I have a 2009 KLX250s that went through the ringer a little over a year ago. I used it as a daily commuter and trouble started just before 20k miles. The engine died due to a bent valve that my local shop replaced. Then, it died again requiring the valve be replaced w/in a 1000 miles of the first replacement. Shop did this under warranty. Then, the engine seized as the engine was oil starved. The head was pretty destroyed: bearings, journals, and cams were all ruined. And, the timing chain broke somewhere during all this carnage. Anyway, there was some back and forth between myself and shop but it all amounted to nothing and the bike sat while I stewed over the whole thing.

So... I finally got off my *** this month and decided to do something. Plan was to do a head replacement. But when I got down to the bottom assembly, it turns out the crankshaft has a broken tooth on the timing sprocket. Ugh! But after a year of no riding and a wife that doesn't support a new bike, I was undeterred and shopped used engines. And now, I have one on the way this week for $900 with 3500mi on it.

Finally to the carb questions. In the process of pulling the engine apart, I found the carb in bad shape after sitting for over a year w/ gas in it. So, I followed some online instructions to pull it apart and clean to prepare for the replacement engine. To start, I used pinesol and it seems to have done a really nice job. But there are some spots where the metal darkened/blackened. And, there are some spots after washing and drying that have a white residue.

1. Should I be concerned about the metal darkening/blackening? Is there something I can do to remove this?
2. What about the white residue? Concerns or additional cleaning?
3. Should I use some carb cleaner and clean again to try and remove these issues?
4. I did a quick dry fit on some of the parts after cleaning and began to wonder if there should any lubrication used on the parts during assembly? Slide? Jets? Needles? Butterfly? Diaphragm?
5. The one item I have not disassembled is the pilot screw assembly because I am concerned about the plug that needs to be removed. Is there any way to remove the plug non-destructively? If not, do I need to get a replacement plug? why is this one plugged like this?

Thanks in advance for any help or advice. I have never gotten deeper than an oil change on my bike. But the one good thing w/ a wrecked engine is that it is very liberating when it comes to taking it apart and looking around. Can't kill an engine that is already dead, right?

 

Nothing gets lubed in the carb. Be sure to remove the pilot jet and inspect it. The hole in it is very small and easily restricted. Remove the plug covering the pilot screw and discard it. It's only there to keep you from obtaining proper mixture at idle. Just carefully drill a hole in it and pry it out.

Ride on
Brewster

 

Jeff, the pilot and needle jets must have all their tiny holes clear and free - FYI: The needle jet is the "thing" the main jet screws into..

To be more clear about this - You'll be removing, inspecting, and cleaning the pilot jet and the needle jet - as well as every other part and passageway inside that carb... You'll do this before you attempt to start the new engine - or after.. Your choice.

Sorry to be blunt, but you need someone to tell you the whole truth..

 

I personally would have taken it to a dealer/independent shop that had a carb washer or ultrasonic cleaner. They are very effective and since you would have the carb in pieces they would have no labor involved other than putting it in the washer, so it shouldn't be stupid expensive.

After working in a dealership and being around it for 22 years I saw too many cases of crudded up carbs that no amount of squirting and soaking would clean, but the carb washer we had would slosh the gunk out with the cleaner and constant motion. Sometimes it would be left to run for several hours on a bad set. We even had some cases where we had to do a set of carbs twice.

Just sayin' been there seen that.

 

Argh. Tragedy. I removed the plug and started to remove the pilot screw and the slot stripped out. Help! I saw some folks online that drill out the center to tap in an extractor or hex key that they in turn use to remove the screw. I tried that w/ a hex key on my bench but it is pretty weak and it bent itself. So, I have Wd-40 soaking around the pilot screw overnight and plan to go get an extractor to fit the 1/16" hole I drilled in the middle of the pilot screw.

 

What the heck did you do that was so bad in a past life to deserve all this? lol.

 

pwjm - i know right?

anyway, major success today. I used a #1 screw extractor on a hole I drilled w/ a 1/16" bit and was able to get the pilot screw removed, along w/ the spring, washer and o-ring. I think that when the shop did some work on the carb they must have gotten some of the adhesive used to fix the replacement plug in the threads of the pilot screw. when I try and screw it back in, it definitely hits resistance at a certain point in the threads.

• will i need to use a tap to "clean" the threading before I put a new jet screw in?
• should I buy a whole carburetor rebuild kit while I am at it?
• or, should I just buy the pilot screw?

Looks like the screw-only is $13 on ebay. But I found a rebuild kit on ebay that is $27 and that has everything (new gasket, new jet needle, springs, float valve, etc)

does anyone that did a jetting kit have one of these sitting around? looks like the spring, washer and o-ring are fine.

 

Reject according to guidelines found here. Either use KLXsters dynojet recommendations or use the standard jet numbers found on the site. This comes out to something like a 38 pilot, a 130 or 132 main and a Kawasaki N1tc needle clipped in the middle.

It's never worth cleaning the jets. Buy new. http://jetsrus.com/

 

Clean the threads with a tap very carefully and try reinstalling the fuel screw to check the threads. If OK, pull it out and add a Kouba fuel screw.

 

Success! Well I've been sitting waiting for the rebuild parts to arrive. I was really worried about the threads on the pilot screw. But when the new part arrived, it went back together. There was a small amount of resistance at the middle of the threads. But it required very little torque to overcome. And so I was able to remove and place the spring/washer/gasket packing on the screw and re-insert.

At this point I did a "dry-fit" reassembly and everything is set, except maybe the diaphragm. It seems to have shrunk ever so slightly and doesn't want to remain in the guide while I replace the cap. It slips off and the new diameter seems just a mm or so smaller so that it doesn't sit directly in place. Should it normally require a slight stretch to fit over the lip? Or, does it normally just sit in place and mine has shrunk slightly?