and metal got caught up in it. I just don't think namura is a good piston for Ktm.

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Did you install the rings correctly and does it look like it snagged on something?

Did you also ensure clearances were correct?

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Did you install the rings correctly and does it look like it snagged on something?

Did you also ensure clearances were correct?

No, of course not.... Its the companies fault, never the mechanic! :rolleyes:

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