do I need to hone?

I have an 03 WR 450 that I am going to change the piston and rings. My question is do I need to hone the cylinder or can I just throw in the new piston.

Good question. I just finished rebuilding my '03 and decided not to hone it since it is a plated cylinder. The manual makes no mention of honing so I'm guessing that they don't recommend it. I did go over the bore with some red "Scotchbrite" just to clean up the surface. Installed new piston & rings . So far I have about 400 miles on it with no signs of smoking or oil consumption so all appears good. Ran Rotella T dino oil to break-in and just made the jump over to Mobil 1.

I would recommend it, as I'm sure many others here would. If you break the glaze on the cylinder you'll probably get a better ring seal.

Usually with the new nikasil plated cylinders, you dont really need to. The coating is super hard and is very resistant to glazing. Unless you ditched the nikasil for a sleeve, there is no need to hone.

be aware that there are different styles (or grades) of honing stones (the abrasive part of the tooling) for every application. the older honing abrasives for cast iron cylinder sleeves are not the correct product for a plated cylinder and may damage it. unless there is visible glazing of the cylinder, there is probably no need to mess with it.

The million dollar question is can you still see the cross hatch from the original hone? if that is still intact then you dont need to touch it.

Another thing is break it in with the oil you are going to run.

You dont need to use dino oil, thats an old school method that was used prior to the new plating and honing techniques.

I agree with TS if there is still original cross hatch the rings will seat, otherwise I would consider a light hone for proper ring seal.

I would get the cross hatch done, as it will affect break in(rings sealing). Not sure why your putting new piston and rings in, but you need to Mic your new piston and your cylinder to make sure they have the right tolerances. You need the cross hatch in order to seat your rings in for maximum seal.

You will probably be fine with out it, but why not do it right.

Thanks I decided not to hone I have new valve shims on order when those come in I will put the bike together and see how it goes.

It will be fine. I've done it twice this way on two different bikes with no problems. If the bore is worn so much that the crosshatch is gone you've got bigger problems that honing is not going to fix. That Nikasil is hard stuff!

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