Trying to build a 20+ hp predator 212

[panchothedog]

You don't need 20 horsepower to go very fast in a go kart. And you don't need a
.356" lift cam any more than a 28mm carburetor. Do you even know what coil bind is? A stock cam with some ratio rockers and 26 lb springs will deliver good performance, especially with increased compression as I explained in my 1st post. Have you even ever taken one apart? Do you own piston ring compressor.
How about a valve spring compressor. You will also need a 1/2" drive torque wrench, and a 1/4" torque wrench calibrated in inch pounds. If you don't have these tools, you won't get to 1st base in trying to build an engine. I am not a professional engine builder. Just an old man who has been working on and racing different things for more than 50 years, and have built about 8 Predators in the last 4 years. It is VERY easy for me to recognize from your post that you are way too fixated on big this and big that. Buy your engine, get.the aftermarket rod and flywheel, delete the governor, put some stiffer valve springs, jet the stock carburetor and put on a pipe and rvl muffler. Mount it on your kart and drive the darn thing. You will then have the foundation to modify more extensively from there going forward.

 

[Denny]

Dude we’ve seen it all, you’re setting yourself up for failure. Learn all the parts, their functions and how they interact with each other first. Then worry about a build. Buy a big block first and remove the governor and you will have more power than any small block could ever dream of for about $100.00 less money! I speak from 40 years experience myself. If you add in the other guys we’re close to 150 or more years.

 

[bob58o]

Shoot the moon! You need more cowbell. When you make mistakes, you learn how to do things.
I’ll look back at my old build. I had an engine on a bike that got stolen. It was a Hemi, probably with a +0.020” connecting rod, a NR .285 cam, and I had to cut a valve relief into the flat top piston to prevent the valve and piston from making unauthorized contact.
But I was able to use my cheap drill press with a dremel attachment to cut the piston. You learn how to do things.

I think I used 26lb springs, heavier springs required the spring pockets cut larger IIRC in the Hemi head.

My threads are pretty much unreadably boring.

Hemi Predator Build #2

CAMSHAFT NR 285-0211 http://www.nrracing.com/product-p/200cam-285.htm 0.285" Lift 250 degree duration (at 0.050") 102 Intake Center Line 111 LSA 7000 RPM Camshaft, 285-0211: Small track cam for serious torque Requires 11:1 or more compression ratio Requires 26lb or more valve springs. This...

www.diygokarts.com

 

[bob58o]

An Isky black mamba jr cam, 26lb valve springs, 24mm carb is a great first engine build for a Hemi.

That was what I did my first time playing with engines. I used a billet rod, but the stock flywheel. It turned over 7000 RPM and pushed my minibike to 52mph uphill. I don’t recommend turning the stock flywheel much more than 5500 rpm or so

I think I used a +0.020 rod, 0.027 head gasket, and milled the head like 0.035”

BLACK MAMBA JR CAM (GX200/CLONE/HEMI) - SMALL ENGINE CAMS

.275" LIFT 230 DURATION @ .050" 104° LSA THE ULTIMATE TORQUE CAM...6,000+RPM! HARDFACE WELDED! DECAL AND SPEC SHEET INCLUDED

smallenginecams.com

 

[Rat]

420 is not that much heavier but has gobs more torque than any 212 could ever dream of! Torque is what makes a cart move!

Lmao just like my 208, that thing will kill a 212

 

[Rat]

I've been watching road to horse power red beard garage is kinda how I found out about the stage 4 kit

Stage kits are for newbs and suckers not smart enough to know better.

You want to donkey punch that 212 into making REAL power the first thing you need to do is sell the Hemi and get a Non Hemi.

Then Get a Mod2 Cam and a non resistor ignition coil from Dover (DIYPowersports). Get an ARC Billet Conrod [3.308] and flywheel package. Then get the old style HD Champion rockersand get that stamped tin trash out if there, you'll need a valve cover spacer or an aftermarket high clearance one for those (NON HEMI ONLY) rockers. You're going to want split keeper spring retainers to actually get the full spring weight of whatever valve springs you go with...22# springs are sufficient to prevent float at 6500 rpm and won't cause parasitic drag on the cam.

Even with the governor removed, you won't rev more than 4500-4800 and if the goal is power you want it to be free to rev until the cam can't make power... and with stock ignition that's never going to happen.

 

[Rat]

BLACK MAMBA JR CAM (GX200/CLONE/HEMI) - SMALL ENGINE CAMS

.275" LIFT 230 DURATION @ .050" 104° LSA THE ULTIMATE TORQUE CAM...6,000+RPM! HARDFACE WELDED! DECAL AND SPEC SHEET INCLUDED

smallenginecams.com

Same specs as a Dover Mod2 Cam

 

[Denny]

But you’re still spending over $600 the hard way to do what a $400 engine will do the easy way! And with double the torque. I just don’t understand it.

 

[bob58o]

Same specs as a Dover Mod2 Cam

Not sure what specs you are talking about?

Mod2 cams have lift of 225/230 with duration of 245 degrees.

Black mamba Jr has lift of 275 with duration of 230 degrees

 

[BrownStainRacing]

Same specs as a Dover Mod2 Cam

Where do you find those specs???

I didn't know Jerry made his own version of the Mod2.

He's got the Holy Moses cams, I think they are restrictor plate racing cams.

His Superman cams are not legal for any class except Outlaw (rwyb).

1 is a torq cam and the other is a HP cam.

Dyno Cams got the market covered with thier Mod2 version.

NRRacing has thier own version of the Mod2, it's got 1 or 2* advance built in it, compared to Dynos version.


The Mod2 is a racing cam at tracks with no duration checks and stock lift rules only.

It's a cam you would want at Talladega or Daytona. But you lift the throttle for a split second, the whole dam field goes by you, .

It's a momentum track cam. It needs to stay above 5k rpm to get out of it what it was designed for.

It's the worse cam we tested for backyard fun, trail buster rides, karts or mini bikes.

We spent alot of time testing the Mod2.

It works best with 10.5:1+ CR, big stall 4500+ rpm, 1.3:1 rocker arm on the intake only, big gears, and small tires to keep the rpm up.

I think I got 1 in a box of used parts last week. It'll definitely get more use in the trash can after I cut in half, .
I wouldn't want to accidentally give it away, and make somebody very disappointed.

 

[bob58o]

But you’re still spending over $600 the hard way to do what a $400 engine will do the easy way! And with double the torque. I just don’t understand it.

because this is a diy forum.

How much money does it cost to build a 8000 rpm big block. You can gear for torque and let the small block scream with the thunder of 212 flying bald eagles.

And what do you learn about engines by putting a stock engine on a kart? You gotta pay to play. You pay for the experience and education.

 

[Denny]

That’s where you’re wrong. It costs just as much (within a few bucks) to build a big block as a small block. And the power will be off the charts! With a big block you don’t need 8,000 rpm, 6,000 will do just fine! Remember you got all that extra torque! Torque moves mountains. Horsepower is a theoretical number about how fast it will do it. It’s also a number that can be easily manipulated by a skilled dyno operator.

 

[bob58o]

Back in the day, Geoff from Vegas Carts used to claim you could make 22 HP with a 420cc by using #35lb springs (I don’t think they are available any more, a 6 degree offset timing key, a 28-32mm carb, head milled and ported, and an exhaust. Then it could be done for $400 including engine.

Stolen from Buggies gone Wild



"I can tell you that Ive spent nearly 20hrs a week since September, R&Ding these 420s and have gone from a stock 420 to a completely built 440 and pretty much every combination in-between. All of my testing has been done on the same white 1992 Club Car DS with 12" rims and 18" low pro tires, utilizing the same CPP clutches that I started out with. So I can assure you that my R&D was completely relevant to the subject.

Furthermore, I have had direct contact with Charles Mosley (minidragbike), Jeremy Parsons (Parsons Racing Engines), Russell @ NR-Racing, Shane @ Affordable Go Karts, and Tim Iskenderian (Small Engine Cams). These people are some of, in not THE, TOP Clone Engine builders in the country. Each and every one of them has led me in the right direction and they have all contributed to my 440 program in one way or another.

My goal was to develop an engine specific to Golf Carts, that was extremely affordable, yet also yielded massive power gains and maintained reliability and low end torque. The goal was to develop this platform and make it available for HALF the cost of a typical v-twin big block swap.

As of right now, I have 440 engines 2 weeks away, and performance parts 2 months away. I have used Parsons and Isky parts exclusively in the meantime to test the 420 & 440 CLONE engines that I have in house. These are the FACTS:

-Big Engines Like Big Cams , The bigger the cam I put in them, the more OVERALL HP and Torque they gained. I tested 7 cams, starting with a 220 Duration/.280 Lift cam. I ended up with a 260 Duration / .410 Lift cam that Isky ground custom for me. Every time that I went up to a larger cam, I gained more power throughout the ENTIRE rpm range. Iam positive that I could go even larger, however, I feel that the 260/410 cam is a great all-around setup and will serve as a dual-purpose cam so even the kart and lawnmower guys can use it. Eventually I will test some .500 lift cams, the real issue I ran into was clearance with the crank. This cam is .020" away from hitting as it is.

-7000rpm is the limit for the big blocks when it comes to reliability(they dont like to rev), thats the reason I stuck with stock size valves. The stock 35/31mm valves wont make power past 6500rpm anyway, the key to keeping these engines alive is keeping the RPMs down. Keep it at 7k or under and you will not have a reliability issue.

-Stock Clutches are good for stock engines, if you want to make power and use it, you will need to upgrade the clutch first. Stick with CPPs Clutch, its rated to 30hp. Im probably making 32-33 and its holding up just fine. You dont see V-Twin swaps with stock clutches very often! More Power = More Supporting Mods...Bottom Line

-A Built Clone with a Billet Rod, Hard-Face-Welded Camshaft, Stainless Valves, Chrome Silicon Springs, Aluminum or Titanium Retainers. Chromoly Pushrods, and Shaft Rockers, is going to be MUCH stronger and more reliable than stock. The stock rod flexes and deforms under high power, it also is a **** poor design for high speed lubrication and will gall the crank. I ran a stock rod and valves for ALONG time and ALOT of abuse. I didnt have 1 problem until the day I put a cam in it. Even the small cam was such a drastic power increase, the stock rod and valves ate the sheets within 4 hours. Stock valves are junk and cannot withstand the higher valvespring pressures of dual springs, so bottom line is, they dont call it a "Built" engine for their health. Its "Built" so it can RELIABLY take the abuse associated with a high horsepower application. Both ARC and Parsons rods have taken tons of abuse on the go kart tracks which are significantly harder on any engine than a Golf Cart is. 6500+ rpm for 30 mins at a time.

-Dyno numbers mean nothing! I have a drag mustang that makes over 1200HP but it only makes 700rwhp on a chassis dyno. There are too many variables to consider with dynos, so its really a waste of time trying to compare them in any way, especially when considering two different setups. I tune clone'd golf carts based on feel, its not like we are drag racing and trying to get every last .01 of a second. All we care about is that the cart starts easily, idles smoothly, and pulls smoothly through the whole rpm band without issue, and of course...it must pull really hard, and do big wheelies

I would continue but Im very hungry at the moment and dinner is ready. I hope to post some good videos this weekend but I just havent had time lately. Im anxious to get the built engine'd cart on youtube. Its way past the point of being safe and is really cool seeing as how you can get soo much power into a stock height cart, no lift kit needed(HUGE advantage of clones over v-twins.)."

With regards to bang for buck, a 420 clone with the following mods will make 20-22hp and doesnt need a billet rod:

-Timing Key
-Ported & Milled Head
-28-32mm ATV/Motocycle Carb
-Header & Free Flowing Exhaust
-HD ValveSprings

Can be done for $400 including the engine.

-Geoff

-Geoff Warner
702-335-4002

 

[Rat]

Where do you find those specs???

I didn't know Jerry made his own version of the Mod2.

He's got the Holy Moses cams, I think they are resistor plate racing cams.

His Superman cams are not legal for any class except Outlaw (rwyb).

1 is a torq cam and the other is a HP cam.

Dyno Cams got the market covered with thier Mod2 version.

NRRacing has thier own version of the Mod2, it's got 1 or 2* advance built in it, compared to Dynos version.


The Mod2 is a racing cam at tracks with no duration checks and stock lift rules only.

It's a cam you would want at Talladega or Daytona. But you lift the throttle for a split second, the whole dam field goes by you, .

It's a momentum track cam. It needs to stay above 5k rpm to get out of it what it was designed for.

It's the worse cam we tested for backyard fun, trail buster rides, karts or mini bikes.

We spent alot of time testing the Mod2.

It works best with 10.5:1+ CR, big stall 4500+ rpm, 1.3:1 rocker arm on the intake only, big gears, and small tires to keep the rpm up.

I think I got 1 in a box of used parts last week. It'll definitely get more use in the trash can after I cut in half, .
I wouldn't want to accidentally give it away, and make somebody very disappointed.

I may be mistaken about my cam coming from dover. The specs are Not quite what Bob said so idk maybe it's not a Mod2 either.

Supposedly it's good for "up to 6500 rpm"
Cam Specs
Intake
Open 30 Close 76
Lift 234
CL 112
Duration @ 050 > 220

Exhaust
Open 67 close 42
Lift 240
CL 105
Duration @ 050 > 223

 

[bob58o]

Those specs are the duration of a stock cam.
The lift on that cam is not much more than stock.

I’m guessing the cam is advanced or retarded, otherwise it’s basically stock. I think the centerlines are actually close to that of a stock cam as well.

so called cheater cams usually have stock duration with more lift (for duration rules), or stock lift with more duration (for lift rules) like a mod2.

Dynocams CL series is close to a stock cam as far as lift and duration. They adjust the timing (advance or retard) to change target rpm range.

the specs you gave seem more like a CL, not mod 2.

It seems halfway between CL1 and CL2-(Retarded 2 degrees) with a 5% increase in lift.

 

[Rat]

Those specs are the duration of a stock cam.
The lift on that cam is not much more than stock.

I’m guessing the cam is advanced or retarded, otherwise it’s basically stock. I think the centerlines are actually close to that of a stock cam as well.

so called cheater cams usually have stock duration with more lift (for duration rules), or stock lift with more duration (for lift rules) like a mod2.

Dynocams CL series is close to a stock cam as far as lift and duration. They adjust the timing (advance or retard) to change target rpm range.

the specs you gave seem more like a CL, not mod 2.

Figures but I guess it's good that its NOT a Mod2 by the sounds of it... I will no longer be referring to it as such that's for damn sure

 

[BrownStainRacing]

Figures but I guess it's good that its NOT a Mod2 by the sounds of it... I will no longer be referring to it as such that's for damn sure

Don't feel bad.
We thought it was the hot ticket too, til we started testing it against stock cams with the same set up.
But we did learn how to get it to move,

That cam you have MIGHT be a restrictor plate cam from Dover, idk much about em.

They restrict the air flow for plate racing, so they play with cams that are retarded and go up on the ignition timing and carb jets.

Them plate engines have come around quite well in the last few years.

I'm not a fan of retarding a cam like that, but I don't race on a rules track either.

If that cam was straight up (108.5* icl and 108.5* ecl) it would make that 76* ivc change to 72 or 73*, making power come on sooner.

In other words, the intake valve would close earlier and put the air fuel mix under more pressure before the sparkplug fires.

But it's not a bad cam from the numbers I see.

The isky BMJ cam has a ivc of 65*, even though it has more duration at .050" lift, it has less advertised duration then your cam, making it a faster ramped cam.

When valves are going on seat and off seat faster, it makes "special magic" inside the combustion chamber.

The isky BM Sr. has a ivc closing of 77*, thats really close to your 76*. But the BM sr has 246* at .050" lift and 108 lsa or c/l. it's a 8000+ rpm cam, but hits like a ton of lead coming outta the hole, and pulls even harder in the mid and high range.

It's actually too much cam for my builds, but it's a hard punching cam.

 

[Rat]

Don't feel bad.
We thought it was the hot ticket too, til we started testing it against stock cams with the same set up.
But we did learn how to get it to move,

That cam you have MIGHT be a restrictor plate cam from Dover, idk much about em.

They restrict the air flow for plate racing, so they play with cams that are retarded and go up on the ignition timing and carb jets.

Them plate engines have come around quite well in the last few years.

I'm not a fan of retarding a cam like that, but I don't race on a rules track either.

If that cam was straight up (108.5* icl and 108.5* ecl) it would make that 76* ivc change to 72 or 73*, making power come on sooner.

In other words, the intake valve would close earlier and put the air fuel mix under more pressure before the sparkplug fires.

But it's not a bad cam from the numbers I see.

The isky BMJ cam has a ivc of 65*, even though it has more duration at .050" lift, it has less advertised duration then your cam, making it a faster ramped cam.

When valves are going on seat and off seat faster, it makes "special magic" inside the combustion chamber.

The isky BM Sr. has a ivc closing of 77*, thats really close to your 76*. But the BM sr has 246* at .050" lift and 108 lsa or c/l. it's a 8000+ rpm cam, but hits like a ton of lead coming outta the hole, and pulls even harder in the mid and high range.

It's actually too much cam for my builds, but it's a hard punching cam.

I don't "race" I just roll dirty as a street sleeper waiting for a local badge to light me up... which is apparently not likely.

So far I've wound it up to 5200 (stock timing key) but the 30series pretty quickly pulls it back down to 3800-4200, which isn't terrible because it's at 40mph (gps speedometer) by that point with more sheave to open and not quite enough road to try punching it like that.

The disconcerting thing is I've had it kickback at the starter a couple times now but I am debating grabbing a fistful of keys and cutting several offset until I find one that brings the ugly out.

I cut a key to roughly 5° and the kickback happened a little more often, and it definitely wanted more fuel to keep cooking and not burn up.

As is there is more than plenty enough grunt considering it will yoink the nose right up from a dead standstill, and will accelerate fairly quick up a steep grade.

 

[bob58o]

Best way to pull the cord is to pull slowly until you feel the compression stroke, then let the cord retract, then give the cord a good yank.

Similarly, when storing small engines, you should do the same. Pull slowly until you feel the compression stroke, then stop and store like that. It means the valves are closed and the springs are relaxed, which I believe is the preferred way.

 

[Rat]

Best way to pull the cord is to pull slowly until you feel the compression stroke, then let the cord retract, then give the cord a good yank.

Similarly, when storing small engines, you should do the same. Pull slowly until you feel the compression stroke, then stop and store like that. It means the valves are closed and the springs are relaxed, which I believe is the preferred way.

LMMFAO that's all good and I know that but there's no cord on this pup. Recoil deleted, Electric Start Only, hand shaped cowl cover plate so the damn thing would stop sucking on my jeans.