WildWillJAX
Seaman Apprentice
- Joined
- Oct 29, 2002
- Messages
- 36
This is a TECH question concerning specific 2 stroke operation as it applies to a 3 cylinder Mercury OB. I am familiar with basic 2 stoke operation of a single cylinder engine.
I have a 1989 3cyl 90hp 2 stroker Merc. For many months I have been experiencing "periods" of power loss. The problem usually begins after running at WOT for 3-5 minutes whereas the engine losses power from one cylinder. RPM's drop from 4,800 WOT to 2,000 WOT. After chugging along on 2 cylinders for a while the 3 rd cylinder will begin to fire intermittently and ultimately come back on line again only to shut down again after running for 3-5 minutes.
This has really turned into a head scratcher?
My question is this.......are EACH of the cylinders charged with fuel/air/oil mixture from a common crankcase area or is the crankcase compartmentalized with a space under each piston for individualized cylinder air/ fuel/oil mixtures with internal crankcase seals seperating them?
Does the "looping scavenge term" mean that air/fuel/oil mixtures from ALL carburetors combine within a common crankase from which each cylinder will be charged as the piston moves through it's intake portion at the bottom of each power stroke?
Can anyone clarify?
Thanks a lot.
Will
I have a 1989 3cyl 90hp 2 stroker Merc. For many months I have been experiencing "periods" of power loss. The problem usually begins after running at WOT for 3-5 minutes whereas the engine losses power from one cylinder. RPM's drop from 4,800 WOT to 2,000 WOT. After chugging along on 2 cylinders for a while the 3 rd cylinder will begin to fire intermittently and ultimately come back on line again only to shut down again after running for 3-5 minutes.
This has really turned into a head scratcher?
My question is this.......are EACH of the cylinders charged with fuel/air/oil mixture from a common crankcase area or is the crankcase compartmentalized with a space under each piston for individualized cylinder air/ fuel/oil mixtures with internal crankcase seals seperating them?
Does the "looping scavenge term" mean that air/fuel/oil mixtures from ALL carburetors combine within a common crankase from which each cylinder will be charged as the piston moves through it's intake portion at the bottom of each power stroke?
Can anyone clarify?
Thanks a lot.
Will