how do i know if my crank seal is needing replacement?

[trd_yota]

I have my 1991 KX 125 and it smokes.......a lot! but it is really jetted fat. right now i went down to a 168 main jet from the 175 that was in there. but i might still go down to a 162 or 158 since all it has is a pipe. it has a new topend but I'm not sure what the symptoms for bad crank seals are. im going to drain the clutch/ gear oil and i think the last time i remember it was all full not sure though (site glass was all black). plug is really oiled up, it looks like my trx250r's plug after a whole season of riding in glamis with fat jetting maybe worse. i know my 250r has good seals since it only smokes with old gas after being stored.so what can it be? any help would be cool thanks!

[stewart]

ive found crank seals  after 5 years old are hard and do not run as good

[trd_yota]

with a bad crank seel will it still smoke if i clear it out? i let it warm up then i went to full throttle for like 5 seconds and then when it idled back down it was only a hint of smoking. could it be more of a jetting problem since the bike is originally from las vegas, Nv? and since im in socal probably tis just too fat? and waht is the part number for the crank seal? that way i can see how much it will take me to fix it. thanks!

[Danger4u2]

Parts look up.
http://www.babbittsonline.com/pages/parts/viewbybrand/default.aspx

[kxracer]

It will get harder and harder to start as you will lose compression.

To replace is and engine out and stripped down.

Change the crank bearing while apart also.

[trd_yota]

ohh okay seems to me then its not the seals. because it starts on first or second kick. they were probably changed when they rebuilt it. i think then its my pilot jet that is supe rich since it there is always visible smoke. plus the power is good really good!