Tahatsu 2005 9.8 A2 four stroke vibration under load and Air bubbling out prop

[Titaniumjoe]

I have a 2005 9.8 four stroke that idles smooth but under load vibrates a lot and bubbles out the prop on idle. The carb was recently rebuilt by outboard repair shop. I looked at the plugs and are burning well. I didn't check the gap though but will do tomorrow. I am not the original owner but have access to the paperwork that was done on it.

 

[pvanv]

If it's an A2, it was likely made in 2004... but as always, year is irrelevant for Tohatsu outboards.
When did this issue start? Has it been doing it as long as you have owned it? Do you always run the carb dry at the end of each and every day?
All Tohatsu motors 8 hp and up have through-hub exhaust, so they are SUPPOSED to bubble from the prop, although at slow speeds, they will also vent a lot of exhaust through the idle exhaust port.
All 4-stroke OBs make oil. If the crankcase level is even a hair high, you could have that symptom. That motor only holds about a pint and a half. Best to keep the dipstick level at about 3/4, rather than completely full. That way, if the level rises, it will not be above the full mark.

 

[Sea Rider]

If under load OB vibrates a lot, adjust tiller load by means of protruding bolt located at middle swivel bracket. Adjust CW to a point that when tiller is hand released, combo maintains a straight water course. This bolt always dissaranges, so adjust back from time to time.

Happy Boating

 

[pvanv]

If it's an A2, it was likely made in 2004... but as always, year is irrelevant for Tohatsu outboards.
When did this issue start? Has it been doing it as long as you have owned it? Do you always run the carb dry at the end of each and every day?
All Tohatsu motors 8 hp and up have through-hub exhaust, so they are SUPPOSED to bubble from the prop, although at slow speeds, they will also vent a lot of exhaust through the idle exhaust port.
All 4-stroke OBs make oil. If the crankcase level is even a hair high, you could have that symptom. That motor only holds about a pint and a half. Best to keep the dipstick level at about 3/4, rather than completely full. That way, if the level rises, it will not be above the full mark.

Of course, you could have a bent prop or prop shatf. That would vibrate a lot.