[liverpoolphil21]

I am having problems with the mid and top end power on my kx125. It will start, idle and run ok but after 1/2 throttle no more power is available. Was adivsed to check power valves, did so and ordered new ones as they were damaged. Anyway, after a series of other problems (stripped cylinder studs) I ended up fitting a full top end from another 87 kx onto mine. Started u p and same problems..no mid or top end power??

Any suggestions on where to look now appreciated

 

[QKENUF4U]

float height ?

 

[CROGG]

I still think the problem is the power valve. Did you assemble the power valve in the other cylinder properly? The problem could be the actuator arm that is controled by the p.v. govenor. The govener spring could be broken or sacked out. I would pull the exhaust pipe off and look up the exhaust port with a flash light. The power valve should be fully closed. Then pull out on the actuator rod and see if the valve opens all the way. The actuator should snap back into place and close the p.v. when released. You could also take the actuator cover off and run the bike and see if the arm has full duration. One last thing....did you replace all of the p.v. parts? If not they could be binding....the above steps should help you to find the problem. Good Luck!

 

[liverpoolphil21]

thanks for the replies. I am sure the p.v's are set right but not so sure on the actuator arm as when i removed the cover and revved the bike, the arm didnt seem to operate. How can I investigate this further?

I have also had the stator coils tested and re-wired suspecting electrical problems, but when I fitted the new stator coils today, it was exactly the same. Do you think it may be the other electircal components (cdi box)

thanks so far

Phil

 

[CROGG]

thanks for the replies. I am sure the p.v's are set right but not so sure on the actuator arm as when i removed the cover and revved the bike, the arm didnt seem to operate. How can I investigate this further?

I have also had the stator coils tested and re-wired suspecting electrical problems, but when I fitted the new stator coils today, it was exactly the same. Do you think it may be the other electircal components (cdi box)

thanks so far

Phil

I don't believe it's electrical or you would be having problems at all rpm's. If the actuator arm is not moving something is binding and I think that is your problem. Manually pull out on the actuator arm. It should pull out firmly but freely and when released snap back into place. You have to determine if the problem is in the cylinder or the side case govenor. Pull off the little c clip off the govenor rod and take off the govenor collar,so the arm is disconnected from the cylinder, then start and rev the bike up and see if the arm moves...make sure it moves to full duration...about 3/4 of an inch. If it does, the problem is in your cylinder, if it doesn't the problem is in the side case area and will have to be disassembled. Could be a broken or sacked out govenor spring or shim. When you say that after half throttle there is no more power available....do you mean it just flattens out and won't rev any higher? Or does the motor die, cut out, sputter, or what. If it just flattens and won't rev any higher, the problem is in the power valve area!

 

[liverpoolphil21]

thanks for the tips crogg!

When I talk about the lack of power after half throttle, I mean that the engine will not rev any higher, it sort of starts to struggle, making a flapping noise in the cyclinder (like something wants to get through but cant). If I persist opening the throttle very slowly it picks up a little power but If I open the throttle right out, it dies and cuts out.

I am now suspecting this problem lies with the right side crack case seal because I removed the L and R KIPS valve covers while the bike was running and could see blackish oil (transmission oil?) seeping through the valve. Also a spoogy black stuff is seeping through the end of the exhaust. A motobike mechanic said if the right seal has gone, it will draw tranny oil into the cyclinder and will not go very far at all. Can anyone give any information on changing it, apparently the case needs splitting because the seal is fitted from the left side.

Thanks Phil

 

[QKENUF4U]

does it smoke EXCESSIVELY ?? does the oil level in the tranny change ? sounds to me like crogg said that the powervalve mechanism isnt working/opening correctly

 

[CROGG]

If your right crank seal is leaking pretty bad the plug would foul almost immedately and your exhaust would be putting out soooo much smoke you wouldn't believe it. If the seal wasn't leaking very bad it is possible that the bike would run just a little rich but it would still rev out like normal. The oil that you are seeing in the p.v. area is unburnt premix which is normal and is used to lubricate the p.v. assembly. I believe that the problem is still in your power valve area...go and do what I posted in the above post and let me know what the results are!

 

[liverpoolphil21]

thanks

A mechanic is going to pressure test the engine for me at the weekend which should help eliminate one or two things. Will also check out the pv etc as you described. Will let you know how I get on

 

[liverpoolphil21]

checked out the pv operating rod and couldnt see any movement in it whilst the bike was revving so it is definitely at fault. i took off theclutch cover and checked the assembly but everything seemed it working order

How exactly does the rod operate? There is obviously a gear attached to to the crank shaft that rotates when the engine is running, but what causes the acual rod to either push in or pull out?

 

[CROGG]

The rod is connected by an arm which is operated by centrifical force through a govenor which is connected to a gear which meshes with another gear straight of the crank shaft. You have to find out whether the problem is coming from the cylinder(top end) or sidecase(bottom end). To do this you have to disconnect the rod from the arm. (I already posted how to do it above). Then start the bike and rev it up. If the arm moves the problem is in the cylinder. If it doesn't move , the problem is in the side case area. Could be a broken govenor spring or gear. I think the problem is in the cylinder portion of the power valve. Eric Gorr has an easy step by step way of assembling the p.v. on his website at www.ericgorr.com. You may have to replace most of the p.v parts to get it to work again since all of the parts work together and reley on each other for movement. When you do get it fixed switch to a full ester based synthetic such as Klotz kl300 or Motul, or Silkolene. They don't gum up power valves like other oils do! And this will never be a problem again!