Vertex big bore kit wr250f instructions

rickyd

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#1
Hi,

A friend of mine bought a VERTEX 300 BIG BORE KIT for his wr250f (I think it is an 06) anybody know of any online instructions? He bought the kit off of an auction site and it came this way. Any help would be appreciated.

Thank you

Rick
 

Rich Rohrich

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#2
What specifically does he need to know?
 

rickyd

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#3
He said there were 4 rings, he needs to know if they go on any specific way or not. Also, he was not sure if there was a locating pin on the piston. Is there a specific was the piston goes on, similar to haow 2st pistons have an arrow facing the exhaust. Do you need a ring compressor or can it be done with the fingers while lowering the cylinder down?

THank you Rich,

Rick
 
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#4
4 rings? That's a wavy one, 2 really thin ones, and one thicker one? The wavy one goes in first, in the bottom ring groove on the piston. That's the oil ring spacer. Make sure the ends don't overlap when you install it. The two oil scraper rings install above and below it in the same groove. The thicker ring goes in the top groove. You can compress the rings with your fingers, a compressor is not necessary. The arrow usually faces the exhaust on all pistons (there are exceptions). It should be easy to figure out on a Yamaha, look at the number of valves on the exhaust side and line up the side of the piston so that the side with the same number of reliefs is under the valve. Don't forget to check your ring gaps.
 

rickyd

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#5
Thank you,

He figured it out last night and got it back together.

There is no locating pin on a 4st piston? I have never done one, just 2st.

Rick
 
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#6
2-strokes have locating pins to keep the ring from rotating so the ends don't snag in the ports. 4-strokes have no ports, therefore, it is ok to let the ring rotate.