How a scooter makes its power

[thedaydreamer]

HI all
I have a question regarding how a scooter makes its power
SO to set it up with a hypothetical

250cc scooter all OEM 20g rollers
lets say this bike can max out at 70mph at 8500 rpms rev limiter

Now lets say I add more power, some engine work, etc and now this same scooter is 300cc
since I have more power but the rollers are the same woulnt I still hit the rev limiter anyway and be stuck at 70mph?
OR since I have more power go to 22g rollers and that should keep rpms lower, BUT the added power will make the 22g work better and now say im hitting the rev limiter at 78mph

I guess, If you have more power should you compensate with larger rollers so that you are not winding out and now the rev limiter will kick in at a higher MPH?

I hope im making sense

TY all

[aeroxbud]

Bigger bikes don't generally get limited in top speed by a rev limiter. It's the lack of power and air resistance that limits top speed.
If they are hitting a rev limit they are geared very low.
If you bike has twenty horsepower to get to seventy. It would need considerably more power to get it to eighty.
Once the variator is maxed out roller weight makes only a small difference. Have a read of this. www.pedparts.co.uk/blog/moped-tuning--rollers

[snaker]

Jun 4, 2023 17:23:34 GMT -5 aeroxbud said:

Bigger bikes don't generally get limited in top speed by a rev limiter. It's the lack of power and air resistance that limits top speed.
If they are hitting a rev limit they are geared very low.
If you bike has twenty horsepower to get to seventy. It would need considerably more power to get it to eighty.
Once the variator is maxed out roller weight makes only a small difference. Have a read of this. www.pedparts.co.uk/blog/moped-tuning--rollers

I like that writeup.
I couldn't read the units very well, but its some good stuff
There are two different camps on the term "overdrive" with CVT's:
1. When the pulley ratio cross's the 1:1 it becomes overdrive.
2. Any increase beyond the CVT's full shiftout is overdrive.

I am with the beyond full shiftout being overdrive camp.
Pretty much what this writeup is covering.

The one time that I would say that different fly weights could have an effect on top speed would be if the gearing is so high that the CVT isn't getting to full shift out.
But yeah if the engine is pulling past full shiftout, then the flyweights are out of the picture.

[thedaydreamer]

One of my scooters is a Yamaha morphous, its a 250, it comes with 14g rollers, the low end is a bit lunky, but after about 45 it picks up and gets into powerband, it tops out at 79mph and 9000rpm rev limit will kick in and you get no more

I switched to 13g sliders and the it now stays in powerband, much quicker, but now tops out at 73mph and when it hits the 9k rev limiter

I want both speed and top end, I lost 6 mph by going to the sliders, any ideas with this bike to max out the top end, keep the rpms resonable all while having good acceleration?

They dont make many aftermarket part for this bike, but I hear you can use the majesty 400 parts like the malossi variator or even the jcosta, I want to hit max top end all while NOT running into the 9k revlimiter


BTW - you know of any shops that could reflash the ECU? maybe change the rev limiter and/or the dynamincs of it?

Any ideas I can try?

TY guys

[aeroxbud]

Me good variator might definitely help. It should hold the revs more constantly.
It sounds what you really need is a year up kit. But from what you say it's unlikely to be available.