KX Riders

Maintenance & Technical => KX500 Original => Topic started by: grunthum on May 26, 2015, 03:24:23 AM

Title: 89 KX 500 Problem
Post by: grunthum on May 26, 2015, 03:24:23 AM
Picked up an 89 KX 500 that hasn't been ridden much but was left outside at some point. Cleaned the fuel system and it tried to fire on the first kick but nothing after that. Has good spark & compression. I believe it is a carb problem. There was a mouse nest in the airbox and the urine settled in the back of the carb and corroded the airscrew which is frozen in place. This is the only circuit I was not able to clean or un-freeze the airscrew....thinking that is my problem. Also one of the float pin holes was broken off. I installed the pin thru the one hole and it seemed to keep the floats in alignment, at least enough to get it started.

Any thoughts on the frozen/corroded airscrew?

Also if anyone has a PWK 39MM in working order that they would consider selling I would be interested.

Thanks Grant
Title: Re: 89 KX 500 Problem
Post by: Foxx4Beaver on May 26, 2015, 09:06:40 AM
I'm not sure what your financial situation is like, but you can get brand new PWK's for relatively short money...that's the way I myself would go, and have gone before....

http://www.ebay.com/itm/KEIHIN-PWK-39MM-39-CARBURETOR-CARB-/291475871357?hash=item43dd50d67d&vxp=mtr
Title: Re: 89 KX 500 Problem
Post by: grunthum on May 26, 2015, 09:30:26 AM
Thanks Foxx

Yes I've checked into them and Sudco was my second choice. I just thought I'd ask. Thanks

Title: Re: 89 KX 500 Problem
Post by: Foxx4Beaver on May 26, 2015, 09:33:32 AM
that's cool....give it a couple days, someone on here might have a really good used one they'd be willing to sell you....but, there's nothing like brand new 8-)
Title: Re: 89 KX 500 Problem
Post by: ID KX500 on May 26, 2015, 11:00:48 AM
Do you still have spark to the plug?
Title: Re: 89 KX 500 Problem
Post by: grunthum on May 26, 2015, 11:16:36 AM
Yes, healthy blue spark. I'm going to run a compression test as soon as I get a chance, but compression seems strong. I'm wondering if it's not the corroded airscrew passage.

Thanks
Title: Re: 89 KX 500 Problem
Post by: grunthum on May 28, 2015, 01:24:44 PM
I took the carb off my CR 500 and put it on the KX and it still would not start. Did a compression test and tested at 130. Checked piston and cylinder thru intake, exhaust & plug hole and looked good. Took the pipe off and washed a big mouse nest out of the pipe plus a lot of crud. Tapped the pipe with a mallet for a while then power washed the inside. Will install & try again tomorrow. 
Title: Re: 89 KX 500 Problem
Post by: Foxx4Beaver on May 28, 2015, 01:38:10 PM
did you by any chance check the plug to see if it was wet/getting fuel?
and was that carb from the CR working alright when it was on the CR?
Title: Re: 89 KX 500 Problem
Post by: grunthum on May 28, 2015, 01:57:10 PM
Yes the plug was getting fuel, getting wet. Rechecked the spark and is healthy blue. The carb off the CR works fine but I disassembled and cleaned before the install. I'm hoping it was the plugged exhaust. Did you have some other advice or thoughts. Always eager to hear.
Thanks Grant
Title: Re: 89 KX 500 Problem
Post by: Foxx4Beaver on May 28, 2015, 02:00:20 PM
see what happens now that the pipe is clear and it can breath.
Title: Re: 89 KX 500 Problem
Post by: grunthum on May 30, 2015, 02:45:19 AM
After cleaning mouse nest & crud out of the pipe, I gave it 5 prime kicks and it started the first kick. Still have the CR PJ carb on it so it isn't jetted anywhere near close. Guess I'll be calling Sudco. I would like to get it race read for our next vintage race in two weeks... just a little worried about the crank bearings since it sat outside for a while. I'll have to figure out photo bucket so I can post some pics. Thanks for the help Foxx, really helps to have a site like this to come to for info! 
Title: Re: 89 KX 500 Problem
Post by: Foxx4Beaver on May 30, 2015, 02:49:33 AM
awesome Grunthum!
you could take off the magneto cover on the left side, and grab onto the flywheel...and see if there's any up and down play(not the most accurate way of checking)...if there is, more than likely it'll need an overhaul.

here's a link for posting pics off photobucket....

http://www.kxriders.com/forums/index.php/topic,10040.0.html  
Title: Re: 89 KX 500 Problem
Post by: grunthum on May 30, 2015, 02:59:53 AM
Thank You sir! More good advice. Thanks Foxx
Title: Re: 89 KX 500 Problem Fixed
Post by: grunthum on June 09, 2015, 12:58:38 PM
Put the new PWK on tonight and it sounds great. A few more things to work on and it will be ready for the track. 
Title: Re: 89 KX 500 Problem
Post by: Foxx4Beaver on June 09, 2015, 07:57:18 PM
sweet...post some pics when you get a chance.