Shax90
New member
Hey guys I'm new to building karts and mini bikes and was curious on what mods you recommend for me to make with my predator 212 I'm building a mini bike.
Best predator 212 mods
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JTSpeedDemon
2019 Build Off Winner!
This article sums it up pretty well: https://affordablegokarts.com/pages/performance-basics
The few things I would like to point out:
- Do NOT upgrade the valve springs unless you upgrade the connecting rod and flywheel.
-An offset timing key is not needed with an ARC billet aluminum flywheel.
-An offset key is usually not needed until you're revving really high, it can be counterproductive if you over-advance the timing, causing detonation.
-None of the stuff other than high flow exhaust/air filter/carburetor rejetting will matter if you keep the governor in, it will just be a waste of money, but it will also limit speed a lot.
-Do NOT bypass the governor. I know it's tempting to simply change the throttle linkage and get ~1600 RPM more, but that plastic governor gear was never meant to spin that fast, and it is very possible that it could fail, causing a lot of very preventable damage. If you want extra RPM, you'll have to open the crankcase.
If you follow all that, you should be OK!
The few things I would like to point out:
- Do NOT upgrade the valve springs unless you upgrade the connecting rod and flywheel.
-An offset timing key is not needed with an ARC billet aluminum flywheel.
-An offset key is usually not needed until you're revving really high, it can be counterproductive if you over-advance the timing, causing detonation.
-None of the stuff other than high flow exhaust/air filter/carburetor rejetting will matter if you keep the governor in, it will just be a waste of money, but it will also limit speed a lot.
-Do NOT bypass the governor. I know it's tempting to simply change the throttle linkage and get ~1600 RPM more, but that plastic governor gear was never meant to spin that fast, and it is very possible that it could fail, causing a lot of very preventable damage. If you want extra RPM, you'll have to open the crankcase.
If you follow all that, you should be OK!
KartFab
Active member
depends on how fast you want it. Keep it stock and do a stage 1. If you remove governor, you should do flywheel rod, springs, and throw a decent cam in there for good fun.
Shax90
New member
This article sums it up pretty well: https://affordablegokarts.com/pages/performance-basics
The few things I would like to point out:
- Do NOT upgrade the valve springs unless you upgrade the connecting rod and flywheel.
-An offset timing key is not needed with an ARC billet aluminum flywheel.
-An offset key is usually not needed until you're revving really high, it can be counterproductive if you over-advance the timing, causing detonation.
-None of the stuff other than high flow exhaust/air filter/carburetor rejetting will matter if you keep the governor in, it will just be a waste of money, but it will also limit speed a lot.
-Do NOT bypass the governor. I know it's tempting to simply change the throttle linkage and get ~1600 RPM more, but that plastic governor gear was never meant to spin that fast, and it is very possible that it could fail, causing a lot of very preventable damage. If you want extra RPM, you'll have to open the crankcase.
If you follow all that, you should be OK!
Thanks! I'll be sure to post pictures when its finished.
txluke
Active member
I have built dozens. The 1st thing I do is add an air pod and adapter, change to a better flowing exhaust and go with bigger jets. I make my exhausts and drill my own jets but you can find all of it in a kit. I also file the timing key to advance the timing a bit. They retard them from the factory to pass emissions. Under the tank there is a rod from the governor linkage to your throttle linkage. On that rod is a spring. Put a small zip tie on it to keep it from expanding. This will give you more RPM'S and allow you to still use the stock throttle setup. Dont worry about a new flywheel. The stock springs will float the valves before you get to the point of danger. I have been ditching the stock carb and have been using a pz22 slide carb on my newer builds. People are always saying how bad the carb on their 212 is. It is not a bad carb, it is just not made for motorsports. It is designed to run equipment at a constant RPM. If you take your stock carb off there is a plastic spacer behind it. The side facing the carb has a round opening, the block side has a larger D shaped opening. You are allowing way more flow when you change carbs and ditch that. You will have to remove your governor but again, the stock springs won't let you rev to the point where you will damage anything. Your throttle response will be so much better. Before you even do any of these I would slap a torque converter on. That will give you the best bang for your buck. My favorite kart has a stock 212cc with a torque converter. My favorite bike has a hopped up 196cc and a torque converter.
JTSpeedDemon
2019 Build Off Winner!
On Briggs at least, you can just keep using the stock linkage. It's probably the same for clones. Or you can remove the shaft and put a bolt in the hole if you want.
txluke
Active member
They sell throttle linkage kits that bolt to the shroud. With that being said, if you remove the governor, the best thing to do is get a slide carb and you won't have to worry about any of the linkage. And it will greatly improve performance. XLYZE Carburetor Air Filter Racing Intake Manifold Kit For Predator 212cc GX200 196cc Mini Bike Go Kart (Red) https://www.amazon.com/dp/B07H6WVL74/ref=cm_sw_r_cp_apa_i_GuihEb59WANVC You will need a new throttle cable with the end for the carb and the jets will have to be changed. I just drilled mine out.
Shax90
New member
If I have a torque converter would that allow me to reduce my gear ratio because people have been recommending ratios that greatly reduce the speed.
txluke
Active member
The torque converter will adjust to give you a lower gear ratio at takeoff (more torque) and a higher gear ratio opened up (more speed).
Shax90
New member
Yes I'm just saying the gearing from the torque converter sprocket and the axle sprocket. Could I have that ratio be smaller than if there was no TC.
Thanks,
Ive gone back and looked at a few videos on what to do. I have adjustable carbs coming in today with new intakes. I may look at that amazon carb down the road, with 2 motors $100 in carbs is a bit high when I have a show truck that needs parts too.
Mylo <>
Ive gone back and looked at a few videos on what to do. I have adjustable carbs coming in today with new intakes. I may look at that amazon carb down the road, with 2 motors $100 in carbs is a bit high when I have a show truck that needs parts too.
Mylo <>
Thx TX,With my setup Im not sure I'd have the room to run a converter without rebuilding the back half. It's pretty tight between motors now. Also how much adjustment is there in these kits? What would you suggest? Thanks for the input as well.
Mylo <>
txluke
Active member
I don't know the gear ratio on the stock bike but because of the increase in torque I know that the torque converter has a lower gear ratio to start. You can change the gear on the torque converter to further change ratios.
Shax90
New member
Okay thank you I dotn have the bike built yet I'm building one from scratch so there is no stock ratio I was just asking if the torque converter would allow me to use a lower gear ratio for more speed than I could practically use on a bike without a torque converter. I remember someone saying you can have your ratio like 40% smaller with a TC than withiut butni wanted to check with you guys
txluke
Active member
I am running 50t rear sprocket, 10t on torque converter and 19" tires and it has plenty of low end torque and I cruise at 43mph.
Shax90
New member
How does everyone think of this 27" diameter rear tire. A torque converter with 12 tooth sprocket going to a 72 tooth sprocket, giving me a 6:1 ratio
JTSpeedDemon
2019 Build Off Winner!
You said in your other thread that you got a scrap dirt bike to use frame parts of. It might be more worth it to just fix it up! You'll end up with a faster bike with less worry about this kind of stuff.
Oh, and 6:1 with 27" is way too high.
Oh, and 6:1 with 27" is way too high.
Shax90
New member
Its just an old rusty frame or else I would have I'm just keeping the wheels and the forks. Do you think I could get away with 7:1? I'm trying to keep some speed. I have riding experience but building this is a whole new thing. Also I really appreciate the help you've been giving.
JTSpeedDemon
2019 Build Off Winner!
7:1 could be done with a torque converter, but it's high enough it will cause premature belt wear. Try going with an 8:1 and see how you like it. Trust me, when you're on a small vehicle like a go kart or minibike, 40 MPH is actually at the point of danger. If you want more speed, the best way to do it is upgrade the engine, or else the drivetrain will wear out quickly.
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