Modern Vespa

I'm back on the road, runs okish, But it's a bit slow to pull off from lights, lots of power as accelerate though, I read a thread that I should change drive belt and rollers, But the air box bolts are very rusty and I cannot crack them, the only options I can see is too keep drenching them in penetrating oil, though their are two exposed sections of thread on each bolt that are hard to get too, or dremmel off the air filter plastic box, then see if I can crack bolts with vice grips and replace air box, have cleaned carb, done oil changes and new air filter, will try new plug too.
Engine is 6000k, low miles, probably last run 2004, probably never had belt change, so definitely on my to do list.
Is stock roller weight on 125 leader engine 9 or 10g? Thread I read advised on replacing with 9.5g weights.

My ET4 150 had 10g rollers and I put 9.3g in when replacing the belt. I think it did give a little pep without really robbing top end speed.

Get replacement guide shoes along with the rollers and don't forget to get a new variator nut. I got the holder tool and am glad I did, but I've seen others use screwdrivers to hold things in place.

On the air box, I'd be hesitant to cut it too. Are you talking about on the front of the transmission cover, or the one above with the air filter? It's tight, but the bigger one can stay in place I think. At least on the 150. Good luck with it all!

If you take the wheel right off and remove the outside of the airbox you can get to the retaining bolts more easily.

Looks like 8.7g on the 125s.

Standard Roller Weights

Carb could still be working out some gunk... but yes, I'd suspect the rollers and belt/CVT/clutch are suffering from moisture/debris/corrosion, if the bolts to the airbox are that far gone. I've heard of tales of people riding the brakes in place to get the clutch bell heated up to get it back into shape (this sounds dangerous), but if the CVT cover isn't removable, 500 hard, hot miles might break your rollers free and slowly make the lower end workable. If you have decent top end speed, at least the variator is moving- that's a big plus.

Seized bolts on the airbox are pretty common in places where they use salt on the roads in winter, or seaside locales. That doesn't mean anything inside the transmission has been corroded though.

Did clean walbro carb, but occasionly slow/hard to start,, may have another go at it, mostly starts first time, fitted new fuel tap / pump, and lines. Ideally would like new diaphragm and seals as, 20 yes old, and guessing a diagphram with hardening rubber would effect low speed., If I can find parts.
Charging at 14.5 v with revs.
Did manage to crack front airbox screw, by using a flat head with vice grips on handle to get bit of extra torque, the back one seam to be rust welded into clip on rear mudgaurd, really Piaggio, I mean really!!!
Will take off rear wheel and hacksaw off rear of screw and drill out I guess, unless by some miracle wd40 frees it up with a bit of soak, cheers.

I have two walbro carbs, I have made the assumption they were same model, but maybe not, have been looking at one in parts box, it has no numbers just walbro wvf and Japan on it, this is off the low milage 2001 engine currently in Scooter, however I can not crack the accelerator pump screw which is rusty and seized, and pump arm is stiff and not springy. I therefore fitted the older carb1999 engine? with diagphram from newer carb, it has two holes of different sizes, on the bottom of the needle holding slide float which I am assuming create a vaccum/low pressure zone above the rubber diagpram due to Venturi effect of air flowing past sucked in by the piston creating a vacumn, and this low pressure allows float slide to rise and supply more fuel. Either the diaphragms are not same on both carbs or a hole could be partially blocked, creating a lack of low pressure and poor low end performance, but why that would not effect fuel in take at high speed as well I don't know, prob poor low end is clutch variator issue.