Waverunner/2 Stroke motor help please

[Benjithx]

I posted this on Green hulk forums, but am not getting much help.


Hi guys,

My cousin came over with her/my uncle's 99 GP800X. Her and her boyfriend launched it and she rode it over to our dock. It apparently was not running correctly and she said it just wouldn't rev up all the way and was idling rough.

I am a four stroke quad guy, and thought that I could take a look at it in case it was something easy so they didn't have to take it in. My cousin said it had run like this before and that there friend told them to run a hotter plug. so they swapped the plugs and it seemingly ran better.

I was pretty certain they had not been maintaining the bike so my first idea was to look at whatever air cleaner setup to check for any restrictions/etc. As you guys already know that there is not much of an air cleaner/filter on them so that was probably not it.

Next I checked the plugs and they were a day old and very oily. My thoughts now are that there might be a fuel filter clog that is not allowing the proper mix.


Anyway I am new to these toys and thought I would run it by you guys for thoughts and troubleshooting ideas. I will now start searching

Thanks!!!

[NacsMXer]

The carbs probably need to be cleaned. The jets will get gummed up and you won't get all the power out of it. If they haven't been maintaining it, that would be the first thing I would look into.

[extremeblastr]

oil injected??? if not they may be mixing the fuel to rich

[Hondamaster5505]

im with extremeblastr

Most 2-stroke quads are premix. Don't know too much about waverunners though. If it's premix, empty the gas and mix it properly with a new plug and see what happens.

[Benjithx]

Yea Its oil injected

[Benjithx]

Also, it is bone stock.

[Hondamaster5505]

Originally posted by Benjithx
Also, it is bone stock.

well, I don't really know much about these things.

Do they ride it pretty hard? like on the throttle alot? If it's anything like 2-stroke quads, if you puts it around all day it's going to foul plugs like crazy and run like crap.

Maybe put a new plug in and ride it pretty hard, and see if it does the same thing.

It could be something very stupid. Check under it for seaweed that was sucked in. It happens to my waverunner all the time.

[Benjithx]

It is an 800cc twin. kind of looks like a big banshee mill

Tried new plugs and they got oil soaked almost right away.

I am thinking it has to be something with the gas oil mix...

would this be a yamaha xlt800?

[extremeblastr]

you may have an issue with your oil injection setup, i would see if there is an easy way to block off the oil injection and mix the gas yourself as i have never seen an oil injection setup that worked well lol

[imjaredandstuff]

I would block off the oil injection first and premix it to the correct gas/oil ratio. If that doesn't fix it, take the carb/s off and give them a good go through. I would bet blocking the oil injection off and premixing will fix the problem though, oil injection units are notoriously faulty.