04 Yamaha 90 2-stroke

[fasternu]

My Yamaha 90 2 stroke has been flawless untill just recently. It has had an intermittent miss in it since the spring, and on a recent trip noticed that the tach would sometimes read twice the rpms than I know it was running. Seems like after it runs for a bit, the miss goes away and the tach runs normal again. Could this be caused by a weak battery? The battery is about 4-5 years old, or is it a sign of something more serious? Thanks in advance.

[fasternu]

marine man or boat-fixer, any ideas before I call the local dealer?

[boatfixer]

Does the miss and the tach issue coincide? I'd run it with a timing light hooked up to it (each cylinder if necesssary) and watch/listen. Light flickers or goes out when it misses then you know to go chasing down an ignition problem. I would also hook a volt meter up to it and see if your voltage stays normal. You can check the charging system and also see if you are loosing primary voltage.

Thats what I would do first, just to determine whether its an ignition or fuel issue. Wont cost you a thing except for gas to try this.