New Piston for 2011 GYTR?

[JLB943]

Going to be putting a new piston in my 11 yz450 over the winter. Is the GYTR piston the way to go as far as price/performance?

Can you run pump gas?(93 octane)

[migs647]

According to GYTR you need 100 octane gas. Not sure how true that is though.

[JLB943]

Yeah, I saw in one of the magazine tests that they ran pump gas and it was ok, but I would like someone has has experience with it. I had a 13.75 to 1 piston in my other yz and did not have issues running the pump stuff. I would like to at the most have to put some octane booster in it. Race gas is just too expensive. I was looking at the CP Project X piston as well but it seems to be alot more expensive, even though I know cp pistons are quality stuff.

[mx369]

You need to know that the GYTR piston only has TWO ring grooves instead of three. I guess for less friction. Son liked it at first but power went down after about 20 hours on it. Removed piston ring and checked gap. WAY out of clearence. Went back to stock piston from Yamaha and have 42 hours and still fine. Just a thought.

[KJ790]

The octane needed is dependent on the cams you run more than the static compression of the piston. If you are running cams with a longer duration you can often get away with lower octane since they tend to decrease the dynamic compression ratio. This is why it is common to run a high compression piston with big cams to try to get the dynamic compression ratio back up to where it was stock. If you don't change your cams and just go to a higher compression piston then you will often need higher octane than the stock engine requires.

[JLB943]

You need to know that the GYTR piston only has TWO ring grooves instead of three. I guess for less friction. Son liked it at first but power went down after about 20 hours on it. Removed piston ring and checked gap. WAY out of clearence. Went back to stock piston from Yamaha and have 42 hours and still fine. Just a thought.

This is the kind of information I needed. 20 hours is too often to change a piston for someone like me who rides mx for fun. I realize the wear will be based of total distance traveled so if it was run in the high rpm range then it may have wore quicker than what I might see but still probably not worth risk.

I didn't think about the cams. In my other yz with the 13.75:1 piston I did have hot cams installed at the same time. Longer duration would increas overlap and bleed off some of the compression. I am having second thought about the GYTR for my application. Is the OEM stock the best replacement or is someone like Pro-X or Wiseco better?

[grayracer513]

The OEM Yamaha piston is a very durable, high quality, and still reasonably priced piece of work designed with an eye to longevity. (It's forged, BTW) For most people, this combination is a more important consideration than a marginal gain in power is. There are aftermarket pistons with two compression rings in the standard compression that are made for longer wear conditions, and some of them do outperform OEM in applications like hare scrambles and Baja racing, but they cost quite a bit more, too, and it becomes a question of whether the additional cost actually buys additional value to the particular end user.

[KJ790]

This is the kind of information I needed. 20 hours is too often to change a piston for someone like me who rides mx for fun. I realize the wear will be based of total distance traveled so if it was run in the high rpm range then it may have wore quicker than what I might see but still probably not worth risk.

I didn't think about the cams. In my other yz with the 13.75:1 piston I did have hot cams installed at the same time. Longer duration would increas overlap and bleed off some of the compression. I am having second thought about the GYTR for my application. Is the OEM stock the best replacement or is someone like Pro-X or Wiseco better?

OEM and Pro-X pistons are both made by the same company (ART). They are the world's largest piston manufacturer. Wiseco, JE, and CP are all good pistons, but they don't really offer any benefit over OEM if you are looking to go with stock compression. For the price it is hard to beat OEM.

[grayracer513]

OEM and Pro-X pistons are both made by the same company (ART). They are the world's largest piston manufacturer. Wiseco, JE, and CP are all good pistons, but they don't really offer any benefit over OEM if you are looking to go with stock compression. For the price it is hard to beat OEM.

Most of Pro-X's stuff is rebranded parts someone else made. As far as I can tell, the $60 cam chain they sell is no different than the $17 OEM one, just as an example.

Of the 3 AM pistons you named, CP is my top pick without any question, then JE. I personally don't care for Wisecos. As I said, if I was building a Baja bike or a big money Off-Road racer where I wanted a 12.5:1 piston that might be tougher than stock under really extreme conditions, I'd go with a CP, but for most people, OEM, like you said.

[JLB943]

My decision is made then, I am going to pickup the OEM Yamaha piston. Actually saves me some money, thanks guys.

Edited November 7, 2012 by JLB943

[luckyguy19]

After 10 years in the automotive parts business, I go OEM on everything I can.

Also, there are a lot of places that say they make the same as OEM, or are an OEM manufacturer, still doesn't mean the quality is the same.

For example. I company has an OEM contract to make water pumps. The contract states that 10,000 water pumps can be made with the mold. After 10k the mold is getting close to being out of spec due to wear and tear. The company will then make another 2k-3k on that mold. These water pumps are still decent, made by the same manufacturer, but just off spec that little bit. Which water pump do you want for your vehicle?

[mx369]

My GYTR piston was a "JE" brand piston

[grayracer513]

GYT-R stuff is mostly rebranded as well, but it's all pretty premium stuff, like JE, Hinson, etc.

[ellisde]

do run my hole gytr kit for over 200h.i cange the piston at about 50h.valves at 100h.cylinder every 2end piston,conection rod at 75h. only normal europen gas under 100 octan.the gytr kit is worth every euro.

[STR8SHOOTR]

I stick with the oem stuff also. I've been tempted to buy the bigger dollar stuff but I havnt. Maybe next time with a big bore kit. I feel that the oem quality and how long the stuff can last with proper maintenance cant be beat.

[poppa]

The OEM Yamaha piston is a very durable, high quality, and still reasonably priced piece of work designed with an eye to longevity. (It's forged, BTW) For most people, this combination is a more important consideration than a marginal gain in power is. There are aftermarket pistons with two compression rings in the standard compression that are made for longer wear conditions, and some of them do outperform OEM in applications like hare scrambles and Baja racing, but they cost quite a bit more, too, and it becomes a question of whether the additional cost actually buys additional value to the particular end user.

how longevity are ya talkin? We have 85 hrs on a 2011 yz450, CC racing. Yamalube 20-50 every race, valves spot on, good gas, do we need a top end?

[grayracer513]

how longevity are ya talkin? We have 85 hrs on a 2011 yz450, CC racing. Yamalube 20-50 every race, valves spot on, good gas, do we need a top end?

There's no realistic way to answer that question because there are no terms to gauge by that aren't subjective. My '06 is probably due, but only as a sensible maintenance thing. I've been running the same bike in desert races for 4 years with other riding tossed in between, still on the original piston, and it hasn't really lost a step, power wise. But I'm quite a bit easier on the bike at the pace I run than the guys who run in the top 10, so there are all kinds of things that 85 hours of "cross-country racing" might mean.

The only way to find out for sure is to open it up and have a look.