Suzuki DT115 1991 No top end power

[Tone]

Last week I bought a boat with this motor on. After hitting the water and traveling along @5000rpm for about 10 minutes Engine cut back to 4100ish and wouldnt go any higher. I checked the water seperator and drained anything in it. And away I went. Well today I have the same problem. I was running directly off a freshly filled tote tank, so fuel quality is good. I have replaced all fuel lines too. I was wondering if maybe one of the sensors is playing up? If the engine limiter is resticting the rpm, will it still restrict it under no load? Also I noticed that after stopping there was a little steam coming out the pee hole. Water is flowing thru the pee hole. Would a naffed impellor cause the rev limiter to come on?
Also if someone was able to tell me the correct spark plug type and gap setting please

 

[Tone]

Re: Suzuki DT115 1991 No top end power

I pulled off the water pump this morning and the impeller looks as thought it has been run without water at some stage maybe. As the lower face has severe scoring and some of the rubber has adhered to the bottom plate. New one on the way. Pulled the sparkplugs. Moist and brownish tinge. Seems ok. Fuel filter all clear.
One thing I noticed was when the drive shaft was engaged to the prop, it wasnt very easy to turn. Is there a preload on this? When not engaged both prop and drive shaft are very easy to turn

 

[Tone]

Re: Suzuki DT115 1991 No top end power

UPDATE:
I spent most of last night working on the motor. Redoing the water pump, unseizing bolts, retapping sheared bolts etc. This morning I pulled the carb. Looked down one of the throats and .....Low and behold...... There was a rubber plug down there. It was one of the ones you remove off the back plastic cover to access the adjustment screws. SO I did a complete strip down and reset float heights, and idle screws etc.
Just waiting on a couple of seals for the g/box and then on to the water. So hopefully have found the problem for the lack of revs and excessive fuel consumption. And lost respect for the marine tech who checked over the motor!

 

[deejaycee_2000]

Re: Suzuki DT115 1991 No top end power

mmmm sounds like you have it all sorted ...... same thing happened to me, one of the airbox screws went straight through the carb and got stuck in the reed valve ..... just glad that is where it stopped ......

 

[Tone]

Re: Suzuki DT115 1991 No top end power

Yeah It was good to nut it out. But the proof is in the pudding, so wont know for sure until the water test. Now just need to suck up to the missus for a cd/radio player. They seem to attact the trout so I am told

 

[deejaycee_2000]

Re: Suzuki DT115 1991 No top end power

hahahaha, well let me know how it runs, and enjoy .......