Two Stroke Motocross

Two Stroke Motocross Forum => Technical => Topic started by: socalcajun on July 12, 2010, 05:11:36 PM

Title: 02 KX250 Spittin black
Post by: socalcajun on July 12, 2010, 05:11:36 PM
(http://i871.photobucket.com/albums/ab278/socalcajun/IMAG0005.jpg)
(http://i871.photobucket.com/albums/ab278/socalcajun/IMAG0004.jpg)
(http://i871.photobucket.com/albums/ab278/socalcajun/IMAG0006.jpg)

My rear fender after each lap ridng last Saturday. It would not get into the band in any gear. It just bogged its way around. Bike starts but smokes lke crazy. Well way more than a 2 stroke should. I have been advised that its my crank seal. Honestly I can't dispute that one bit sounds about right for what I was experiencing.

Put your thinking caps on smoker heads. Any input will be appreciated.

Thanks,

Dan
Title: Re: 02 KX250 Spittin black
Post by: Coop on July 12, 2010, 05:46:19 PM
Did you lose transmission oil? Drain it and see. If it's smoking that much and puking that much oil, if it's the crank seal your transmission oil will be greatly diminished. If not check your compression.
Title: Re: 02 KX250 Spittin black
Post by: TMKIWI on July 12, 2010, 05:46:32 PM
Yep, that fender looks pretty black.
Check your gearbox level.
The latter kx's have a sight glass for the gearbox.
I take it you havnt changed the fuel mixture at all.
Could well be the crank seal.
Remove your right hand case and have a look.
You will need to remove the clutch and crank drive gear. Replace the seal behind the crank gear.
Title: Re: 02 KX250 Spittin black
Post by: Coop on July 12, 2010, 05:47:54 PM
Yep, that fender looks pretty black.
Check your gearbox level.
The latter kx's have a sight glass for the gearbox.
I take it you havnt changed the fuel mixture at all.
Could well be the crank seal.
Remove your right hand case and have a look.
You will need to remove the clutch and crank drive gear. Replace the seal behind the crank gear.

Unless the new models had a case change, on KX's you have to split the cases to change that seal. KX's have a lip and the seal installs from the inside of the case.
Title: Re: 02 KX250 Spittin black
Post by: TMKIWI on July 12, 2010, 06:15:11 PM
You well may be right  :)
I was actually meaning just to check.
Title: Re: 02 KX250 Spittin black
Post by: Coop on July 12, 2010, 07:43:14 PM
You well may be right  :)
I was actually meaning just to check.

I thought maybe you were, but wanted to clarify so socal was aware  :). I have owned and worked on a lot of KX's and I think that lip is a ridiculous design.
Title: Re: 02 KX250 Spittin black
Post by: socalcajun on July 12, 2010, 08:50:17 PM
Yeah crank case oil level went down.  Pretty good indicator of the seal then.  It's been a long time since I've wrenched like this. Guess I was in a bit of denile.  Let the fun begin. Thankfully it's a 2 stroke. :D

Thanks coop and tm. I appreciate your responses.
Title: Re: 02 KX250 Spittin black
Post by: Coop on July 13, 2010, 04:56:42 AM
Might as replace both crank seals and check and/or replace the crank bearings while you have it all apart. Probably a good idea to measure the piston and bore too and at least throw some new rings in for cheap insurance.
Title: Re: 02 KX250 Spittin black
Post by: socalcajun on July 13, 2010, 11:22:42 AM
Yeah coop that's solid advise.  Already have the list made out. Starting at the bottom and working my way up.
Title: Re: 02 KX250 Spittin black
Post by: scotty dog on July 13, 2010, 12:53:58 PM
Gee thats no good cajun, thats gonna cost ya some ridin time, cant have that now...
I'd replace all the tranny bearings and seals too, put a new ring in and pull the powervalve to bits and give er a good scrub up too while ya there
Title: Re: 02 KX250 Spittin black
Post by: Coop on July 13, 2010, 01:43:24 PM
...pull the powervalve to bits and give er a good scrub up too while ya there

Dangit, I knew I forgot to suggest something!  :D
Title: Re: 02 KX250 Spittin black
Post by: socalcajun on July 13, 2010, 03:27:03 PM
You bet the power valve is on the list.  Checked it the day of and it was as black with oil as the ace of spades.
Carb cleaner pretty good for that purpose?

Title: Re: 02 KX250 Spittin black
Post by: scotty dog on July 18, 2010, 01:42:08 PM
Yep carbie cleaner and a little wire brush ya get from ya local hardware store, they bout the size of a tooth brush. Good luck bro. ;D
Title: Re: 02 KX250 Spittin black
Post by: socalcajun on July 23, 2010, 04:31:09 PM
Well I have a turn on this story. I found a wrench of great reputation to crack my cases and replace the seals for 175 plus the cost of the seals. Not bad I think, so instead of me tearing into it for 6 months then maybe having to take it to have it put back together I'm going to have this cat to do it. Oh yeah since he has to tear it down anyway he'll replace my top end for the cost of the parts. I'l be riding again in no time. :D
Title: Re: 02 KX250 Spittin black
Post by: TMKIWI on July 23, 2010, 04:49:36 PM
Good job.
If your not comfortable doing it your self thats a cheap price to then know it will be done right.
Get it done and get out there riding  :)
Title: Re: 02 KX250 Spittin black
Post by: socalcajun on July 25, 2010, 03:40:14 PM
Good job.
If your not comfortable doing it your self thats a cheap price to then know it will be done right.
Get it done and get out there riding  :)

That is certainly the plan bro. I'm dying here. Way too much quality time iwith Mrs. cajun. :P ;D
Title: Re: 02 KX250 Spittin black
Post by: Coop on July 25, 2010, 04:25:31 PM
Nothing wrong with paying someone to do the work. Getting back riding is what is important!
Title: Re: 02 KX250 Spittin black
Post by: ford832 on July 25, 2010, 05:56:13 PM
Yep carbie cleaner and a little wire brush ya get from ya local hardware store, they bout the size of a tooth brush. Good luck bro. ;D

You need to be careful with that.Some PV's have a coating that will be damaged by a wire brush.At the very least the scratches will cause carbon to stick more readily and gum up quicker.Soak it in cleaner and use a soft cloth to remove the residue.
Title: Re: 02 KX250 Spittin black
Post by: redrider611 on July 26, 2010, 09:11:48 AM
Too bad you dont live near San Antonio. I would do it for free. Just pay for parts. I help people all the time around here.
Title: Re: 02 KX250 Spittin black
Post by: socalcajun on July 26, 2010, 03:14:19 PM
Yep carbie cleaner and a little wire brush ya get from ya local hardware store, they bout the size of a tooth brush. Good luck bro. ;D

You need to be careful with that.Some PV's have a coating that will be damaged by a wire brush.At the very least the scratches will cause carbon to stick more readily and gum up quicker.Soak it in cleaner and use a soft cloth to remove the residue.

Gotcha ford. Rather be safe than sorry that's for sure.  I will put my wire brushes away where I'll know where to find them ensuring that I won't find them for 6 months. ;D
Title: Re: 02 KX250 Spittin black
Post by: socalcajun on July 26, 2010, 03:15:29 PM
Too bad you dont live near San Antonio. I would do it for free. Just pay for parts. I help people all the time around here.

Thanks redrider611. Its cool that you help folks out.