Running rough

[Barnzy]

I have a yamaha 2 stroke 225 which seems to be using excessive oil. We recently had the plugs changed and the motor ran very smoothly *****ing at 2200 rpm for about 4 hour then missed a little, as we were 8 miles from home we decided to run in and could only get 3800 rpm and the rpm would drop back to 1500 rpm then surge up to 3500 all the time missing. We pulled back to 1500 rpm and ran all the way back runnign rough at that speed and by the time we were back to the harbour the engine wouldnt run over 2000 rpm.

I have checked the plugs and they seem reasonable fouled for only 10 or so hours.

Does this appear to be an oiling up problem, can the engine be set to run leaner without doing any damage?

Could this also be a carb problem, when should carbs be replaced?

[Hamfisted]

More likely just a carb problem. How old is the motor? How long did it set up before using it? Yamaha carbed motors are notorious for clogged carb jets if they sit for more than a few weeks without being run. Yours is probably flooding. Do you notice excessive blue smoke like way too much oil? Yes the oil pump linkage is adjustable, it should sit nearly closed with the throttle at idle.


Mike.......... Miami, FL

[Ken]

Barnzy,
Yeah - what Hamfisted said.
If the motor has set up for any length of time, say a couple of months w/o being run, then the carbs are probably gummed up .
I would first do a shock treatment on the fuel system using a strong detergent like Seafoam or Yamaha RingFree (go see my post to "CLL" dated May 27, 2005).
If a shock treatment does not help, then remove all the jets of the carbs you can access w/o carb removal - you need a Yamaha shop manual to show you the jet location. Squirt Berryman's Chemtool into the jet orifices to clean out gum/varnish.
If jet cleaning does not help, then a carb removal and teardown, cleaning and kit install is in order.
If the above does not solve your problem, then I would suspect fuel pump(s). If they have not been replaced in five years, then you might consider it.
Good luck [img]smile.gif[/img] ,
Ken K

[Barnzy]

I changed the plugs and went out for a few hours *****ing this evening, ran smooth right away and sounded as though it was starting to miss a little after a couple of hours, ran very well back at 4500 rpm for 15 mins back to the dock, so thinking the high oil consumption seems to be clogging the plugs is the main problem. The motor is run almost every weekend year round so there shouldnt be any chance for gumming up.

The engine has approx 550 hrs

[jb123]

what year is the motor and did you check the oil linkage setting.