RPM won't go above 6K, suggestions? By extremejoy (Read 11,490 times)

[extremejoy]

Hey guys,

I have a 2012 Taotao Powermax 150 & this is what I have done as far as modifications:
- 15/37 final gear ratio.
- Koso 11g variator weight slider.
- Kevlar CVT belt.
- "Racing" blue CDI.
- Orange Coil.
- Regular spark plug replacement.
- Basic fluid replacement maintenance.

When my scooter was stock, it will go up to around 7500 RPM but after the replacement (actually right after final gear process) it will cap itself out at 6K, at best 6100 RPM.

This is what I tried:
- Replaced the blue CDI back to original CDI, result: slower acceleration & didn't fix the problem.
- Replaced variator weight from stock (I think it's 13g or 14g) roller to 11g slider (which is equivalent to 10g roller), result: quicker acceleration and noticed the RPM rise very quickly but RPM caps out at the same, 6K-6100 RPM.

I want my 7500 RPM rev back! I miss it...

Any suggestions or what am I doing wrong? I know that GY6 style engine likes to cruise at 6K RPM and it will not hurt the engine but I want that extra "power on demand" available for me whenever I need it.

Also, this is something that's always in the back of my mind, whether it's in stock form or at this current stage, my scooter top speed has always been around 55MPH, actually during stock I was able to squeeze it to 58MPH but I'm redlining at 7500-7700 RPM, now it tops out at 55MPH but the RPM is around 6100. I heard about the speed limiter washer that's by the variator but I don't see it, if it was there I would have removed it myself already. Does Taotao scooter (like mine) have a limiter somewhere else? Please let me know and I'll remove it like a bad habit. If anyone of you reading this have the same exact experience but not the same mod, please let me know how you fixed it & I'll try it out.

Any suggestions to make my scooter better are always welcome.

[JR]

The 150's don't come with any limiters including the washer on the variator that I'm aware of, only 50cc scoots do that.

What was your gear ratio before the change? This alone will make a big difference on top end RPM. Dropping the roller/slider weights will help but you've negated that a lot when you went to what looks like a higher gear ratio. Higher ratios will drop the RPM and still give the good top end and will increase the MPG along with engine longevity. But if you run in the hills you will suffer from engine drag and like you are experiencing loss of top end. You got your take off back by going to lighter sliders but the higher gears are off setting the final top end.

JR

[alleyoop]

Rev it up on the CENTER STAND and see if the RPMS CLIMB HIGHER THAN 6K.

If it does rev up higher than the 6K without a load, then that eliminates a problem with the CDI.
If it still does not rev up then I would suspect the CDI. Now many have had problems with the BLUE CDI with low revs.

If it revs on the center stand then I would say your motor does not have the power. You may want to adjust your valves incase it is loosing a little bit of compression.
Set them both to .004 inches.
Alleyoop

[extremejoy]

JR:
Sorry I forgot to mentioned that info.

Original final gear ratio is: 13/40.

Thank you for clarifying the limiter, now I wouldn't have to search for that unicorn...

As for the gear ratio causing it to drop top end RPM. You are right about the lighter roller weight giving me back the take off acceleration that I lost when I put the new final gear on which kind of balanced things out on the low end. The ride on my commute is mostly flat with a very minor incline on the way home so I only noticed drag for just a short period of time. Now the scooter is 6K happy so if I'm not paying attention it will go to 6K and stay there until CVT catches up to speed.

I guess now my only questions would be, is there anything that I can do to bring the RPM higher so maybe I can squeeze the top end to higher than 55MPH? My whole goal for getting the 15/37 final gear ratio was hoping I can get my scooter to top end around 65MPH or so which means the RPM at 65MPH would probably be close to almost 8K RPM, correct? I kept seeing some Scootdawg forum members claiming such of speed so I was hoping to be one of them as well...

Alleyoop:
I've done that test and when my scooter is on the center stand, I was able to bring it up to 8K real quick, didn't want to go any higher because I was scaring the neighbors. I haven't tried the valve adjustment yet but thank you for letting me know, I will make that the next task on this puppy. When I ride the scooter it sounds like it has more to give but I feel like it's being held back at that specific RPM mark, that's why I was wondering about the "limiter" from the beginning, I think it still have some power left in it to at least squeeze out another 300-500 RPM, no? BTW, thanks for the info on higher gear oil, I put 85-140W and now the "rrrrrr" sound went down a lot.

[alleyoop]

Also have you adjusted the CARB, do you have a Free Flow FIlter, it could also be running rich which will make it loose a lot of power.
Alleyoop

[JR]

Since you have done what Alley suggested which was right on unless you do find something with the engine off as far as adjustment or such, to me it's apparent what's going on. The higher gear ratio is lugging the engine, like the old saying "there is no replacement for displacement."

Alley and I have played with many combinations over the last couple of years and he will tell you also the sweet spot or max HP to RPM curve on this engine is around 7200 RPM. With everything tuned perfectly and the CVT matched up perfectly, that's the goal to reach with an additional 300 to 500 RPM in reserve left if you can. You're right 8k or more is red lining this engine and it'll not hold up that well long at those RPM's.

At your gear ratio IMO about the only help you're going to get for more RPM's is possibly a shorter belt that is if you are running the 842 length and going to the shorter 835 and don't laugh but what is your tire pressure? If you have them a little low for a softer ride it'll cost you RPM and MPG. Airing up the tires to a hard ride reduces friction and increases speed along with RPM. Every little thing adds up.

Or............... you may need to reconsider your gear ratio. If you drop the slider weight any more she'll take off like a BOOH but you'll really sacrifice the top end in fact going to a combo of about 12 to 12.5 sliders I'm thinking might be better?

Here is a lot of common final gear ratios for the GY-6 including your 15/37

2.57 14 front 36 rear
2.64 = 14 front 37 rear
2.71 = 14 front 38 rear
2.78 = 14 front 39 rear = high torque (hill climber)
2.4 = 15 front 36 rear
2.46 = 15 front 37 rear
2.53 = 15 front 38 rear
2.25 = 16 front 36 rear
2.31 = 16 front 37 rear
2.375 = 16 front 38 rear
2.11 = 17 front 36 rear = high speed (flats slow takeoff)


Another look at these ratios:

14 front 36 rear = decent top speeds (larger hills, better takeoff)
14 front 37 rear = slower top speeds (larger hills, better takeoff)
14 front 38 rear = slower top speeds (large hills, great takeoff)
14 front 39 rear = slowest top speed, high torque (mountain climber) Best for people who have to climb large hills alot but sacrifice top speed. Low 40's mph
15 front 36 rear = good top speeds (small hills, good takeoff)
15 front 37 rear = good top speeds (average hills, decent takeoff) Best balanced. Mid 50's mph
15 front 38 rear = good top speeds (small hills, slow takeoff)
16 front 36 rear = high speeds (small hills, decent takeoff)
16 front 37 rear = high speeds (flat roads, slow takeoff)
16 front 38 rear = high speeds (flat roads, slow takeoff)
17 front 36 rear = highest speeds (flat roads, slowest takeoff) Best top speed but takes a while to get there. Mid 60's mph



Your 13/40 = 3.07


Lots of people find that tuning the stock OEM gears work best.



See the rating on your 15/37? You may want to try the little things that is suggested or re-think your gear ratio? Also as far as the 65MPH on a GY-6? Not get into that debate and all I'll say is lot's of factors to consider, even as much as your weight, simply put a 150 lb rider will go faster than a 250 lb. rider Even a windshield correctly installed can add speed.

JR

[extremejoy]

Thank you Ally for the information, I still haven't gotten a chance to test the valve adjustment yet. My scooter won't start today and I had to drive to work, but will check on it once I get home. As for the carb, at this moment it's still stock since I haven't gone into that area as of yet. I do notice that the engine is a bit hotter when I come to a stop at a red light from a decent cruise. I know this is air cooled but I never noticed to feel that hot before, isn't that a sign of running lean instead of rich? Also, should I be more concern with that progress or it's just normal for a long amount of cruise?

JR
Thank you for the information, I will check the tire pressure. I am currently using 835 right now since 842 belt was rubbing on my CVT case really bad.

I did took sometime and research on the gear ratio of what I can do that would be best for what I wanted and I still believe that the set up that I currently have is good for me. I was thinking about 12-12.5 sliders as a replacement but I wanted to acceleration to come back which the 11g did the trick, but I am open to try to get the other sets to see if it's better outcome.

Alley & JR:
I have a question, for me to gain more HP, what would you recommend as to doing so? I know a lot of people would go as far as BBK & if I'm going to adjust the valve, I might as well dive into it. But for some reason I think it might be too premature since I only have this scooter for less than a year and doing BBK would be almost a major modification, I may want to start off minor first but if BBK is the only probable solution then I wouldn't have much of a choice. From my understanding GY-6 that I have from Taotao Powermax 150cc should be producing close to 9-10HP, correct? How much would a BBK push the HP to? If I change the stock intake and exhaust or even carb, will that give me enough power to push the RPM pass 6K without going BBK route? Do you guys have experience the changes and put in in writing of what minimum required HP will do what with specific gear ratio? I know at this point I may be asking for too much & I would totally understand if there aren't such information available, but I figured it's worth asking so I know what I have to tackle to get what I want.

Thanks so much guys, I really appreciate your expertise advice.

[JR]

Personally since you only want to get another 300 to 550 RPM IMO a BBK is a waste of money and time IMO. Reason I say this? You have already said that you ride mainly on flats with a few small hills, the minimum gain (and that is what it is) with a BBK will certainly help you hold RPM's in the hilly areas, but all the HP in the world will not change the gearing and CVT set up.

As I mentioned there is the curve that one tries to reach, in your case like many you want that little extra RPM when needed at a moment's notice. You had that but the scooter naturally would red line. What did you do? You went to a higher gear ratio which drastically dropped the RPM and still gave you the 55 MPH.......but you dropped out of the best HP to RPM curve and lost the extra spare RPM's.

You've now tweaked the CVT but now don't have the ponies to support the high gears. You're already using a 835 belt so that possible gain is gone and I do believe you will help a tad by going to 12 to 12.5 sliders but after that? IMO the 16/36 will get what you want and make the BBK unnecessary if that's all you want. Even with a BBK I believe you'll still have to change the gears?

JR

[extremejoy]

;-X LOL!

I was hoping you wouldn't say that but I have to accept the truth that is in front of me. I understand about the sweet spot of where the power curve maxed out at 7200 RPM & I would love to be able to touch that spot again, but at this point I would be happy with the 300-500 RPM gain if the top speed will come with it...

Questions:
If I were to change the gear to 16/36, will I still get into the slow acceleration from dead stop?

Is the difference between 12 & 12.5 that noticeable?

If I were to place them in the variator, what would you recommend for road condition that I ride if I did go with 16/36, 12 or 12.5 sliders?

Final curious question from an eager mind, 16/36 final gear ratio, will that cap me out close to the sweet spot of 7K RPM range or will that drop my RPM cap lower than where I am not which is 6K RPM?

This is just a general estimate, I don't expect an exact # but since I don't even know where to begin, I'll take your expert answer than my guess any day!

[JR]

Question? Did you try changing the roller/slider combinations with your OEM 13/40 gears at all? What roller weight did it come with? By your own statement you said you had good RPM with the OEM set up but wanted to reduce the RPM but keep the top end with a little reserve left?

I'll let Alley weigh in here, he has done a lot with gearing but I believe a 16/36 with 12g sliders will be close? Since you already have 11g sliders you might want to buy a set of 12g, and 13g sliders. This will allow you to mix with the 11g you already have and match to give you ratios of 11.5g and 12g and 12.5g a good range.

Again lets see what Alley thinks?

JR

[extremejoy]

My stock roller I believe is either 13g or 14g, I never tried the sliders because the final gear were the first thing that I changed out of all the modification that I had done.

I would love to see Alley's input for me to make a better decisions and get my scooter where it needs to be.

Thank you so much JR.

[JR]

Sent Alley a email, sure he'll weigh in.

JR

[alleyoop]

Here are my mods on my Trike which by the way WEIGHS IN at 350 lbs plus my butt of 180lbs.
Here is what my PST150H Ice Bear Trike currently has it was a 149.6cc Motor now it is 182cc motor:

62mm BBK
60mm Stroker Crank

16/37 Hoca Tranny Gears – Original were 13/40

Reduction gear is 43 teeth

K&N Air Filter with a Short Stack
SuperTrapp Muffler
1 1/4 Header Pipe
24mm Carb
#122.5 Main Jet
#38 Pilot Jet
Peformance Coil/CDI
Manual Choke
Iridium Plug
Prodigy Variator
12g Dr. Pulley Sliders
205/65-10 Kenda Load Tires-3"s taller than OEM
29 tooth Drive Sprocket-came with 24 tooth.
DID 428 Pro V Series O-Ring Chain
Givia 29" tall Windshield
All Led bulbs Except the Headlights-I do not drive at night
4 way Flasher
Turn Signal Beeper
Relay for the Beeper connected to the Brakes
VIP Trunk with Led lights

Flasher on Vip Trunk lights
Radio with SD card,MP3 connections

Best thing to first do is MARK your Variator and crank that sucker up and see how high the belt is climbing with the weights and rpms it is currently producing.



That will tell if a weight change will help up or down. Down will get you around 500-600 more rpms BUT that also may hurt your top speed it all depends on how high the current weights are moving the belt up on the Variator.
Alleyoop

[JR]

Well I said 16/36 with 12 to 12.5g sliders and Alley is using a 16/37 and 12g so I would say I was close. ;D

JR

[alleyoop]

DON'T BELEIVE those guys on SD doing 65-70 unless their scoots are EFI and or water cooled NO WAY HOSA(HAHA). Ask them to prove it and they CAN'T they always have some excuse. I have gotten into PISSING MATCHS and in trouble when I asked them to prove it OTHERWISE IT DIDN'T HAPPEN OR I tell them WHAT CLIFF did you push your scooter off of(HAHA). I tell them not to be telling lies like that because others with similiar scoots that are only doing 50mph think something is wrong with theirs.

150s are good for 50+ and some MAY GET TO 55mph but the MOTOR IS SCREAMING over 8KRPMS. MOST 150s only hit 49-52mph STOCK. A few CVT changes and 55mph is possible.
**************************************************


Ok, how do the rpms ACT when you open up the throttle and it is getting up to speed?

1. Do they go up drop a little then go up and repeat.= WEIGHTS ARE TO HEAVY
2. Do they Climb up really quick= WEIGHTS ARE LIGHT
3. Do they Climb up STEADY and gets you to 55 but then not climb higher.= MOTOR DOES NOT HAVE THE POWER to pull the taller gears on short runs. IT NEEDS LONG STRETCHES of BLACKTOP to create more RPMS and MORE SPEED.

If you have a place with say 1/2 mile stretch try it there and see if the RPMS and SPEED climb.

The other thing is For a STOCK MOTOR I always recommend going only 2up and 2 down on the gearing.

The way it should work is you crank on the throttle and depending on your motor it reaches a certain RPM like 6-7K and stay there until the BELT climbs as high as it will climb THEN ONCE THE BELT has climbed as high as possible the RPMS should start to climb again picking up speed as the rpms climb. If you feel the belt is sliping you may need a stronger CONTRA CLUTCH SPRING.
But the motor has to have enough power to get you to the speed quickly enough so that the BELT reaches
its highest point(which by the way is around 40mph on a 150). Then the rpms will start to climb as well as the speed.

But I bet your running out of road.
Alleyoop