ju1ce

(I am new here!) I have a 2007 Yamaha VX Base model. (Over 600 hours)

This year, I noticed it did not seem to want to go about 30mph or 6,500 rpm.
(It will rev to max rpm out of the water. And starts and seems to run ok.)

Plugs: I went ahead and replaced the plugs, they didn't look too bad (But have not been done in at least 2 years)

Air FIlter: I pulled the air filter. It was not wet, but was pretty dirty, and matted looking. (So I ordered a new one)

Is it possible for those things to cause a 10 to 15 mph drop?

Ernest T

Yes. Plugs alone could do it easily. The small plugs on these engines foul easily, and you cannot always look at the plug and tell. Check the oil level......it is easy to overfill, and will also cause the engine to bog. Over filling the oil will also foul the air filter. Even a little oil on the air filter will significantly reduce performance. Best replacement air filter is an R&D brand, which is cheaper, works better, and is washable unlike the OEM filter.

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2008 Yamaha FX HO Cruiser
2010 Hurricane Sundeck 2100

ju1ce

Thanks. Yeah, I bought an R&D Filter. Should be here soon.

I REALLY hope my performance increases.

Any other maintenance suggestions or DIY stuff that could help? (Throttle Body Cleaning, etc.)

jetboater

Some fuel injector cleaner in the gas tank would clean out any gunk that's accumulated--- i do it once or twice a year and i can really tell the difference.

Ernest T

+1 Run some injector cleaner through at least once per year. Yamaha Ring Free Plus is the best (I run it in every tank). A Techron based cleaner is 2nd choice. No need to do anything to the throttle bodies, but if the ski sits for long periods the injectors can get clogged. In some cases you have to remove and clean them (best done by a professional with an injector flushing machine).

If you are still having problems, check the compression next. On your ski with 600 hours, you might want to check the valve clearances if the compression is OK. Most of them will still be in spec. at 1000 hours, but you can see carbon buildup earlier depending on how it was maintained, fuel used, etc., and that can also cause performance decrease.

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2008 Yamaha FX HO Cruiser
2010 Hurricane Sundeck 2100