anyone know anything about those 300 cyl/piston kits? not sure I'd trust the piston but the cylinder might be ok ?

 

Hello Rim,
I put on a AHL 300 kit from Amazon (china) and I am very happy with it. Only problem I ran into was the supplied head gasket cooling holes did not line up correctly on one half. I had a new stock gasket and it was a better fit. So look for that if you get one.

Here is the link.

 

I have 1,500 hard miles on mine, running good, no problems.

 

kinda tempted by this if my stock top end ever gets tired of life

 

I've got one waiting to go in over the winter

 

As do I. Just got the lights up in the shop yesterday, now to get the furnace mounted and more equipment moved in and I'm ready to screw around with the bikes.

By the way, make sure it is the AHL 299cc top end, there is some Chinese 292cc kit that has a weird lower tensioner set up that won't work. The 299cc kit works with a minor modification to the cap bolt from the stock cylinder. If I remember right it is grinding a small amount off of the threaded length.

 

I just did the conversion in mine over the weekend. The head gasket provided, the holes do not line up exact with all the cooling passage holes. 2 of them were half covered. The gasket also does not exactly match the perimeter of the head. The lower OEM cam tension bolt was slightly too long. I had read 4 mm to trim off. You can screw it in by hand without the spring and feel it bind against the cam chain. I trimmed 4.5 mm to be safe. You can trim even more, doesn't really matter, it just holds a spring that does the work.

I bought the Cometic #7302 gasket kit for the 97-02 KLX300R. Seeme to be the perfect fit.

On first start up, mine seemed to run perfect but after break in, I noticed the oil looked a little light color like I still had a head gasket leak. My local Kawi shop said they had never resurfaced a head in all their rebuilds and it was unlikely mine would need that. I trusted that call and appears they were wrong. Mine had overheated badly which is the reason for all this.

I used a thick piece of glass as a level surface then first 120 then 220 then 320 grit sand paper to polish the mating surface. I used a sharpee marker to first cover the surface to see how I was doing. Sure enough, huge area right next to combustion chamber was not touching. Took prob 20 mins to polish it back level.

I have a 37.5 pilot and 128 main. Unsure yet if these are the best.

New gaskets ordered again and have to reassemble after the weekend. Going camping with wife, no bikes aloud.

 

Thank you for replys. Sounds like more sucesss the 299cc kit . Does it use the std 300 78mm bore ? I'd hate to be locked into 1 piston choice? Also did anyone measure the deck height before bolting the head up ?

 

Engine all back together, stepped up pilot to keihin 40 and main to keihin 140. After some good runs, checking plug, I feel like I'm in the neighborhood. Texas weather has been cold one day and warm the next so having any kind of consistency right now is difficult.

Got some good miles on bike where I can start pushing on it to see how it really runs. The 300 is a nice little kick in the pants. Pulls stronger, slightly deeper tone thru exhaust. It's nice to be able to roll on throttle to accelerate vs drop a gear. Unable at this point to determine what kind of mpg change I will see, I'm having fun using the power.

 

Jk, I don't know how you are running your airbox (your signature line does not include that info..) but I hope it is not lidless - with a K140 main jet, lidless fueling will be extremely lean. At any rate, when you're ready to "unleash the beast" ( Lidless airbox and a proper lidless CVk setup), just speak up..