1995 KX 500 Power Valve

[grywache]

I just picked up a 95 kx500, when I bought it it had no power at all. I found out that the power valve was not moving at all so I was told to clean it with carb cleaner just by taking the pipe off and spraying it until it moved. It worked a bit but it still doesn't have the legendary power I was told it would have, my brothers yz 426 and my k5 are neck and neck all around. I have jetted it according to the chart on the site but it still hasn't made a difference. I havent tested the compression yet but it seems very strong when I ride it other than it doesn't want to rev right out,  maybe thats a sign that it needs a new top end. Also it smokes like crazy, if it idles or you are riding bush trails and can't wind it out in 5th then everything is blue behind you. I have been told by many people that it is probably a carboned power valve.  I'm just wondering if anyone knows how to properly clean the power valve and if I should rebuild the top end at the same time.

[stewart]

just watched some drag racing on dirt with a good running yz 426  agianst the k5  the k5 was averaging   15 lenghth lead in about 300 feet  the farther the race the farther behind the 426,, the 426 had a new tire pipe etc nice bike and good rider...my buddy dave was riding one of my spare bike he is 300 pounds  i was watching ,,hope this helps

[jfabmotorsports.com]

I also have a nice running 02 YZ426. All my K5's will spank the yz. However, the YZ426 is what made me buy a KX450 and quit riding the stock K5. I think Motorrad might back me up on this one after his last ride. 

[DoldGuy]

The mosquito fogger sounds like it needs crank seals too

[grywache]

If it needed crank seals would it be noticeably using bottom end oil? It doesn't seem to use any between changes. I'm mixing 32:1 but I've seen a lot of posts on here saying it should be more like 40:1

[grywache]

DoldGuy,

I read your posts on the best kx 500 mod and you really emphasized putting new crank seals in. I have now decided it is probably best to do a complete teardown this winter to "freshen things up." I was really trying to avoid it because of my lack of experience with 2-strokes but I should be able to do it with all the combined knowledge on this site. Thanks!

[blueoval]

grywache, I am new to working on 2 strokes (with the exception of the top end).  I am going to do the seals with the help and knowledge on this site, also.  I have a 2000 K5 that I recently purchased.  It suffered from lack of maintenance.  It seems to run real good at this moment - after working on it every night for a week.  When I took it for the first ride last weekend it would idle high, like it was running out of gas, after a stretch of high speed runs.  I took it home and took it apart "superficially."  Rejetted the carb, set the float (it was way too low), completely cleaned out the "pig pen" of an airbox, put a copper gasket in the cylinder between the pipe and cylinder (when I took the pipe off there was no gasket in there.........why, I don't know), put a new UNI airfilter in it, new pipe springs (they look so much better when clean and new), new throttle cable, grips, handle bars, hand guards, plug, wired in an ipod (modified the pad to hold a nano ipod and wired it so the plug in is just by the seat....I'll see how well it works out when listening to music while riding the bike), took the ugly stickers off,   Took it out for a ride yesterday and it didn't do that "lean thing" after a full throttle run.  Next, will be Maxxis IT desert tire (the Dunlop on it is trashed), new gas tank (the stock one is way to small and it leaks gas from around the neck as the guy before me cracked it somehow and tried to glue it together....it didn't work...imagine that), O ring chain and new sprockets, new seat (why did the 2000 come with a seat that has wierd "vinyl" on the sides....slide all over the place on that stupid seat), when the engine comes out I plan to have the frame powder coated.....etc....I want it trick and nice.  Will do a little bit at a time.  Boy, this still costs a lot of money, but it is not even in the same universe in costs when compared to sprint car racing!!!!!!!!  I don't know where all that came from...maybe because I am becoming obsessed with this K5 and this site!    ted

[DoldGuy]

DoldGuy,

I read your posts on the best kx 500 mod and you really emphasized putting new crank seals in. I have now decided it is probably best to do a complete teardown this winter to "freshen things up." I was really trying to avoid it because of my lack of experience with 2-strokes but I should be able to do it with all the combined knowledge on this site. Thanks!

If your power valves were that carboned up, I doubt that the previous owner gave the bottom end any attention (my 2001 was that way) and can almost assure you it could use the bearings & seals. I hope to have all of my parts in by next week & start the reassembly of my motor & will take pictures along the way so those interested can do their own as it is not too complicated for someone with a little mechanical knowledge. Will also post the results of the Vacuum/Leakdown test.
DoldGuy