gear up

[Deleted]

this is an area i dont know much about. Parts For Scooters has 3 different gear sets so how do you know which to use? the bike intended has a 10" wheel

www.partsforscooters.com/169-206_QMB139_Gear_Set?sc=11&category=735

racing planet has what they call a 10% kit but they dont give specs
www.racingplanetusa.com/scootertuning-secondary-transmission-gear-naraku-139qmbqma-p-8550-1.html

i think we discussed this before and decided on 17/41 but i cant remember exactly

[jmkjr72]

i wouldnt even know where to start what is the gear ratio that you have right now
and what are you looking at for speed
normaly on the zumas with a nice street kit thye look to change the gearing so that the final ratio is around 12 to 1
but im not sure about the 4 stroke stuff

[vvtr]

i went with the 10% on my 4t baotian qt9 and it worked very well with bbk & other mods...
enabled the scoot to cruise at 45-50 at low rpm with a top speed of just over 60mph which i was happy with.
for me, this is an ideal mod if you already have a well balanced cvt tune.

i have a +10 kit in the speedfight as well and again the top speed is great with traffic speed cruising without screwing the engine.

[Deleted]

Mar 2, 2012 18:58:06 GMT -5 vvtr said:

i went with the 10% on my 4t baotian qt9 and it worked very well with bbk & other mods...
enabled the scoot to cruise at 45-50 at low rpm with a top speed of just over 60mph which i was happy with.
for me, this is an ideal mod if you already have a well balanced cvt tune.

i have a +10 kit in the speedfight as well and again the top speed is great with traffic speed cruising without screwing the engine.

thats cool but what is it? 16/42 or 17/41 etc...

[Deleted]

I just read a 17/49 is 2.88 which is supposed to be a 20% increase

[vvtr]

Mar 2, 2012 19:37:35 GMT -5 stroker said:

Mar 2, 2012 18:58:06 GMT -5 vvtr said:

i have a +10 kit in the speedfight as well and again the top speed is great with traffic speed cruising without screwing the engine.

thats cool but what is it? 16/42 or 17/41 etc...

not a clue tbh without going counting the teeth on the old gears lol.
i dont have much info on the baotian apart from what ive learnt working on them, same with the pug.
i went for the 10% simply because it was higher gearing than stock, but i figured going as far as 20% would bog it too much.
all i thought was if it cruises at 50 mph now, +10 would take me to 55 & keep the rpm down so i'm not killing it by cruising high engine speed all the time.
and also, just changing the gear set is a much cheaper and simpler option than arsing about swapping out o/r pulleys, race clutches, springs, rolers etc.
on most scoots, a stock cvt will work well, give good smooth acceleration and max out on both pulleys.... it's a cheaper & simpler option to change the gearing & keep the cvt as is.
(works for me!)

compare the costs of replacing just the gearset against the costs of replacing the variator & torque drive assy & over range pulleys... which will probably mean you lose the starter too..
then you will find you still want to up the gear ratios, so still end up buying the gear up kit, which then won't work as you've overgeared it with the cvt mods lol.

much easier & cheaper to just fit the gear up kit first, leave the cvt as it came...

[bigkahuna427]

I have had no experience swapping gears myself but would certainly do it on the right scooter. I think a lot of people who are looking for more top speed increase performance which gets you more horsepower. Although many people are looking for better top speed they do not consider the gearing. The impressive part of increased torque and horsepower for the driver is improved acceleration from a dead stop and usually some more speed. So if you have done performance modifications and if you have the horse power to pull your weight and overcome wind resistance moving up in gear ratio makes sense to me. If you go to high on the gear ratio then your going to end up with an engine that is lugging and slow to accelerate. Theoretically you could just increase horsepower to overcome this. Too bad there wasn't just a horsepower adjustment screw you could turn on the side of the engine (I bet you could sell those!).

I don't know if this helps anyone reading this but you have two sets of gears in the final drive. So to know your final drive ratio you have to know what the ratio is on both sets. To know the ratio on a set of gear divide tooth count of the driven gear by drive gear. So for 16/42 the smaller number is the DRIVE gear the larger number is the DRIVEN gear divide 42 by 16 = 2.625.

I used to see more people at the drags that would pour money into creating horse power and then have highway gears in their cars. In drag racing your trying to get the car to move from a dead stop . So the first 100 feet really counts and a lower gear ratio (in this case) would have really helped a good number of those guys. Try to get some of them to understand that was like talking to a stone wall because that wasn't what they read about in Hot Rod magazine.

[90GTVert]

The percents don't mean anything to me. I'm used to cars with 3.73:1 and 4.10:1 and stuff like that, so I always do the math to come up with what the final drive ratio will end up stock and with the gears. Beyond that, it depends how much you need the gears. How fast it accelerates, how easily it tops out, how much top speed or acceleration would I be willing to sacrifice, etc...

There's a speed calculator at the link below. Keep in mind, because of the CVT your final drive gearing isn't seeing the same RPM your crank is, but perhaps it could provide some insight. I dunno, fun to play with anyway. lol
49ccscoot.com/calculators.html

[90GTVert]

Here's some info on gears from my Venus thread in case it's helpful to anyone.

Sept 22, 2010 13:05:37 GMT -5 90GTVert said:

Now you have a choice to make. You should have both the gearset from the scooter and the ATV at your disposal at this point. Either set should be compatible with the ATV transmission case.



Both sets of gears are likely to be different final drive ratios, so you should choose the set that will be most likely to help you accomplish your goals with the engine swap. In my case, the 90cc gears would be more useful for top speed and the 50cc gears would provide superior acceleration.

90cc Gears
Primary = 15/47 = 3.133333333333333:1
Secondary = 11/31 = 2.818181818181818:1
Final Drive Ratio = 8.830303030303029:1

50cc Gears
Primary = 13/48 = 3.692307692307692:1
Secondary = 12/36 = 3:1
Final Drive Ratio = 11.07692307692308:1

If you aren't sure what all that means, let me explain it briefly and how you can find your final drive gear ratios. I believe a lot of 50cc and 90cc rations will be the same as these, but it never hurts to check.

There are 2 gearsets in the transmission that form one final drive ratio. They are the priomary and secondary gears. Primary gears are the gear on the end of the shaft drive by the clutch and the gear that it drives. Secondary gears are the gear on the axle and the gear that drives it off of the primary gears.



To determine your primary, secondary, and ultimately the final drive ratio, begin by counting the teeth on each gear and writing it down. t is often helpful to mark the tooth that you start counting on with a dot from a marker so you don't forget exactly where you started. If you have any doubt that you miscounted, do it over again to be sure.

You sohuld now have two numbers for your primary gears and two numbers for your secondary gears. Using my 90cc gears and an example :

Primary : 15 / 47
Secondary : 11 / 31

Now we can use division to determine the ratios of each gear set. Divide the number of teeth the gear being driven has by the number of teeth of the gear driving it. Again using my 90cc gears as an example :

Primary : 47 / 15 = 3.133333333333333:1
Secondary : 31 / 11 = 2.818181818181818:1

Now you know both your primary and secondary gear ratios, so you just need to combine them to determine the final drive ratio. Multiply the primary and secondary ratios to find the final drive ratio. Using my 90cc gears as an example again :

3.133333333333333(Primary) x 2.818181818181818(Secondary) = 8.830303030303029:1(Final)

You've determined the final drive ratios of each gearset, but what do those numbers mean? The gear ratio expresses how many revolutions of input are needed to output one revolution. In the case of the final drive ratio, the number represents the quantity of revolutions of the clutch bell turning the driveshaft that are needed to rotate the tire one full revolution. For example, my 90cc gears have an 8.830303030303029:1 final drive ratio. So my clutch bell revolves 8.830303030303029 times in order to rotate my rear tire just once.

The more times the clutch bell has to rotate to spin the rear tire once, the greater the potential for acceleration. The less revolutions the clutch bell needs to make to rotate the rear tire once, the greater the potential for top speed.

Numerically Higher Gear Ratios = Greater Acceleration/Higher Cruise RPM
Numerically Lower Gear Ratios = Greater Top Speed/Lower Cruise RPM

Determining exactly what speed you can achieve with these gear ratios is a little tricky, but the numbers should give you some idea of what you want to try. I went with the scooter gears (11.08:1) on this build and so far I've seen 58MPH at as much as 8,800RPM. Acceleration is great.

[Deleted]

49ccscoot.proboards.com/index.cgi?board=transtech&action=display&thread=404

didnt he mean to say 'stock is 51/15?'

[Deleted]

enviromoto.ecrater.com/p/5506961/naraku-performance-gear-set-52-14-139qmb

'Works best with stock engine, otherwise little gains will be had.'


Shouldnt that say 'little gains will be had on a stock engine'?

[dude]

4.10 will take more RPM's to go the same speed as the 3.73.

[Deleted]

if thats true then a 3.73 would take more rpm to go the same speed as 3.40 so the naraku gear swap posted above should have the opposite affect.

[90GTVert]

That gearset was a topic of debate for a while. I was always confused by claims of speed increase with deeper gears. I thought for a bit that perhaps the GY6 just didn't have the muscle to pull the stock gears to a good speed. Rather than just say it was wrong, I bought the gears myself and installed them on my SunL. Big surprise, I went slower. I did find that I was faster consistently, but not max speed for sure. I don't even know that most people would cruise faster consistently, because I'm and extreme example. I was 300lbs at that point, so I needed a lot more help than most would to keep speeds up. That's all documented in my SunL build thread. A while ago, that was the only gearset commonly available. Now you have a lot more choice and can get gears that really are good for higher speeds if you have the power to pull them. That's a big thing with scoots. It's not like my car with 500HP and 600TQ I can pull about any gears I want. You put some crazy tall gears in a scoot and you might find it can't even pull itself to go 40.

[Deleted]

Numerically Higher Gear Ratios = Greater Acceleration/Higher Cruise RPM
Numerically Lower Gear Ratios = Greater Top Speed/Lower Cruise RPM


so if stock gears (according to racing planet) are 51/15 (3.40) how can installing their 52/14 (3.71) give LOWER rpm at speed?