Modern Vespa

Hi,

I'm getting horrible gas mileage. It is so poor mileage that I'm only getting ~30 MPG.

I am a big guy at 200 pounds and drive only in city, up and down San Francisco hills.

It is a 2006 GT200, with 250 miles on the odometer. I bought it from my boss a little while ago when it had 86 miles on it. Since then, I have changed all fluids - brake, coolant, oil, gearbox oil. Tire pressure is fine so is the tread. It has never been dropped.

Any suggestions on what can be checked / done?

Thanks!

My guess is that the hills are the problem. Have you tried running a full tank on the flat to see what the difference in mileage might be?

I get pretty crappy mileage on my 125's if doing a lot of hill riding.

wait a bit and avarage it out at 2k miles, also fresh gas

Give it a new spark plug. There is a hot new plug out there.

Sounds like you've only filled it up once or twice. With the small tank in a scooter, one or two fill-ups (especially if they are partial fill-ups) is not going to give you anything close to an accurate assessment of the actual mileage. You need to average at least 4 or 5 fill-ups.

Shoudl hae also said that i changed the plug, too. I stuck in a NGK Iridium Laser Performance Spark Plug CR8EIB.

is this not hte right plug?

That plug should be fine.

If the apparent economy doesn't improve after averaging over a number of fill-ups, I'd pull the plug back out to check its color. If it's black and sooty, you're running rich for some reason.

Did you happen to change the air filter too? I understand a clogged filter can kill your mileage.

sure you're not running massively rich?

that's not normal, ever, for a GT200, even in break-in. I never got mileage like that on the hills of SF, ever, since this is where I first started riding...

No, i haven't done so. Guess the air filter will be next on the list. no idea whether i'm running rich. How would I know if i'm running rich? (and don't say check my pocket, because i'm running poor there.)

I have noticed that when i get started from a stop, that from 0-10 mph takes a bit then from 10-40 it really gets up and goes. I guess the torque curve is such that it doesn't kick in until whatever rpm 10mph corresponds to, with almost WOT.

Unless you're leaking fuel or the carb is horribly maladjusted, 30mpg is damn near impossible. More likely you are improperly calculating your fuel economy.(it's ok, it's a common mistake) If you do a quick search, you will find plenty of threads that speak about the proper way to do it. What method are you currently using?

How many ways are there to calculate MPG?

i can go fifty (50) miles on 1.75 gallons of gas.

50 / 1.75 = 28.6 --> ~ 30mpg, no?


thanks!

Read my post above regarding the spark plug. Also have someone follow you to see if you're blowing black, sooty smoke. That would indicate really, really rich.

yeah, black smoke = rich. plug's gonna be harder to really see the effects of running rich on a 4T, but yes, it'll show that a bit.

the other thing will be a lot of backfiring... though that could also be a timing issue.

when you take off does it sound like you've got high RPMs even though you're going slow..?

don't think there is black smoke, though i'll have someone follow me for a bit.

no backfiring.

yah, i would say that the RPMs should be enough to think i should be accelerating fairly strongly from stop, but am quite sluggish till ~10mph

thats somewhat normal tell 10mph, its the friction zone

there really isn't a "friction zone" per se on these things.

it's just the properties of the CVT starting up at low RPM.

Is it possible that the CVT belt is slipping to the point where you are not getting full motion or that the incorrect belt was installed and it will not travel high enough in the CVT ?

I am just trying to come up with ideas on why you could run fine, not smoke and have smooth riding but poor performance. What is the top speed you have taken the scooter too? I would think if it were slipping you would be able to smell the belt, Then again, if you were running at reduced speeds, fuel efficiency would be good.

Don't think it'd be the wrong belt. The original owner bought it from Vespa SF. No reasons it wouldn't be the stock belt. But the belt is many years old, at this point, almost five years. Is this a concern?

Fastest I've gone is 50 mph; i just tool around the city. Prior owner was at 65 on freeway, one time.

You should get 45-55 MPG on that scooter its not injected. the carbs get less MPG. like I said you need to ride it for at least 2k to find an average then you may find its ok.

Also top off the tank and run it dry. carry a 32oz bottle of gas with you then you'll know have far a tank will take you.

with that said I'll bet you get 130-150 miles on the tank of gas

no need to get fancy a gatorade bottle will work just fine for the test.

Actually, you can get in the 65-75 range. injection has very little to do with it, the right air/fuel mix does, as does your riding habits.

May be true, but I'll still bet he gets -130 -150 mpg on the tanks with all around riding. I don't think anything is wrong with the scooter its still in the run in range of miles. But he can always do a dyno run for the truth.

Maybe a jet went bad or cam lose?

The 05 GT I owned got terrible mileage.

On a long highway ride into the wind the bike got 33, yes 33MPG 2 fillups in a row.

She ran great. And she was lovely. Sold her.

Someone who knew of such things had played with the jets tho....

R

8)

Silly question but how are you checking your mileage? Do you fill up and run until the tank is near empty, record the fuel you put in and divide that into the miles you ridden?

In other words, not trusting the fuel gage

i'd start with a general tune up-- plug, air filter, fluids.

then i'd pull the carb and check it out. with only 250 mi in the span of 4 or so years, it's entirely possible that you've got a clogged jet, stuck needle, bad diaphram or some other such nonsense.

finally, i'd check the valves.

also, check your tire pressure.

after all of that, if the problem still persists then it's time to open up the trans and check those components. chances are, again, due to age that you may need some love there too.

best,
-greasy

Don't forget the bike isn't even broken in yet. All the parts in the engine are still tight. See how it is at 1000 miles and after it has had it's first service and valve clearances checked.

Yes, very distrusting of gauges, even in the car. I do the math of how much has to go back into the tank to fill it up to the point in the neck of the tank to which it was previously filled. That is the divisor i use with the miles in the numerator.

I'm with greasy, above.

Now this is why you don't like the low mile scooter

I have a GT200 and I think the tank is small, I do not get 150 miles on a tank-I might get 130 on a good day, I haven't checked recently. I ride fast most of the time, and long distances usually. I often go 70 miles rt just to get to/from a ride, and ride more on the ride, and I usually have to gas up again at some point or I will be pushing it home(no fun).
I am a good size person(okay fat), I go 50-65 mph average to get to and from rides on highways and country roadways and up and down hills. The hills definitely use up more gas.
Also, my bikes got a few thousand miles on it now, and it runs very differently than it did at first. The engine sounds different, the exhaust does, the acceleration is different, etc. The engine is louder, the exhaust throatier, etc. (I would have to go look at it, but I think I put 3,000 miles on it since I bought it used) it was past the breakin miles when I got it, so I can't compare for that for you. I dont' worry about mileage because it's so much more economical than a car anyway, and I ride for fun, not a commute.
If it's mechanically running well, I would wait a bit to see how it does on the flat and other types of terrain than hills to be sure it's not just the hills combined with the break-in period giving you low miles. I don't think you can ever expect optimum miles on mostly hilly terrain. Sally

The first tank that I filled up on my GTS got 54mpg. I since have gotten 66-70mpg. So, I think the first few fill ups could be lower due to break-in, like others have said. Wait a bit and see if they improve.

When I bought mine it had sat for about a year and a half. I found the oil in the air filter had drained to the bottom of the filter (bubble was full). I also changed the fuel right off the bat and added some Sea Foam to the tank. It runs great thanks to some help from Copper Dolphin and this forum.

Yours has sat longer so definitely would do what Greasy suggested.

A carb adjustment may be in the works, there is no doubt something is wrong. I suspect you are not calculating properly.

Now I know why your boss sold it.

I don't know I think I'm about 100-120 miles between fill ups. I tend to ride quite a bit on the freeway at full throttle though, which was why I assumed I got the low mpg.

but you're not quite 200 lbs, are ya?

Why haven't you taken it to a properly qualified Vespa repairman?

My GT gets 55-65 mpg regularly. Mine was bought in a similar fashion to yours sitting for 3 years with only 250 miles on it. The difference was the dealer who I got it from went over everything . I have had no problems except a sometimes rough idle which I adjusted and am rid of now that I'm using Seafoam every time I get gas. It now has 5000 miles on it.

Yeah I'd try doing a tankful on all flat ride and not push the speed over 55 and see what you get. Also my guage is a little tricky it says I have a 1/4 tank or more then the fuel light comes on.

I live in Colorado and deal with substantial hills 5 days a week and get approx 65 MPG. Also, I weigh 235 LBS.

It can't be break-in. Not 30mpg!

He's doing the right math for sure and knows what to look for when he measures, so that can't be it either. One correctly measured tank can't be that far off, so it won't take 2000 miles to know.

We don't know about tire pressure, but even if he's almost flat, it couldn't cause 30mpg.

The filter can't be it either, or the scoot wouldn't speed up like he says it does.

My money is on the carburetor or related issues, or the belt.

My ET4 gave crap MPG as well, now with 1500 miles on it i get about 50-60mpg , takes a wee while to settle in