Just bought a mint 2003 K5 today, not as much power as expected?? have pics :)

[Polar-Bus]

after we set the jetting, and inspect the top end and it proves to be good, the only other remote possibility I can think of for sub par acceleration is a bad clutch... but that's stretching it.... we see. I will certainly post pics and details when/if we find the suspect...

                     Rich

[95formula847]

hopefully its something simple. Im having problems with my 91 also.

[JustinSB]

Another kind of random thing that can cause problems is excess carbon build up in the expansion chamber.

[95formula847]

I have put a new top end on, Cleaned and re-jetted carburetor to recommended jetting for my area, all new gaskets and a few seals, new power core silencer and pro circuit platinum pipe and it still doesn't run right. I ordered V-Force reeds and got a reed spacer from jfab so im hoping my problem is in the reeds as they don't have much  "tension". I also did a test by filling the valve with water and holding it shut... then releasing and counting how long it takes to empty the water. Most say 6-10 seconds is good for stock reeds and mine take under 2 seconds!

Not stealing a thread just tossing out my situation if it helps the original poster.

[93cbra]

Well Rich looked in the exhaust port and found the problem. The piston has a chunk missing from it. I'll try to tear it down today and take some pictures.

Thanks for your help Rich!

[Polar-Bus]

Well, Jeff and I met today, and we talked and share LOT in common, great guy.

Now for the disturbing news, Jeff's 500 definately had  less compression than mine. His compression also took more kicks to reach a max of about 150 psi, where as my 500 reached a max of 175. First, I grabbed a flashlight, and closely observed the powervalves, and everything looks good, next Jeff is slowly kicking the bike over as I watch the piston, and te piston and rings look worn, then as I get my head even closer to the exhaust port, I focus on the piston crown, and the bad news is spotted.... The piston has a good sized chunk broken off the crown directly above the top compression ring... dammit,  NOT what I wanted to see ! ... I'm sure he will chime in with his comments... I just hope there is no cylinder damage, and the head is ok.
In my experiences with a piston crown failure, it usually bangs up the head, and the cyl as well, lets keep our fingers crossed until he get the cylinder off.

Jeff post up pics of the piston, maybe some of the more experienced KX engine gurus can explain what might have happened to cause the psiton to break like it did...

[93cbra]

Ok well here goes. I disassembled it and found some issues.
First, can you guys look at this video and please tell me my bottom end bearings are not bad??
http://www.youtube.com/watch?v=73_h-AEUlXo

Next, here are some pics of my piston and cylinder. Unfortunitly there a few spots where the finish has come off, I circled those areas in red. Also it looks like I have a crack in my exhaust port. What do you guys think, can it be fixed? Is this abnormal? There were no scratches in the walls of the cylinder anywhere, just finish rubbed off.

[Polar-Bus]

Jeff, i'ts hard to tell from pics, but It looks like a typical dirt ingested siezure. Dirt siezures usually result in piston damage (but not limited to) near the intake sides. Cold siezures usually scuff the 4 corners of the piston skirts (which doesn't seem to be the case here). Lean burn, or lack of lubrication siezures usually stem from the exhaust port first, but can also go all the way around the piston. The piston looks like it siezed, and peeled off the Nikasil coating up near the top of the cylinder. This might be how the top piston crown failed. By the looks of the black carbon below where the piston failed, your 500 has been driven for a while with the blown piston. Obviously from a idiot previous owner who was clueless...

Your crank rod play is normal. There will be some side to side play in the rod. What you don't want is ANY verticle play within the crank to rod journal fit. Any other member comments?

I know of a REALLY seasoned Kawasaki tech/ veteran dirt racer buddy of mine down in Salisbury, MA. If you want a really good opinion of what to do about your cylinder...

                    Rich

[kaw rider]

Looks like a common problem with a cast piston. Looks like alittle lean on oil ratio with baked oil under crown of dome. Maybe alittle det. could cause that ring glan breakages.

[93cbra]

Thanks guys, glad to here the bottom is normal. Is this cylinder fixable? If so do I need to send it out to get welded or sleeved. Does that crack look like a show stopper?

Jeff

[DoldGuy]

93CBRA,
The cylinder can be stripped, the bridge welded, bored (stock size 86) & then plated. The top of the cylinder looks to have had coolant leaking into the bore from the head (usually see some type of errosion). From that piston you are very lucky to not have more damage. While the motor is at this stage I would recommend going thru the bottom end and install new crank bearings and seals and measure the play in the crank along with it's alignment. As stated above the crank should have NO play up & down but a small amount side to side but you can have too much. Also sure once you are finished with the build you will be VERY happy with it's new found performance.
I hope our members realize how bad ones motor can be even as new & clean as your 2003.
Keep us posted on your progress!

[93cbra]

93CBRA,
The cylinder can be stripped, the bridge welded, bored (stock size 86) & then plated. The top of the cylinder looks to have had coolant leaking into the bore from the head (usually see some type of errosion). From that piston you are very lucky to not have more damage. While the motor is at this stage I would recommend going thru the bottom end and install new crank bearings and seals and measure the play in the crank along with it's alignment. As stated above the crank should have NO play up & down but a small amount side to side but you can have too much. Also sure once you are finished with the build you will be VERY happy with it's new found performance.
I hope our members realize how bad ones motor can be even as new & clean as your 2003.
Keep us posted on your progress!

Thanks man I appreciate it! I'll send the jug out to be fixed.

[93cbra]

Rich, you think I should send it out to be fixed or buy a new one?

Here's one on ebay for $500

http://cgi.ebay.com/ebaymotors/NEW-OEM-2004-KAWASAKI-KX-500-CYLINDER-11005-1564-KX500_W0QQcmdZViewItemQQ_trksidZp3286Q2ec0Q2em14QQhashZitem2302cdbca3QQitemZ150370892963QQptZMotorcyclesQ5fPartsQ5fAccessories

[kaw rider]

It should only cost around $200.00 to replate that cylinder.

[Polar-Bus]

It should only cost around $200.00 to replate that cylinder.

It's going to cost more the $200 to fix that cylinder, especially if it needs weld repair.