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Author Topic: 92 kx500 problem  (Read 7440 times)

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Offline shixanget

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92 kx500 problem
« on: January 20, 2016, 07:33:33 PM »
Hello all. Just picked up a nice 92 kx500 a week ago. So far was running great and man is this thing a beast. Was riding yesterday and was running the same as usual got done and parked it. Next day tried to start and well it's not wanting to start. Got it to start two times and the has great compression as well. Air filter is clean. first time I took it off choke and it died. Second time left it on choke tried giving it some throttle and it's like I never twisted the throttle. No response until I fully opend it and it bogged down. Throttle is hooked up correctly and opening the carb still. One issue I just found is there is about a 1" crack on the expansion chamber. Could that cause this?? Thanks!
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Offline Foxx4Beaver

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Re: 92 kx500 problem
« Reply #1 on: January 20, 2016, 09:47:06 PM »
Welcome to the site shixanget...

Start by pulling the carb off, and give it a GOOD cleaning, pull all the jets out and blow compressed air through all of them, and write down all the current jet sizes for reference.
While you have the carb off, pull the reeds out too and check for broken petals, and/or gaps around the edges...the reeds should be sitting flat all around the reed block. If there are gaps, you can try to flip the petals over...but if that doesn't get them to sit flat, you may need to get a new set of petals.
Toss in a new spark plug if you have one...gapped at .024, and verify it for spark....put it all back together, throw some fresh fuel in it...and see if it'll fire up and run like it should.
It would be a good idea to get that crack in the pipe welded soon, or it could get bigger....or buy a new or used pipe....but if it's just a hair line crack, that shouldn't cause it not to start.

Let us know how you make out....if it's not better, a compression test, and a leak down test may be in order...but it sounds fuel related.
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Excuse me, ma'am...but you've got extremely nice legs!!!...what time do they open???                                                                                                               https://www.youtube.com/watch?v=n8tCgN3aryQ

Offline sandblaster

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Re: 92 kx500 problem
« Reply #2 on: January 21, 2016, 02:46:23 AM »
Quote from: Foxx4Beaver on January 20, 2016, 09:47:06 PM
Let us know how you make out....if it's not better, a compression test, and a leak down test may be in order...but it sounds fuel related.

+1

And welcome to the site  8-)
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The four stroke engine: That's one stroke for producing power and three for wearing the engine out.

Offline reklessj

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Re: 92 kx500 problem
« Reply #3 on: January 21, 2016, 12:02:17 PM »
My T4 did the exact same thing pulled the carb and the needle had broke and was just sitting in passage as the slide operated normally. Just a thought.
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My rides: 1994 KX500, 1988 T4, 1998, ZXI 1100 JETSKI, 2003 MOUNTAIN CAT 900
WIFES (Baby Fiver) rides: 2004 KTM 105SX,1992 LT250R, 1995 ZXI 900 JETSKI,  2011 RMK 600
SONS ride: 1995 YZ125,2002 RM 250
other rides: 2007 RMZ450 RC Ediition, 2003 RMK700

Offline shixanget

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Re: 92 kx500 problem
« Reply #4 on: January 21, 2016, 05:39:10 PM »
Got around to pulling everything off today. Carb looks excellent. Clean as far as I can tell. (New to the 2stroke game) but I believe a carb is a carb right? How many jets are there? From what I can tell I saw one flat head jet in the carb and one flat head on the side. Which I was assuming is the air/fuel didn't mess with it. Reeds looked good. Both laid flat to the surface. Compression test around 155. And might I mention it's been around 20 degrees here for the last few weeks. Good ol Kansas. Tried to start but eventually gave up after 4-5 kicks. I'm not sure how temperamental 2 strokes are in the cold so. Now I'm stumped.
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Offline sandblaster

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Re: 92 kx500 problem
« Reply #5 on: January 21, 2016, 06:09:12 PM »
Quote from: shixanget on January 21, 2016, 05:39:10 PM
but I believe a carb is a carb right?

In a word.... No  :-o

Read this, look at the pics then post questions  :-D
http://www.oem-cycle.com/forum/viewtopic.php?f=40&t=550
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The four stroke engine: That's one stroke for producing power and three for wearing the engine out.

Offline shixanget

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Re: 92 kx500 problem
« Reply #6 on: January 21, 2016, 06:30:01 PM »
Okay I read it. So how could it go from riding fine one day and then the next just not even want to start? Will it being jetted wrong prevent it from starting or just running rough? I didn't remember to look at the number on the jets.
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Offline Foxx4Beaver

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Re: 92 kx500 problem
« Reply #7 on: January 21, 2016, 10:16:18 PM »
one grain of sand/dirt in a carburetor can and will prevent a motor from running.
there's two jets inside...the main and the pilot. You should verify the choke is actually working too, and not sticking in one position.

It's possible the rubber tip on the valve float could be worn....or the needle seat could be worn...allowing more fuel than necessary in...which can also give quite similar symptoms as you're describing.
I would also remove the fuel tap, and be sure there's no sand/dirt clogging the filter that's attached to the tap inside the tank...and verify you have good fuel flow going into the carb.

Another simple thing you can try, that I don't think will help, but has at times in the past...is to disconnect the kill switch at the handlebars...just remove the one screw and let the kill switch hang off to the side when you try to start it. 
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Excuse me, ma'am...but you've got extremely nice legs!!!...what time do they open???                                                                                                               https://www.youtube.com/watch?v=n8tCgN3aryQ

Offline b4himdude

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Re: 92 kx500 problem
« Reply #8 on: January 22, 2016, 04:32:12 AM »
check this out . i dint know everything youve done to it yet or what the symptoms are like exactly . but remove the rotor cover and verify that there is a good woodruff key on the shaft and the rotor is tight. ive had issues on the past with these 500's and their rotors snugging em down tight enough. if its just loose and key is still in good shape make sure you get that some bitch on tight tight tight,. i use rattle gun and then smack it with a rubber mallet and rattle it again. then if that doesnt do it locktite . just check its easily accessible and would be good to look at anyway. also if the stator plate came loose its could be the issue. easy fix you'll need a flywheel puller though.  under $20
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Offline shixanget

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Re: 92 kx500 problem
« Reply #9 on: January 22, 2016, 11:08:58 AM »
Figured it out. Pulled old spark plug gap was at .045 got a new spark plug (ngk iridium) gapped at .024 started second kick! Runs better than ever! Thanks a lot guys! Still going to lurk around here so I can blow many on these cool parts I've been reading about.
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Offline Foxx4Beaver

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Re: 92 kx500 problem
« Reply #10 on: January 22, 2016, 11:15:29 AM »
excellent!!...good to see I, "got a little wood on the ball", with the new correctly gapped spark plug suggestion. :lol:
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Excuse me, ma'am...but you've got extremely nice legs!!!...what time do they open???                                                                                                               https://www.youtube.com/watch?v=n8tCgN3aryQ
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