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Top end - which piston?

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2015 KX450f
Time to do a top end, after 85 trouble-free hours of trail and vet mx practice. 
The 2015 came with a re-designed piston for Kawasaki "box bridge design".
Should I get the OEM replacement or Vertex, Pro-X? 
Thanks
 

If you got 85 hours, I would say that's a good top end. Oem everytime.

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85 hrs doesnt seem like too much. granted i dont know how you ride but we have a 13 kx450 with about 150hrs on all OEM stuff. says a lot about the quality of oem. on the other hand i have used pro X and vertex in the past and havent had any issues with their products.

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OEM is always best. I only use aftermarket pistons in big bore kits where oem won’t fit anymore. 

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Either oem or wossner. I just rebuilt mine with a wossner piston kit I did alot of research before doing mine. A very reputable local Moto machine shop told me to go wossner. They are very popular in Germany and are just making there way into the us. They make beautiful forged pistons and I am trouble free this far. Whatever you choose just don't go wiseco there are too many horror stories

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I used a CP Carillo rod and piston, it's about the best you can get. But personally i would recommend OEM over weisco, vertex or pro-x. The OEM pistons are pretty good.

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Went with OEM, thanks guys.

Pulled it down today - a few notable findings. Piston looked identical to the new one, down to the casting marks. Carbon build-up on the top of the piston, but no scuffs on the skirts or underside. 

Piston wrist pin had a few wear marks where it seats against the piston, but no grooves. 

Cylinder still has all cross hatching, a slight scuff on the exhaust side that is slightly visible to the eye, but cannot feel it with fingernail. 

Overall, very happy with how the top end wore though 85 hours.

VALVE QUESTION: specs are (.17 - .22 exhaust) and (.10 - .15 intake). Measure at .18 and .11. I have never checked clearances until this point and have never experienced hard starting. Should I shim into range or continue to run and re-check in another 20 hours?

Thanks!

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On 1/9/2018 at 0:40 PM, Chaser503 said:

Went with OEM, thanks guys.

Pulled it down today - a few notable findings. Piston looked identical to the new one, down to the casting marks. Carbon build-up on the top of the piston, but no scuffs on the skirts or underside. 

Piston wrist pin had a few wear marks where it seats against the piston, but no grooves. 

Cylinder still has all cross hatching, a slight scuff on the exhaust side that is slightly visible to the eye, but cannot feel it with fingernail. 

Overall, very happy with how the top end wore though 85 hours.

VALVE QUESTION: specs are (.17 - .22 exhaust) and (.10 - .15 intake). Measure at .18 and .11. I have never checked clearances until this point and have never experienced hard starting. Should I shim into range or continue to run and re-check in another 20 hours?

Thanks!

i wouldnt touch them valves.  What kind of oil you run. Nice to see someone getting 85hrs on a top end

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Not to cause a firestorm - but I ran Rotella Synthetic oil and Tusk oil filters, changed every 5-7 hours, without fail. I also rotated 3 OEM air filters and NoToil oil and grease, changed when they got dirty. 2 races, but mostly vet MX practice and trail riding. I'm slow, lol. 

Ran into a slight issue with the base and head gaskets not sealing - I didn't sand down the surfaces so I probably missed a tiny spec of old gasket material. Have 3-4 drops of coolant working their way out. Sucks to have to tear it down again, but I'm getting to be a pro at it! 

Can I re-use the gasket if I've only ran it for 1 heat cycle???

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You can see a few drops of coolant here - there are a handful of drops like this when the bike is running. So I'm thinking I didn't get the gasket surface clean enough. 

 

2745661024532980095.jpg

2520953933314700424.jpg

Edited by Chaser503

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16 hours ago, Chaser503 said:

Not to cause a firestorm - but I ran Rotella Synthetic oil and Tusk oil filters, changed every 5-7 hours, without fail. I also rotated 3 OEM air filters and NoToil oil and grease, changed when they got dirty. 2 races, but mostly vet MX practice and trail riding. I'm slow, lol. 

Ran into a slight issue with the base and head gaskets not sealing - I didn't sand down the surfaces so I probably missed a tiny spec of old gasket material. Have 3-4 drops of coolant working their way out. Sucks to have to tear it down again, but I'm getting to be a pro at it! 

Can I re-use the gasket if I've only ran it for 1 heat cycle???

Right on . I run same oil and bout the same maintance but use Flo filters for oil and twin air for air. Vet riden only.  Our 250f i have always gotten 50hrs out of topends. This is my first 450f so was hoping to go a little longer.

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Just a quick update - 

I pulled everything down again, wet sanded the mating surfaces of everything (cylinder, head) and installed OEM base and head gasket. Buttoned it all up and there are no leaks. For what its worth - I'll go with OEM gaskets every time. 

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i wouldnt touch them valves.  What kind of oil you run. Nice to see someone getting 85hrs on a top end

106 hours on this one.20180103_182946.jpg20180103_161005.jpg
Valves haven't moved at all since it's first start.

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Granted I do no mx. All single track trails so I know there is really no comparison between the two. This piston has around 500 hrs on it. All I ran was yamalube semi synthetic.MVIMG_20180118_205541.jpg

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