Why would you need/want an adjustable drive boss?

[acrab78]

On some of the aftermarket variators for sale they come with adjustable drive bosses what would be the purpose of this?

[blue]

it would be a pain just to get everytime you wanted to adjust it.

[wordslinger]

..adjusting boss length comes into play when really fine-tuning a setup..mostly for racing...

..a shorter boss will, potentially, result in a bit more top speed..

..however, and especially inna 4t, shorter boss might cause a lag at initial take-off, due to the belt being squeezed tighter in the variator...

..could also make the 4t harder to start with the pushbutton..

[blue]

what would happen if you put a shorter belt in. would that be to much strees on the crank.

[wordslinger]

..a shorter belt will result in a loss of top speed!...

..not to mention screwing your current cvt setup all to hell...





..dont do it brother!!


             

[OregonDad]

..a shorter belt will result in a loss of top speed!...

..not to mention screwing your current cvt setup all to hell...
             

So a longer belt will give you more top speed???

I have seen some of you post that you use a longer belt size.

[baddi]

So a longer belt will give you more top speed???

I have seen some of you post that you use a longer belt size.

Using a 743 gave me an additional 6 km/h top end, and enabled me to drive with lower rpm at the same speed as would have been top speed with the stock belt.

[streido]

So a longer belt will give you more top speed???

I have seen some of you post that you use a longer belt size.

A 737mm belt on a standard 38mm long smooth boss gave me almost the exact same performance improvememt as i got from a stock 729 belt with a shorter 36.8mm long smooth boss.

Im on the shorter boss and belt now and gets over 50mph downhill (scoots speedo not actual).

[acrab78]

Did a gps speed run and my scoot said 50 mph and my gps speed was actually 43.6.... Felt like I was flying though!
When I do get her rolling that fast  (downhill) it makes a noise like the belt has reached its limit on the variator (stock) is this normal?

[streido]

Did a gps speed run and my scoot said 50 mph and my gps speed was actually 43.6.... Felt like I was flying though!
When I do get her rolling that fast  (downhill) it makes a noise like the belt has reached its limit on the variator (stock) is this normal?

 its prob that the variator cant get pushed any closer to the outer variator by the rollers due to the 38mm boss you have. I had the same issue for about 6months where at 45-47mph (speedo speed) it felt like it did when i hit 31mph on my restricted scoot, kinda like it wanted to go faster but was being held back. Then i went to the 737 belt and that seemed to cure it, untill the belt wore down a bit then it came back. After months of head scratching etc Wordslinger pointed me in the right direction, shorten the boss a little.

Take off 0.8mm-1.2mm off the length and try that maybe? Or try the longer belt? Both will let the belt go higher up and gain some speed.
My last gps gave me 46mph when speedo said 50/51mph. It was windy tho

[acrab78]

Yep that's how it feels and sounds...  planning on upgrading to the malossi variator anyways maybe I will get a little longer belt then too... 

Still tweaking her out....  haha

[streido]

Yep that's how it feels and sounds...  planning on upgrading to the malossi variator anyways maybe I will get a little longer belt then too... 

Still tweaking her out....  haha

The Malossi has different shaped guides for the rollers than stock so that may well cure it without needing a longer belt, i would fit that 1st then if it doesnt help try a longer belt or the boss. The Malossi kit has a boss inc so it may be all you need.

If goin longer on the belt or doing the boss you will lose a little take off acceleration like Word said but you can compensate for most of this with tuning roller weights and the torque spring rating. I went down from 5.5g to 5.1g rollers when i shortened my boss and that did it for me.

[streido]

And also if you go too long on the belt it may hit the starter bendix a little. 736/737 long seemed ok for me at the time i used that length, that got me over 50 for the 1st time after being stuck at 48-49 and screaming at it downhill "C'MON, JUST ANOTHER 2MPH YA BASTARD!!!!" 

[wordslinger]

The Malossi kit has a boss inc


..which measures 37.5mm

..generally, the multivar will give you another 5mph, and make getting there much more fun!!

..but, as streido has pointed out, might require a bit more mods to get the desired acceleration..

..NO PERFORMANCE PART IS A PLUG-N-PLAY INCREASE!!..

                                           

..every mod creates the opportunity for tweaking...

[acrab78]

Yep I have already upgraded the springs to the 1500 all 4. And have played with the rollers some but the stock work best so far. The mallosi  kit has 6g rollers and a 1000 torque spring think that could be about the perfect setup....  will try to order this week. Extra 5 mph sounds good!