Jetting or bad crank seal?

I have been having issues getting my 04 cr125 jetted properly, if I let it idle for 30 seconds it fouls the plug, it pulls pretty well from closed to a quarter throttle with a 37.5 pilot jet. (Which is one step leaner then stock). Air screw is out about 2.5 turns, when I try to step down to 35 pilot it runs like crap no matter the air screw setting. My question is does this seem like a jetting issue or another problem to make it seem rich. My bike dumps out what seems to be white smoke, especially after it idles for more than 10 seconds. I have a video of the smoke, any suggestions or help would be greatly appreciated!
Thank you!

 

 

Edit: here is the video, sorry for the poor quality was taken with my phone! 

 

th_IMG_0341_zps7a481f5a.jpg

Edited by standbyguy13

Yes, crank seals need replacing.

Thank you for the fast response! Looking at seal kits now. Is a counter shaft seal the same thing as a crank seal? :confused:  Just want to verify before ordering. 

If the oil smells like trans oil, it's your CRANK seals

If the oil smells like old socks, it's bad gas

If the oil smells like sugar, it's not smoke, it's vapor, and you have a blown head gasket.

If your trans oil is is white, you have a bad water pump seal.

Counter shaft seal has nothing to do with your problem, that's outside of the motor and in the trans only.

 

If the bike smokes BADLY under load, it's 90% the crank seals

Thank you for the useful info! Hopefully I will have time this week to replace my crank seals. I will let you know how it runs after!

Holy crap, my bike is doing the EXACT same thing.  Bought it used and it ran great the first 20-30 hours, then all of a sudden it started to bog unless I wound the hell out of it, and it keeps fouling plugs.  

 

I couldn't understand why it felt like it was running lean, but the plug is wet after 10 minutes of riding.  

 

 

Bought mine used as well, rode well when I test rode it, then I brought it home, and started to act up. Replaced the carb slide as it was cracked, still running like crap, hopefully the new seal will be the cure!

Okay now I'm stumped. Made a leak down tester, and my bike has been sitting at 7 psi, and only leaked about .2 psi over 10 min. I'm really stumped. Already 2 steps lower on the pilot than what the jetting graph recommends in my service manual. Why am I fouling plugs after letting it warm up for just 30 seconds!? I'm stumped.

Okay now I'm stumped. Made a leak down tester, and my bike has been sitting at 7 psi, and only leaked about .2 psi over 10 min. I'm really stumped. Already 2 steps lower on the pilot than what the jetting graph recommends in my service manual. Why am I fouling plugs after letting it warm up for just 30 seconds!? I'm stumped.

 7 psi isn't going to tell you anything !!!

 

You need to be above 85psi and then time it. 

 

IT'S NOT THE JETTING QUIT F'ING  WITH IT

Edited by Krannie

85 psi for a crank seal leakdown test?!? I'm almost positive it is about 7 psi

8 psi and for 10 mins with no more than 2- 3 psi loss- in my opinion

Thanks for clarifying! So I guess at this point I'll keep an eye on my crank case fluid. If that stays the same height then I guess I'll just fiddle with different 2 stroke oil.

If I still have a problem fouling plugs I'll try to lean it out a bit on the pilot and fine tune the air screw. After looking up a lot of stuff about jetting this bike it seems the manual is way off for jetting specs.

Air screw is for idle only

Pilot jet determines idle and 1/16 throttle

Needle is 1/16 to 7/16

Main is above that'

 

You determine lean or rich by how it runs at a certain throttle opening, not rpm

 

If you are fouling plugs in 30 min, you are sucking trans oil, or mixing 10:1, or your main jet is 5 sizes too big.

 

Your description lends towards sucking trans oil. 

 

When you do a leak down test, you should be spraying the areas that can leak with windex or similar to look for bubbles.

The plugs only fouls while not under load. Usually after I let it idle for more than 10 seconds.

It's seals, time to tear it down and do the bearings & seals on the crank. Check the other internals while your there just to be sure (think lower end rebuild). In therory you can replace crank seals w/o tearing the whole thing down, but I've never had any luck doing it.   

Edited by GSjimmy

Looks like I have myself a winter project. Thanks for the replies

Okay now I'm stumped. Made a leak down tester, and my bike has been sitting at 7 psi, and only leaked about .2 psi over 10 min. I'm really stumped. Already 2 steps lower on the pilot than what the jetting graph recommends in my service manual. Why am I fouling plugs after letting it warm up for just 30 seconds!? I'm stumped.

Why is everyone saying crank seals when it passed the leak down test? My 06 is doing the same thing...

The 04 is funny as hell with jetting, I'm trying to figure mine out right now. On a full rebuild, I am running a 32.5 pilot and 400 main with the JD jetting red needle in 2nd clip.

Hay guys could u change your trans fluid and put bean oil in and run the motor, if the seal is bad you would smell it know for sure it was sucking trans oil?

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