are namura pistons good ?


40 replies to this topic
  • honda4eva

Posted July 20, 2012 - 07:38 PM

#1

hows the reliability of these pistons and whos run/ran them and any feed back looking to get one this week

  • Mikel.Laundry

Posted July 20, 2012 - 08:18 PM

#2

i would get one. they couldnt sell them like they do if they have a high faliure rate!

  • shrubitup

Posted July 20, 2012 - 08:43 PM

#3

got about 35 hours on mine. works fine. no issues. trail riding a CR250.

  • honda4eva

Posted July 20, 2012 - 09:03 PM

#4

i cant find any store online that carrys them where would i get them besides ebay ?

  • Dirt Addict

Posted July 21, 2012 - 12:25 AM

#5

NO NO NO! Do a search on here for namura. They are poor quality pistons. I made the mistake of running one . I got about 15 hours out of it before it blew. I got it even after reading about others failures. It cost me over $300 to get running again. It was one of those "pay now or pay later" things....
Maybe if you putt around and never rev the bike you may get decent life out of it... maybe not.

  • 94cr rider

Posted July 21, 2012 - 09:17 AM

#6

i have about forty hours on my and i ride mx and im about to replace it the really nice pistons

  • Mikel.Laundry

Posted July 21, 2012 - 11:15 AM

#7

NO NO NO! Do a search on here for namura. They are poor quality pistons. I made the mistake of running one . I got about 15 hours out of it before it blew. I got it even after reading about others failures. It cost me over $300 to get running again. It was one of those "pay now or pay later" things....
Maybe if you putt around and never rev the bike you may get decent life out of it... maybe not.

you got a lemon. there are lots of them out there that work perfectly.

  • MattFisher

Posted July 21, 2012 - 11:30 AM

#8

Absolute crap, and they will not stand behind their products. Here's a pic of a low-hour piston that was in my son's RM85. The circlip broke off 1/4" from the end and wedged itself in the piston crown. Ruined the piston, the cylinder, the head, and the race that day. If you look closely you can see the circlip still properly seated in the piston. It was simply a metallurgy issue.

When I contacted Namura they said "[color=navy][color=navy]What we are willing to do is replace the piston kit. Due to the abnormal nature of this failure, this is all I am authorized to provide."[/color][/color]
I asked if it had been a "normal" failure if they would replace the cylinder and head? Oh, and it took them 8 weeks for them to come to this conclusion.

In 30 years of wrenching on bikes I've used just about every piston mfg that you can think of, and have even had custom pistons made for a project of mine in the past. This is the only one that I would label "fail".
Namura can go piss up a rope. I can only think of one place I'd put their piston...

Posted Image

Edited by MattFisher, July 21, 2012 - 11:32 AM.


  • 94cr rider

Posted July 21, 2012 - 01:09 PM

#9

Absolute crap, and they will not stand behind their products. Here's a pic of a low-hour piston that was in my son's RM85. The circlip broke off 1/4" from the end and wedged itself in the piston crown. Ruined the piston, the cylinder, the head, and the race that day. If you look closely you can see the circlip still properly seated in the piston. It was simply a metallurgy issue.

When I contacted Namura they said "[color=navy][color=navy]What we are willing to do is replace the piston kit. Due to the abnormal nature of this failure, this is all I am authorized to provide."[/color][/color]
I asked if it had been a "normal" failure if they would replace the cylinder and head? Oh, and it took them 8 weeks for them to come to this conclusion.

In 30 years of wrenching on bikes I've used just about every piston mfg that you can think of, and have even had custom pistons made for a project of mine in the past. This is the only one that I would label "fail".
Namura can go piss up a rope. I can only think of one place I'd put their piston...

Posted Image


looks like you installed it the roung way

the open end should be strait down

  • noobi

Posted July 21, 2012 - 08:37 PM

#10

I had a Wiseco piston fail, the ring locator pin broke and the ring rotated and munched the cylinder. Wiseco said tough cookies.
I will never use Wiseco again.
However I know this view isnt true for everyone, and some people swear by Wiseco. There are more good stories than bad, and this is true for Namura as well.

  • Wild Alaskan

Posted July 21, 2012 - 09:09 PM

#11

man i thought i was the only one that has had a cir-clip break before (yz 125), although mine was a stock one not related to namura

  • honda4eva

Posted July 21, 2012 - 09:26 PM

#12

where would i buy one besides ebay ?

  • BDubb106

Posted July 22, 2012 - 11:08 AM

#13

Im running a Namura piston in my Yz 250 for heavy MX riding with no issues to date. 33.7 hours on the piston at the moment. I only put 40 hours on my pistons in my practice bikes so I will be pulling it soon to see how it looks. 20 hrs on my race bike so depending on how it looks I may switch permanently. First one Ive used (actually havnt used a cast piston before other than the stock piston). Ridden in every kind of soil possible including almost 20 hours of hard sand riding in SC.

They are built to the same specs as stock pistons so I gave it a shot. Quality seems pretty good. Just be sure to take all the appropriate steps when installing a fresh top end no matter what the brand.

I wouldnt hesitate to buy off a reputable ebay seller, I buy all my pistons from there for a fraction of the price you would pay through a big distributor.

Edited by BDubb106, July 22, 2012 - 11:09 AM.


  • MattFisher

Posted July 22, 2012 - 12:19 PM

#14

looks like you installed it the roung way

the open end should be strait down


It was straight down when I installed it. I moved the circlip slightly when trying to figure out which side I wanted to push the pin through. Ended up coming out the opposite side.
Additionally, the issue wasn't from a circlip that compressed and popped out or broke in the center from fatigue (the potential issues of having it at the 3:00 or 9:00 position), it broke 1/4" from the end of the circlip.

The funny thing was that I didn't realize that the circlip had failed when I snapped that picture. At first I thought it was the ring itself that broke off and was sticking up. A cursory glance at the circlip didn't make me think anything was amiss, it looked fine until I pulled it out and compared it to the other circlip. I was really baffled as to how or why a circlip would break in that that spot.

  • Mikel.Laundry

Posted July 22, 2012 - 05:17 PM

#15

rich much? look at the blow by and the black carbon on the piston. how many hours were on this?

  • BDubb106

Posted July 22, 2012 - 06:20 PM

#16

rich much? look at the blow by and the black carbon on the piston. how many hours were on this?


Ive been wondering what the underside of that piston looks like, def. looks like it got HOT to me! Ill back the OP in saying its a low hour piston because the coating is still on the skirts. The coating was gone on mine within 5 hours. Something wasnt right with either the piston or the bore. That wear looks a little abnormal to me. Hard to judge by a single pic though.

Edited by BDubb106, July 22, 2012 - 06:21 PM.


  • Tha Breeze

Posted July 22, 2012 - 07:48 PM

#17

I rebuilt my 01 YZ125 with a Namura piston and the thing ran like a beast, for the first 4 rides. Then it lost all compression and wouldn't start. Somehow a hold ended up right about where the ring pin was.

  • MattFisher

Posted July 22, 2012 - 08:59 PM

#18

Ive been wondering what the underside of that piston looks like, def. looks like it got HOT to me! Ill back the OP in saying its a low hour piston because the coating is still on the skirts. The coating was gone on mine within 5 hours. Something wasnt right with either the piston or the bore. That wear looks a little abnormal to me. Hard to judge by a single pic though.


Sorry I don't have a pic of the underside of the crown without the pin in the way. There's no indication that it was running lean or hot. Of course, it would have to get blowtorch hot to cause the circlip to fail, and that wasn't the case in the apx 5 tanks of fuel that were run past that piston. Zero issues with the prior 4 or so pistons that had been run in there.

I understand that even the best products have failures. How it's handled by the company (that old "customer service" thing) is really important to me. Hence my chiming in whenever someone asks about Namura products- no one wants to deal with that. If I wanted shitty customer service, I could just mosey on down to the DMV...

Posted Image

  • BDubb106

Posted July 23, 2012 - 01:14 PM

#19

Sorry I don't have a pic of the underside of the crown without the pin in the way. There's no indication that it was running lean or hot. Of course, it would have to get blowtorch hot to cause the circlip to fail, and that wasn't the case in the apx 5 tanks of fuel that were run past that piston. Zero issues with the prior 4 or so pistons that had been run in there.

I understand that even the best products have failures. How it's handled by the company (that old "customer service" thing) is really important to me. Hence my chiming in whenever someone asks about Namura products- no one wants to deal with that. If I wanted shitty customer service, I could just mosey on down to the DMV...

Posted Image


Fair enough, I was just curious. Something was def. wrong though, possibly with the piston (not insulting you mechanical skills what so ever), prior to installation of that piston. With that much blow by in the short amount of time you ran that piston I feel very confident saying that.

  • MattFisher

Posted July 24, 2012 - 08:44 AM

#20

I went back and looked at my notes, and there had only been 2 or 3 tanks fuel run through it with that piston; I've since started using a hour meter.
When I bought the piston I was unaware that Namura makes 3 different sized pistons for the RM85. Although I don't know for certain, I would suspect I had the smallest size piston while I should have had the largest. Especially given that the bike wasn't jetted rich prior to the piston being installed I didn't change anything for this one. Even when I ran pump gas there was zero spooge in the silencer, plug always looks good, no bogging or burbling, etc. I certainly agree that there was way too much blowby for that low of hours on the piston.

Not that the blowby has anything to do with a defective circlip, or with lousy customer service.





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