Here's evidence of what can happen with a cheap "knockoff" cast piston courtesy of a post Enduronut wrote a few years ago. Use caution when selecting a piston. 

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<Start quote from Enduronut post>

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ENDURONUT wrote: ................Below are a few photo's of a Chinese piston I replaced in a failed Yamaha motor.

In the first picture, if you look at the ring land grooves around the two gap locating pins, you will see that the aluminum piston material was not strong enough to support the ring ends from opening up a sizable gap.



In picture two, the large gap created allowed the rings to rotate around the piston until they finally snagged for good in the exhaust port.

 

Picture three shows it also has a cracked wrist-pin boss because of the very poor casting and the inferior aluminum alloy used.




<End quote>
 

Hey MarkT I can’t view the picture’s anything I can do on my end Thanks 

Let me try to fix that later tonight...   

Cheap $10 pistons are same as cheap $10 carbs. Pay a bit more, and you will have something, which is likely to work very well.

Mitaka in the UK has remanufactured many pistons for older bikes, and their site includes all the information needed, to help see if a piston for another bike, will work in yours.

Their DT175MX pistons, work perfectly in TY175 for example, and quality is comparable to OE.

Forged pistons are ok if cast are not available, but higher cost, and increased bore clearance, means that on balance cast are preferred.

Mitaka UK site looks like a much better resource than the standard Mitaka page we get in the USA

The biggest strike against Mitaka is they order pistons in bulk from China and then market and sell them. (This is not the same as re-branding known quality parts from the actual OE manufacturers companies like Yamaha and Kawasaki use.  In contrast, Pro-X has been re-branding parts from actual OE manufacturers for decades.)  

Bottom line is Mitaka is a marketing company that is having cheap copies of pistons and other parts made in China.  Does that mean Mitaka pistons are junk?  No.  Just "questionable" for me at this point. 

Speaking of questions....  you mentioned that the DT175MX Mitaka works great in the TY175...  do you think Mitaka made a mistake when they added the note I circled in red?  I would think it would fit both of those models as you said?  Or am I looking at the wrong piston? 



P.S I have a couple of rare (in the USA at least) bikes.  One of them is extremely popular is Indonesia and Thailand.  They have been modifying and racing them there for years.  I've stocked up on spare parts for obvious reasons.... Mitaka sells a piston kit for this model and it is sold there very cheap ($10 US).  I was advised to spend a couple of dollars more and buy OEM Japanese piston kits (available there pretty cheap from Kawasaki $28 US) or Wiseco (available there from a racing parts company that has Wiseco make batches of them...  very expensive).  My sources said they've seen a few Mitaka pistons break off skirts at high rpm...  This is a highly stressed engine with peak power over 10,000 rpm in factory trim so Mitaka might hold up fine on a lower revving Enduro or Trials bike?  (They did say they believe Mitaka uses Japanese-manufactured NPR rings that are identical to OEM on my model...  they tossed in a couple of sets for free with one of my orders.)

 

Interestingly, the owner of Mitaka used to run a Yamaha road race team for many years, and as well as pistons, sells con-rod kits, and makes things like CNC clutch baskets in house, also builds cranks and does rebores.

The DT175MX piston fits TY, as does the Blaster piston. The DT piston is better, as there is more material in the thrust face, and it's less likely to rattle.

Check the info on the DTMX drawing, and other than bigger boost windows in the MX piston, and different rings, it's pretty much exactly the same as a DT/TY piston, and is a direct replacement.

Mitaka as well as all the various bike parts, sells SPS cylinder boring bars, which are perfect for bike cylinders.

Their info on con-rods is useful, and it confirmed what I was told by someone who used to work for Yamaha, that a YZ465 rod fits the TY Mono, and was used on the bike that won a world round in 88.

Yamfan, In other words you have no clue as to why Mitaka clearly says the DT175MX piston does not fit the TY175 or IT175?

I understand you say it does fit, I'm not going to argue because I haven't seen the piston myself.

I just find it curious the Mitaka page goes out of its way to state it does NOT fit those models.

Next time I speak to them, I will mention the error. As they only sell to motorcycle trade, I would think anyone wanting a TY175 piston, will already know the DT175MX pistons work fine?

Yamfan wrote:  ".................................As they only sell to motorcycle trade, I would think anyone wanting a TY175 piston, will already know the DT175MX pistons work fine? "

Is the above statement a joke?  Ignore the warning in the listing because anyone who knows anything about the motorcycle trade knows it will work fine? 

DT175 has a very narrow boost port at rear of cylinder.  I don't know the boost port width of a TY175...  (The pictures of the TY175 Rich ported show a pretty wide rear boost port, but it may have been widened.)

I do know the IT175 has the transfer ports crowded forward and a wider boost port.  A 13mm ring pin offset is pretty narrow...  it is definitely is possible that it's not safe to use this piston in a TY175 or IT175.  (That doesn't mean all DT175 pistons won't work in a TY or IT175... but perhaps this specific one isn't safe.) 

It is a very bad idea to use an IT175 piston in a DT175 due to the different ring pin locations...  I found that out first hand. 

Anyway, if it's your bike you can chance at destroying it if you want to....  hopefully nobody takes your advice without checking carefully for themselves.

  

Just a piston composition question.
I stumbled on a facebook page showing a Destroyed MX360 motor where the piston had 'let go' & someone said it's because it has a DT360 two ring piston & 'not' an MX piston as mx pistons have a higher silicon content for higher revs.
Is that right??????? something i've never considered.
I'd have said Bull S--t until i thought back to my KX125 that continually elongated the gudgeon eye of every 'genuine kawy parts box piston i fitted regularly to keep it sharp, well sharp power with new rings [kawy genuine piston kit].
Was it a lower quality genuine piston. Kawy factory getting replacements made cheap.
But original lasted & lasted & it went back a in couple of times if need be while awaiting a new kit.
Replacement would get rattly & knew it was 'time to go'.
Could move the piston up & down by feel grabbing both sides standing over the top & pull up & down--was very obvious without trying, & could rock it on the pin. Not pin in the rod rock.
Quality of original that came in the bike in "86 looked better, or maybe i was getting paranoid but thought it looks nicer quality.
Interestingly kawy did gudgeon bearings in incremental fits by memory, not that i ever needed to go away from std on mine.
So is it al Bull pucky?. I'll see if i can find the pic. Ok hope that link works.
www.facebook.com/photo/?fbid=70410449192...t=a.2074899449210013