2002 250hp ox66

My motor has 40 hours on her, and I have recently had all filters changed by the Yamaha Dealer ( I knew you would ask). Here's the problem which has occurred since day one: In idle the motor purrs. However, when I put it into gear (very slow forward), it sputters and vibrates. If I give it a little more gas, it purrs again. The real problem is that here on the Chesapeake Bay, we like to ***** for Stripers this time of year. To be successful, you have to go really really slow which, with my motor, means putting up with all the shaking, vibrating, etc. It doesn't seem like it's very good for the motor anyway. I heard that Yamaha has a v6 that shuts down two cylinders at slow speeds. Does mine do that? That would explain the roughness.

Thanks

[boats.net]

Yes that engine runs on 4 cylinders from idle to 1200 rpm's, above 1200 rpm's it runs on all 6 cylinders.

That does explain the roughness. Is there anything I can do keep it running on all six at idle forward?

Thanks for the reply

[boats.net]

No I'm afraid not.

Yes that engine runs on 4 cylinders from idle to 1200 rpm's, above 1200 rpm's it runs on all 6 cylinders.

What year did that start?

[boats.net]

In the OX66 engines it's only the models with "SX" model number, the VX run on all 6 cylinders.

In the OX66 engines it's only the models with "SX" model number, the VX run on all 6 cylinders.

So if I am reading this right--a 98 OX66 SX225 will also do the same thing?

Runs 4 cylinders to 1200 rpm and then lights all 6--- This would be great news to me.

How about a temp alarm coming on when in reverse for extended time--like 3 or 4 minutes? Suppose to be a new Yamaha powerhead and lower end. It pisses water out the side just fine at idle--strong stream. Maybe faulty temp sender?

Thanks for any help here.

H20SKE...

[boats.net]

No I believe the 1998 used model number S225, The SX started I think about 2000. I have never tried to run a motor that long in reverse but the water inlet is facing forward and if there is any turbulance from prop it may cause it to overheat.

So did the 98 225 ox66 saltwater series II cut out 2 cylinders at the low rpm as well?

After looking at the water intake I can see the issue with reverse for that extended time. (we were Halibut fishing and trying to save some gear).

H20SKE...

Thanks for the helpD