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New Piston and Head

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I DID IT !

'07 Head and 13.5:1 J&E Piston from RHC

It's supposed to be delivered Monday or Tuesday next week.

I am excited and nervous at the same time.

At 75 hours on my 2005 250X wouldn't start. The right intake clearance went to less than .002", probably closed. I had checked it at 70 hours and it was .005". So with all of the valve posts I've read and the fact that it went that fast, I shimmed it once and got a whole 1.5 hours out of it before it went to 0.003". I put it up on the stand and called Ron Hamp.

My question is........anything out of the ordinary to watch out for or tricks when replacing the piston and head?

Thanks in advance!

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Nice, nice! Same setup I am looking at down the road, toss us a ride report once you get everything back together!

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Make sure you hone the cylinder(I used a 83mm ball hone), dry install the piston and rings(read the instructions with JE piston for direction of piston because it is opposite of stock), after assembly kick it over 50 times to preliminary seat he rings, and finally ride it like you normally do when you break it in. If Ron installed the cam double check the clearances after you torque down the head & cam, they can change after tightening everything down. If you didn't already this is a good time to update the cam.

Good luck

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Make sure you hone the cylinder(I used a 83mm ball hone), dry install the piston and rings(read the instructions with JE piston for direction of piston because it is opposite of stock), after assembly kick it over 50 times to preliminary seat he rings, and finally ride it like you normally do when you break it in. If Ron installed the cam double check the clearances after you torque down the head & cam, they can change after tightening everything down. If you didn't already this is a good time to update the cam.

Good luck

:thumbsup::ride:

The new nikasil cylinder brushes are nice too. The clean the glaze and are less agressive. I also use Ball Hones to save a cylinder. I run then with mineral spirts or a water bath to cool the hone and help clean the grit. Wash the cylinder many times before you install it.

As a side note, I did the dry build 3 times in a row amd recently a semi dry build with new cylinder, both ways all went perfect. In the semi dry build I used a new cleaned cylinder, wiped out with WD40 only after washing in soapy water, rewiped with a clean dry rag. The piston also got some SAE 10 oil and wiped with a clean dry rag. So some oil just filled the pores of the crosshatch and the piston surface. The rings stayed dry upon installing.

Warmed it up untill super hot, checked for leaks and hammered it up and down the driveway and yard. Let it cooldown, retightened it all, checked the valves and have been riding it for a while (until the trans let loose).... other bikes done like this includeding 2 450's have been awesome ..no oil burning

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after assembly kick it over 50 times to preliminary seat he rings, and finally ride it like you normally do when you break it in.

Good luck

I'm sorry, but I don't see how rings are going to seat with ring pressure alone. If this was true, then an easy break-in would work. But we break in our engines using the hard method because we want to build cylinder pressure which forces the ring against the cylinder wall thereby seating the ring. I believe that kicking it dry will only increase the chances of scuffing the piston skirts.

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This is from my CRF250R post, I got into a thread there about the RHC head too, Just in case you don't see that one, here's a copy:

So far......so good!

My son and I just got back in from the garage.

I followed skipn8r's instructions Top End Notes Part 4- Break In

I did everything except for #14 - hammer it up and down through the gears. At 1:00am, even starting it was pushin' it. Well, that's what my wife said anyway.

The bike definitely sounds different. It sounds smoother than the original engine. (Maybe that's what I want to believe).

In the morning, I am going to take it for a spin, check for leaks, check the valves, change the oil, and then I'll do #14.

Many thanks to skipn8r for the great post. I wouldn't change one process on your list.

I'll give a valve/head & ride report in the next couple days.

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I DID IT !

'07 Head and 13.5:1 J&E Piston from RHC

It's supposed to be delivered Monday or Tuesday next week.

I am excited and nervous at the same time.

At 75 hours on my 2005 250X wouldn't start. The right intake clearance went to less than .002", probably closed. I had checked it at 70 hours and it was .005". So with all of the valve posts I've read and the fact that it went that fast, I shimmed it once and got a whole 1.5 hours out of it before it went to 0.003". I put it up on the stand and called Ron Hamp.

My question is........anything out of the ordinary to watch out for or tricks when replacing the piston and head?

Thanks in advance!

At 75 hours my valves are still in spec-runs like new! It's a Yamaha oops!

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At 75 hours my valves are still in spec-runs like new! It's a Yamaha oops!

wow! we havent heard that befor! hows trying to get 42 horse power going?

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At 75 hours my valves are still in spec-runs like new! It's a Yamaha oops!

Trust me you dont want to start this stuff with me. I will not allow people to troll forums. :thumbsup:

Thanks

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Quote: At 75 hours my valves are still in spec-runs like new! It's a Yamaha oops!

haha same with mine too...woops mine is not a yamaha a CRFX can go past 75 hours no problem

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75 hours on a yamaha must be good?

well i got way over 500 hours on my 04 250X! just checked valves mon and still in specs! i ride the bike hard 5-7 hrs a day twice a week! bike still runs like a champ!

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This is from my CRF250R post, I got into a thread there about the RHC head too, Just in case you don't see that one, here's a copy:

So far......so good!

My son and I just got back in from the garage.

I followed skipn8r's instructions Top End Notes Part 4- Break In

I did everything except for #14 - hammer it up and down through the gears. At 1:00am, even starting it was pushin' it. Well, that's what my wife said anyway.

The bike definitely sounds different. It sounds smoother than the original engine. (Maybe that's what I want to believe).

In the morning, I am going to take it for a spin, check for leaks, check the valves, change the oil, and then I'll do #14.

Many thanks to skipn8r for the great post. I wouldn't change one process on your list.

I'll give a valve/head & ride report in the next couple days.

were can I find skipn8r's instructions top end notes.

I did a search but could not find?

Thanks

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