Need build advice for 212 Predator!

[scottygrape]

Hello! I am going to order a bunch of parts and could use some advice. Here is the build list.

212 Hemi Predator
Governor Removed
Billet Flywheel
+.02 ARC Connecting Rod
Performance Intake and Exhaust Kit with upgraded e-tube and jet
Wiseco Piston
Black Mamba Jr Cam
22Lb Valve Springs
Chromoly Push Rods

Any critiquing would be great!! I am shooting for a good torquey motor and want a max rpm of 7500. The drivetrain on my cart will be as follows..

Road Frame Kart
12 Inch Wheels
TAV 30 Series Torque Converter
12T Clutch Sprocket
60T Axle Sprocket

My questions are,

Will this be a good setup for what I am looking to do? I am shooting for a top speed of 45 MPH and be able to drift easily and do good burnouts.

What kind of rockers do I need for my cam setup? What ratio?

Do I need titanium valve retainers?

How much would i benefit from a Mikuni Carb Kit?

Thank you in advance and sorry for the long post!

 

[Bbqjoe]

The very best thing to do, is do all those mods at the same time.
That way when it won't start, you won't know whether to sh!t or wind your watch.

 

[MTNSleder]

I easily go 45 mph on a stock engine and drift easy (With TC). Your kart will be like a little devil in the heat when your done

 

[itsid]

Well I'm too lazy to look up the specs for the Black Mamba Cam but I think, no matter what;
that engine will be a blast to run.

12" wheels with an engine like that and a series 30 TC hooked in between...
I think 5:1 should do fine...
maybe you'll need some more TC belts as average joe, but with a modified engine,
and the urge to leave rubber on the road, that'd be expected anyways, right?

But since you "only" want ~45mph.. may I suggest a 6:1 ratio instead (good for nearly 50mph)
since that'll increase the life of your TC belts and also increase the torque at takeoff significantly
(easier to loose traction and spin wheels)

IIRC the Mamba cams are all lifters *shrugs...still too lazy to look them up*
So 1.1 rockers should do nicely.. 1.3 might interfere with the flattop piston (depending on the cam profile)
titanium retainers.. *shrugs* sound unnecessary to me tbh.
mikunis are easier to adjust IMHO and provide a slightly better flowing profile...
but a well setup stock carb is just as performant really.
if you want to increase the carb's diameter though (say mikuni or gx390)
I'd go for the mikuni (just a personal preference really)
If the diameter of the stock carb is sufficient for your fueling needs,
and it's just the slide carb you're after.. then I'd run the stock carb instead of buying a mikuni tbh.

'sid

 

[Hellion]

He wants it all and he wants it now, Joe. Time's a wastin'! Those days of experimentation, progressive learning and gaining mechanical wisdom are long gone.

I am shooting for a top speed of 45 MPH and be able to drift easily and do good burnouts.

I haven't seen a go kart yet that'd do 'good burnouts' with a TAV or even a regular cent. clutch.

For all the wonderful gear ratios and usability that TAVs provide, they are a sizable parasitic drain on the drivetrain.

 

[scottygrape]

Thank you for all the input! And Sid, I do also have a 72 tooth clutch on the way to make it a 6:1 drive ratio. Also, does anyone know the best way to plug the holes left from removing the governor and oil pressure sensor?

 

[Joe-405]

So you know you could buy a bsp engine that's ready to start for less and be at the same hp correct ?

And your gonna want a 22mm Mikuni kit with that setup. The stock carb will choke it down with one of those cam profiles. You will see a noticable increase in power with the Mikuni.

 

[scottygrape]

Yes I know that Joe. The reason I am building it is because that it is simply a blast! I love building things. And this way I also have a much better understanding of how my motor operates.

 

[itsid]

So you know you could buy a bsp engine that's ready to start for less and be at the same hp correct ?

And your gonna want a 22mm Mikuni kit with that setup. The stock carb will choke it down with one of those cam profiles. You will see a noticable increase in power with the Mikuni.

I think I understand what you are trying to say Joe;
BUT what you actually said makes almost no sense

A BSP engine (all stock clone engine with just a flywheel basically)
"ready to start" is equipped with a rejetted stock carb.
So, if those "same hp" and performance can be fed with a rejetted stock carb,
why can't the "same hp" engine Scotty builds?

See what I mean?

And frankly, a BSP engine is alright, but it's still a stock industrial engine, with all it's power drawbacks and such.
with stock springs I doubt it'll hit the targeted 7.5k rpm Scotty is aiming at for example.


So as a wild guess.. I'd say Scotty will have ~10% more grunt and likely around 20% more roar (yes, that's torque and hp)

Here's what I understand from your post:
A BSP engine with just some minor additional mods can hit the desired rpm and speed target, maybe even the torque he's aiming at.

But then again, that's basically leaving the flattop piston, and cam out of the building equation (the con rod is a good idea to keep)
at which point I'm not sure the BSP isn't going to be more expensive than a fresh predator mod.

and that the additional power he's getting from the cam and compression increase is what makes the engine choke on the stock carb.

IDK if that's true at all... I really don't, but it doesn't sound too plausible to me,
venturis are great if jetted correctly
I have an engine with a tiny little venturi carb (17mm)
stabling 16 horses
(two stroke alright... still a lot of air is being moved through that orifice at 14k rpm )

Again, I'm all for mikuni carbs, but I wouldn't say it's a mandatory purchase here *shrugs*.
I'd try the stock carb first(rejetted E140-tube) and if that's not satisfying... mikuni.


'sid

 

[B_Bimmer]

Also, does anyone know the best way to plug the holes left from removing the governor and oil pressure sensor?

I like to find bolts that are just long enough, coat them with rtv sealant and get them loosely started in the holes, let it set up, and crank um down. Obviously you never want to see them vibrate loose so I'll generally use a locking nut as well. If you're motivated and want to clean up metal shavings you could also tap threads and put a bolt in from the outside. The advantage of that is there is nothing to eventually come loose inside and it would look very clean and finished, but it's a mess.

 

[itsid]

bolts are nice..
JB Weld is quick
(some prior roughening with a needle file improves the bond)

'sid

 

[KartFab]

Hello! I am going to order a bunch of parts and could use some advice. Here is the build list.

212 Hemi Predator
Governor Removed
Billet Flywheel
+.02 ARC Connecting Rod
Performance Intake and Exhaust Kit with upgraded e-tube and jet
Wiseco Piston
Black Mamba Jr Cam
22Lb Valve Springs
Chromoly Push Rods

Any critiquing would be great!! I am shooting for a good torquey motor and want a max rpm of 7500. The drivetrain on my cart will be as follows..

Road Frame Kart
12 Inch Wheels
TAV 30 Series Torque Converter
12T Clutch Sprocket
60T Axle Sprocket

My questions are,

Will this be a good setup for what I am looking to do? I am shooting for a top speed of 45 MPH and be able to drift easily and do good burnouts.

What kind of rockers do I need for my cam setup? What ratio?

Do I need titanium valve retainers?

How much would i benefit from a Mikuni Carb Kit?

Thank you in advance and sorry for the long post!

Disclaimer: ive been doing a lot of research so i think i know things that i have no real world experience in doing. Have been doing some performance mods recently, and just have a few questions that you can answer yourself
clearances: cam to crank, rod to block, piston to deck, valve to piston, cam to block,
timing you measure and set it? what about valve lash? (cam card info)
valve train if you are going to have a lot of sustained rpms above (ehh i forget) you do the stainless valves, etc as regular valve trains cant handle the abuse of a high lift cam, and the stock valves may warp under that heat. If you do end up doing valve train adjustments, you will for sure need to do some real work on it. I opted to not do any of that because meh... lots of work, and i wotn be revving high consistently.
clutch and rpms so target max rpm of 7500 with a 30 series torque converter? This may not be a smart thing to do. Please consider a disc racing clutch or a more expensive centrifugal race clutch. the 30 series robs lots of hp at high rpms, belts 'explode' at high rpms, and 100% of the racing people use some sort of centrifugal/clutch disc for high rpms (ive seen exceptions, but very few, and these exceptions were for karts on small tracks that maintained lower rpms.

Also, the carburetor is one of the most important things to get right, and a stock carb with bolt on performance mods flows poorly. MAking the decision to switch from a regular carb to a mikuni/tillotson is a great idea, especially if you want to hit a high rpm goal.

 

[scottygrape]

What about a 40 series torque converter? Will that do the trick? I do not plan to race this kart. I just want to mess around the house. 2 more questions I have, how do I adjust the timing to 32 degrees for the black Mamba Jr cam? And also I plan to go to fastenal after work to get a 3/8 bolt and a 3/8 aluminum washer to seal off the hole for the low oil sensor. Will this seal it off?

 

[Kleyny]

Do you need to modify the intake to accommodate a gx390 carb or will it just bolt straight up?
Edit.. I found that there's 10mm difference in manifold bolt distance.

 

[itsid]

hehe the bigger diameter has to go somewhere
but just a matter of flanges for the intake manifold

'sid

 

[Hellion]

What about a 40 series torque converter? Will that do the trick? I do not plan to race this kart. I just want to mess around the house. 2 more questions I have, how do I adjust the timing to 32 degrees for the black Mamba Jr cam? And also I plan to go to fastenal after work to get a 3/8 bolt and a 3/8 aluminum washer to seal off the hole for the low oil sensor. Will this seal it off?

ANY TAV is a power robber and a 40 series would be overkill. He's not telling you that you have to be a racer only to utilize a centrifugal/racing clutch; he's telling you that because it's a high-speed application and the best way to reach your top speed goal.

If you wanted your kart to perform like a stick shift car where you can rev it up and dump the clutch (i.e., burnouts), then I would suggest a 3D manual clutch.

To advance or retard your timing, there's special flywheel keys that are offset to provide the desired timing.

Providing the nut and bolts you're going to obtain will fit the diameter of the low oil sensor port once it is removed, that alone will not provide a proper seal. I would suggest tapping the port for the bolt you're going to use and sealing it off with high temperature thread sealant so there's no oil constantly weeping from the hole. Why chance it?
Nothing better than metal on metal....

 

[scottygrape]

Okay thanks for the advice Hellion! I wonder how much power a 3D clutch would hold. I'm having a hard time deciding on a cam. I want to make the most power everywhere I can in the power and. I don't know if I should go with a Black Mamba, Black Mamba Jr or a Mod 1. I would like to be able to rev as high as possible. But I would like it to ide properly also. Does anyone know if you have to grind away at the crank if you install the black Mamba or mod 1?

 

[Flyinhillbilly]

Okay thanks for the advice Hellion! I wonder how much power a 3D clutch would hold. I'm having a hard time deciding on a cam. I want to make the most power everywhere I can in the power and. I don't know if I should go with a Black Mamba, Black Mamba Jr or a Mod 1. I would like to be able to rev as high as possible. But I would like it to ide properly also. Does anyone know if you have to grind away at the crank if you install the black Mamba or mod 1?

I saw a video somewhere with one on a 55hp open modified. The hottest clone i'm aware of was just over 31hp, and it was a big bore, high compression stroker on alcohol. I think you'll be fine.

 

[Joe-405]

I missed his target rpm range. The bsp will go to 5000-5500 only. My mistake. And yes your right sid.

I have about $300 total in my bsp engines and they make 10hp out of the box. Bsp told me they will make 11-12 with the Mikuni but it's not allowed in the bsp class they designed the engine around.