2007 150 Speedster SCIC lost 500 rpm

[Russ Brown]

2007 150 Speedster SCIC. Mods include: 4" intake, external intercooler with strainer, SS wear ring, 19 Solas, Riva Gen II wheel. Supercharger has been rebuilt twice. Last Aug. went with the above wheel, which pushed the boat to 8,000 rpm consistantly.

This year, have run through 4 tanks of gas, and struggling to get 7,500 rpm.

Prop and pump assy all OK.

New plugs, after 2 tanks. Still look excellent.

Boat shows 96 hours, however actual is closer to 300. Boat has always ran perfect.

Oil was slightly high, < 1/2 quart too much over winter change. Removed after 1 tank of gas. No impact.

Yesterday, boat suddently picked up major miss. After 2 minutes, this stopped. Has never done this prior or since.

Planning to check compression this week.

Anyone have any ideas? I am thinking fuel filter, or injectors need to be cleaned but I feel like I am totally guessing. Any thoughts appreciated.


Russ

 

[Dr Honda]

I'd start with the basics since you are mod'ed.

What do the spark plugs look like, and what's the compression?


How much extra boost are you running, and did you re-map the fuel for the extra air? Also, since you have a better interecooler, you have more dense air. (also needing more fuel)


One more thought. Check the valve clearance. In the dirt-bike world, of modern, high revving 4-strokes... we beat the hard coat off the valve faces, and the clearance starts to close up. When that happens, it looses power, and becomes hard to start. (but most aren't fuel injected) Shortly after those symptoms show up... you break a valve, and eat the top end.


Let us know what you find.

 

[Russ Brown]

Dirty fuel filter

Removed fuel filter and it was extremely dirty. Ordered new. Re install and try this weekend. Will advise.