• 2001 Kx 125 Top End Rebuild
• 98 Kx 125 Top End
• Kx 125 Top End Parts

Hey guys, update with the power valve. Checked with the previous owner who stated that there was a full top end rebuild about 18 months ago when he bought it but the bike has been used 3 times in that time frame, for 12 months it's been sat in his garage doing nothing. So took it apart today and there is oil everywhere in there, but no carbon build up as when I wipe the oil away inside the chamber it's like brand new in there.( guess this supports the rebuild statement? ) The seals where all perished, falling apart as I tried pulling them off the housing and cases. Also the spark plug has oil on it. Below are photos of the piston, Powevralve housing and spark plug. Would you guys say that this is just the seals breaking down over time due to the bike being sat full of oil for 12 months?

I'm going to clean it all and replace seals and put it back together and see how it goes. Thanks again for your comments paw paw, appreciated. So I have a lot of problems then?

Would you be able to advise a plan of attack so to speak on addressing the issues you have raised please? In your opinion is this going to be expensive? With regards to tearing the engine down with that much dirt, I wasn't sure how to go about finding my problems without looking? Have I caused more damage by doing so? Or do you mean that the amount of dirt on the outside could find its way in and cause problems? Thanks again. Yes tearing down a dirty engine will allow dirt to get inside easy and cause even more issues.

Always wash before you tear down an engine. The first thing to do is to have the cylinder measured to see if it's in spec. If not then it will have to be replated or replaced. In either case a new piston and rings will be needed to either match the new cylinder, the replated cylinder or in your good used cylinder. The crank seal should not be a big item to replace except that most Kawasaki's have them being installed from inside the case after it is split. I will check to see if that is the case on your bike.

2001 Kx 125 Top End Rebuild

You are talking several hundred dollars to get all this done, even if you do most of the work yourself. OK, I checked and your clutch side crank seal can be replaced without splitting the case. Much appreciated paw paw, a little bit of light there at the end of the tunnel haha. Whilst I'm changing the clutch side seal are there any other recommended consumables I should be changing?

What about any other seals on the other side? When I previously started the bike I recall it sounding very tinny, almost like a ball bearing pinging around a metal case if that makes sense. I will make sure the engine is clean before tackling anything else and get the cylinder measured. What would cause the cylinder to wear down? The piston hitting it?

Thanks again for your help, it's appreciated. Be sure to check the crank bearings. If there is wear in them they will sound rather tiny in sound. On the stator side you can just see if the flywheel will move any, either up and down or side to side.

98 Kx 125 Top End

If so, they are bad as well. Do the same with the rod on the crank. Any movement up and down is not good and would indicate that the crank needs rebuilding or replacing.

It's best to find all of this bad stuff now and fix it one time rather than having several very costly failures one right after the other. You really need to get a service manual for your bike.

They are cheap and will save you hundreds in the long run. Before i order the new seals and bearings (might as well if I'm replacing seals and opening up the case), from this diagram which bearings and seals should i be ordering.Just the ones on the clutch side or do i need to look at the left side to.? If it is just the right side would it be 92049a 5e And looking at the manual to get to the clutch side crankcase bearings and seal replaced I need to remove the clutch (I need a clutch holder before doing this) and then the crankcase cover? It does mention splitting aswell but Paw Paw has stated that this is not the case and I have seen some threads where people have mentioned not splitting the case.

Just to give an update, i have removed the engine from the frame, cleaning it all up, degrease etc. Am then changing all seals around powervalve, will remove replace crankcase seal and then put back together. Will then see how she runs. I had a question around setting up the idle valve and air screw though. From what i have read should the air screw be turned 1-1.5 turns from seated and the idle valve 1 turn from seated as a default?

Then get bike running and warm. Adjust idle valve until bike idles (as this is what i want to achieve), and then to make adjustments adjust air screw in small increments (1/8 turns). I should be applying throttle and listening for the way the bike returns to idle, listening out for a smooth increase in rpm and a smooth decrease in rpm Is this correct? Wrote: Just to give an update, i have removed the engine from the frame, cleaning it all up, degrease etc. Am then changing all seals around powervalve, will remove replace crankcase seal and then put back together. Will then see how she runs.

I had a question around setting up the idle valve and air screw though. From what i have read should the air screw be turned 1-1.5 turns from seated and the idle valve 1 turn from seated as a default? Then get bike running and warm.

Kx 125 Top End Parts

Adjust idle valve until bike idles (as this is what i want to achieve), and then to make adjustments adjust air screw in small increments (1/8 turns). I should be applying throttle and listening for the way the bike returns to idle, listening out for a smooth increase in rpm and a smooth decrease in rpm Is this correct? Pretty much yes. I'm not sure about the settings tho. Print this manual and have a read. Lot's of good information in there. Wrote: Just to give an update, i have removed the engine from the frame, cleaning it all up, degrease etc.

Am then changing all seals around powervalve, will remove replace crankcase seal and then put back together. Will then see how she runs. I had a question around setting up the idle valve and air screw though. From what i have read should the air screw be turned 1-1.5 turns from seated and the idle valve 1 turn from seated as a default? Then get bike running and warm. Adjust idle valve until bike idles (as this is what i want to achieve), and then to make adjustments adjust air screw in small increments (1/8 turns).

I should be applying throttle and listening for the way the bike returns to idle, listening out for a smooth increase in rpm and a smooth decrease in rpm Is this correct? If you're talking about your carb I would pull it apart and check your jets, making sure that you restore it to stock jetting for the meantime. Go to page 41 and 42 of this guide for your carb specs: Did you check the ID on the cylinder?