KX85 Big Bore Kits & Sleeve v. Plating

[plysWfire]

My son's KX85 ate a piston this past weekend. I'm gonna fire that damn machanic yet... oh wait that's me.

Anyways, I was looking at my options for cylinder repair, and found a deal on a 107cc big bore kit. Has anyone tried one of these kits? We ride mostly desert and trails, so any extra power is always a good thing, and we aren't worried about any AMA regulations.

Also, if I was to repair the cylinder, I've heard sleeve by one person, and re-plate by another. Any suggestions, pros/cons here?

Thanks in advance for the always useful replies.

 

[Mike's 2003 YZ250]

Hi, I can help a little I think. Back in 1991, I had a brand new KX80. After owning it for a couple years, I decided to get the big bore kit that was out for it. At the time, it was a 105cc kit. I remember it all went together perfectly without a problem, and I really enjoyed the boost in power. :cool: It was so long ago, I really cant remember too much, other than that it went together very well and the money spent and work done was worth it when it was all done. Mike :ride:

 

[Chili]

From what I've been told over the years plating is by far the better option for performance and reliability than sleeving. We had US Chrome redo the cylinder in my sons KX last fall when it munched the piston, the repair was top notch and we had no issues. Big bore is always a fun possibility but we had to heed the cc rule for racing in the 85 class.

 

[DRZ_Dad]

To sleeve it would be to retard the bikes technology back 15 years,

Do yourself a favor and call Eric Gorr, or check his website before you buy! The deal you found may not be such a good deal, You will not find anyone more knowledgable or honest than Eric, plus he can port the cylinder to put the power where your son uses it,

 

[plysWfire]

Thanks for all the replies. I passed on the big bore kit, and have decided to just re-plate the stock cylinder. Everything said here makes perfect sence!

Now, anyone know a good place send the cylinder to from So. Cal?

 

[DRZ_Dad]

Here>>>>>http://ericgorr.com/

 

[Motogrl307]

I ran the 107 bigbore with no problems. Lots more bottom end and lose a little top end.Takes the hit out of the bike. It bolts right on just make sure to cut the power valve down or it will hit the piston. Mine was a bored and replated cylinder. Just sold my extra cylinder last week.

 

[gwcrim]

I ran the 107 bigbore with no problems. Lots more bottom end and lose a little top end.Takes the hit out of the bike. It bolts right on just make sure to cut the power valve down or it will hit the piston. Mine was a bored and replated cylinder. Just sold my extra cylinder last week.

Just dug up this thread and like what I see. I'm curious about trimming the power valve though. How involved is this?

I have an air grinder and I know how to abuse it. :eek:

 

[gwcrim]

Thought I'd edit my post to reflect my results.

In order to put a KX100 top end on a KX85 bottom you need the following:

-jug
-piston
-head
-powervalve

The powervalve from the 85 can be modified to fit. I used a hand held air grinder. May god have mercy on my soul!