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JLB943

GYTR Head - Questions on Piston/Cam Compatability

8 posts in this topic

2011 YZ450

I installed a GYTR head with Vertex High compression piston. The engine turns over so far but it seems the piston is touching the head or at least binding.

 

Does anyone know if the GYTR head combustion chamber is different from stock?

Has anyone run GYTR head with Vertex HI-COMP Piston and Hot Cams?

 

Trying to determine what the issue is that is causing the binding. I thought I may have installed the piston backward. I installed it with the arrow toward the intake (front of the bike). I believe this is correct.

 

Any help appreciated, I assembled and disassembled head/cylinder bunch of times today, cannot determine actual issue. I am going to contact manufacturers Yamaha /Vertex/Hot Cams see if I can get any info from them. However, I thought the GYTR head was designed to be run with even stock components.

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Verify the piston is the right one- and in correctly. Make sure cams are correct. Then clay the head to measure clearances.

Did you take the spark plug out and roll it over? How do you know it's binding? Like goes to contact and then don't move ?

Edited by Ctown208

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Piston is installed backwards. I went be the Yamaha manual which stated letter should be pointed toward the intake. Vertex puts an arrow on the piston which should be pointed toward the exhaust. In the literature provided with the piston it did not state this. Only after calling them and then finding additional information on website could I confirm this.

 

As far as the binding, the piston will rotate freely until a certain point and then stop dead. Without the head on the piston goes completely through stroke. Likely it is catching the valve since the valve pocket is wrong (reversed). Hopefully this solves the issue.

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Industry standards generally have any orientation arrows on the piston pointed toward the exhaust side.  Yamaha probably switched this because the intake side is forward on this engine.  But, a piston with such obviously different cutouts for two different sized valve pairs shouldn't really need an arrow marking which direction it goes, should it?  :cool:

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I would have rather had no mark at all so I might have stopped and thought about it or send something with the piston stating, "point the arrow toward exhaust ".

 

It is a bonehead mistake and I did at one point question it but then when the manual back it up. People like me who do this kind of stuff once a great while need it to be more idiot proof!!!

 

On another note, the circlips on the vertex piston are nice in the way that they make installation fairly easy. However, after playing with the thing for an hour or so until I looked on Youtube where Vertex had a video of the installation. 30 seconds later I had the circlip in.  Really would be nice if the little piece of paper said - Go see this video for easy installation.

 

I guess these are required experiences to become proficient at this stuff.

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That's how it works all right.  Your hammer didn't come with instructions, but you remember learning to keep your fingers out of the way.

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