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Was wondering what your guys thoughts were on this cylinder. And how much play between cylinder wall and piston is ok. This is an Athena cylinder jug. Oil was getting by not sure if I need new cylinder? Any comments would be appreciated.
 
Thanks, justin

IMG_0575.JPGIMG_0579.JPGIMG_0576.JPGIMG_0580.JPGIMG_0578.JPGIMG_0579.JPG

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i'd be more concerned about the exhaust valves hitting the piston....


Yes I am aware of this the previous owner had timing off and piston installed incorrectly. My concern is the cylinder like I stated previously.

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That cylinder looks like it is in PRISTINE condition. The last jug I saw that looked that good was off a 2014 vulcan... That said I would measure it and see if you can find a correctly sized piston to match. Looks like the piston/rings are undersized to me. Generally speaking most piston manufacturers will make pistons in just about any size, they are not bike specific. Do some research and find the correct one for the cylinder size and you'll be good to go.

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if oil comes up into the head, that's a sign of piston rings upside down mounted... get a set of new rings, and you'll be fine...or if piston got over 100 hours..get a new one.. 

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3 hours ago, photonicreno said:

That cylinder looks like it is in PRISTINE condition. The last jug I saw that looked that good was off a 2014 vulcan... That said I would measure it and see if you can find a correctly sized piston to match. Looks like the piston/rings are undersized to me. Generally speaking most piston manufacturers will make pistons in just about any size, they are not bike specific. Do some research and find the correct one for the cylinder size and you'll be good to go.

where can you see the rings which look undersize ???? and every piston is bike/engine and model year specific

the piston top is always way smaller in diameter, cos it gets friggin hot and expands most...

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12 minutes ago, Bernie Nottelling said:

where can you see the rings which look undersize ???? and every piston is bike/engine and model year specific

the piston top is always way smaller in diameter, cos it gets friggin hot and expands most...

If the rings weren't under sized then the piston would be centered even with a certain amount of ring gap. He mentioned that the cylinder is an athena one which is a company known for aftermarket big bore cylinders. And while they are larger on the top, the clearances should not be able to be measured by eye. As you can visibly see the gap, the piston is quite clearly the incorrect size.

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If the rings weren't under sized then the piston would be centered even with a certain amount of ring gap. He mentioned that the cylinder is an athena one which is a company known for aftermarket big bore cylinders. And while they are larger on the top, the clearances should not be able to be measured by eye. As you can visibly see the gap, the piston is quite clearly the incorrect size.

You are correct, I did some research and found the piston isn’t even an Athena piston. The cylinder calls for a 96mm piston. The one in the pics is a 95.6 mm I know it’s not much but is a difference. Do you think that little difference can be the problem?

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55 minutes ago, Grapeape3258 said:


You are correct, I did some research and found the piston isn’t even an Athena piston. The cylinder calls for a 96mm piston. The one in the pics is a 95.6 mm I know it’s not much but is a difference. Do you think that little difference can be the problem?

where at the piston did you measure the 95.6mm ?

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18 hours ago, Grapeape3258 said:


You are correct, I did some research and found the piston isn’t even an Athena piston. The cylinder calls for a 96mm piston. The one in the pics is a 95.6 mm I know it’s not much but is a difference. Do you think that little difference can be the problem?

I did some research and on the 2007-2017 KX450F the stock piston size is 95.95, so you need to re-measure the piston at the top and bottom of the skirt, and at the very top of the piston in atleast 2 different directions. That will give you an accurate measurement. But if you did measure properly and 95.6 is your measurement, it sounds to me like that is the stock piston that has been worn out. I would make sure you also at the very least use a caliper, a micrometer is more ideal for this kind of measurement.

As for the Athena piston, it does not matter too much who manufactures the piston itself. Wiseco, Vertex, and Athena are all just suppliers of the same product. Some will offer more performance, some offer longevity. That is a personal choice, what matters is that you get a correctly sized piston.

Could you find out the cylinders part number and post it?

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