Need some advice on a running issue with my 1991 KX500 please..

[umberto]

This is Sandblaster's electronics trouble shooting guide that I used when mine wouldn't start.  It's really helpful if you are a little rusty (or confused) on electronics.  I actually printed it out and put in a coil bind with my KX manual I found online.

http://www.oem-cycle.com/forum/viewtopic.php?f=40&t=163

[Lon]

Well didn't get far,still gotta take the bowl off and check the jets ..Did check the reeds and the bottom half had a pretty good gap so flipped both top and bottom reeds,no gap but still getting a new set..Pulled the plug and its for sure running rich as hell and I think its from the reeds..I could almost slide a dime in the reeds,thats how big the gap was..Still plan on checking the jets and will post numbers tomorrow..

[Lon]

Ok,got the carb apart ..Bike is stock other than pipe,FmF Gold Series ..

Slow jet --> 60
Main jet --> 168

I also pulled the bowl off the carb that came with my parts bike and these are the jets it has..

Slow jet --> 48
Main jet --> 158

[Foxx4Beaver]

what's your elevation?...ballpark guess.

keep the 168 main jet in there for now....
but get a 55 pilot/slow jet...
what position is the clip in, on the needle?....and try to read the digits stamped on the needle.

[Lon]

what's your elevation?...ballpark guess.

keep the 168 main jet in there for now....
but get a 55 pilot/slow jet...
what position is the clip in, on the needle?....and try to read the digits stamped on the needle.

Looked up sea level and were around 575 above..
I'll get the 55 jet but could I use the 48 jet from the other carb for now?
C-Clip is in the very top/first slot of the needle and numbers on it are N82M..I also checked the needle from the parts bike carb and it has N85C on it..

[Foxx4Beaver]

could I use the 48 jet from the other carb for now?
C-Clip is in the very top/first slot of the needle and numbers on it are N82M..I also checked the needle from the parts bike carb and it has N85C on it..

I'm starting to wonder if you don't have a bad clutch side crank seal....your plug should be white as hell, and running dangerously lean with those settings!
have you noticed your tranny oil mysteriously going low?....does it smoke excessively?

[Lon]

could I use the 48 jet from the other carb for now?
C-Clip is in the very top/first slot of the needle and numbers on it are N82M..I also checked the needle from the parts bike carb and it has N85C on it..

I'm starting to wonder if you don't have a bad clutch side crank seal....your plug should be white as hell, and running dangerously lean with those settings!
have you noticed your tranny oil mysteriously going low?....does it smoke excessively?

Nope,not using a drop of oil (ATF Type-F) from the crank case..Just the normal 2 stroke smoke and if the seal was bad,it would be smoking white pretty good...Can't smell it either and ATF smells nasty as hell..

[Foxx4Beaver]

don't use that 48 Pilot...that's too big of a jump at once...drop the needle clip into the 2nd from top.
something's not adding up...your settings are way leaner than mine...and I run within a couple hundred feet of your elevation, and I'm running very lean.
I think a leak down test should be the next thing on your menu...something's wrong.

*EDIT*
what 2 stroke oil are you using?, and what ratio are you mixing it at?

[Lon]

don't use that 48 Pilot...that's too big of a jump at once...drop the needle clip into the 2nd from top.
something's not adding up...your settings are way leaner than mine...and I run within a couple hundred feet of your elevation, and I'm running very lean.
I think a leak down test should be the next thing on your menu...something's wrong.

*EDIT*
what 2 stroke oil are you using?, and what ratio are you mixing it at?

Go easy on me,im still learning all this  ..
Could the reeds give the top end power issue im having or no?When I checked them,the whole top half had a nice size gap..Was big enough that I could slide a penny or dime between the reeds and cage.I already flipped them and all are nice and flat now but haven't started it yet..
I'll get the 55 jet asap but I have a question about it also..Could that give the top end power issue,running too lean?
I clearly have alot to lean and I couldn't thank you enough so far for the help man..Been wanting a KX500 for a good 20 years as its my dream bike..Now that I have it,I wanna do everything the right way down to a "T" ..

I'll also do a leak down test in the next few days just to be 100% sure..

[Lon]

Oops,missed the edited..
Running Klotz mixing it 32:1 ..

[Foxx4Beaver]

yeah, replace the reeds a.s.a.p. if they were that bad....no sense playing with jetting if they are that gapped and worn.

how did you check that spark plug?...to do it correctly, you want to run it on a straight-away wide open for a couple seconds, providing you have a place that allows you to go that fast. Then pull in the clutch and hit the kill switch immediately whilst you're still coasting...then pull the plug and check it's color. This will tell you what you need to do...whether to go richer or leaner.

I would keep the riding to a minimum until the issue gets figured out....or it could turn very expensive very quickly.

[Foxx4Beaver]

mixing it 32:1 ..

that's not bad...
a few of us are running 40:1
I've never used Klotz...just Bel-Ray and Motul

[Lon]

Well Foxx,you were on the money bro..My dang crank seal is done  ..I didn't wanna believe it because the bike was running like a top but I could feel top end power was a dog..Thinking it was the reeds when I saw how bad they were so flipped them and waited until we went riding..Well we went yesterday and the first 45mins to a hour were good..Low end was ALOT better but top end was the same,got worse as the crank case oil/ATF was fouling the crap out of the plug to the point where it was breaking up pretty good..Just putted it around with my son but kept a eye on the oil level which did drop some..I always run the oil level a little below the top of the site hole..Kept a eye on it and by the end of the day,it dropped down to the middle of the site hole..

This wasn't a big deal until I found out I gotta split the d**n cases JUST to change the d**n seal which is pretty stupid..Turns a 1 1/2 to 2 hr job into a few day job over a stupid seal but its all good..Bike is new to me so now I get to go through and check everything while its apart ...

I already have YamaBond for the cases when I put them back together so ordering the Tusk oil seal kit so I can replace them all..
What a pain in the ass over one seal    ..

[Foxx4Beaver]

Well Foxx,you were on the money bro..My dang crank seal is done  

I know.

your jetting and plug color gave it away.
someone was trying to jet it as lean as they could to bypass the bad crank seal...whether the previous owner knew he had a bad seal or not, I don't know...probably not.

Either way...at this point, replace as many bearings and seals that your wallet/wife will allow you to spend, since you have to split the motor open anyways....definitely replace BOTH crank bearings and seals regardless!!...go over the tranny really good too.
Be sure you have a service manual for easy reference ...you can find them cheap all day long on e-bay...don't be afraid to ask questions...a lot of info is already in this site, you just have to use the "search" option.

[Lon]

Well Foxx,you were on the money bro..My dang crank seal is done  

I know.

your jetting and plug color gave it away.
someone was trying to jet it as lean as they could to bypass the bad crank seal...whether the previous owner knew he had a bad seal or not, I don't know...probably not.

Either way...at this point, replace as many bearings and seals that your wallet/wife will allow you to spend, since you have to split the motor open anyways....definitely replace BOTH crank bearings and seals regardless!!...go over the tranny really good too.
Be sure you have a service manual for easy reference ...you can find them cheap all day long on e-bay...don't be afraid to ask questions...a lot of info is already in this site, you just have to use the "search" option.

To be honest man,the guy I got it from knew d**n good and well he f**ked me big time....Before we traded,he told me the bike only needed the rear shock rebuilt and rear caliper rebuilt..Also he wouldn't meet me during the day so I can see the bike really good,claimed he worked alot of hrs and all kinds or other BS storys..But being me and wanting my dream bike (sounds stupid but it is lol) for a good 20 years,I fell for his BS..But it is what it is and im doing what I can to get everything done right which I have so far..Main reason I bought a 1993 KX500 basket case,so I can fix this one..

When I split the cases,i'll check everything over for sure..Just really sucks people can't be upfront and honest anymore...Thanks man...