Reduced speed on 80 hp jet ski

[BuggsIslandlake]

I have a 1996 Yamaha 3 seater. When I first bought jetski the top speed was about 56 mph. for the last several years I have noticed that the speed has dropped significantly. Now the top speed is no more that 45-46. It runs well at any speed up to the max. It will pull tubes and even skiier but the top speed is just not there like it use to be. Jet ski only has 100 hours on it. I change plugs at the beginning of each season. I had thought that maybe the impeller waas messed up, but I don't know what would have caused that. I have always tried to stay away from shallow waters, etc. Thanks for any help.

 

[Jeff Walkowiak]

Re: Reduced speed on 80 hp jet ski

probably a worn impeller or the liner is going bad in the pump , look at the clearance between the edge of the impeller and the liner, it should be only a few thousands of an inch of daylight between the two, or your speedometer finally realized it was wrong because no 3 seater with 80 hp will go that fast even with a empty gas tank, so it could just be a problem with the guage

 

[hondaf12x]

Re: Reduced speed on 80 hp jet ski

i see by your other posts you are having problems with the reverse on this ski. if it is out of adjustment it may be blocking the jet thrust and slowing you down. take it to a dealer or get a service manual to adjust it properly.<br /><br /><br />Mike

 

[sloopy]

Re: Reduced speed on 80 hp jet ski

You probably sucked something in and wore the impeller lining. It is an old ski so you really can't ask for much more. I am having trouble believing you are getting more then 40.

 

[Jeff Walkowiak]

Re: Reduced speed on 80 hp jet ski

yamaha pumps corrode and swell up behind the stainless liner causing it to gradually wear down the impeller and loose pump preasure, usually a new pump liner housing and a new impeller will solve the problem, those nozzles also wear out real bad where they pivot and this will allow the nozzle to move further back when under a load from the pump, I suspect the nozzle is making contact with the reverse hood and causing it to stick, when the pump is off the nozzle is not being pushed in to the reverse hood and then it will go back to it's up position.

 

[waterinthefuel]

Re: Reduced speed on 80 hp jet ski

Wow, 56? According to what? Our bike is 75hp, a very light 2 seater (400lbs) and can do a GPS speed of 46, and that hasn't changed since new. It may be slower than it used to be, but I highly doubt your bike will do 56, in fact I'd be willing to put some money on it. The previous suggestions are good ones. These guys are sharp as a tack.