Top Speed?

[Nireen]

Hi friends,

OK got my new belt and new rollers but I still don't have my top speed.  What is it??

[CROSSBOLT]

Mine does 80 mph and I quit. Fast enough with some throttle left. Plenty good.

[Nireen]

I use to be able to get it to about 135 km top speed and than I lost speed about a month before I changed the belt and rollers and you all thought I might get it all back once I changed things and I did but it did not bring back my  135.  It sits at about 125 km.

[stuo]

Here's some info: On my stock 2011 DT 300i the tachometer reads 7000 rpm at 70 mph (indicated), which is what? 113 Km? See what your DT says at 7000rpm or at 113Km/hr. My scoot has about 4500 miles on it, original belt, so that gives you some idea of something, right? If your tach reads more than 7K at 113km it would indicate the belt is worn narrow or the rollers are too light. Am I correct or wrong, fellow readers?

Do you notice better acceleration or any other changes from before you tinkered with it?

[Nireen]

OK I will pay attention to this.  I would not make a fuss over this but when I travel the highway at times that little extra really makes a difference! Like when I want to get away from traffic fast and or passing those big trucks! cars etc.  It really made a difference but now I just have to relax lol.

Here's some info: On my stock 2011 DT 300i the tachometer reads 7000 rpm at 70 mph (indicated), which is what? 113 Km? See what your DT says at 7000rpm or at 113Km/hr. My scoot has about 4500 miles on it, original belt, so that gives you some idea of something, right? If your tach reads more than 7K at 113km it would indicate the belt is worn narrow or the rollers are too light. Am I correct or wrong, fellow readers?

Do you notice better acceleration or any other changes from before you tinkered with it?

[scooterfan]

I use to be able to get it to about 135 km top speed and than I lost speed about a month before I changed the belt and rollers and you all thought I might get it all back once I changed things and I did but it did not bring back my  135.  It sits at about 125 km.

To my mind your experience actually proves my point - compared to a brand new belt, top speed will be higher with a slightly worn (narrower) belt, and overall performance will be better with a slightly worn belt.
The reason is very simple - a slightly worn (narrower) belt will be sitting lower in the Variator and higher at the clutch Pulley during take off, and at top speed the belt will be sitting higher at the Variator, and lower at the clutch Pulley.
Therefore overall performance - including top speed,  will be better with a “slightly” worn belt.

But obviously - I’m quite new to scooters, and I’m not suppose to know anything.

[Nireen]

Well I will let you know if it changes.  I do hope your right!!! I want that back!  I did also lose my top speed a couple of months before I changed my very worn out belt and rollers. At top speed  I was getting like a slight kick back with the motor but that is gone now with the new belt but still no speed.

To my mind your experience actually proves my point - compared to a brand new belt, top speed will be higher with a slightly worn (narrower) belt, and overall performance will be better with a slightly worn belt.
The reason is very simple - a slightly worn (narrower) belt will be sitting lower in the Variator and higher at the clutch Pulley during take off, and at top speed the belt will be sitting higher at the Variator, and lower at the clutch Pulley.
Therefore overall performance - including top speed,  will be better with a “slightly” worn belt.

But obviously - I’m quite new to scooters, and I’m not suppose to know anything.

[scooterfan]

Well I will let you know if it changes.  I do hope your right!!! I want that back!  I did also lose my top speed a couple of months before I changed my very worn out belt and rollers. At top speed  I was getting like a slight kick back with the motor but that is gone now with the new belt but still no speed.

I think the best preformance should occur when the belt is somewhere between “slighly worn” (maybe between 2 to 3 mm wear) and “badly worn” (about when the belt start slapping against the housing).  Hopefully long before it breaks.

Looking forward to see some results !

[stuo]

To my mind your experience actually proves my point - compared to a brand new belt, top speed will be higher with a slightly worn (narrower) belt, and overall performance will be better with a slightly worn belt.
The reason is very simple - a slightly worn (narrower) belt will be sitting lower in the Variator and higher at the clutch Pulley during take off, and at top speed the belt will be sitting higher at the Variator, and lower at the clutch Pulley.
Therefore overall performance - including top speed,  will be better with a “slightly” worn belt.

But obviously - I’m quite new to scooters, and I’m not suppose to know anything.

My logic is...if the belt is narrow it will not be forced to the top of the variator and therefore top speed will be lower than possible. Also your argument is questionable in that yes, the narrow belt will be lower in the variator but also lower in the clutch pulley.

Like you, I am ignorant of the real world answer. It's fun learning, though...

[scooterfan]

To my mind your experience actually proves my point - compared to a brand new belt, top speed will be higher with a slightly worn (narrower) belt, and overall performance will be better with a slightly worn belt.
The reason is very simple - a slightly worn (narrower) belt will be sitting lower in the Variator and higher at the clutch Pulley during take off, and at top speed the belt will be sitting higher at the Variator, and lower at the clutch Pulley.
Therefore overall performance - including top speed,  will be better with a “slightly” worn belt.

But obviously - I’m quite new to scooters, and I’m not suppose to know anything.

My logic is...if the belt is narrow it will not be forced to the top of the variator and therefore top speed will be lower than possible. Also your argument is questionable in that yes, the narrow belt will be lower in the variator but also lower in the clutch pulley.

Like you, I am ignorant of the real world answer. It's fun learning, though...

 When the belt is lower in the Variator, My logic is that the belt will not be lower in the clutch pulley - it will be higher.  The reason being, those pulleys work in opposite directions. I.e. when the Variator groove becomes narrower, the Clutch groove becomes wider - and vise versa.

If the narrow belt would be lower in the Variator  and also lower in the Clutch pulley like you mentioned - the belt would be “too long”, and the belt would be slapping like hell. The reason being -the center to center distance  between the Variator and Clutch shafts always remains the same, but the contact area on the pulleys where belt would have “grip on each pulley would be closer to each other. Therefore  the belt would become “too long”.
I think in theory a narrower belt would be suppose to sit lower in the Clutch pulley as well - but in reality I think the big spring at the clutch should force the narrower belt higher up the pulley groove.

[Stig / Major Tom]

Per my 3 different service manuals - loss of power:

~dirty airfilter
~belt worn beyond service limit (but yours is new)
~Loss of compression, cylinder or valves worn

I don't know, really no idea - but how many miles you can run a 300cc scooter at max or near-max revs before the engine internals begin to get a little tired....causing slight drop in top speed?

There could be many things at play causing your loss of top speed - but maybe that 300 is simply showing its age?
(as for the belt wearing and increasing your top speed - the service limit on my belts is less than 1mm from new....then you replace. The early symptom of worn belts is loss of top speed.)

You have a new belt, correct OEM I hope, so slim chance it continues to be belt related.



Stig

[Nireen]

Per my 3 different service manuals - loss of power:
Scooter is 3 years old 27000 kms on it Stig.  I don't go all out full throttle.  I just like it in certain situations on the highway.  Most of my Km's are highway miles each year I go on about 3 long trips which is about 1000 km each trip.
~dirty airfilter
~belt worn beyond service limit (but yours is new)
~Loss of compression, cylinder or valves worn

I don't know, really no idea - but how many miles you can run a 300cc scooter at max or near-max revs before the engine internals begin to get a little tired....causing slight drop in top speed?

There could be many things at play causing your loss of top speed - but maybe that 300 is simply showing its age?
(as for the belt wearing and increasing your top speed - the service limit on my belts is less than 1mm from new....then you replace. The early symptom of worn belts is loss of top speed.)

You have a new belt, correct OEM I hope, so slim chance it continues to be belt related.



Stig

[Nireen]

Yes Stig I lost my top speed about two months before I changed the belt and rollers.

Per my 3 different service manuals - loss of power:

~dirty airfilter
~belt worn beyond service limit (but yours is new)
~Loss of compression, cylinder or valves worn

I don't know, really no idea - but how many miles you can run a 300cc scooter at max or near-max revs before the engine internals begin to get a little tired....causing slight drop in top speed?

There could be many things at play causing your loss of top speed - but maybe that 300 is simply showing its age?
(as for the belt wearing and increasing your top speed - the service limit on my belts is less than 1mm from new....then you replace. The early symptom of worn belts is loss of top speed.)

You have a new belt, correct OEM I hope, so slim chance it continues to be belt related.



Stig

[Nireen]

Tell me where should the RPM sit at when your doing whatever speed?  I know nothing of this.  As soon as I can get out on the highway (warming up here) I will take note of different measurements.

[stuo]

Nireen: Please read my two recent responses posted on your earlier thread under "valve adjustment", which address your top speed problem. Due to my advancing decrepitude I went to the wrong thread.