which cam is best for the predator
- Thread starter TankforGod3
- Start date
- Tags 212 predator best mods camshaft??? go kart
I won't even pretend to act like I understand cam technology enough to tell you how a cam with less lift and duration seems to pull the same as one with more of both, but it does. It seems to be a smoother more consistent powerband across the entire RPM range. They are quite similar in performance somehow and have the same max target RPM and both recommend the use of larger carbs. I couldn't honestly tell you that one was better than the other.
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Hahaha...:thumbdown: It's like high school all over again except without the girls. I have to say, I am a little disappointed, that a few of you who I know have quite a bit more knowledge and experience than me with these engines, can only laugh at an immature joke made by an old fart who pretty much despises these motors, (& probably anything from this era lol) instead of any real input or opinion on the subject at hand. Not even another suggestion for a cam y'all like...
Everyone likes the MOD2 because that's what GPS and their sponsors like. Being a drop-in cam (at least for 5-bolt covers) and having an improvement over stock, it seems like the perfect cam for a semi-technical store to sell to non-technical people. This website saved me from the MOD2 and encouraged me to do my homework before I buy.
And yes I agree the MOD2 is good but very overrated. Hint hint, it's marketed as a cheater cam for mid/top end racing, not a low/midrange cam to be used with a TC on some guy's minibike that "needs" more power. It sucks how all the real advertising goes to one cam.
Now if OldMiniBikes or NRracing had a C&C or RBG, CL's, CM's, CS's, and an occasional MOD2 would be flying off the shelves.
And yes I agree the MOD2 is good but very overrated. Hint hint, it's marketed as a cheater cam for mid/top end racing, not a low/midrange cam to be used with a TC on some guy's minibike that "needs" more power. It sucks how all the real advertising goes to one cam.
Now if OldMiniBikes or NRracing had a C&C or RBG, CL's, CM's, CS's, and an occasional MOD2 would be flying off the shelves.
Does anyone have dyno graphs showing the power curves of these 4 cams? CM, CS, CL220 and Mod2.
I agree the Mod2 is way over rated for minibikes (it may be OK for a racing go-kart though).
If YOU were to choose between these 3 cams, CM, CS, CL220, which would you pick for a minibike, street riding (occasional drag race)?
Pred 212, stock head, stock rockers, stock compression, billet rod, billet flywheel and header.
Danford1
I agree the Mod2 is way over rated for minibikes (it may be OK for a racing go-kart though).
If YOU were to choose between these 3 cams, CM, CS, CL220, which would you pick for a minibike, street riding (occasional drag race)?
Pred 212, stock head, stock rockers, stock compression, billet rod, billet flywheel and header.
Danford1
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Well, there are a few guys that would like to know so let's give 3 answers.
1. Stock with correct jets
2. Bored stock with correct jets
3. 22mm Mikuni with correct jets.
Those are the popular choices. Since the engines mentioned would be stock bore, stock stroke, stock head, stock compression they aren't all out race engines. Those 3 carb choices should be sufficient.
Just a good all around engine for a Minibike.
Danford1
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Here is your dilemma the stock compression is low so a long duration cam will lower it more and you will have to compensate with a tighter LSA. In addition all these cams are low lift so you would need to use ratio rockers. I myself looking at these cams and if forced at gunpoint I would pick the CM. However I would not use any of them. Can't you put a flattop piston in the motor? If it were me I would get a black mamba Jr and if you are keeping the dished piston have it on a 104 LSA. also use either ratio rockers or pony up for a 310 lift BM Jr. its under his custom grinds. You need to pick a cam around the heads you are using, in your case a stock one. I would also go with the 22 chikuni or bored stock carb.
FYI From a guy at AFR
Heads are the star of the show....everything else plays a supporting role with the camshaft certainly the "lead" in the various supporting roles to consider (induction, exhaust, fuel system, ignition, etc.)
With a really great set of heads you can almost miss every other player in the build and still have above average results when the smoke clears.
LOBE SEPARATION ANGLE
Above 114 Deg. = Extremely Wide
114-112 Deg. = Wide
112-110 Deg. = Moderately Wide
110-108 Deg. = Moderate
108-106 Deg. = Moderately Tight
106-104 Deg. = Tight
Below 104 Deg. = Extremely Tight
VARYING LOBE SEPARATION ANGLE
Tighten.................................................Widen
Moves Torque to Lower RPM.................Raise Torque to Higher RPM
Increases Maximum Torque..................Reduces Maximum Torque
Narrow Power Band..............................Broadens Power Band
Builds Higher Cylinder Pressure............Reduce Maximum Cylinder Pressure
Increase Chance of Engine Knock.........Decrease Chance of Engine Knock.
Increase Cranking Compression...........Decrease Cranking Compression
Increase Effective Compression............Decrease Effective Compression
Idle Vacuum is Reduced........................Idle Vacuum is Increased
Idle Quality Suffers...............................Idle Quality Improves
Open Valve-Overlap Increases.............Open Valve-Overlap Decreases
Closed Valve-Overlap Increases...........Closed Valve-Overlap Decreases
Natural EGR Effect Increases................Natural EGR Effect is Reduced
Decreases Piston-to-Valve Clearance...Increases Piston-to-Valve Clearance
Miss the heads though and you can nail everything else in the build and only produce so-so results.
Heads represent the greatest restriction in the airflow pipeline and due to that fact represent the largest source of all your gains.
Heads are the star of the show....everything else plays a supporting role with the camshaft certainly the "lead" in the various supporting roles to consider (induction, exhaust, fuel system, ignition, etc.)
With a really great set of heads you can almost miss every other player in the build and still have above average results when the smoke clears.
LOBE SEPARATION ANGLE
Above 114 Deg. = Extremely Wide
114-112 Deg. = Wide
112-110 Deg. = Moderately Wide
110-108 Deg. = Moderate
108-106 Deg. = Moderately Tight
106-104 Deg. = Tight
Below 104 Deg. = Extremely Tight
VARYING LOBE SEPARATION ANGLE
Tighten.................................................Widen
Moves Torque to Lower RPM.................Raise Torque to Higher RPM
Increases Maximum Torque..................Reduces Maximum Torque
Narrow Power Band..............................Broadens Power Band
Builds Higher Cylinder Pressure............Reduce Maximum Cylinder Pressure
Increase Chance of Engine Knock.........Decrease Chance of Engine Knock.
Increase Cranking Compression...........Decrease Cranking Compression
Increase Effective Compression............Decrease Effective Compression
Idle Vacuum is Reduced........................Idle Vacuum is Increased
Idle Quality Suffers...............................Idle Quality Improves
Open Valve-Overlap Increases.............Open Valve-Overlap Decreases
Closed Valve-Overlap Increases...........Closed Valve-Overlap Decreases
Natural EGR Effect Increases................Natural EGR Effect is Reduced
Decreases Piston-to-Valve Clearance...Increases Piston-to-Valve Clearance
Miss the heads though and you can nail everything else in the build and only produce so-so results.
Heads represent the greatest restriction in the airflow pipeline and due to that fact represent the largest source of all your gains.
So I would get the hemi piston then just put it on the stock rod with just the wristpin to measure your in the hole measurement with the hemi piston as it is .020 shorter from wristpin hole to the top. Then measure your in the hole measurement. Say its .040 you could get the arc rod that is .020 over and your in the hole would be .020. On my non hemi build I just got the .020 over length rod and my in the hole was .014 so I just stacked two .009 predator gaskets so I had .032 piston to head deck clearance. That would bump your compression up and not require the 104 LSA. just get the standard mamba Jr. You could also go here for a 18cc head.
https://cloneenginepartsonline.com/products/18cc-2524108-77c
You can get them with larger valves. I also have some heads that are ported, with either 28.5 or 32mm valves, I will have to see what I have that would be usable. I put a 14cc head on the NH predator that I built with a 32mm valve.
https://cloneenginepartsonline.com/products/18cc-2524108-77c
You can get them with larger valves. I also have some heads that are ported, with either 28.5 or 32mm valves, I will have to see what I have that would be usable. I put a 14cc head on the NH predator that I built with a 32mm valve.
So I watched a video on LSA, lift and duration. LSA is a little hard (for me) to grasp at this point. I'll just say that based on what I viewed, and what you wrote, I should be looking for moderately tight LSA for my mini bike with a torque converter. What cam (if any) would you pair with the ARC Racing HI COMP 14cc Cylinder Head, keeping budget in mind. Or are both or either of these even worth the hassle. I might add a "615" Box Stock class carb if that would help round out the package. Just trying to ad a little extra pep for the fun of it, without getting crazy with the $$$ and keeping it ride-able and reliable.
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Lol! You think Dave needs a moron like you to stand up for him? Get off the man's dick you little suck-up. I'm sure Dave's been called worse over his many, many years...lol! I have plenty of respect for him and others on this forum, but you deserve none. You're just a know nothing hater trolling the site.
Thanks for the legit responses from Ole, Danford and TheDullCarbide. Once again, I got lost in Ole's technical jargon, but now have a little better understanding of LSA. I agree the Mamba JR is one hell of a cam and that the stock compression is too low for any real fun. But if doing a billet connecting rod anyway, I would get the .020 longer rod and ditch the thick fiber head gasket,(Hemi) for a nice little bump in compression. But to a guy just building and tinkering with their motors for the first time, a $30ish-$50ish cam may sound more doable than a $70-$100 cam, which is why I was sticking in that $50ish price range. I also believe the Mamba Jr might be a bit too much of a leap from stock for a novice/amateur, especially the $100 .310 lift custom grind where you will probably have to clearance the block. Some guys prefer baby steps and or just might not need that much cam. My Mamba JR motor is a beast! Almost violent in the bottom end...
Thanks for the legit responses from Ole, Danford and TheDullCarbide. Once again, I got lost in Ole's technical jargon, but now have a little better understanding of LSA. I agree the Mamba JR is one hell of a cam and that the stock compression is too low for any real fun. But if doing a billet connecting rod anyway, I would get the .020 longer rod and ditch the thick fiber head gasket,(Hemi) for a nice little bump in compression. But to a guy just building and tinkering with their motors for the first time, a $30ish-$50ish cam may sound more doable than a $70-$100 cam, which is why I was sticking in that $50ish price range. I also believe the Mamba Jr might be a bit too much of a leap from stock for a novice/amateur, especially the $100 .310 lift custom grind where you will probably have to clearance the block. Some guys prefer baby steps and or just might not need that much cam. My Mamba JR motor is a beast! Almost violent in the bottom end...
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