first rebuild on 2002 kx125

[Xtremesports445]

i am soon going to be doing my first top end rebuild on my 2002 kx 125. Here are my following questions:

1. Are there any special tools that i'll need?

2. Will i need to measure the cylinder? and will i need to get a different sized piston depending on my cylinder?

3. Should i inspect my powerjet/kipps valve?

4. What else do i need to know to get the job done right?

Thanks for your help!

 

[Xtremesports445]

Anybody got some insight?

 

[Xtremesports445]

come on guys, i really need some help here. please answer my questions

 

[CRazy250]

you need basic knowledge of your bike and the cylinder. you only need to change piston and bore out the cylinder if the cylinder is scored badly or if the piston is or just worn out. as far as tools go most bikes need 8, 10, 12mm wrenches. also if you dont have a manual get one they can help out alot.

 

[MXFastGuy]

i am soon going to be doing my first top end rebuild on my 2002 kx 125. Here are my following questions:

1. Are there any special tools that i'll need?

2. Will i need to measure the cylinder? and will i need to get a different sized piston depending on my cylinder?

3. Should i inspect my powerjet/kipps valve?

4. What else do i need to know to get the job done right?

Thanks for your help!

These answers are based on general know-how, I have never done a top-end on your specific bike:

1. No, unless you consider needle-nose pliers a special tool.

2. No, unless the bike has a ton of hours or has been ridden very hard. Having the bore honed would be ideal, but is optional. I believe there's only one size piston available for your bike (could be wrong).

3. Yes, you should inspect it, it's fairly easy to disassemble and re-assemble. I would recommend giving everything a good cleaning and de-carboning.

4. I would recommend purchasing a service manual for your bike before you do your top-end. This will take you through it step-by-step and also tell you if any special tools are necessary. As a general rule, it doesn't get any easier than a 125 top-end, but if you've never done one before the manual will help.

Good luck!

 

[kawicam250]

a side note: consider installing a Wiseco piston and rings :cool: .

 

[rmc_olderthandirt]

1. Are there any special tools that i'll need?

A torque wrench is always a good idea to have.

Depending on the condition of the cylinder a cylinder hone might be needed. The hone is used to "break the glaze" on the cylinder walls so that the new rings will "seat" properly.

Otherwise, the basic set of wrenchs and sockets.

2. Will i need to measure the cylinder? and will i need to get a different sized piston depending on my cylinder?

If the cylinder has been scored or otherwise messed up then it will need to be bored out to the next "oversize" and you will need to get a new piston to match.

Measuring the cylinder is not easy and unless you are skilled in the art you probably would not be successful even if you had the right tools, which can be expensive. You can take the cylinder to the machine shop and have them measure it for you. Another way is to buy a new set of rings for your current piston, slip the ring into the cylinder (not on the piston, just the ring) and measure the end gap. If the gap is larger than the specification then you need to bore out to the next size or replate (if your cylinder is the type that is plated)

4. What else do i need to know to get the job done right?

You will certainly want to buy a gasket set. Don't even think of reusing the head gasket.

Buy a manual, if for no other reason so you can get the specifications for ring gap and torque settings of critical bolts. Torquing down the cylinder head is a critical process and if it is not done correctly it can cause a lot of problems.

Rod

 

[Xtremesports445]

thanks for your responses. I'm wondering how much a cylinder hone would cost?

Kawicam: that's what i was thinking too!

 

[lukesh40]

get a clymer's manual for your bike. they are way better than the factory manuals. has actual pictures of your bike. I did my first top end this summer on my 125, this manual made it so easy! Its not a hard job to begin with but your first one is nerve racking

 

[Xtremesports445]

lukesh40: i actually have 2 manuals for the bike, the factory one and a clymer. the problem is the clymer one only goes up to 2000 and they haven't made a new one for my bike yet, so it's a little inaccurate.
*In fact, does anybody know how different the 2000 kx 125 and the 2002 kx 125 really are?*