Wednesday, April 14, 2010

Kawasaki KLR 250 Carb Cleaning Information

Bottom View of the KLR 250 CVK34 carburetor showing the main and pilot jetsIf you were to browse any KLR250 related forum the most common ailment you'd hear owners complain about is some type of starting or running problem, usually carburetor related. These problems aren't biased to just the KLR, any carbureted bike can experience them. They're usually due to dirt in the fuel clogging a jet, or varish gumming everything up. The only solution is to remove the carb from the bike and give it a thorough cleaning and inspection. Thats what this article is meant to do, show you the basics of the KLR250 carburetor and give a quick run through on how to clean it.We won't get into how a carb works, but if you're interested in learning more check out The Care and Feeding of the Keihn Carb.

Kawasaki KLR 250 carburetor diagram cvk34The KLR 250 comes with a Keihn CVK34 carburetor. Don't let the parts diagram to the left fool you, CVK34 is a very simple design. To clean the carb you'll need to remove it from the bike. Probably one of the more painful processes whenever you have to work on your bike's carb is trying to get it out of the bike. At the very least it'll require removing the side plastics, seat, and fuel tank, though we have found that unbolting the exhaust muffler and the top bolts of the subframe (the part the seat bolts to) make things easier by allowing you to pivot the entire subframe backwards giving better access to the carb. Once you've gotten to the carb follow these steps to disconnect and remove it.

Removal:
1. Turn off the fuel petcock on the fuel tank
2. Place a container under the fuel drain hose. That is the hose which leads from the fuel drain screw to just in front of the rear wheel.
3. Open drain screw, located on the bottom right side of the carb (on the float bowl) and allow all of the fuel to drain from the carb.
4. Remove the fuel line from the left side of the carb (black rubber line from the fuel tank)
5. Remove the throttle cables, one screw holds the bracket in place.
6. Carefully unscrew the plastic choke cable nut from the left side of the carburetor. This is where the choke cable screws into the carb. The plastic nut is very fragile so be careful!
7. Loosen the clamp on the front side of the carb holding it to the engine.
8. Remove the rear carb to airbox tube

OK now you should have the carb out of the bike and holding it in your hands. Next step is tearing it down while being very careful not to lose or damage anything in the process.

KLR 250 Carburetor Picture PhotoTeardown:
1. Remove the four screws on the plastic piece on the top of the carb. Underneath there should be a diaphragm, spring, slide, needle and white piece of plastic. Make a mental note of the order of those parts (slide, needle, white plastic piece, spring) and remove them. Be careful not to tear the rubber diaphragm.
2. Remove the float bowl. That is the metal bowl on the bottom of the carb, held in place with four screws. Be careful when removing it as the float and needle valve can fall out. Make a note of the position of the float and needle and remove them.
3. Next step is to unscrew the main and pilot jets from the carb body. (see diagram above for their location)

Pilot Screw Info:
The KLR's carb has a pilot mixture screw which controls the amount of fuel that enters the engine while at idle. However to stop owners from fiddling with it Kawasaki covered the screw with a small tin cap. The only way to get to this screw is to carefully drill a small hole in the tin cap and then pry it off with a small screw driver. The utmost care must be taken so you don't screw all of the way through to the pilot screw itself. Once the screw is accessible then you can remove it. There should be an o-ring, washer, and spring on the end of it, note their order and set them to the side.

Cleaning:
Thats about all you need to disassemble. Wasn't that hard was it? Now its time to clean everything. Just about everyone has their own way of doing this but what we suggest is buying a few bottles of carb cleaner (the kind you pour in your car's fuel tank) and a couple cans of spray type carb cleaner that have the small plastic tubes on them. Fill a small container with the carb cleaner (bottle type) and soak all of the metal parts in it, including the carburetor body. Note: Do not use either carb cleaner on any plastic or rubber parts, it'll eat them. What you're trying to accomplish is the removal of all varnish from inside the carb body, and jets. After they've soaked for a couple of hours its time to spray out all of the small passages in the carb body, and the tiny holes in jets with the spray type carb cleaner and then follow it up with a blast of compressed air. You're trying to make sure there is nothing clogging up those small holes, you leave one grain of sand behind and you'll be doing this again so be diligent! By this point you should have a sparkling clean carburetor, all that is left to do is reassemble everything.

Reassembly:
There isn't much to say here, just reassemble everything in the reverse order you took it apart. When the time comes to re-install the pilot screw make sure the o-ring, washer, and spring are in place and screw it in all of the way and back out two full turns. (further adjustment may be needed but this is a good starting point) When you re-install the slide components be careful not to pinch or tear the rubber diaphragm.

Float Adjustment:
While you have the carb apart and cleaned this is the perfect time to check the float height adjustment. Simply install the float and needle valve onto the carb body and hold it as shown in the diagram to the left. You want the needle to be lying on its seat but not pushed down. To check for proper adjustment measure from the float bowl mating surface, and the top of the float. (4) The adjustment should be 17mm. If you find its not 17mm then you correct it by ever so slightly bending the float bowl tang with a pair of needle nose pliers. (see arrow in this picture) Small adjustment result in big changes in the float height, so go easy. Once you've got it to 17mm you're all set.

Thats it! Now re-install the carb back in the bike and you're good to go!

Image Sources: Gadjetjq.com - KLR650.net - Kawasaki.com
Note: The top image is of a CVK40. While it is a different carburetor than the CVK34 in the KLR 250 their layouts are almost identical.

54 comments:

  1. Many thanks for this, I've just bought a non-running KLR250 that the previous owner tried to start up after 2 years in storage without draining or changing the petrol. I've cleaned out the tank and the petcock, next job is to follow your instructions and clean the carb. Thanks again!!

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  2. Thanks for consolidating this info into blog format. Much as I like the give and take of forums, this layout works much better for finding what I need quickly. Thanks much and keep up the good work!

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  3. Thanks for your pictures and descriptions. I just overhauled my carb yesterday and this really came in handy. Thankfully I got it all back together again and it started right up and now runs great. I have a 1997 KLR 250 and it is a pretty good bike, I love the on/off road abilities.

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  4. looks almost the same as a BR250 carb.
    Anyone know if its the same?

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  5. The Kawasaki BR250 used a CVK36 and the KLR250 uses a CVK34.

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  6. I removed the pin holding the float in place (part #16031 in the figure), but the float will not come out. Should I force it, or have I missed something?

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  7. If that pin is removed the float should basically fall out.

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  8. What order do the parts of the pilot mixture screw go in?

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  9. O-ring, washer, spring and finally the screw.

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  10. Thank you! I followed your directions and got my 94 KLR up and running really well! I really appreciate the detail!

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  11. Hi, does anyone know how the coolant pipes go from the carb to the block? I'm just rebuilding an '85 KLR and have got to this stage, but the manual is no help whatsoever. There's a bifurcated T from the carb front, but how do they connect to the rest of it?! I've seen no evidence in the whole of the blessed Internet...
    Regards,
    Cheese

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    Replies
    1. I'm not sure what you mean. There aren't any coolant pipes that goto the carb that I know of.

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    2. on my 94 plate their are coolant pipes fit on to bottom of carb at each side next to float bowl one goes on left side one right side you cant go wrong its the omly pipes fit down at float bowl

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  12. Hi Mike, thanks for your prompt reply. It appears that it's an anti-icing circuit: http://www.thumpertalk.com/topic/691847-mysterious-klr-carb/
    It is most definitely there! I've taken a photo of it, but for future reference, CVK34 carbs in the UK may have this on. I'll try replacing the standard black rubber pipes with transparent ones to verify that the coolant circuit is active. Many regards,
    Cheese

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    Replies
    1. Interesting! If I come across any info on the proper routing of those lines I'll post it here.

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  13. Hi guys,

    I have a 99' KLR250...I have a problem with fuel leaking out of the bottom of the float bowl..if the fuel is on, it is a constant stream (and bike wont run). I have taken the drain screw out, and checked it..tightened it etc etc..but the fuel keeps draining out the hole at the bottom..any ideas why?? and how to fix??

    cheers Steve

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    1. Steve, more than likely there is dirt or rust stuck between the needle and seat. An old trick is to knock on the side of the float bowl with a screwdriver to dislodge it. If that doesn't work then the next step is to remove the float bowl and see what the condition of the needle, seat and float are. It could be that the needle/seat are worn and need replacing. The float can also have a small leak in it that doesn't allow it to do its job properly. If you suspect float you may be able to hold it under water and look for air bubbles escaping the float.

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  14. THanks Mike,

    I pulled the whole carby out, and yep...your right there was a big chuck of junk between the needle and the seat. A mate and I cleaned the whole carby up nice, and it is running like a dream now. I also added a fuel filter..there isnt much room for it (especially with the big radiator resivour in the way)..but I managed to fit everything back where it should be!

    It was my first attempt at pulling a carby out, and giving it a clean...and it's not that hard once you work out what does what!

    Thanks for your advice Mike. Much appreciated. I dare say I will have other questions as time goes by!!

    Cheeers Steve

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  15. Glad to hear everything worked out for the best!

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  16. I have a 98 klr250 with this carb on it. I am confused about the ports on carb. Looking at the carb from Left side of bike the fuel inlet is bottom right, just above float bowl. I also have a line/port/hose barb, whichever you prefer to call it, near top middle of carb on same side. This port comes out at 90 degrees and points back and down toward rear tire area. Then there is a third port on top left toward front of carb, it faces straight up and has a vac cap on it.
    I have the fuel line hooked up and the top one capped off, center port that faces down and back has nothing attached.
    Can someone please educate me on these???? And thank you in advance for any help at all.

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  17. That line is a drain / vent. You should have a clear line that runs from this port back down to by your rear wheel.
    Matt

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    1. Thank you. Had the same question and couldn't find anything anywhere.

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  18. Mike, very helpful article. Thank you. Do you have any recommendations for rebuild kits? I'm in the US. Thanks!

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  19. Thanks! I'm not sure that there are many carb rebuild kits for these bikes but I think you can find them on ebay at times.

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  20. Hi Mike are you still doing replys to this pal?

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  21. I could really do with some help here

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  22. Hi Mike,

    I just took the carb off my '95 KLR 250 and discovered it has a sticking float needle. I'm assuming it would be a good idea to replace the seat at the same time, but I am unsure how to get the seat out of the carb. Also, the numbers on the carb are CVK near the top, and near the bottom are KEI HIN. Just above where the float bowl attaches are the numbers 122 and G18. Is this a CVK 34? I did not see the number 34 anywhere. Many thanks for your helpful article.

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    1. Yea that sounds like the cvk34. I've never had to change the seat but I believe it is pressed in. You may be able to use a small wooden dowel or something similar to knock it out from the other side. If it was me, I would just try changing the needle and see if that fixes it before messing with the seat. Most likely it isn't worn anyway.

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    2. Well I replaced the needle but the bike wouldn't start. Turned out the seat was completely clogged (this was after a good soaking in carb cleaner and spraying out with canned carb cleaner). I was able to clear it with a very small wire and more carb cleaner. Put it all back together and then the needle wouldn't seal in the seat. Gas flowed freely out of the overflow despite having verified the correct float level earlier. Took it apart again and took a good look at the seat, which appeared uneven and possibly corroded. Tried to get it out but couldn't budge it. Ended up trying to clean it up with a very small pointed stone on the end of a dremel, then recalibrated the float level. Needle and seat are now working properly. New problem now though. Bike fires two or three times but won't fully start. Going at the idle adjustment next.

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    3. The old KLR is finally running again and sounding great. Didn't have time to take it for a test ride but it's running good in the shop. Had to open up the carb again and check the pilot circuit. Removed the pilot jet and discovered it was clogged, so cleaned it out with a very fine piece of wire. All the carb cleaner and air pressure hadn't touched it. My carb cleaner was quite old so maybe that's why. Fired right up after that. With it running I was able to adjust the pilot mixture, then set the idle. Running like a sewing machine now. Last thing to do is add the Stead Engineering alloy choke nut, which should be arriving soon. Thanks so much for your informative blog Mike, it was a big help to me.

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  23. Thanks, I will give it a go with just the new needle. I forgot to mention that this is a California edition bike with the extra smog equipment. In searching for carb rebuild kits I haven't seen anything specifically for CA bikes so I'm guessing it's the same carburetor as non-California KLR 250's. Does that sound about right?

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    1. Yea it should be the same carb with different jets but the needle should be the same.

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  24. Hi, I've been following this blog with my 85 KLR 250. My problem is that the bike won't start unless I spray starter fluid into the carb (or the choke orifice). Once it's warmed up it seems to run fine. I've replaced the plastic choke plunger with a steel one from Stead Engineering and cleaned out all orifices especially the ones leading to the choke, but it still won't start cold without starter fluid. Any ideas?

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    1. That's a tough one because techincally it could be a number of things causing that and possibly a combination of things. If you haven't set the valves in a while that is definitely something I'd start with, along with giving the carb a through cleaning. Since you have to use starting fluid to get it running that means there is a lack of fuel or too much air entering the engine. Possibly a leak between the carb and engine? Or a clogged pilot jet or starting circuit in the carb.

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  25. Thanks for the reply- I will check out the pilot jet. What is the purpose of the pilot jet? Also, what is the "starting circuit" you referred to- is that all of the passages that lead to the choke that aid in starting?
    As far as the valves, they were supposedly set by a mechanic recently but I'll try to check them as well. So if I understand correctly, misadjusted valves could affect starting but maybe not affect normal operation when it's warmed up?
    And that's a good idea to look at the seal between engine and carb- definite possibility of extra air getting in there.

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    1. Yep, improper valve clearances will definitely make the bike hard to start. The pilot jet controls the the fuel flow at idle and just off idle. And yes, the starting circuits are just the passages in the carb that aid in startup and idle.

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  26. I have this same bike. I have tried over and over to clean the carburetor. Nothing new been doing these cleanings on outboards all my life, but this one has stumped me. I dont have Japanese size fingers so makes for a very frustrating day in the hot sun taking the carburetor in and out and eventually I abandoned the project. The bike has sat for nearly a year and i was looking yesterday online for anyone else with this problem and came across your post. Went right down your list. Just put it all back together and it fired right up and runs like a top.
    Appreciate the tip..

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  27. Hi Mike - back again with another question. After completing the carb overhaul a 3 months ago the bike ran great. I put it away, then was out of town for awhile. The other day I tried to start it again, and it wouldn't start. No fire, nothing. After wearing my leg out on the kick starter, I finally relented to having to take the carb off again. Doing so, I discovered the pilot jet is clogged again. I stuck a wire down the middle of it but the wire bent. I used a paper clip, and it bent too. I tried the end of a safety pin - same result. It's as though it was made this way, but I know it wasn't since I cleared the same jet 3 months ago. It seems like everything I put in that hole hits metal (or something equally as hard) halfway down. To clariify, this is part # 92064 in your parts diagram. I'm about to order a new pilot jet, but wanted to see if you had ever heard of a jet clogging this badly before. The gas has Stabil in it and I did install a fuel filter back in May, but possibly something was in the system already. Thanks for any advice.

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    1. I guess it's possible if it's clogged with rust. Check inside your fuel tank when its empty and see if there is any run. If so then go with a brass style filter between the tank and the carb. My bike had tons of rust in the tank and would clog the carb time after time. The fuel filter fixed it.

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  28. Hey guys I'm so lost! I have an 87 klr250 and I have the carb off and disassembled due to the fact that it has been sitting for 5 years. We got her to start with starting fluid but dies as soon as thats burned up. Simple, not getting fuel. I have cleaned everything but now my problem is the fuel inlet (the black nipple on the bottom) I think Is clogged? I can't blow through it or suck. Somehow for some reason nothingg is getting through there.... any ideas? How do I clean that? I'm not sure how to remove the black nipple without breaking it and I'm not sure on the float needle removal... any ideas would be so greatly appreciated

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  29. Thanks for your help.
    Does anyone know if the pilot jet screw should be clear all the way from the screw driver end to the tube? I can't get any pin through it. My 2003 klr 250 carb is cleaned, but the engine only starts with starting fluid with open throttle and will stay running that way. Only 3200 miles on this bike. The jet looks like it has a drilled spot in the middle of the screwdriver slot. Thanks for all help.

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    1. I had an identical issue. Couldn't get anything through the pilot jet and couldn't see any light through it. Finally ordered a new pilot jet, blew out the carb and thoroughly cleaned the float bowl (especially the lowest point near the drain where dirt can get trapped), put it all back together and all's well. Looking through the new pilot jet it appears there are three tiny holes inside the orifice so there's no way to get anything through there larger than possibly a single strand of small wire. I had tried that with the old jet but the wire just kept bending. Good luck.

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  30. Knowing my 2005 KLR250 would be sitting for about six months, I ran the carb dry with the fuel valve in the OFF position, then drained the gas tank. Fast forward to today. I put about a gallon of fresh gas in the tank, and the bike started right up! Problem though! Even with the fuel valve in the OFF position, fuel ran out the over flow hose until the tank was empty. Is it possible the fuel valve is defective AND the needle and seat are stuck at the same time…all while the bike runs great? Help!

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  31. just bought a klr 250 runs but as soon as I give it some throttle she looses rpms and will die if I don't throttle down I have to slowly power up and it will only get to about 4000 rpm and then falls flat . I have never worked with these damn diaphragm carbs before. any ideas?

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    1. I have a pretty similar problem. I think that the throttle position determines which jet or combination of jets is supplying fuel at any given time. If the problem is like mine, then at a medium throttle position, the bike goes steadily, but on opening the throttle, there's a noticable delay/diminishing revs, unless you open the throttle quite slowly, when the revs pick up ok. If this is the case, then it's likely to be main/needle jet wear, which can cause 'rich cut', effectively flooding the bike as surely as putting the choke on. Anyway, replacement of these shouldn't be too expensive or difficult and can only improve performance of any bike in any state.

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  32. Great info! There is also a great four-part YouTube video that shows the disassembly/reassembly of a KLR650 carburetor, which is almost identical in every way; here is part one of the video: https://www.youtube.com/watch?v=YUHbq07qcCk&app=desktop

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  33. Great info Mike. I have a question about a CVK carb on my KLR 650. How does the starting circuit work? I know the fuel is picked up in the bowl then it goes to the choke plunger but where does the fuel go from there? In other words how does it get to the carb throat after it comes out of the choke plunger? Thanks Mike.


    k

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  34. It's possible that Mike is no longer monitoring this thread, but just in case...
    I followed - and greatly appreciated - the step-by-step process to clean the carb. I admit that I hoped that was the problem with the bike. 2003 model KLR 250. I've had it for 2500 miles. It ran perfect when I got it. I was riding it less after I added another bike to the family, but still at least monthly. Recently is started sputtering on initial take-off after a warm up. Rolling on the throttle got little reaction, and then all of a sudden it would kick in. Weeee. It would also occasionally hiccup en route. So I figured that even if it didn't fix it, cleaning the carburetor couldn't hurt.
    After putting it all back together, it starts great, but if I even try to roll on the throttle, it stalls out. Worse now, since I can't ride at all, then before. :( . Thoughts? Help?

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    1. Have you tried adjusting your valves yet? Seems that you should around every 3k miles (if memory serves me right)..looks like you're due. Wouldn't hurt to check / have checked...much more expensive result if they're in need of adjusted and get neglected.
      Otherwise, perhaps you overlooked some foreign material upon Carb assembly.

      Hope this helps ya.

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  35. Anyone have any idea why I would find a washer between the Needle Jet holder (13091 above) and Jet Needle (16017 above)?
    I've been having trouble with cold starts since I bought this bike 3 years ago (95 KLR 250), have been thru the carb numerous times, adjusted valves, replaced choke plunger, etc, etc) and haven't been able to solve the issue.
    Tonight, I decided to tear into her again only to find pilot jet clogged...I'm SURE I cleaned that out last time but...anyway, I noticed that there is an extra "washer" between the two items mentioned above. Seems that it shouldn't be there as I compare to the exploded view above.

    Any takers? Maybe the well is stripped out and P.O. put it there to compensate?
    Perhaps some weird mod that is designed to "help" in some way or another?
    Any takers? Thanks, Jason

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  36. I'm the same guy from 4/11/16 post directly above.

    I've been "cheating" by using starting fluid (I'm embarrassed to admit that yes...I drilled a small hole in the air cleaner box, installed a small "door" to cover it after shooting ether into the box). After all, I'm in my 40's, have flamingo legs and it's killer to kick this animal 50+ times before bringing her to life.

    Attempting to take one last stab at her before just buying another carb, I've finally identified the trouble.
    Seems that the starter jet is / has been clogged.
    Looks like the P.O. found out too as there are witness marks on the brass flange of the starter jet (assuming left by vice grips or pliers) and also it appears that he started to drill it out as there is material lapped over the hole...and she's plumb plugged beyond that...
    I have:
    Adjusted valves
    replaced Pilot and main jets, idler screw, etc, float plunger
    Installed a brand new plunger assembly ("choke")
    Cleaned carb 4x now
    Opened up the air box to ensure good air flow
    replaced air filter

    I'm CERTAIN this is my problem. Fuel can't make it's way through the winding passages up to the choke circuit for the "next" start.

    Wondering if anyone has experienced similar trouble and what the thoughts might be if I were to just drill out the STARTER jet.

    Any takers?
    Any help / advice would be GREATLY appreciated!

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  37. Thought I'd throw this in just in case someone is in the same boat that I was. If you're having trouble with a hanging erratic idle, make sure you have that spigot on the top of the carb plugged up. I think it's specific to the California model, and the P/O had removed the fuel recycling system leaving that spigot unplugged. I was going crazy for months, and felt pretty silly once I realized that was my quite simple issue.

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  38. Hope someone can help, I have a 92 KLR250, which haven't had very long, and had been running great, but come to start it after a journey out and it don't want to know. Found I have a problem with a loose pipe which has petrol dripping out of it. Being a girlie - bit thick here with engines I'm afraid, can't see an obvious place for it to go back. So simple terms and preferably a clear picture or two of the carburettor and pipes, so get an idea of what I should be looking at, would be very much appreciated, can anyone help please?

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