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Powervalve service question 97 kx 125....

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I am assuming you have to take motor out to service/clean powervalve linkage cuz the frame is in way of the front cover... and what is a good cleaner to use to clean all the GUNK off ? Oven cleaner? brake cleaner? wd 40? thanks in advance :thumbsup:

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You don't have to remove the entire engine, just the top-end.

Be careful with solvents when cleaning the parts, if they are very acidic (like oven cleaner) they will etch the aluminum parts if left on for very long.

I use a polishing wheel on a dremel to remove the carbon deposits.

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Be careful with solvents when cleaning the parts, if they are very acidic (like oven cleaner) they will etch the aluminum parts if left on for very long.

I don't think I'd use oven cleaner on aluminum at all. Not saying it can't work but I'd be really careful.

Oven cleaner is alkaline, not acidic.:thumbsup::ride:

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You don't have to remove the entire engine, just the top-end.

Be careful with solvents when cleaning the parts, if they are very acidic (like oven cleaner) they will etch the aluminum parts if left on for very long.

I use a polishing wheel on a dremel to remove the carbon deposits.

im taking motor out anyway to paint frame ... do i have to have the piston out or can i just leave top end on and do it from the front and side covers??

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im taking motor out anyway to paint frame ... do i have to have the piston out or can i just leave top end on and do it from the front and side covers??

You should be able to do it. With it out you will just pull off the covers to get to it. The top end does not get in the way. Here is the problem, if your cleaning the exhaust valve areas and getting all the carbon out, the last last last thing you ever want to do is blow some carbon into the cylinder. Carbon is highly abrasive and can destroy your top end components. So with that said if your going to have the entire engine out, then just pop off the top end, its easy and way safer. Make sure you cover your bottom end as soon as the top end is off so that your don't drop any screws, tools or crap into it. You would hate to find that out after you put it together and fire it up and.....boom. My sons bike is stripped down to the frame right now for a tranny issue...unknown right now, but what your doing is fresh on our minds. Hope you find this helpful. Good luck.:thumbsup:

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you do have to remove the top end to fully disassemble the power valve. The whole assembly should be completely disassemble, cleaned and reassembled. You get yourself a service manual if you don't already have one as there are about fifty little parts which have to be assemble in a sequence. The shafts and gears must also be timed correctly for the valve to work properly.

I just did my first top end my 95 kx250 and found that the po had rebuilt the powervalve wrong which caused a nasty bog that had me chasing my tail with carb jetting. If you plan on painting the frame and cleaning up the bike you may just want to do the top end / bottem end inspection while you have the bike apart.

Good luck

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you do have to remove the top end to fully disassemble the power valve. The whole assembly should be completely disassemble, cleaned and reassembled. You get yourself a service manual if you don't already have one as there are about fifty little parts which have to be assemble in a sequence. The shafts and gears must also be timed correctly for the valve to work properly.

I just did my first top end my 95 kx250 and found that the po had rebuilt the powervalve wrong which caused a nasty bog that had me chasing my tail with carb jetting. If you plan on painting the frame and cleaning up the bike you may just want to do the top end / bottem end inspection while you have the bike apart.

Good luck

That part I did not know, thanks for the update here. Are the timing issues discussed in the manual during the reassembly part.

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You should be able to do it. With it out you will just pull off the covers to get to it. The top end does not get in the way. Here is the problem, if your cleaning the exhaust valve areas and getting all the carbon out, the last last last thing you ever want to do is blow some carbon into the cylinder. Carbon is highly abrasive and can destroy your top end components. So with that said if your going to have the entire engine out, then just pop off the top end, its easy and way safer. Make sure you cover your bottom end as soon as the top end is off so that your don't drop any screws, tools or crap into it. You would hate to find that out after you put it together and fire it up and.....boom. My sons bike is stripped down to the frame right now for a tranny issue...unknown right now, but what your doing is fresh on our minds. Hope you find this helpful. Good luck.:thumbsup:

oh yes ... thats right .... i will pop top end off .... and by the way the powervalves look very black with carbon at least the top ones ...the side sub valves look pretty clean ..no carbon ....

but my question is looking thru the exhaust port the valves dont seem to move very much when i move the arm on the side? and when i rev the engine the arm does not move ?? either its stuck (seems pretty stiff to move with my finger?) or the little ball bearings in govenor are gone? stuck? haven't checked yet?

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you do have to remove the top end to fully disassemble the power valve. The whole assembly should be completely disassemble, cleaned and reassembled. You get yourself a service manual if you don't already have one as there are about fifty little parts which have to be assemble in a sequence. The shafts and gears must also be timed correctly for the valve to work properly.

I just did my first top end my 95 kx250 and found that the po had rebuilt the powervalve wrong which caused a nasty bog that had me chasing my tail with carb jetting. If you plan on painting the frame and cleaning up the bike you may just want to do the top end / bottem end inspection while you have the bike apart.

Good luck

should the actuating arm move pretty easy when reving the engine?? mine does not move at all ....except when i move it with finger ??? must be gummed up or ball bearings stuck in gov?? any advice ? thanks in advance:thumbsup:

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the manual(I have a clymer$29.00 on ebay) will walk you through the assembly. It seems confusing to read, but if you sit down at well lighted desk follow it step by step it becomes clear.

You should be able to move the actuating shaft fairly easily. I could be wrong but I remember reading that while kips system is a very effective power valve it is also high maitanence and should be cleaned and disassembled during top end rebuilds.

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oh yes ... thats right .... i will pop top end off .... and by the way the powervalves look very black with carbon at least the top ones ...the side sub valves look pretty clean ..no carbon ....

but my question is looking thru the exhaust port the valves dont seem to move very much when i move the arm on the side? and when i rev the engine the arm does not move ?? either its stuck (seems pretty stiff to move with my finger?) or the little ball bearings in govenor are gone? stuck? haven't checked yet?

The drum valves are probably carbon-seized, and that's bad. The steel teeth on the actuator rack will sheer the aluminum teeth right off the valves if they become seized.

You can't service the valves with the top-end on. You need to disassemble the entire KIPS system to inspect and clean everything, and you need to be able to clean the valve pockets in the cylinder casting.

Pay close attention to how everything lines up as you take it apart. I have read from more than one poster that the KDX factory manual gives an incorrect procedure for reassembly and timing the valves.

If the actuator rod doesn't move at all when you rev the engine, the governor rod may have broken inside the engine cover. That's a known issue with the KDX.

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