DRZ400S - Up in Smoke!

[netdoggie]

My 2004 DRZ400S has been weeping engine oil out the airbox this summer.  I thought I might have overfilled it, and think I did have it overfilled at one point.....but siphoned some oil back out when I discovered the error.  Been difficult to start for the past month too, especially when cold, and has been running rough.  I figured I needed to remove the carb and clean it out, but haven't done that yet.  Then yesterday I was heading out for a short ride and a couple miles out of the driveway it hiccupped a few times and quit.  Looking behind me, I saw a big cloud of blue smoke following me.  On attempt to restart, engine would turn over (with more blue smoke out the tailpipe) but not fire.  So walked home whilst being eaten by deerflies.  I'm not afraid to tear into the engine, but while I'm a competent wrench-turner I haven't worked on this engine before.  Any guidance on how to identify the problem?

[Gary in NJ]

Smell your oil (really) and see if it smells like fuel. Probably and failed petcock. 

[netdoggie]

7 hours ago, Gary in NJ said:

Smell your oil (really) and see if it smells like fuel. Probably and failed petcock. 

Thanks Gary.  I sniffed the dipstick (uncomfortable with that phrasing) and couldn't detect any gas smell.  But I think I'll drain the oil and see what I've got as a next step.

[bumtarder]

The oil may also be overfilled.Do you know how to check the oil level correctly?

[netdoggie]

11 hours ago, bumtarder said:

The oil may also be overfilled.Do you know how to check the oil level correctly?

Yes, although I haven't gotten it right in the past and definitely have overfilled it in the past.  Pretty sure that wasn't the case recently.

[DPete]

Cut the oil filter apart, see what's in it, may give a clue as to what happened

[netdoggie]

12 hours ago, DPete said:

Cut the oil filter apart, see what's in it, may give a clue as to what happened

Also good advice, and will do.

[netdoggie]

Just a followup.....  I drained the oil and it WAS loaded up with gas.  So pretty sure I understand how that happened - carb needs cleaning as the float valve was likely sticking open.  And I have an Acerbis tank that does not have the vacuum shutoff petcock.  I haven't been too diligent about shutting the gas off (but I sure will be in the future).  Next step is a compression check and get the carb off to clean it up.  Thanks all for the advice!

[bumtarder]

If your Mikuni carb is that old it is long overdue for a complete overhaul. Mikuni offers a Suzuki bsr36 OEM kit. You get everything except jets which they sell separately. The float needle seat has a o-ring under it that turns brittle and deteriorates and causes the fuel leak you have. There is a good article about the repair in the faq forum.

[netdoggie]

1 hour ago, bumtarder said:

If your Mikuni carb is that old it is long overdue for a complete overhaul. Mikuni offers a Suzuki bsr36 OEM kit. You get everything except jets which they sell separately. The float needle seat has a o-ring under it that turns brittle and deteriorates and causes the fuel leak you have. There is a good article about the repair in the faq forum.

Probably makes sense since I'll have the carb out anyway.  I also haven't done the 3x3 mod to this bike and this might be the time for that as well.  ty!

[bumtarder]

And the JD jet kit to go with it.If you have access to a ultrasonic cleaner that would be best to give it a deep clean.

[shuswap1]

Don't overlook that o-ring under the float needle valve seat, that hardens and leaks far more often than the needle tip or the needle sticking. There is a reference to this in the FAQ

[netdoggie]

All, tysm for the great guidance!  Got the gassy oil out of the crankcase (which presented a disposal challenge) and completed a carb rebuild last weekend.  Since I was working on the carb I decided to do the 3x3 mod and rejet with a JD Jets kit.  All this went smoothly, I got it back together and it runs like a champ!  The 3x3 mod is the shit - should have done it sooner.  So I'm back to having fun instead of fixing.  (I recently acquired an 88 CR250 which looks like will fulfill my need to fix things for a while.)