MDZ1rider wrote: If you're replacing the head, that, and the piston crowns are the only place you'll get any kind of build up in the combustion chamber. You can clean the piston tops while you have the head off.
I personally wouldn't use any kind of flushing agent in the crank case. You're really just thinning the oil with solvents. It's like running a very low viscosity oil. If you've got marginal bearings or seals, you'll find out the hard way. Plus, if there is any stuck crude, the flush may break it loose and circulate it thru your engine. I've never worked on a KZ650, but you should be able to remove the exhaust and drop the oil pan with the engine still in the frame. That where any sludge or loose parts will accumulate. A new oil pan gasket is about the same price as any of these engine flush additives. It's a 2 hour job and only requires basic tools. That the route I'd take if you want to clean your engine's bottom end.
Yes, absolutely! Never use an engine with flushing fluid in place of motor oil, no matter what it says on the side of the can of engine flush you might buy!
The "oil pan" (sump cover) can be removed with the exhaust off and the engine in the frame on the KZ650's - you must first remove the oil filter bolt and cover before removing the pan...and yes, this is the best thing to do to clean out the engine without taking it apart completely, as the sump is where the second worst amount of solid oil contaminants settle, after the oil filter housing, of course. Next worst place is the clutch housing, which can also be cleaned out easily with the engine in the frame, also for the cost of a new gasket and some cleaning solvent, shop towels (rags), a gasket removal spray and scrapers (avoid gouging the gasket mating surfaces while cleaning the old gasket off),
Happy wrenching!
