Synthetic Oil

Read and believe, the XJ650 is allergic to synthetic oil in the crankcase. Like a DA I'm learning the hard way, maybe one day I'll take up reading the directions. Meanwhile anyone know of an easy way to purge the synthetic oil out of the engine?
After adjusting valves, rebuilding petcock, cleaning and rebuilding carburetors to include making and installing a siphon tube in one, completely rebuilding front brakes, new speedometer cable, repairing tach, repairing corroded turn signal switch and starter button, and updating turn signal relay I did something really stupid, I changed the oill and filter and put in 100% synthetic oil.
Got out on the road and after a while noticed something strange, when accelerating in third and higher gears the speed did not seem to be advancing with the RPMs. Started off in first and second fine but in higher gears things just didn' t feel right. So, as is typical with me I decided to read the manual. Lo and behold that super duper and expensive synthetic oil can play havoc with the clutch. What I don't understand is why it didn't affect first and second gears more. Any ideas?

 

Lower Gearing lets the Engine need to do less work to get all the weight in motion.
Less friction required.

 

Not to rain on your parade, but if it's synthetic oil that is JASO rated, in other words made for MOTO's then you have bigger issues than an oil change. I have been running FULL synthetic motorcycle rated motor oil in the 550 with no issues and also in the XV750. Both wet clutches are not balking at the superior oil AT ALL. Of course they are also both adjusted correctly and are not worn.

You might consider a rebuild of your clutch, but on the other hand if you used Automotive Synthetic oil with friction modifiers your clutch may be just fine, AUTO oil is a big NO NO.

 

I love how everybody seemingly assumes a 30-year old, wet-plate clutch is gonna be just fine after sitting for dozens of years, half in and half out of whatever oil was in the bike when it got parked.

ALL of our bikes sat for some extended period of time, the low-mileage examples longer than the ones that got ridden more frequently. The half of the friction plates that weren't submerged dried out and became linoleum.

And then we come along and put the bike back in service and expect the clutch to perform as it did before it literally became a fossil. 'Tain't gonna.

Rebuild your clutch. New friction plates and springs; you can probably re-use the plain plates after cleaning them up with Scotchbrite. Anyone with a resurrected XJ will end up needing to eventually if it wasn't done as part of the recommissioning. It's not difficult: http://xjbikes.com/Forums/viewtopic/t=29541.html