problem with Yamaha 115

[prolineez]

I have a 2005 Yamaha 115 hp 2 stroke. After running the motor for about 15-20 minutes at 4000-4600 rpm the rpm's drop down to 3600-3800, then back up to 4000 then back down again. At full throttle I normally get 5600. When the problem begins I get only about 4200- 4600. I had a mechanic check the motor and he says it is not fuel related, but it is an ignition problem. He thought it was the cdi unit so I replaced that, and I still have the same problem. He now says it is something called the pulser plate or coil pulser, I'm not sure of the name. The price for the part is about $350.00 plus 3 hrs. labor. Before I spend more money I would like to get some info about this part or if anyone has an answer to this problem I would like to hear from you.
I hope rodbolt is still on this site. Thanks

 

[rob711]

Re: problem with Yamaha 115

sounds electrical...but. i'd suggest find a different mechanic..first he said the cdi..that was wrong, now the pulse thingamabob..what happens when u replace that and the problem remains..just a idea but did u try squeezing the primer bulb when the rpms dropped?

 

[Ray Neudecker]

Re: problem with Yamaha 115

Sounds like a fuel restriction problem to me. How is he determing the parts are supposedly bad? A new tech is definitely in order.

 

[fldiver1]

Re: problem with Yamaha 115

I know this is going to sound very simple. Mine was doing the same thing. Friend of mine is a Yammie tech and said to check the plugs. Looked fine to me but he said to change them anyway. Seems that one of the resistors was breaking down in one plug. Wouldnt get over about 4000 or so rpm on that motor before, now will run fine. Try the plugs first, cheapest and quickest possibility.