From 31t to 39-40t???

[buggyMike34]

Hey all
My 2009 Taotao ATK 150A has been doing very well with the mods I have done so far(just about everything but a BBK), but it is still not quite living up to the old Carter 150's acceleration and top speed. The Carter was running a 39t rear sprocket(17t front? I think)...
I have 16/31 sprockets on my new buggy-and I want to upgrade to the 39t...but I am running a 530 chain...so aside from changing the front sprocket to accomodate a different chain/rear sprocket setup-I figured I would find a 530 39t rear srocket-only problem is: I can only find a 40t #530 rear blank(I will have to drill my own mounting holes)...
So-my question is: Has anyone run into a similar issue? Have you used a 40t sprocket-and-did you gain the torque(I would assume so), but not lose too much top end??? I know it is only a tooth difference but we all know how that can get. I just want to avoid a lot of assembly/disassembly of the rear as much as possible-ie: I only wanna do this once
I do realize that I may also be looking at an internal gearing issue, as that would also add to the problem...but I will look into that after the sprocket has been shaken down.
Any help/info would be much appreciated! Thanks guys!
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[xlint89]

I scored a 36T 530 sprocket from Tractor Supply for around $35. When I went from a 31T on my Yerf to a 39T, I lost alot of top speed.

[SLESTAK75]

My experience with the same sprocket ratio left me with the desire to change sprockets. But after installing the A12 cam I noticed a very nice improvement in low to mid rmp performance. I will soon be getting a port and polish done on the head. Everyone says there is no greater performance gain than a good port and polish. I will post results in a few weeks after I get it done. If you change the sprocket you WILL lose top speed, but if you keep the gearing the same and build the engine for more power you will gain the bottom end pull that you want and gain acceleration and maybe even a bit more top end.

[SLESTAK75]

Originally Posted by xlint89

I scored a 36T 530 sprocket from Tractor Supply for around $35. When I went from a 31T on my Yerf to a 39T, I lost alot of top speed.

So how did the 36t compare to the 39t and the 31t. How do you like it?

[buggyMike34]

Good look guys...
I do have the A10 cam waiting to be dropped in. The port and polish are definitely in the mix as well. I would be VERY interested in hearing about how the PnP goes. I suppose I should just install the cam then and see. She does have some good pull...and I am running a (beefed up-3000rpm springs)stock clutch/bell and stock variator with 10g rollers...so I can go from there as well I suppose.
Thanks for the help guys!
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[SLESTAK75]

From what I have read (not from experience)the A10 cam is more of a top end cam and won't affect the lower rpm power as much as the A12. I think most will recommend stiffer valve springs with that cam as well due to the increased lift and greater possibility of floating the valves. Still going to make alot more power than stock cam, it's just a matter of what rpm you want the power. I heard some say they ran the A12 with stock valve spring so that's what I'm doing for now. So far so good.

[xlint89]

Originally Posted by SLESTAK75

So how did the 36t compare to the 39t and the 31t. How do you like it?

Never ran the 31T with the reverse gearing. (stock was a 9T sprocket and reverse is 13T, so there would be 0 bottom end) I like the 36T thus far. i do have the 2.2mm stroker crank now though, so I'm hoping that is pulling me through a little bit more too.

HATED the 39T on my Yerf. Lost a ton of top speed and over revved to the point I destroyed both valves. (I willingly knew what could happen and still floored it anyway)

But you have to also know that the Yerf came with pretty low internal gears from the factory. You hardly ever hear Yerf owners say their kart won't climb something. It's usually they want a little more top speed.

Originally Posted by buggyMike34

Good look guys...
I do have the A10 cam waiting to be dropped in. The port and polish are definitely in the mix as well. I would be VERY interested in hearing about how the PnP goes. I suppose I should just install the cam then and see. She does have some good pull...and I am running a (beefed up-3000rpm springs)stock clutch/bell and stock variator with 10g rollers...so I can go from there as well I suppose.
Thanks for the help guys!
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The A10 isn't going to help you much in what you're looking for. The A12 or even the A11 would be a better choice. (more power aimed at lower RPM range)

I am presently running the A10 on mine, and I can tell you the power band doesn't come on until midrange and up on mine.

I have not heard of 3000 RPM springs. Do you mean 2000 ? (red) Are you using them on the clutch, or the big spring? Or both?

[

[Johnny 5]

I just put the 31t back on both of our dune 150s. Also both have a12 cams and ncy valve springs. The take off is slower and wont spin the tires as much on take off like the 39t sprocket.

The good news is the top speed is up and crusing rpm is down. Last trip the blue buggy with the 3mm crank and the 62mm srp ceramic ran 28mph maxed out and the red 155cc buggy ran 31.

Now the blue buggy ran 37mph and the red 39mph and would go faster but ran out of smooth road and had to stop. The blue buggy tached 8200rpm and that was all it had and I got off it before I blew it up.

Running 10/11 sliders in the new dr2 on the blue buggy.
After our first ride changed out the 9/10.5 rollers that came with it due to the 7200 rpm all the time when accelerating.

The red buggy tach didnt work it kept going off and was not reading the right rpms, but didnt sound as reved up as the blue at 8200rpm.

The a12 cam improved the power alot on the 183cc motor and climbs without bogging down, and both buggys in a drag race are even. Sad to say the 155cc red buggy is fast and could be because the motor is a howhitt with the better cylinder head.

As for flat out speed the 31t is awesome and worked good for the desert and the a12 cam has good power on the low end.
If we were in the woods or tight trails the 39t would be nice.
The other benifit of the 31t is the motor ran cooler and wasnt always at max rpm.

I do miss the power on the take off but the 31t is better for our riding.
I wish that buyatvs online had the 36t sprocket they advertise but say is out of stock.

As for the cdi the red buggy runs best with the orange cdi and the blue runs best with a stock black cdi. The stroked and bored motor ran rough and notchy with the orange cdi.

Anyway we had a good trip only had a coil wire come off due to a melted plug cap probally from last trip getting way too hot. Had to tow my wife back and the red buggy had no problem just kept speed at 10 mph. Had two more coil wires back at the trailer.

We stayed for three nights and the frame at the chain adjuter cracked on our last ride. Must be the torque of the 183cc motor. Also the first day it was muddy from the rain the day before, got alot of cleaning to do but it was fun slidding in the mud and drifting into corners.

Time to weld it up and add some angle iron bracing on both buggys.

[bear]

Glad to hear you had such a good time! it's so cold here all I can do is watch vids of other buggy people having fun! I got your pkg. in the mail last week, can't wait to try it out, thanks again "Jman"!

[buggyMike34]

Thanks for all the info guys! Saving me some headaches for sure!

As for the cam...well, I guess I have an A10 for sale now... I will definitely need the A12 it seems. I may want the 39t because of the tight trail riding and hill climbing we do on a day to day basis...top speed is not what I am looking for in this buggy...
The springs that I bought were advertised as 3000rpm springs...for both the main spring and the clutch springs...white, yellow, and red were available and the red ones were the highest engagement...? So not too sure...Got them from a place called Jaguar Powersports on Amazon.

Just for gits n shiggles, what was the Yerf Howit's internal ratio>13/36? 17/40? Something different?

I really appreciate all the input! Looking for the A12 now...do a port n polish, then maybe a 155 kit. See where I am then...
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[SLESTAK75]

Going solely on your sprocket sizes and approximate top speed, if you go with the 39t sprocket that will be about a 20% change in sprocket ratio. That will yield an approximate 20% drop in top speed and same approximate increase in acceleration. So top speed would drop to around 30mph or so. If you don't feel you will regularly reach and maintain this speed then it will be well worth it. As Johnny5 stated. He was able to spin tires on takeoff before going back to 31t. Only thing to keep in mind is that with that gear change it is much easier to over rev the engine. But it will definitely climb.

[ckau]

Originally Posted by buggyMike34

Just for gits n shiggles, what was the Yerf Howit's internal ratio>13/36? 17/40? Something different?

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Howit stock are 13/40, Good torque, good climber, fast off the line but top end around 30mph. 13/40 has a ratio of 3.07. If your looking for a little more top end without loosing any real noticable pulling power use the 14/38 (2.78 ratio) you'll pick up about 3 to 4 mph. Acceration will be a touch off but you still pull good. This is with a no reverse motor with the 13/31 axle set.

[buggyMike34]

Thanks Ckau! I am looking for a lot of pull with the least amount of top end loss(aren't we all?)...
Those ratios are all ones I have been looking at...but I do have a reverse and a 16t front sprocket.
Sorry if I am asking kinda dumb questions, but I have never been proficient at gear ratios and electrics(hahaha the hard stuff)..so I really appreciate the help.
Thanks as always guys
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[bear]

No such thing as a "dumb" question!!!

[Johnny 5]

I liked the 39t/16 with 13/40 internal gears for tight trails and great take off, but I also noticed that on take off the tires would spin and cause the cvt to upshift too fast and cause a bit of a bog when you punched it out of the hole.

Now with the 31t/16 13/40 the total ratio is 5.00 Top speed 39mph
With the 39/16 13/40 the total is 5.50 Top speed 31 mph

I am thinking of getting 13/43 gears with the 31t/16 it will have a 5.23 total ratio.
Almost the same as a 36t.

I also want to have speed and take off, 39t take off the 31t speed.
So with the 13/43 internal gears this will put it in the middle with the 31t/16 set up.

I have to clean off the mud from our trip and weld the cracked rear frame first on the blue buggy first before I try to modify them any more.

As for pressing the gears I took a old set from our junk motor to see how hard it was to press and it was very easy with no binding or exessive presure to get them apart.

Good luck with your buggy.

My wife tells me that they run fine and to quit changing stuff and leave them the way they are. But I have so much fun with the results and the ability to make them custom for our ridding style and terrain.

I have been keeping a log book to chart the changes so you can remeber what worked and what didnt.

I was telling my friend at work about my buggy mods and he called me a buggy tweeker.
I said thanks for the compliment.

[buggyMike34]

hahahaha buggy tweaker! Up for days and hallucinating about buggies...
Thanks guys for all the info...That was a wealth of good trails there-thanks a lot! That got me where I need to be as far as where to go next.
Thanks again!
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[x-bird]

hey mike, you want to buy back your carter/sym engine after i drop the 250 in? it has the internal gearing and low end/top speed in stock form with a 31 T sprocket that most are after. it'd be a real ripper with a 39 T sprocket and no other changes. well, i did put a knock-off uni on it.

[ckau]

[QUOTE=buggyMike34;30295]Thanks Ckau! I am looking for a lot of pull with the least amount of top end loss(aren't we all?)...
Those ratios are all ones I have been looking at...but I do have a reverse and a 16t front sprocket.
Sorry if I am asking kinda dumb questions, but I have never been proficient at gear ratios and electrics(hahaha the hard stuff)..so I really appreciate the help.
Thanks as always guys
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Working out the ratios is the easy part . It’s just some simple math formulas you can do on any calculator. The hard part is deciding what you need . Unfortunately the only true way to know is try them. There’s probably a dozen different trans gear ratios available but only a few axle ratios available without having some custom stuff made.
Using a basic stock Yerf with no reverse as example the basic math formula for getting final ratio:
Trans gears- 13/40 13=(A), 40=(B)
Axle gears 13/31 13=(C), 31=(D)
Divide A into B (40/13) = 3.08 [trans gear ratio] = (E)
Divide C into D (31/13) = 2.38 [axle gears ratio] = (F)
Multiply E and F (3.08 x 2.38) = 7.33 ( final drive ratio) (G)
This means for every complete rotation of the axle sprocket the motor turns 7.33 times.
Another way to see it: @7,000 rpm the axle sprocket make approximately 1,000 rotations ( 7.33 to 1)
The higher the final ratio number (G) the more torque and acceleration.
Lower the number (G) = more top speed.
Keep in mind this number (G) is to the axle sprocket. Tire diameter plays a part in this too. Taller tires lower the number. There’s another formula to work out the ratio between tire diameter and sprocket rotation
To figure the true final ratio you will want to use IPR (Inches Per Revolution) which means the number of inches the buggy will travel per each revolution of the motor
To Figure IPR:
Rear tire Circumference (X) 22in. is a popular tire size.
Multiply by ( C) 13, outer trans gear. If with reverse this number would be 16
Then divide by ( D) 31, axle gear. (X*C) / D = IPR
( 22 x 13 ) / 31 = 9.22 . This means the buggy would travel 9.22 inches for each revolution of the motor.
The higher the IPR number the faster you go !
With reverse: (22 x 16) / 31 = 11.31 Which shows with a reverse unit your covering more ground. with the same motor rpm.
Are you confused yet? I am! At this point I usually get a brain meltdown. You can play with these formulas to see what different gears will do. It can help to make some sort of educated guess before spending time and money .

[buggyMike34]

X-yea man I would definitely be interested in the old SYM...message me with some details and we'll go from there.
Ckau-man you are a mad scientist! A lil bit of grey matter leaked out of my nose, but other than that, I think I got it!
I haven't torn the engine down on the new buggy yet(well, not all the way down)so I really don't know what my gearing is...and as far as I can tell, I am the only one on any of the forums with a Taotao ATK-150A buggy-so I am guinnea piggin it for now.
With all this info I am pretty sure I am looking in the right directions-so thanks again for the help. My outlook just keeps gettin better with every post...soon as this is done I gotta swing back to finish the Colaris-Talon Blazer 300ex
Hahahahahaha!
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