KX Riders
Maintenance & Technical => KX250 / KX125 => Topic started by: MXonaKawi on May 28, 2015, 10:18:10 AM
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My bike suddenly died on the track today when riding. It bogged on the face of a jump and then shut off completely. It would not kick over and the kick starter won't even move past 10 o'clock. The piston is completely stuck in it's position. The piston and cylinder appear to be in great condition though. It's the rod that seems stuck and won't move. Any advice or pointers would be greatly appreciated.
Dirt and metal debris I found sitting atop the piston.
(http://i59.tinypic.com/2427x9c.jpg)
Metal shards sitting below the piston (on the crank? I think it's called).
(http://i58.tinypic.com/34iqvb5.jpg)
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If you remove the cylinder you should see what happened.
It's hard to see much of your cylinder but my guess is it's time for a top and bottom.
Get that cylinder off and let us know what you find.
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If you remove the cylinder you should see what happened.
It's hard to see much of your cylinder but my guess is it's time for a top and bottom.
Get that cylinder off and let us know what you find.
Sandblaster thanks for the reply. My top end is brand new. I just put it in 2.5 months ago when I finished the rebuild. The cylinder looks great and the inside feels smooth as ever, no visible scoring. The piston looks pretty much the same as when I installed it too, with just some slight signs of wear all around but not in any one spot in particular.
I've still got the piston attached to the rod, but it won't budge. The rod is stuck and as a result the kickstarter obviously won't budge.
I'm wondering if that metal circle type debris pictured above is a piece of a broken thrust washer from the connecting rod.
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I've still got the piston attached to the rod, but it won't budge. The rod is stuck and as a result the kickstarter obviously won't budge.
try taking off the magneto cover, and grab onto the flywheel and try to rotate the motor backwards...I've seen a lot of guys have good luck doing this with a locked up motor.
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Looks like a thrust washer debris (copper in color). Check the big end rod bearing should be a thrust washer on both sides of the rod. Lucky no top end damage!
DoldGuy
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What year and model is your bike? I have a 98 kx250. After 3 years trail riding then 3 racing my big end rod beading melted. The photos aren't showing up on my phone but it sounds like the same failure. Likewise my top end had no damage other than dents in the cylinder head from bearing shrapnel.
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Well thanks to Foxx4Beaver I was able to remove the magneto cover and free the stuck piston. It moves freely now and while I was rotating it, 2 more pieces of metal debris surfaced. They are pictured here. I'm guessing it's shrapnel from the thrust washers or rod bearing.
(http://i59.tinypic.com/2a636kh.jpg)
If that's the case, it seems I have two options:
1) Buy the Hot Rods Connecting Rod Kit for $100 and hope that solves the problem.
2)Buy the entire OEM crankshaft assembly for $250, gasket kit for around $40, and crankshaft bearings for around $30 and have complete confidence that my bottom end is perfect.
Which do you think is the best solution?
My bike is a 2000 KX 125.
Here is quick video of where I'm at currently in regards to motion.
View My Video (http://tinypic.com/r/2j2ga6b/8)
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probably not a good idea turning the engine over with the piston slapping around like that
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probably not a good idea turning the engine over with the piston slapping around like that
I didn't want to say anything but I felt a huge pucker when I saw that... :-o
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probably not a good idea turning the engine over with the piston slapping around like that
I didn't want to say anything but I felt a huge pucker when I saw that... :-o
Yea I definitely won't make a habit of that. Do you have any suggestion on which of the two aforementioned options I should take?
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aforementioned?
Too many syllables for me :lol:
I'm all about doing it right.. And I'm not a big Hot Rods fan.
Since your splitting the cases, check your trans bearings out especially the out put shaft bearing.
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If you can afford it, the complete crankset is a faster way probably, but a properly rebuilt crank should be just as good, if not better since the factory might not be as anal about the trueing of the crankhalves as a good mechanic is...
Oh and do replace the mainbearings and seals, might have debris embedded in the bearings that can cause another failure...
Hope you get it running soon
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Well thanks to Foxx4Beaver I was able to remove the magneto cover and free the stuck piston.
:wink:
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I rebuilt mine with Kawasaki parts complete crank, bearings, seals, trans bearings and top end. One year racing on it and rock solid reliable. I would recommend OEM. Also my rod moved so much that it contacted the bottom of the case and embedded some steel that I had to remove.
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I rebuilt mine with Kawasaki parts complete crank, bearings, seals, trans bearings and top end. One year racing on it and rock solid reliable. I would recommend OEM. Also my rod moved so much that it contacted the bottom of the case and embedded some steel that I had to remove.
Ok, well I think this may be too big of a job for me to do myself with the exception of the top end. I'll probably bring it to a mechanic or shop for the bottom end.
So to be clear. I will need to start with part #13031-1465 from the Crankshaft/Piston diagram.
As far as the bearings and seals and trans bearings, I'm completely lost. I'm a bit out of my league when it comes to the Crankcase diagram.
Can anyone point out the part #'s for each?
I'd like to order all the parts myself and then bring them all with the engine to whoever I choose to do the work on it.
http://www.motosport.com/dirtbike/oem-parts/kawasaki/2000/kx125
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if you plan on re-using that piston...you better look it over REAL good...cause there's no way you didn't put some kind of a nick/ding in it when it was slapping the cases like that!
get a "fine" file and smooth out the ridges it made....or you will destroy that cylinder as well.
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if you plan on re-using that piston...you better look it over REAL good...cause there's no way you didn't put some kind of a nick/ding in it when it was slapping the cases like that!
get a "fine" file and smooth out the ridges it made....or you will destroy that cylinder as well.
Yea the whole top end is going to get replaced...and I'm a moron lol
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Yea the whole top end is going to get replaced...and I'm a moron lol
eh...you're better off going all new...again.
live and learn.
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Ok I've ordered the entire crank assembly OEM. I also ordered gaskets for the entire engine. I'm going to throw another Wiseco piston in there. Now I just need to know which bearings to buy and as for seals...
Do you guys think this will cover me as far as seals go for the entire job?
http://www.ebay.com/itm/261460130300?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
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Cometic for gask and otters
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Shoot! Sorry to see the damage.
You might consider Inside Line Moto in Orange to do the rebuild. They're an independent shop and can likely do the job for less than the Kawi dealer charges. I don't have any experience with them. I know about them because they advertise in the AMA District 37 newsletter.
Good call on getting an OEM replacement crank.
The seal kit looks as if it's complete.
Yes, you should consider replacing the transmission shaft bearings, especially the output shaft bearing.
I used a Cometic top-end gasket kit last time I replaced my piston...so far so good, and I would use that kit again.
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Shoot! Sorry to see the damage.
You might consider Inside Line Moto in Orange to do the rebuild. They're an independent shop and can likely do the job for less than the Kawi dealer charges. I don't have any experience with them. I know about them because they advertise in the AMA District 37 newsletter.
Good call on getting an OEM replacement crank.
The seal kit looks as if it's complete.
Yes, you should consider replacing the transmission shaft bearings, especially the output shaft bearing.
I used a Cometic top-end gasket kit last time I replaced my piston...so far so good, and I would use that kit again.
Thanks Kevin! It's understandable, because the bottom end was the only thing I didn't completely replace besides the stock suspension on my rebuild.
But it's time and I plan on doing it now. I'll check out that place for pricing on the labor. Thanks for the heads up.
Can anyone point out the part # for the transmission shaft bearing and output shaft bearing to me? They are just listed as bearings on the diagram and I don't know my way around the bottom end.
Hopefully I'll see you out at Milestone soon! I'm planning on having this done asap and being out on the track again in 2-3 weeks.
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I've got a few things to fix on my bike, too! Sounds like we'll both be ready for the track about the same time.
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See you back out there soon Kevin!
Question: How often should a clutch be changed on a two stroke? That's one of the other only things I haven't replaced and figured I may as well inquire about it while I'm having the bottom end done. I see there are clutch kits that come with the plates and springs for under $100 to just over $100. Then there are also some that include the clutch basket. These are all over $300. Is it necessary to occasionally change the clutch plates and springs? If so, how often should the basket be changed, if at all?
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a clutch/tranny can last a long time providing you use a good oil, and you change it frequently.
typically if it starts slipping while under acceleration...meaning if it revs to the moon if you're in 3rd, 4th or whatever gear, and you're only going 5mph with no pull from the motor...then it's slipping, and it's time to inspect, or replace the plates. .
Pay attention to how much/little adjustment you have in the cable at the lever.
I just use OEM plates...but most of the top brand aftermarket ones will work fine.
You can get different springs with heavier or softer "pulls".
If the fingers on the basket are really grooved bad from the plates....you could file them smooth to get a little more life out of it...but a new basket would be in the near future.
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a clutch/tranny can last a long time providing you use a good oil, and you change it frequently.
typically if it starts slipping while under acceleration...meaning if it revs to the moon if you're in 3rd, 4th or whatever gear, and you're only going 5mph with no pull from the motor...then it's slipping, and it's time to inspect, or replace the plates. .
Pay attention to how much/little adjustment you have in the cable at the lever.
I just use OEM plates...but most of the top brand aftermarket ones will work fine.
You can get different springs with heavier or softer "pulls".
If the fingers on the basket are really grooved bad from the plates....you could file them smooth to get a little more life out of it...but a new basket would be in the near future.
Thanks for all this great info! I have no reason to believe the clutch needs replacing other than the fact that the bike was in poor condition when I bought it. But the clutch feels great to me while riding. I haven't had any indication that it's slipping or over-revving. With that said, a visual inspection wouldn't hurt. That's what I'll probably do now to just have an idea of what it looks like in there.
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my thoughts are if you want to have confidence while youre on the throttle take the time necessary to do the job correctly as you CAN afford it. nothing sucks worse than knowing you should have or you would have as you stand there with your hands on your hips helmet on knowing why youll be pushing your bike. the only time you to cut corners on a bike is when youre riding it. never while youre working on it. just my thoughts....