Can a KX 125 run without power valves

[liverpoolphil2130]

My old 87 kx is playing up

The bike starts and idels great but give it any throttle any it loses all power

HOWEVER, if I remove the LEFT KIPS valves cover (at the side of the barrel) it runs like a dream and pulls my arms off (but fouls plugs after about 30 mins of riding)

Can anyone help me on this?

Also a guy at the local dirt track said I should totally remove the power valves completely, is it ok to do this?

Thanks

 

[Pete Payne]

Remove the cylinder and fix the powervalve would be your best bet.

 

[g_man80]

I had an '89 KTM 250 with a broken power valve. Idle and low end was fine, but as soon as you twisted the throttle it would fall on it's face. I completely removed it and it ran fine. Well, not perfect, but it came to life. It lost some bottom end, but would turn on like a light switch. I ordered a new one right away, but the wrong one was shipped. I ended up riding it like that for about 3 months. Just had to get used to the power delivery. :yikes:

 

[liverpoolphil2130]

Today I completely removed the pv assembly and replaced the lot with new parts, the teeth on one of the pv's were worn slightly so I thought replacing them would solve the problem, but NO, when I fired it up it was exactly the same.

Although again, when I removed the left KIPS cover (or even just loosened it slightly to allow some air into the cylinder) it ran great!

It seems to help 100% by allowing air into the clylinder but I cant figure out why?

The reason why I am thinking of removing the valves is becuase when I got the bike it ran perfect, although after about 3 months the problem appeared. When I removed the head, I only found 1 pv installed so I am thinking that if I reinstall only 1 pv, then it may retun to the way it was

Long shot but if this doensnt sort it, then I think I am going to sell it on

 

[steve.emma]

the left kips cover that you pull off...does exhaust gas come out of this when you rev the bike? if so it may be that the exhaust pipe or muffler is blocked and thats why it wont run,removing the cover vents the exhaust gas allowing it to rev.
i dont think air is supposed to enter the motor from that cover i believe its an exhaust surge chamber that helps boost low end power.

steve.

 

[blanc]

Sounds like you need more air. JET YOUR BIKE

 

[liverpoolphil2130]

steve.emma I think you got it! The pipe was totally blocked up

Removed the pipe and ran the bike breifly and it sounded 100% better

Pipe getting a full de-carbonising and hopefully problem solved

Thanks for your help

 

[steve.emma]

hey good going! im glad you got it sorted, it will probably go like a rocket now with a cleaned out pipe! :ride:

 

[liverpoolphil2130]

I found the reason why when I removed the top end in the first place, I only found 1 pv, thats becuase the other had lodged itself in the pipe and was stopping any air flow!

Bike is running great now so thanks all for your help. ALTHOUGH I have just posted another thread on an over revving problem and would appreciate your help on this one. Steve.emma, get your thinking cap on!