Modern Buddy

Hey all you wise and sage Stella experts,
I picked up a 2008 2T Stella a few weeks ago. It had been out of use for a while, but fired up and I almost made it home before the scoot started dying or bogging in gear with throttle. I got home and replaced the plug, gear oil, rebuilt the carb, and did a compression test (150 psi)
After the rebuild it started with choke but died without, even when warmed up. I also noticed a little bit of gas blowing out the top of the carb/airbox when I was kicking it over. Now it's not even firing.
All the gaskets seem seated and correct, so what could be causing this?

Fouled plug? It doesn't take much.

I'll check that out.

Another question- http://www.scooterloungeonline.com/file ... rettor.jpg

Is gasket 16 the airbox to Reed block gasket? Because it looks different on that schematic than the one I installed there, which is this guy - http://www.scootermercato.com/4723698.jpg

These are the correct gaskets.

http://www.scootermercato.com/Scooter-P ... ets/472133

a bit of fuel blowing out the top of the stock carb is normal if the air filter is off.
just FYI

Ah OK. I just noticed the CDI ground wire was frayed and split, reconnected that I can start under choke + throttle, but still no idle. There are two loose wires back there and looks like someone might have replaced the CDI with a Ducati.

So in summary,

I've drained the old gas
Drained gear oil, no gas smell or gas present in it
Checked the Killswitch for malfunction
Switched the plug out for a new one
Reconnected a frayed CDI ground wire
Rebuilt carb with fresh gaskets and needle
Jets are flushed and clean, carb was soaked and cleaned
Mixture screw is 2.5 turns out

And I'm back to where I started. It will idle only with choke and bogs down/dies under throttle in gear, but revs fine when it's not.

I'm starting to think it's the CDI? I just noticed it's a Ducati, which means someone replaced the old one once. And there are 2 random wires not connected to anything back there.

The two wires in question

It will idle only with choke

Doesn't sound like an electrical issue if the choke / no choke impacts how it behaves, as does if its under load or not. Sounds more like either fuel flow or an air leak into the crankcase.

Are you sure your fuel flow to the float bowl is ok ? If you take the fuel line off at the carb does gas gush from it when the petcock is open? If you give it throttle when out of gear, what impact does the partial choke or full choke have? Same choke test when its in gear under load. Be sure your fuel tank is vented, run these tests with the fue cap on but not sealed completely to verify its not vaccuume buildup in the fuel tank .

Be careful to not run it too much until resolved - the lean mix can cause a seize.

Running with cap loose had no impact. Fuel flowed out of the gas line when I drained the old fuel out, but now that I think about it, the flow wasn't exactly that strong. Draining it all took a good long time. I'll check this out next

I also put in brand new jets just because this whole thing feels so much like a fuel feed issue. Do these petcocks usually get restricted that badly?

Do these petcocks usually get restricted that badly?

Well, it shouldn't actually Gush out, but the flow should be a decent dribble. Was the volume of flow different on 'reserve' vs the regular 'on' position?

For your idle setting, have you adjusted the rear-facing idle screw to the strongest rpm? (This should only be an idle effecting adjustment.)

Also while you're doing stuff, be sure the exhaust clamp is tight where the pipe connects to the stub from the engine, sounds odd, but an air leak at the exhaust clamp can make for over heat conditions.

By rear facing idle screw do you mean the mixture screw? I've tried adjusting that one within 1-4 turns out without success. The actual idle screw is probably a little higher than normal.

I'll check the exhaust clamp too

By rear facing idle screw do you mean the mixture screw? I've tried adjusting that one within 1-4 turns out without success.

Yes, that one in the rear (not top) of the carb, the one you access from the rear. When new, the round access hole thru the sheet metal is blocked off by a plastic plug. Adjusting it should have a seriously significant impact on idle.

When you rebuilt the carb did you do a full rebuild? Take it all the way apart, replace the float and needle etc?

Yup, I got a full rebuild kit plus new jets and needle.

OK, you've eliminated the possibility of a fuel blockage to the carb. You also have it running on choke, so that says either an air leak into the crankcase or carb issue.

If adjusting the idle mix screw has no effect, that's definitely an issue that needs resolved because it should have a major effect on the idle. In getting new jets, make sure the new ones are the same as what came out, can you list what # the new ones you installed were? Also make sure you use the correct carb base gasket because you don't want to block off the 2T oil flow coming from the auto-lube - some incorrect gaskets will do that. See the previous gasket advise.

Call the previous owner and find out if they modified either the exhaust, air filter or jets, as either of these can make a difference.