Here's a quote summing up the problems:Here's a couple of threads on the topic:Originally Posted by Lapine Rider BurgmanUSA Supporter
I own a 2004 Suzuki Burgman AN400 too. If you read through these two threads you’ll see a number of AN400 owners believe the crankcase breather plumbing can deliver enough oil to the intake tract cause problems if the engine speed and engine load are high enough for long enough.
Some solutions have been suggested as well as I’ve made a couple of posts although it does not appear to be a problem for my scoot with the speeds / loads I experience.
The AN400 crankcase vents to the intake plenum and uses the typical closed system, but does not appear to have a PCV valve or any other inline air/oil separator.
It does have the usual PAIR system with solenoid so I suppose that could be interacting with the crankcase breather plumbing at high speed / loads as the both feed into the intake plenum.
Some people have had enough oil loss (and quickly enough) to seize the engine and have it re & re’d by Suzuki under warranty!
I’m guessing the crankcase is ejecting the oil. I figure the simplest way to confirm this would be to plumb an external crankcase breather and monitor it. That way (at the least) you would be assured of narrowing the fault down to either intake vacuum or crankcase puking. I'd bet it's crankcase puking.
I’ve thought of few methods that could be tried separately or together:
- Venting the crankcase to the atmosphere with an old style crankcase breather.
- Increasing the diameter of the tubing from the crankcase to the intake in the hopes the oil would return before reaching the intake.
- Increasing the length of the tubing from the crankcase to the intake and/or making a “drip loop” in hopes the oil would return before reaching the intake.
- Installing an empty in-line oil reserve canister that would carry the excess oil until such time as conditions allowed it to drain back to the crankcase.
- Something similar to what of "kfir" proposes only I would do it by modifying an old style crankcase breather or at the least using the material as found in the old style crankcase breathers.
- Disabling PAIR
I’m going to watch my oil level really closely and the next time I clean my air filter I'll have to look for excess oil. I believe I saw a bit, but I put it down to over-oiling the foamy.
Has anyone had this happen on a modern motorcycle engine and if so what steps did you take to correct it?
Here is an interesting thread on how a Jaguar V-12 owner built and installed a PCV Air/Oil Separator: http://bernardembden.com/xjs/pcvfilter/index.htm