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Gunner354

Which hone to buy?

6 posts in this topic

Getting ready to refresh one of our 09 yz450 with over 350 hours. Looking on eBay and there r different grits. What size and grit is the proper one?

Just a side note, this bike has been amazing. Absolutely doing this out fear and not need. This will be the first time this bike has been touched. No valve adjustment etc. Just good maintenance practices.

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You should use a ball hone ("bottle brush", "spring-ball", etc.) unless the bore needs any more than a de-glazing. Your best source for these is Brush Research. Their hones are listed by the size of the bore they will service, and are already slightly larger than the listed size, so there is no need to guess how much larger they need to be. That's been figured out already. You would want the 3 3/4" (95mm) unit

In addition to different grits, they also offer about seven different abrasives. Opt for either of the softer two (silicon carbide or aluminum oxide). Then follow the guidelines in this post:

http://www.thumpertalk.com/forum/showthread.php?p=4380759#post4380759

This type of hone will remove almost nothing from the cylinder, which is what you want. It is a good idea to check piston clearance after honing/cleaning just to be sure.

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i have NEVER used a hone on any of my 400s, 426s or 450s when rebuilding. 7 bikes total. WONT DO IT!! EVER.

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To hone or not? Never heard of not honing prior to rebuild. Just curious if you had an oil consumption and or smoke out the exhaust with this method?

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This topic always engenders a somewhat impassioned debate.

My experience with ball hones on the hundreds of cylinders I have replaced rings in over the years has been nothing but favorable. The rings, especially modern rings, seat almost immediately, and I have not had one engine ever use oil or show bad leak down numbers.

The debate often centers around the fact that YZF cylinders, like most modern high performance motorcycle engines, are plated with a very thin layer of Nikasil, usually only about .002" thick after the bore is finish honed at the factory. Those who say "don't hone" claim either that the coating is too thin and too much will be removed when you hone it, or that the coating is so hard that a ball hone won't restore the cross hatch, so it's a waste of time. The funny part about that last is that those same people will turn around and say that you should "scuff up" the bore with Scotch Brite. If silicon carbide isn't hard enough, how will Scotch Brite do anything?

Because I was aware of the thin nature of the plating, and was concerned about damaging it, I contacted a couple of reputable engine builders before using a ball hone on plated cylinders. They were each very enthusiastic in their support of using them, and from my own experiences since then, so am I. Every engine I've used one on has seated the rings just as quickly and successfully as the rest.

Be sure you check the bore for straightness and wear both before and after the honing. Don't cut corners and try to use one that's at or beyond the .002" wear limit.

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