For you guys who have already installed the KLX 300 piston & cylinder have a question for you before I start in on mine this weekend. I have all the parts, service manuals etc., and my question may be answered once I get my present cylinder off, but too much info never hurts. Looking at the set of rings that I have from Ron Ayers for the 300 piston, I notice that one of the rings (black one) is marked as specified in the manual to denote the top of the ring. The other ring (silver) is not marked at all. I'm assuming that on this ring it doesn't matter, even though the 250 service manual shows both rings as marked. Anyone else run into this? Also am assuming that once I get the present cylinder off ,that the top ring, 2nd ring location(black, silver) will be apparent seeing as how only one of the new rings is marked. Can any one shed any light on this? Yes I have double and triple checked the silver ring for some type of marking and have checked the ring set for correct part number. Thanks.

jb7

 

I used Wiseco XG rings.

Go to http://wiseco.com/PDFs/Catalogs/CB07/comp-rings.pdf for pictures. I aligned my rings just like the picture.

The marking "top" on your ring that is marked, may refer to orientation of which way is "up" when installing the ring. I read somewhere (probably wiseco.com) that rings that are not maked, either face can face up.

For my Wiseco rings, the top ring is the one that is "Alloy steel, ferrox coated, chrome faced". The second ring is "nodular iron, phosphate coated, taper faced". The oil ring is "3 piece oil assembly, stainless steel spacer, chrome faced rails". It seemed odd to me that my ring set did not come with instructions, but a quick trip to wiseco.com and it was obvious which ring went where.

Plus, as soon as you have the old piston off, you'll have something to compare to...

 

How is the bike running now with the 300 piston? Is there a great improvment? How did you break it in and isthe 300 piston a flatop design also?

 

I used a Wiseco piston. It is a shallow dish, with the standard cutouts for the valves.

I broke in my original cylinder using the manufacturers suggested method, and the 250 cylinder and piston look new after 2200 miles. I'm not taking it that easy on the new one, but I'm not abusing it either. I got used to shifting based on the sound of the engine. The 300 revs so easy that I've found it up to around 7-8k unintentionally. I only have about 40 miles on the new piston/cylinder, and it's getting stronger every mile. It looked like I was running a little rich with the previous setup (based on the plug) so I started out with the same jets. I had quite a bit of decel pop, so I upped both the main and pilot jets. I still have a little decel "gurgle" and a little popping when the engine is cold. I'm waiting on jets for my Bill Blue Mikuni, so I may adjust the CVK again. I was planning on one change at a time anyway. I also have a 50 tooth rear sprocket waiting to go on (14/50 is the standard ratio on the KLX300R).

It only added 43cc, so it wasn't that big of a change. Don't get me wrong, it did add noticeable power and it's getting stronger as the rings seat. I think I'll run it as a 300 (292) until the cylinder wears out, then I'll get it bored out to 331 or 340. It feels like I thought it should have as a 250. I now have the power I was expecting from the beginning.