Yamaha V6 Excel LH Engine sputters

[Kowalchuk]

Hey all, looking for a little help here. Recently my dad gave me his old boat. It is an 87 Hydrostream Valero with i think an 87 Yahama V6 Excel 225HP 2Stroke on it. I could be wrong on the exact year. He kept the boat in good shape, and its in good condition for its age. The boat sat for ~7years before i got it.

After we went and picked it up from where it was stored. We took it back to my shop cleaned it up put some fresh gas in it and it started up.

Thinking that everything was good on it we took it to the lake and we went for a rip. The boat seemed to work perfectly for ~10-15mins. Then it would start to sputter around 4000rpm and and drop 3-500rpm then go back up.

Thinking it was dirty carbs i took it to a local shop and i got them to clean the carbs.

We then took the boat out again and the boat did exactly the same thing. It would work fine for 10mins then start to sputter around 4000rpm.

Any help would be Greatly appreciated.

 

[Kowalchuk]

I should also mention before we took it to the boat shop we took it to the house and we pulled one spark plug cap off at a time. It seemed like 3 out of the 6 cylinders affected the engine idle.

I asked the shop to check spark and they said it was all good.

 

[99yam40]

check to see if the alarm system works properly, so you can see if it is going into rpm reduction

 

[Kowalchuk]

Good idea I'll check that. I know my alarm system for my oil low level works. But I didn't check the other ones. Maybe it's over heating And causing a reduction in rpm.

 

[Tinkertoy250]

Good idea I'll check that. I know my alarm system for my oil low level works. But I didn't check the other ones. Maybe it's over heating And causing a reduction in rpm.

if you still have this motor and need any help or parts please let me know. I have owned an excel since new. they are wonderful engines properly maintained

 

[crazy charlie]

see if it has an o2 sensor.My year 2000 does. within the housing there is usually carbon build up that needs to be cleaned .There is also a pin shaped like a small barbell that needs to have the center cleaned out with a small drill bit.Post back.charlie