KX Riders
Maintenance & Technical => KX250 / KX125 => Topic started by: keithluneau on March 31, 2009, 05:06:34 AM
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First, let me say that this is a great site for Kawasakis! I've been lurking and searching while I waited for my account to be approved. Loads of good info here! :-D
Now on to my bike. I just picked up a '89 250. Long story short, the engine was supposed to be rebuilt top and bottom and running great, the only problem was supposed to be a stuck float. I didn't get the hear the bike run, but bought it anyway. I get it home, find that the overflow tube on the bowl is broke off, and fixed that. Float was fine. Put gas in it and fired it up. It blew water all out of the head gasket and smoked white like it was burning water too. It ran a couple minutes like this, then I shut it off. I pulled the head off and cleaned up the cylinder deck and head, and put it back together with sealant on the gasket and it stopped leaking water, and wasn't blowing water out of the radiator anymore.
The bike refused to run now though. It would start, run a second or two, and die. I tried new plugs, checked spark, went over the carb again, checked the reeds, etc. Every now and again, it would try to start then die. Most of the time it wouldn't do anything at all. Then all of a sudden, it started, cleaner out, and started to run great. It idled for about 5 minutes and warmed up, so I got on to take it down the road. It would start to sputter right about when it should get into the power band. Low end power was great. I made it about a mile down the road before it started dieing out, and just quit all together. Now it refuses to run.
I've checked spark, it's strong and blue. Compression is great, it's got a fresh top end on it. I put a little gas in the spark plug hole and tried to kick it over, still won't even pop. Could it be the timing is off? I pulled the flywheel cover and there was water in there. The gasket was old and torn up. There was rust on the flywheel and the timing plate. I cleaned up the flywheel and pickup with sandpaper and got all the water and rust out that I could. Should I pull the flywheel and check the stator, and that the key isn't sheared?
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Well I pulled the flywheel this evening, and this is what I found behind it...
The Key is fine, slots in the flywheel and crank are both fine. The stator however, is another story. I'm not to impressed with it... :|
(http://scale4x4rc.org/keith/images/KX/1.jpg)
(http://scale4x4rc.org/keith/images/KX/2.jpg)
If anyone has a flywheel and a stator that will work, I'd love to pick them up for a fair price!
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I would just clean those up. Some naval jelly or other rust remover should work. On the stator, mark the position with a punch, clean it up and replace the retaining screws with new ones. Make sure you spray abunch of wd40 or similar over it all before you put the cover on (to prevent more rust). Splurge on a new gasket (or make one) and seal it up good. Cam.
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Thanks for the reply!
I did just that, took the stator out and cleaned in the motor, the stator, and the flywheel. I got them all nearly spotless, and put everything back together, set the gap on the pickup, and it started first kick after that. I was happy. ;)
Then I found the rest of the problems.
Here's what I've been dealing with since then. Looks like someone put a sleeve in the cylider, and did a crappy job!
(http://i257.photobucket.com/albums/hh223/k_luneau/1.jpg)
(http://i257.photobucket.com/albums/hh223/k_luneau/2.jpg)
So I had it pressed back in place. It'll probably move again, but maybe I'll get to ride a little while I hunt down another cylinder...
Here how it looks now.
(http://i257.photobucket.com/albums/hh223/k_luneau/3.jpg)
I'll put the top end back together while I wait on the drive gear for the governor. I pulled the side cover to change the water pump seal, and found that plastic gear was broken. The center valve in the main exhaust port was in a bind with the sleeve hanging it up. So none of the valves were working. I got all that sorted and cleaned up too.
As soon as the gear shows up in the mail I can get this thing running right, unless that sleeve decides not to stay put... :-o
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That port mismatch might the cause of your "no power" problems. It doens't take much of a trasfer port mismatch to screw things up. Back in the 70's I remember some husqvarnas came from the factory with the sleeve mismatched like that or twisted. They had to heat up the barrel then twist or press it back like you did. Those ones stayed in place if I recall. Good find. Unfortunately the steel sleeve makes them slower. Cam.
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That and the powervavles not working are probably both to blame! :|
This is quickly turning into a fun project though. I like working on these. I just wish I could have got some riding in! I'm dying to ride this one, it's the first two-stroke bike I've had... :-D
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How much does a steel sleeve affect on power output? Is the difference significant compared to a nikasil cylinder? :|
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Jopiz,
As a teen I used to race a rotary valve KX125. Very fast but had a chrome bore (not nikasil) and they would eventually chip. In those days no-one could replate so a steel sleeve was the only fix. No matter how well we matched the ports the bike was always slower than before. The only thing I could attribute it to was the higher friction of the steel liner. Cam.
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I believe that the steel sleeve requires a looser tolerance than with nicasil. I'm pretty sure that I read that on here. Since the sleeve is iron and the piston is aluminum, they expand at different rates and to different amounts. Stock cylinder is the way to go. Can a stock nicasil sleeve be put in there, or is it toast once you put an iron sleeve in it?
You're definately getting the crash course in engine service. :-D
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I had forgotten about the greater piston clearance required. The nikasil can run a tighter tolerance since it essentially is a thin hard coating over the base aluminum cylinder and so expands and contracts at the same rate as the piston. A steel liner expands differently so needs more clearance. Once you are sleeved you can't go back since they bore the cylinder larger to accept the thickness of the steel sleeve. It may be possible to go for a 300 kit or something similar with a larger than stock bore. KL, keep in mind that although this has been a hassle, look how much you have learned about your bike. Always valuable. Cam.
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Definitely! I'm the type of person that enjoys learning about and working in these things as much as riding them! ;)
Two weeks ago I had never laid eyes on a KX250 in person. As of a few days ago, I've been through the engine, top and bottom. :-D
The drive gear for the governor shipped out yesterday, I'm hoping to have it by the weekend so I can get the engine back together. Yesterday I got the top end back together, repacked the silencer, and buffed the rust off the pipe. The bike is looking better and better everyday!
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Just an update...
The gear for the governor came in the mail today, so I put the bike back together and got it running again. The top end power is MUCH better than it was before. Now it's running the way it should. :-D
I've got a new problem however... The bike loads up bad when it idles. If it idles for about 30 seconds, then I get back on the gas, it sputters and smokes BAD until it clears out, then starts hitting hard again. It wasn't doing this before I cleaned up the powervavles and got them working again. Could moving the sleeve make that kind of change in the carb. tuning, or maybe the valves? (they were stuck closed before)
I tried to adjust the pilot screw, but don't really know how to tell when it's close, I've never tuned one of these before.
Any ideas?
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I put a sleeve in an 89 years ago and couldnt keep a head gasket in it. I dont think the steel liner transfers the heat properly . After going back to a stock lined jug I never had another problem. Keep an eye on your coolant and overflow tube. Good Luck