After some digging it looks like the klx300 was cloned years ago and was sold as the Loncin 300. This is why only the 300 kit is produced. I think the AHL kit is probably pretty good.
I am going to give it a shot as I don't want to lose my original cylinder, piston. And, if it goes bad, couldn't it be bored and sleeved to a 351 if the block is ok? I'm pretty sure with jetting airbox slipon etc I can get what I'm looking for.
AHL also sells through Aliexpress
https://www.aliexpress.com/item/Moto...304.4.1.6AuVav

 

Keep us posted. Again, I may pick one up just to keep on hand in case i ever have any more 351 issues. Cant drop any more money like that on the big bore stuff.

would like to hear a build story on this...quality wise etc.

would be curious if bill would be willing to bore one of those up.

 

I will definitely keep everyone informed. I think the company is supplier to a lot of bike manufacturers and seems to have pretty good reviews quality wise. We shall see. Pretty cheap experiment.

 

Just heads up, AHL lists 2 klx 299cc kits, one for klx300 96-07 and the other for klx250 93-14. I read elsewhere someone had a head gasket fit issue, i wonder if they had bought the wrong kit.

 

Stromer The gasket supplied did not match their own cylinder. It blocked some of the water galleries.
You hit the nail on the head about the 300 Loncin engine, I believe it is used in various ATV's. We are are just a little side show in the big picture. It just happens to work as a big bore for us . We were not and never will be a direct target for them. There never will be a 330 or 350 made by them for us. The only way is if they decide to punch out the the atv's to a larger capacity. They deal in thousands of units ,not dozens.
Until a few days ago all of our back country was closed, due to extreme fire hazard. So a couple weeks ago I decided to install my AHL kit. I have never done anything more than a cam chain on an engine before, so it was a bit of a risk.
A little background on the bike. It is a 2006 that I picked up a few months ago and it had 1100 miles on it. Power wise it ran no better than the worn out Klr250 that I scrapped a few years back,although It is certainly a much better bike overall. So I researched here and did the MCM and rejet. It improved the midrange greatly, not so much the low and high revs.
I did the install over several days, with many google breaks. Got it back together and it fired right up with no flying metal or scary noises. I left the carb and the MCM unchanged. It wouldn't idle so It took 2 or 3 turns of the idle screw to get it to 1300. I had 3.5 turns on the air screw and the fact it would not idle, led me to believe the #35 pilot was too small..The first 100 miles was smooth accel-decel at partial throttle working up to 6000 rpm .The next 100 I worked it up to full throttle in easy load situations and 8000rpm, still with a lot of decel.
Today I installed a #38 pilot. The DJ138 that I ran with the 0352 needle on top notch still left the tailpipe sooty as it had before. The next smaller jet in my arsenal is a DJ132 so I put it in and went to the third groove on the needle. #38 pilot air screw 1.75.. It started and got off choke quickly and idled at 2200 when warmed up. Set the idle down and went for a ride. Whack the throttle in 4,5 or 6th and I get a big nothing, worse at 4-5000 and less so after 7000. Zero soot at the tailpipe. I should point out that I am running lidless with a slip-on with a baffle. I'm new to carb tuning but my guess is the drop from dj138 to dj132 was too much. I raised the needle to compensate.
I am waiting for an adjustable air screw, I just guessed at 1.75 turns with the 38. The startup and idle are much improved at this setup. Until I get more jets I may try different needle positions.
There are two things that I have to keep in mind about the MCM, first ,the 06 and 07 250s are reputed to not respond as well to MCM as the later models. The 300 also is said to respond less.
I took my stock 06 directly to lidless DJ MCM slip-on. So the improvement I got from the MCM is an unknown compared to DJ stage 2. I intend to get it running as good as I can with carb tuning, then I may go back to stock cam timing If I'm not happy.
So far ,after 220 miles, I see no smoke and hear no unusual noises. My gas mileage dropped from 75mpg imp. down to 60 but once I stop playing with the throttle it should improve. The oil change at 100mi showed no shiny stuff. All seems good now except my jetting, but if it doesn't survive the long haul I have the low mileage 250 to put back in.
If anyone has suggestions on the carb, I'm all ears.

 

Wow, thanks Howlinsage for the report. I'm not surprised the kit is working out, but yes tuning can take some time. I've done carb jetting in the past and it can take some time to get right. I will be searching here for more info for basline tuning. Like you, i'm not sure exactly where to start with it. Like, do I start with the recommended DJ kit for my bike 2182, or for the older KLX300 kit. You have made most of the changes i plan to make, except I am going to forgo the MCM mod and see how good I can get it from idle to rev limit with the stock cam timing. BTW I bought my bike in Penticton last month and what a bad fire season you have this year, we even had smoke from the interior pour out over the island here on the coast.

 

I have an OEM 300 which is the same displacement. The following config works well for me:

KLX300R cylinder
Megabomb header
FMF Q4 with 1 1/8" quiet tip
K&N air filter
DJ2148 kit w/ 132 main
Lid in place
KDX snorkel

My setup is geared toward maximum performance with minimum noise. It's a good middle ground between stock exhaust/snorkel and a fully unrestricted slipon and lid removed.

Good to hear that the AHL cylinder appears to fit up nicely. Was concerned about the lower camchain tensioner bolt being the wrong size. Will keep watch for updates as to reliability.

 

Nice report, Howlinsage. Just to be technically correct, if you're running the stock carb, it has a fuel screw, not an air screw. Turning this screw out allows more fuel through the pilot circuit.

 

Hey QoS-
Have you tried running your current setup with and without the KDX snorkel? I'm running the FMF Q4 w/ quiet tip and airbox lid w/o snorkel and am looking for options to quiet mine down more. I suspect much of the noise I'm hearing is coming from the airbox, and am considering reinstalling a snorkel if it will help.

 

Howlinsage, If I may, a few thoughts..
if the carb worked perfectly before the 300 wrench session, it should have worked perfectly afterward - the CC bump would/should have no effect on the idle quality, decel popping, etc.. What are the chances that there are leaks in the induction system (bad idle) and exhaust system (decel popping) ?

If you are near sea level, the #38 pilot will normally need at least 2.5 turns out - usually 3 out is about right..


In your case, black soot in the tailpipe is not a sign of bad fueling. It signifies that you run your bike aggressively (lots of WOT) and that the top end is seeing a proper AFR for max performance. Unless you are at a significant elevation, or have an issue within the carb , there is no way a DJ138 can overfuel your bike.. And using the DJ0352 @ 1N will certainly keep the low/mid very snappy with a properly lean AFR..

IMHO, put the carb back exactly as it was - but keep the #38 @ 3 turns out - and if the bike doesn't run correctly, look for leaks at seals, boots, flanges, etc etc..

While you can't provide a dyno butt assessment on MCM+300cc, I can assure you it should have exactly the same effect it did on your 250 - big gains up to about 6500 rpm, with near "stock timing" power above..