Modern Vespa

Hi Everyone.

I am having some trouble with some upgrades I made to an ET2.

I have been around scooters for awhile, but I admit I am more familiar with vintage vespas.

Here's the problem:

The scoot starts, and I can get the bike to idle. After that, is where the trouble starts.

When turning the throttle with the engine under load, the bike does not go. Turn the throttle and the engine RPM's actually go down. Does not pick up and is slower than stock.

Here what's been done:

- Malossi 70cc Kit (No porting)
- Malossi straight cut primary gears
- Malossi Fly Clutch
- Malossi Clutch Bell
- Top Racing Variator w/ 5 gram rollers
- Pinasco Performance pipe with restrictor removed
- Dell'orto PHBG 19 Carburator. - Main Jet #75
- Slow Jet # 45
- Idle Jet # 60
- Needle #W9
- Slide #30

I am keeping the oil pump on it too.

I hope someone can help me understand why I am not getting any power out of the thing on acceleration.

Thanks,

Do you still have your original airbox on????
I would say that you have a too much gas, or you have a air leak in the carb plumbing.....
A number 9 needle is pretty big...What spot is the clip on? A 75 main jet is close....
I have a 17.5, with original airbox, needle clip on the second notch, and a 78 jet......

No airbox. Just a pod filter.

My needle is on the 2nd notch from the top.

Think I need a smaller needle?

The problem with doing a bunch of stuff and then trying to make it run is that you don't know which of the many things you did is making it not go.

From my own experience, albiet with Minarelli 2T engines, 4g rollers and 1500 rpm clutch springs work best for streetable 70cc bikes. I have found that changing the big spring in the clutch usually didn't do much either, and often slowed the bike down. Air cooled two strokes for the street just don't make enough horsepower to pull a lot of the mods that work with liquid cooled track bikes.

And it sounds like you are getting way too much air.

If you have the OEM airbox, you might want to try putting that back on and then taking out the little rubber restrictor where the air enters, if there is one, ride it before you do anything else, and you may find that it gets enough air with just that little change, and if you think it needs more air, you can then try adding a few small holes with a drill, one at a time, then riding it, and if that's good, try a little more. Malossi makes a neat little plug that costs about 50 cents each so your airbox looks nice after you've drilled it. Don't drill a bunch of holes all at once. Slowly give it more air and see how it acts.

You can either put the carb back the way it was except for the bigger main, or leave it the way it is now, and try this...
Take duct tape and start blocking the airflow around the pod. Then try to make it work. Usually when you block it down to about 10% open, the bike starts to work again.

Cool let me give these a ideas a shot.

I'll keep the bigger carb and try to use the stock airbox again.

I called my local shop and ordered a couple smaller needles just in case.

I would say the pod filter is letting too much air in and it bogs down. Try putting the original air box back on. May need to put a hole in one side to get a better air flow, or simply switch to a malossi red sponge. Try that and see if it helps. Those pod filters are like running no airbox at all. Not restrictive enough usually.