Lack of power issue- any ideas?

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jpphotof64
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Lack of power issue- any ideas?

Post by jpphotof64 »

I have a 1990 kdx200. Bought it last spring -the top end was in a box. Since then Millennium has re-plated the cylinder and did the power valves. New Piston/rings etc. I left the bottom end alone as the crank play was acceptable. It starts right up and idles great. But you hop on to ride and it has no power and bogs down. There is a black oily/gas dripping from exhaust after a while. I removed the head to re-check power-valve install - that is ok. Took carb apart I have a Main jet#152 and Pilot jet #48, needle at 3rd tick. Compression check measured at 154psi. I can see light show through on one half of reed valve. Gas mix at 40:1 it smokes alot of blue smoke. Plug is black kind of fouled. I intend to check the float adjustment and check if the muffler is blocked. Crank seal leaking???? Any ideas?? I am in colorado at 6000 ft. Also

Jeff
Last edited by jpphotof64 on 05:58 pm Jul 18 2014, edited 1 time in total.
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bufftester
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Re: Lack of power issue- any ideas?

Post by bufftester »

replace the reeds, ensure the intake/exhaust tracks are mechanically sound (no tears in boots, all gaskets/seals/springs in place, fresh fuel, new plug, clean filter, etc) then run through the jetting guide and enjoy your new found green woods goodness.
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Re: Lack of power issue- any ideas?

Post by scheckaet »

bufftester wrote:replace the reeds, ensure the intake/exhaust tracks are mechanically sound (no tears in boots, all gaskets/seals/springs in place, fresh fuel, new plug, clean filter, etc) then run through the jetting guide and enjoy your new found green woods goodness.
+1

Did he mentioned replace the reeds, and jet your bike properly? :lol:
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Re: Lack of power issue- any ideas?

Post by Julien D »

Losing trans oil? Any oil behind stator cover? That would point to leaky crank seals. The jet block gasket could be leaking, perhaps? That will cause a lot of issues with bogging down, smoking, running pig rich.
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Lack of power issue- any ideas?

Post by Deseret Rider »

My 200 runs at about the same altitude. It runs best with a 140 main and a 40 or 45 Pilot with the needle hung from the third notch from the top. You should also check your float level----If you see overflow gas exiting your overflow tube when you tip the bike ---maybe 15-20 degrees to either side----that is a good indication that your float is set too high which can cause the symptoms that you describe.
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jpphotof64
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Re: Lack of power issue- any ideas?

Post by jpphotof64 »

Ok... if anyone is interested here is what I discovered. I replaced the reeds and checked for leaks...none found.checked the float level and installed new jets Main 140 Pilot 42 to get in the ballpark. Started it up and THE SAME PROBLEM. It just bogs and wants to die giving it gas. Note that it still idles fine. So as a last resort I remove the FMF muffler and start it, rev it a few times and let out the clutch- It does a wheelie into my garage narrowly missing my FJR1300. I have created a scud missile! Blocked muffler was the main issue is my guess.

Thanks for all your help!
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Re: Lack of power issue- any ideas?

Post by Deseret Rider »

Thanks for the feedback-----take that muffler apart and repack it (I favor using scotch bright 'Stainless steel scouring pad--donuts" in place of fiberglass matting simply because it doesn't tend to foul with oil and cause restriction as you have found to be the source of your problem------good work there.
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Re: Lack of power issue- any ideas?

Post by newbbewb »

I remember back in my pyro days I made a screw on silencer for my potato gun, and I used steel wool for the packing, and boy does that stuff burn. maybe the stainless variant doesn't burn...not sure.
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Re: Lack of power issue- any ideas?

Post by Deseret Rider »

newbbewb wrote:I remember back in my pyro days I made a screw on silencer for my potato gun, and I used steel wool for the packing, and boy does that stuff burn. maybe the stainless variant doesn't burn...not sure.
The SS steel used in those scouring pads is quite a but courser than the steel wool you are referring to-----and does not burn in this application. These pads are about the size and shape of a donut. They come in two varieties---copper or Stainless steel. Either will work as they are not prone to rust. If you work your fingers down into the middle area you can unravel the mesh to form a hollow which then slides over the holey pipe----Just push them together moderately tightly and squeeze the assembly into the muffler core. Thus modified---the muffler will be---should be----less restrictive to gas flow and may move your powerband up or down in the RPM range-----My experience has been that the bike pulls good down low and rally "comes on the pipe' hard fairly low in the rpm range. Your experience may differ----I think it depends on how tightly you pack the muffler? Mine isn't a quieter machine than it was---but I don't notice that it's any louder either.
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Re: Lack of power issue- any ideas?

Post by bufftester »

jpphotof64 wrote:Ok... if anyone is interested here is what I discovered. I replaced the reeds and checked for leaks...none found.checked the float level and installed new jets Main 140 Pilot 42 to get in the ballpark. Started it up and THE SAME PROBLEM. It just bogs and wants to die giving it gas. Note that it still idles fine. So as a last resort I remove the FMF muffler and start it, rev it a few times and let out the clutch- It does a wheelie into my garage narrowly missing my FJR1300. I have created a scud missile! Blocked muffler was the main issue is my guess.

Thanks for all your help!
Which goes back to my first post about making sure that your intake/exhaust tracks are in good mechanical condition...works every time. Glad you got it sorted!
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Lack of power issue- any ideas?

Post by dsmitty »

this is my 1st time here. I just got a 1988 kdx 200. Been a LONG time since I had one. I actually had the 175 when it was a couple years old. Anyhow, this is a barn find. sat for 8 years ago or so. I believed the guy when I took the mouse nest out of the air cleaner!! Cleaned carb, new plug, fresh gas, and fired right up. I rigged an air filter out of pillow stuffing for mean time cause old one fell apart and small pieces of it were in the carb. It seems to have no bottom end, very strong mid., and cuts out up top. like it's missing or some thing. Also, the carb has no air fuel screws, just an idle screw. Any help guys? Is there a power valve on the air cooled motors? Ports? My air filter? Jets? ALL THE ABOVE LOL!!!!
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