[ryanbgb22]

Just bought an SLX, had it out for the first time last week and was topping out at 54 according to the mfd. It had older looking plugs, but could that be causing me to lose almost 10mph from where I should be? I checked compression prior to buying, and got 132, 132, 123 from front to back. I was told that that compression is well within reason and would be fine. Any input would be great.

 

[DrSunny]

Same Problem.

Have you had any luck with this? I'm having the same problem. I bought a '99 SLX and have had a couple problems but I think they're all related to bad spark plugs. She's temperamental starting up and max's around 55mph as measured from my buddy's ski.

Have you been pre-mixing your fuel or just using the oil injector?

 

[fedorov5549]

What are the rpms? Try some treatment in the fuel to free up the rings and clean up your engine. I know yamaha makes some good stuff for this. Could be the high speed adjusters on the carbs could be worked a little to get some speed but I think you are about maxed. Check the impeller also.