Here I am again/still having to work on this piece of junk.

Ok, It starts and idles just fine... But 'most' of the time I have a lot of hesitation and loose power when i step on the gas. Every once in a while it will 'kick in' and run pretty good for a while, sometimes even for a day or two.

To me it seems like it's starving for fuel. So I have tried a new fuel filter and fuel lines, that didn't help.

What I'm thnking is the fuel pump might be bad. Can a fuel pump be "going bad"? Or will it just work or not work?

I'm just guessing here but,
Usually when we have problems at top end, it is one of 3 things (Usually)
A faulty coil wire or CDI
Air leak at the manifold or vacuum lines or
junk in the main jet. (fuel flow)
There are other things that will cause this but I find that is is usually one of these.
Can you slowly get to top end without pressing hard on the gas if you nurse it there?
When you stomp on it, does it feel like some 400 pounder is hanging on to the back of your buggy or does it spit and sputter?
Let us know and I'm sure someone here will have some more ideas for you.
Good luck!

Thanks Kidinme...

I can get it to almost top speed if I am light on the gas. But when I stomp on it it feels like I'm im deep sand. No spitting or sputtering, just a big loss in power. It does this regardless RPMs. Also, even when I am light on the gas it sill only go to about 4,000 rpm. Should be able to get 6,000+

What should the spark plug gap be on this thing? I didn't have any reference when i changed them out, so we just took a guess.

Hi,im running ngk b7es at .032, ive never had a problem with these plugs. The ngk no. for iridium is bpr6eix, i here a lot of good things about iridium plugs,a little spendy 8.00 last time i checked. Irdium is very hard, ive read they will run three times longer than platiums,as far as a performance advantage,the kernal is not any larger than a regular plug,just last longer. Sounds to me like your running out of fuel check your float levels. By the way 650 sandspider if well maintained is one of the most reliable buggy's made to date by anyone. Hope this helps Ghost

My buggy is an EFI, no floats. It does seem like a shortage of fuel though.
The plugs I put in were just an Autolite 63 that say they have a copper core. I have them gapped at .76mm/.030".

Plumb a gauge in the fuel line and see what your fuel presure is, darnd if I can remember what it is suposto be but Van or one of the tech guys should help you out. Sounds to me your fuel presure regulator might be bypassing too much fuel back to the tank. Just a thought.

W.C.

I have the same type buggy not EFI though and had the same issue. Mine turned out to be a plugged main jet and it happens whenever I get in the deep wet mud. I'm thinking of changing out to a sponge type filter like what's on a dirt bike.

I've seen a couple guys saying "maybe a clogged jet"... I din't have jets, but, could a clogged Injector create the same symptoms?

Pull injectors should niece very fine spray, check fuel pressure, remove air cleaner,make sure throttle body butterfly is opening to wot.