Slide Carb Conversion

124 posts in this topic

Posted

definitely lost acceleration and not sure if I gained any top end. My scooter is just not powerful enough to push the gears to the fullest. However at high speeds it is smooth and seems to be able to maintained MPH a bit easier.

I do believe that going up to a 16 tooth you need more torque to be able to push the gears to its potential. You are taking away the leverage the factory gear was able to keep up, the 15 tooth for a stock engine is about the highest you would want(10in wheels would be 16 tooth since smaller wheels have better torque output than 12in). If you want to use those gears you would want to stroke it to get your wanted/needed torque.

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Posted

I do believe that going up to a 16 tooth you need more torque to be able to push the gears to its potential. You are taking away the leverage the factory gear was able to keep up, the 15 tooth for a stock engine is about the highest you would want(10in wheels would be 16 tooth since smaller wheels have better torque output than 12in). If you want to use those gears you would want to stroke it to get your wanted/needed torque.

I had 13\40 stock, so I am thinking about trying 14/38. That should give me about 10% more top speed and that is all I think I need...

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Posted (edited)

I had 13\40 stock, so I am thinking about trying 14/38. That should give me about 10% more top speed and that is all I think I need...

 I would say to go with 15/38, I ordered 15/36 since I have more torque than I need at the moment. I'm more straight roads than city driving as it is. If you want to have the best balance you should stay around 2.4-2.7 gear ratio. Any lower you would then need torque upgrades to push it off the line. Stock gear ratio is 3.08 so the lower the number the more top speed but the more torque needed from the engine to push it, higher the number the more torque but higher rpms needed from the engine. Hope that helps.

Edited by BLK8WDW
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Posted

 I would say to go with 15/38, I ordered 15/36 since I have more torque than I need at the moment. I'm more straight roads than city driving as it is. If you want to have the best balance you should stay around 2.4-2.7 gear ratio. Any lower you would then need torque upgrades to push it off the line. Stock gear ratio is 3.08 so the lower the number the more top speed but the more torque needed from the engine to push it, higher the number the more torque but higher rpms needed from the engine. Hope that helps.

I might go with NCY 14*37 = 2.64 since I am now running 16*38=2.375, so that would be in between...

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Posted

I might go with NCY 14*37 = 2.64 since I am now running 16*38=2.375, so that would be in between...

 that's a good compromise, generally when you go 16T stroke to +2-3 17T stroke to +3-4 18T stroke to +4<

All of that information has been obtained from different forums and most post I've come across accept this as good info. I've done allot of digging and research for every part I want to work on and still have more to do. I hope you get it going the way you like, I hate having to work on it so much and not riding and I'm sure every one else does to.

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Posted

I went ahead and installed 9grams sliders to see how the scoot would perform and holy crap it picked a lot.  Did not have a chance to go for a long drive but it hits 60cmph super quick, but my rpm on take off are like 8600 rpm. Not sure what my top speed rpm is going to be. Do you guys think I am going to break something at these rpms? 

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Posted

I went ahead and installed 9grams sliders to see how the scoot would perform and holy crap it picked a lot.  Did not have a chance to go for a long drive but it hits 60cmph super quick, but my rpm on take off are like 8600 rpm. Not sure what my top speed rpm is going to be. Do you guys think I am going to break something at these rpms? 

I think your good, just measure what is the rpms are at top speed and adjust from there. Check temps and you should be ok. 7500-8000 is around the peak range of best performance and anywhere above or below you are just wasting it.

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Posted

I went ahead and installed 9grams sliders to see how the scoot would perform and holy crap it picked a lot.  Did not have a chance to go for a long drive but it hits 60cmph super quick, but my rpm on take off are like 8600 rpm. Not sure what my top speed rpm is going to be. Do you guys think I am going to break something at these rpms? 

Difficult to predict.

The NCY Valve springs are Junk!   

I have two fairly large down hills I have to enjoy to town, I hit bouts 8,200 rpm on both Dailey both ways.. it is for a fairly short period of time.

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Posted

Correction

 That trip was 8,320  max rpm both ways. and again thats only a few seconds or so.       ya maybe I'm pushin it, 

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Posted

Correction

 That trip was 8,320  max rpm both ways. and again thats only a few seconds or so.       ya maybe I'm pushin it, 

Lol, man, I was hitting 8700RPM when accelerating that is what I saw when I rode underneath a light as it was night time. I'll try to go for quick ride tonight before it gets dark hopefully. I am thinking as long as I stay below 9k i should be safe, but I could be wrong and find out the hard way... if that is the case it would be time to go to 63MM BBK :ok:

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Posted

Correction

 That trip was 8,320  max rpm both ways. and again thats only a few seconds or so.       ya maybe I'm pushin it, 

what speeds are you hitting :D

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Posted

talk me out of this

You're funny :rofl2:

You do realize that the first link is only for 5 jets, not a carb.... The second link, well, that carb will not fit your scooter - note intake side..... 

Are you looking for a carburetor? And would you like some help with your search?

Ask (and measure) twice, pay once. :ok:  

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Posted

lol dabs had me like..., but how bout dis: http://www.ebay.com/itm/Koso-PWK-28-Carb-28mm-Flat-Slide-Carburetor-Dirt-Pit-bike-ATV-Buggy-Quad-Kart-/281332864286?hash=item4180bed51e:g:1CAAAOSwmmxW2nSY&vxp=mtr

 

yea i found a 7$ rebuild for my stocker, but i really want a slide carb, and i think i want the "gy6 high torque performance intake w/bolt" near the bottom of this page:http://www.scrappydogscooters.com/125_150cc_Performance.html

 

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Posted

First link - That gets a [Maybe] ...  :dunno:  ... I actually have 2 of those in my personal collection I bought way back before I started dabbling in parts.... Picked up a couple of OKO (clones) and Maikuni (note generic spelling)  and some no name brand PWK's (flatslide).. After reading a bunch of horror stories and nightmare scenario's from people trying to use them, I decided against using them..I could not bring myself to put them in my store either..... That's what actually led me to NIBBI.....  NIBBI started out in Italy and has only recently moved to China for manufacturing... They have a really nice quality control team...   But this isn't me trying to sell you on NIBBI... If you want to buy that carb in the link, I'll sell it you at the same price... LOL... Mine is in the USA and ships out same (or following) day.

As to the intake, I have no clue if that would work... I don't think it would work on too many 150cc's scoots because there's this stupid bar right behind the frame (it's part of the actual engine mount)... That bar makes it so you can't even stick on most aftermarket air filters without ducting..... That intake may make the problem worst, or solve it...  Not sure... Too me, it's looks like a stock intake off of a dune buggy/ATV GY6 engine.. There's a note there saying it works with the higher number cams - That's a lot of power at take off, not so much at high RPM... You may want to contact Scrappydogs and ask for details. 

-------------------

Take note, When you upgrade from a CVK (stock vacuum) carb to a PE or PWK, you also need a new cable (or refit the end of your existing cable)... You may also need a new throttle tube. Also, you need to make sure both sides of whatever carb you get fits your intake and whatever you come up with for air intake/filtration. 

 

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Posted

i was thinking since the cable is top mounted, i might could turn it around and run the filter forward(super modified), ever heard of anyone doing that? i might buy that carb off you today, do you know what jets are in it? i saw the cable on the ruck shop...

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Posted

:thinking:

DSCN1083.jpg

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Posted

:thinking:

DSCN1083.jpg

i really wanted to test some lengths out to see what benefits this had. Have any insite?

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Posted

i was thinking since the cable is top mounted, i might could turn it around and run the filter forward(super modified), ever heard of anyone doing that? i might buy that carb off you today, do you know what jets are in it? i saw the cable on the ruck shop...

I don't know what jets are in it, no... They do come with extra jets, but the jets are worthless because they're not stamped...

Direction of cable is not why it doesn't fit... PWK/PE and CVK use a different style of throttle cable... The ends are different.. It could maybe be converted, but you would have to know how to build throttle cables and have the tools to do it... Much cheaper just to buy a cable.... I sell PWK cables BTW. 

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Posted

ima call you tomomorrow, i will need jets asap im going to drill out  the rivits on my muffler to gut it, it rattles and sounds like sand inside , i have it off to remove the rear tire for a new stem, the needle is on the second from the highest setting and i think i got a 107 now.

I don't know what jets are in it, no... They do come with extra jets, but the jets are worthless because they're not stamped...

Direction of cable is not why it doesn't fit... PWK/PE and CVK use a different style of throttle cable... The ends are different.. It could maybe be converted, but you would have to know how to build throttle cables and have the tools to do it... Much cheaper just to buy a cable.... I sell PWK cables BTW. 

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Posted

i really wanted to test some lengths out to see what benefits this had. Have any insite?

no but i wanna tall one, like the drag cars from the 80's, but every time i rip her i find another prob...

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Posted (edited)

 

Adding Length  will Increase Velocity of the Intake Charge, BUT there is only so long you can go. They'll Pop Back when she won't take any more.

We use to add length to Two Stroke Piston port motors, increase the length till she Pop's the carb of then you know ya went a lil to far.

 

 

 

 

 

Edited by pistonguy
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Posted

wonder of the math for a j pipe would work, it finds the length of the sound wave

:thinking:

DSCN1083.jpg

how u do dis?

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Posted

Long intake tract more torque,,,short intake tract quicker response ,,,,this is the exact reason that high performance Japanese bikes have variable length intakes and exhausts,,,and no not the chuff we talk about here,,real live engines that make serious power,,with only 2-4 year life cycles from race winning at the track to production ,,,hell even my dinosaur zxr1200r with the muzzy touch had modified intake tract length and exhaust work,,,and that thing is an antique compared to what's going on now,,,almost bought a lightly laid down cbr1000 a week or so ago,,,,but I regained my senses and passed on it,,,,but there is nothing like pulling the trigger on a modern big bore four,,,

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