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Old 01-28-2019, 08:15 PM
HONEYBADGERFTW HONEYBADGERFTW is offline
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Default Is it engine tuning or what?

Predator 212 with GPS intake kit (.038 jet), new factory style carb, 10T jackshaft sprocket and 60T live axle sprocket, 16x6.5-8 rear tires, straight pipe exhaust, Max-Torque torque converter, and thatís on a Big Thunder kart.

I read how to adjust the carb on here (starting point etc), but Iím not sure if I have it set exactly where it should be (at idle should it surge slightly, be steady or what, still learning these karts). Top speed is around 20 mph. I havenít pulled and cleaned the converter to clean and inspect springs yet (just got the kart a couple of weeks ago). The pulley on the shaft of the engine stuck engaged a couple of times when I stopped the kart, quick light tap and it released.

So, my question is according to some online calculation tools I should be able to get closer to 30 mph yet Iím not so is that a tuning issue (air/fuel), maybe axle bearings jackshaft bearings need replacement etc (robbing HP via resistance), torque converter springs bad/converter needs cleaning, or what?

It felt like I had more ďget up and goĒ left when I was on a long flat straight shot but something is preventing it. I donít think it was the governer either lol.
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Old 01-28-2019, 10:39 PM
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As a first step, I would clean the TC just to ensure that the perceived problem isn't coming from there. Just remember that a 6:1 ratio with 16" tyres is pushing it, even with a TC and slightly modified engine
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Old 01-28-2019, 10:58 PM
HONEYBADGERFTW HONEYBADGERFTW is offline
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Pushing it in what manner?
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Old 01-29-2019, 02:50 AM
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Is it as heavy cart? are you a heavy person?

A quick calc i get ~28mph. If you remove the governor you may get another 10mph.

sounds like used cart? so start by cleaning everything. I agree with landuse, clean the TC first.

at idle engine should be steady once warmed up and choke off. surging could be an issue. not sure what could be cause. dirty carb. bad fuel. bad air/fuel mix?

maybe check spark plug as well.
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Old 01-29-2019, 05:00 AM
HONEYBADGERFTW HONEYBADGERFTW is offline
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Ok thanks. I’m going to clean up the tc and whatever else I can get to lol.

Yeah, it’s a used kart.

I am going to drain the gas tank and put fresh in it.
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Old 01-29-2019, 06:10 AM
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Quote:
Originally Posted by HONEYBADGERFTW View Post
Pushing it in what manner?
Pushing it in the sense that the gear ratio is a bit high. You can think of it like taking off from a standstill in a manual car while you are in second or third gear. The car will struggle to get moving and the clutch will wear out real fast and get real hot. With a TC you will find that belts will wear a lot faster if you are geared too high

I'm not saying that that is your problem....its just something to think about
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Old 01-29-2019, 10:45 PM
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Quote:
Originally Posted by landuse View Post
Pushing it in the sense that the gear ratio is a bit high. You can think of it like taking off from a standstill in a manual car while you are in second or third gear. The car will struggle to get moving and the clutch will wear out real fast and get real hot. With a TC you will find that belts will wear a lot faster if you are geared too high

I'm not saying that that is your problem....its just something to think about
Excellent info. I am going to order new sprockets and was originally going to keep the same setup, but it would be a good idea to lower the ratio to prevent belt failure frequency given that information. What, in your opinion, would be a more appropriate ratio? Iím not an expert by any means so any help is appreciated
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Old 01-30-2019, 08:38 AM
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Mine came with a 22" tire with that gear ratio and torque converter.

That ratio is fine with a torque converter at 16"....

You need to clean the drive unit hub splines and apply dry moly or dry graphite spray after it is already clean
This is how to clean it


My gut feeling is there could be two issues

1) you said intake kit, but did not mention exhaust. An engine needs to breathe, so a high flow intake AND exhaust are needed. Breathing is IN AND OUT, you only have the in part taken care of? If you just did one, the jetting might be overly rich:
TEST: check your spark plug. After a full throttle run and immediately cut off engine and slam on brakes. Pull out plug. plug should be light brown, if black, it is too rich, if white, it is too lean for the most part.

2)Torque Converter: You may have issues that are out of whack with the torque converter, alignment, center to center ratio, or not being able to engage correctly, or even THE BELT ITSELF.
TEST: check the top width of the belt and the center to center distance of the belt. If the belt has worn too much, the top width will be more narrow, and it will easily slide into "overdrive" position but not be able to perform well. When you stomp on the gas, you will EASILY launch hard, and accelerate quickly with that setup.

THIS is MY thunderkart WITH a less powerful engine AND the 20 series torque converter, and tires that are 6" BIGGER. My 20 series was so far gone, that i just had to order a new drive unit, but i was able to keep the driven unit. See how it actually should perform in the real world. Gearing is not your problem.

https://youtu.be/__EfI0MB1ls

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Old 01-30-2019, 05:55 PM
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It's straight pipe exhaust, no muffler, no spark arrestor. I mentioned it in my original post but there was a lot to it and easy to overlook some things.

I pulled my driver pulley assembly, to clean it, and found it looked like I might be the first person to ever clean or inspect it lol, the brass bushing cracked 1/3 of the way through the width (new one on the way) and currently searching for the correct springs that go around the weights. Is the Max-Torque Converter a 20 or 30 series as far as springs etc. are concerned?

I found another issue with the driven assembly while attempting to take it off to clean...it's "stuck" on the jackshaft by rust etc. My understanding is that it's supposed to move freely on the shaft to self-align. I'm at work currently and before leaving home I soaked the shaft/pulley mating areas with penetrating oil and will attempt to free it when I get home to clean it.

---------- Post added at 06:55 PM ---------- Previous post was at 06:36 PM ----------

For size/weight reference this is what my kart would have looked like new, but mines been quite used, repainted, etc before I got it:

http://b48f9f6cb6fc21f9e129-7ce11be9...e95032610.jpeg

I don't have the battery holder parts, the "dash" under steering wheel, and pretty sure I'm missing more hardware/incorrect hardware etc as I've yet to dissemble/inspect/clean everything.
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Old 01-30-2019, 06:14 PM
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A few pics (I cleaned more after the pics, just forgot to take more pictures)
Attached Thumbnails
AB4E10AF-DA9D-4EC0-8F21-E7C562AE0181.jpg   2825E4A3-09E8-42B9-BD55-405CB4920DB8.jpg  

812E25BF-60BB-415F-A725-1D8D079E6ED0.jpg   DADF36AE-91C6-419D-B26E-B2339BBD6270.jpg  

18287115-9EE7-403C-976C-8CE599C54A1F.jpg   952C0963-43B3-4F48-B7B2-51F811825F11.jpg  

  #11  
Old 01-30-2019, 11:24 PM
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Should be a 20 series
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Old 01-30-2019, 11:47 PM
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Quote:
Originally Posted by KartFab View Post
Should be a 20 series
So, any manufactures 20 series springs should work? Along the same lines, what is the difference in 20/30 series?

If I'm not mistaken on my terminology, my TC is outboard, correct? I would like to replace the driven pulley spring and wear tabs as well as springs in my drive pulley (weights too?).
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Old 01-31-2019, 06:37 AM
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https://www.gokartsupply.com/mobile/tcbelts.htm
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Old 01-31-2019, 05:11 PM
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So symmetrical or asymmetrical belt is the only difference? Thanks again KartFab
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Old 01-31-2019, 06:37 PM
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No... the one part of the sheave is angled or not inwhich dictates what belt to use..
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Old 01-31-2019, 07:59 PM
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Quote:
Originally Posted by mckutzy View Post
No... the one part of the sheave is angled or not inwhich dictates what belt to use..
Yeah, that's what I meant. Guess I wasn't too clear on what I meant, but asymmetrical belt used on one flat sheave and one angled other and symmetrical both sheave angles are the same (15/15, 13/13 etc) requiring a belt that is angled the same on both sides, other than that the springs/weights are interchangeable, correct?
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Old 01-31-2019, 10:46 PM
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Quote:
Originally Posted by HONEYBADGERFTW View Post
Yeah, that's what I meant. Guess I wasn't too clear on what I meant, but asymmetrical belt used on one flat sheave and one angled other and symmetrical both sheave angles are the same (15/15, 13/13 etc) requiring a belt that is angled the same on both sides, other than that the springs/weights are interchangeable, correct?
Correct
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