Modern Buddy

I have a 2009 Rattler 110 that has developed a sputtering running issue while accelerating. The scoot only has about 500 or so miles on it. I have drained and put in new non-ethanol gas, cleaned the carburetor throughout, installed a new fuel filter, cleaned both air filter elements, installed a new NGK BPR7HS plug and the air screw is set at 1-1/4 turns out. It kinda runs like the auto enricher/auto choke is on even when the scooter engine warms up a bit. I unplugged the auto choke and it didn't seem to correct the running issue. Any of you experienced scooter enthusiast/mechanics/tuners have a clue what the problem may be, in the interest of me further troubleshooting?

Did it happen gradually or all at once? Did you check the needle? Without making any other changes or adjustments, if you pull the whole airbox off & take the Rat for a ride, does the situation improve, get worse, or stay the same?

To the best of my recollection, it happened all at once. No, I didn't check the needle. But, I will do that for sure. I'll try the air box suggestion too. Is there supposed to be a paper and a foam filter in the air box? I was a little baffled by that, but maybe that's the way it is supposed to be. It seems a bit overkill to me, but maybe not. I am wondering if maybe a bad or malfunctioning auto bystarter. It's running way too rich for some reason. Thanks!

Yep, the airbox dual filters are OEM. All at once could be a vacuum leak of some sort, maybe even a cracked or broken reed petal (less likely). I suggest also checking for intake manifold leaks.

Need to inspect the air intake manifold and reed valve, so is it possible to do this without removing the engine hanger bar just above the air intake manifold? I'm thinking not, but maybe I'm wrong. Thanks!

fiddlefan wrote:Need to inspect the air intake manifold and reed valve, so is it possible to do this without removing the engine hanger bar just above the air intake manifold? I'm thinking not, but maybe I'm wrong. Thanks!

It's a tight fit but it can be done. I did it.

B02S4 wrote:

fiddlefan wrote:Need to inspect the air intake manifold and reed valve, so is it possible to do this without removing the engine hanger bar just above the air intake manifold? I'm thinking not, but maybe I'm wrong. Thanks!

It's a tight fit but it can be done. I did it.

Well, I've got the air intake manifold all loose, but can't seem to wiggle it out from under the engine hanger shaft without causing damage to the reed valve attached below the manifold. I have never messed with an engine hanger shaft before, but can the nut on the left side of the shaft be taken off and the shaft pulled/pushed to a point to get the air intake manifold off without causing damage?

Well now...I'll have to take a look. Maybe I missed something. More to follow.

B02S4 wrote:Well now...I'll have to take a look. Maybe I missed something. More to follow.

Never mind, I got it, finally. Once I separated the gaskets and base of the reed cage from the bottom of the air intake manifold, I was able to get the manifold and reed valve out. I feel like a complete idiot that I didn't think of that before. It came to me when I was looking at a parts diagram late last night. Anyway, I don't see anything damaged with the reed valve, as far as I can tell. I shined a light up through the reeds and saw no damage (chips or cracks). The gaskets look fine too. And I didn't see any damage to the intake manifold either. I am so stumped with this! I am wondering if it could be some sort of weak spark issue maybe????

Another possibility...the automatic fuel valve can fail, either by dumping raw fuel into the manifold via the vacuum line, or by keeping fuel from flowing due to a stiff diaphram. I replaced the fuel valve on mine with a manual valve.

Also, what is the fuel level in the float bowl? Some clear tubing connected to the drain and held vertically should tell you, provided that fuel is flowing.

I bet my bottom dollar it was a spark issue. just pulled my reeds and exhaust has so scoring but I can't find a new piston so I threw it back togetherand she ran good for one whole ride around the block, scratched my head for a minute and had lunch, went out and checked bolts and went around for a quick ride but right after it ran fin it started acting up and sputtering again. went to move the plug wire and it shocked me. so there is that