Modern Vespa

Hi all,

Just looking for some general discussion and to hear other owners experiences here.

Okay, so what do I mean by illusive kick. The kick I am referring to is a little burst of power you can get on acceleration, usually from take off. Basically the engine revs like mad and it feels like the torque sets in to give you a real boost, enough so you feel it and it pulls you back a little. I aint talking screeching wheelies here or anything.

When I bought my bike it ran pretty sluggish (although i didn't know it at the time) When I had a crash and it was written off as a cat c I bought it back as mechanically the bike was okay. My friend who did the repairs also changed the plug for me and put some carb cleaner on and ran some Red X through the fuel system. After this is when I first experienced the kick. The bike would pull pretty rapid up to 30 mph and after that was a much more subtle acceleration.

A year later we gave the carb a proper clean, stripping it down. Some of the jets were clogged with fuel. After this the kick was even better and even the acceleration beyond the 30mph was improved. So I concluded the source of the kick to be a healthy carb.

A few weeks ago my outer variator pulley came loose and was hitting the transmission cover. I simply re tightened the nut (not knowing at the time these were one use only) For a few days the bike ran real nice and quick. Less of an immediate kick but a good strong pull throughout the whole range. Then the outer variator stripped.

I cleaned the crank and replaced the part, the rollers then became very noisy and all kick was gone and acceleration was very sluggish. I figured as these rollers had done 42000km it was time to replace them. I know that's a lot of miles for a set of rollers, but hey, up until then they had been working fine.

I replaced the rollers and belt and the result was staggering. The kick was now present all through the range. At any speed even up to 50+ mph I could give the throttle a twist to WOT and the bike would rev like nuts and pull like a train. I was very happy. Then, boom, the new variator stripped again after a couple of days. What I had done like an idiot is not put the belt far enough into the clutch and it was too tight around the variator. This meant the washer that goes behind the outer variator and touches the spacer was not sitting flush so when tightening the assembly it was not done right. Once the belt went to the top of the variator whilst rising the assembly must have been loose which is what I assume caused the nut to come loose.

Today I bought another outer pulley and did the job (I hope properly) That is to say all washers and spacers were sitting flush. However, now, even with the new rollers and belt I am getting no kick at all. Acceleration is pretty slow, but the pull once above 30 is nice and smooth but nowhere near what it was.

So here's the head scratchers

The carb obviously effects the kick, but to what extent

How come when the variator wasn't fitted correctly the bike performed totally freaking awesome.

I'm thinking because the belt sat lower and rose higher, so effectively changing the cog sizing down? especially setting of from stand still.

If so how come you cant buy a more angled variator that would allow this kind of performance.

Time will tell if once the new belt and rollers settle performance increases.

Sorry for such a long rant but I am very interested to know if other riders get this kick, and more important what is the main factor for it to happen.

Maybe I am chasing something illusive like a leprechaun and his pot of gold but hey, its fun to tinker.

If you made it this far, thanks for reading. And your also probably very bored or very stoned.

dk`

i get my rollers changed every 5000kms, and belt at 10000 - 12000kms. As i ride my bike all day (10hrs) Stuff wears out fast and I can feel the performance change and loss of Mpg. Sometimes worn rollers will make the bike accelerate faster off the line or give small bursts of power out of the blue, due to flat-spots on the rollers. Worn rollers and belt often allow the bike to get to high revs very fast, giving a good punch off the line.

Dropping 2-3 grams off the roller weights will give you a boost off the line. Check your exhaust for any holes, once you get a hole the bike will rev up a lot faster, seem quicker but you will flat-spot the rollers fast and loose mpg.

You would get more kick with an aftermarket variator- I believe the polini nine roller is well liked, but you're be changing rollers frequently (or you should be, 42000 kms?, really?. ).

I made this same mistake. Make all starts progressively -no more jackrabbit take offs- and double check the splines on the crankshaft next time you have the belt off.

Some wear to the splines is normal, but if you keep stripping variator pulleys at some point the splines will wear to the point they won't be up to the task of holding the pulleys and you will have to replace the crankshaft.

I just went through this with my 200, which is a lot less forgiving with this kind of error.

Thought I would post a little update about the pursuit of the nice kick.

The last time I posted I put the new outer pulley on and the bike was running a little sluggish. No real kick on take off but a pretty smooth pull from 30mph up.

After doing about 100 miles on the new belt and rollers, the acceleration kick got much better, as did the general pull through the range. I hoped this was a result of the belt settling in and checked the tightness of the variator nut and all seemed okay.

Having stripped two variators I decided to take it of and re do it just to make sure the speed increase was not a result of the variator having loosened. On this install I got the belt into the clutch further than I have on any of the previous installs and the variator assembly went on nice and flush. The belt was putting no tension on the pulleys.

Just had a little 25 mile ride home and it was running the same as before re doing it. Nice kick from take off and a nice powerful pull all the way through the range. So far pushed it to 60mph and had no power loss through the band.

The kick is not as prominent as when I had not seated the belt correctly on the second variator that stripped. And the throttle needs to be pulled more open to achieve the kick. Which I think is due to the belt been seated higher on the pulley as opposed to when the belt was sitting lower?

So it seems a nice clean carb, and fresh rollers will achieve the nicest pull throughout the who band. No surprise there. My bike has a leo vince on and to what extent it can be done has been de restricted. I ain't chasing performance beyond what the stock bits can do. Just trying to get everything running smooth. Only put the leo vince on because the stock exhaust developed a hole. Though im glad it did cause the noise is lovely And it was de restricted by my mate when repairing it from the crash. The old rollers only did a nice kick up to 30mph then the acceleration slowed between 30-45. Maybe that was the result of where the flat spotting was? but that would not add up with what gtdespatch said.

Yes the old rollers did 42000km they were on it from new. I got the bike at 12000km and have done the 30000km over two years.

Any way don't know if any of this info is of any use to anyone but hey, just thought I would share the experience. And if this variator strips now I think bonfire night may be coming early.

Thanks for reading and thanks for the responses

dk`