Cam v.s. Head Work

[Moedog07]

What rear sprocket is on there? What number teeth? Is it #35 chain?

One of mine has a 12"tires and a 72 tooth rear sprocket it tops out at around 28mph.

 

[Greedy_Jayp]

What rear sprocket is on there? What number teeth? Is it #35 chain?

One of mine has a 12"tires and a 72 tooth rear sprocket it tops out at around 28mph.

10 on the clutch and 30 on the sproket..keep in mind im spinning at 5000 rpm and the tires are 12 or 13"

 

[Moedog07]

Whew! 30 on the sprocket? Is it a dog on take off?

If I leave on full throttle it will stand up.

 

[Greedy_Jayp]

Whew! 30 on the sprocket? Is it a dog on take off?

nah it goes off the line but can be faster..ill be upgrading my sproket this week..and i believe i have the #41 chain..any videos or pics of your engine

 

[Moedog07]

Take a predator 212 out of the box, I add a 1" header re jet an adjustable Honda GX200 carb and you got my set up. (Right now :hammer

 

[Greedy_Jayp]

Take a predator 212 out of the box, I add a 1" header re jet an adjustable Honda GX200 carb and you got my set up. (Right now :hammer

sounds like my set up..for now lOl:laugh:

 

[minidragbike]

so my computer fan puts out more than a stock cam? So your saying that if you took say 2 guys with doodle bugs with 2 of the same clones,set them up for a 1/8th mile race.if you only could spend no more than $200 bucks....what would your mods be on one of them?

You didn't read the thread in that link I see. ut:

READ, and remember this is test done without the stock parts on the head, so it flows less with them on.

http://karting.4cycle.com/showthread.php?t=286595&highlight=.450"

 

[minidragbike]

OldSalt post is good, but the problem is that you don't gain that much power.

We could only wish with milling only we go to 10, or 11 hp. But we only get 7-8 in reality.

The BSP kart motors are making 11-12hp, and they can't do any porting, or milling more than .030". So that power is coming from a opened up stock carb and .242" lift cam swap.

That little cam has more duration, and a little more lift than stock. This is where most of the power is made, and for less than $100.

 

[minidragbike]

NOS
I can build a motor that makes 20hp, and ride all day long. I own one, and it goes 65mph.

 

[Newoldstock]

NOS
I can make a motor that makes 20hp, and ride all day long. I own one, and it goes 65mph.

I believe you.
But your starting by building in many cases larger displacement engines that are mechanicaly much stronger than most people build.

 

[minidragbike]

I believe you.
But your starting by building in many cases larger displacement engines that are mechanicaly much stronger than most people build.

No, the engine is stock size

Bigger motors are on alky and are 30+hp

We have a event going on out here and all the motors are stock size making 20hp.

 

[Newoldstock]

No, the engine is stock size

Bigger motors are on alky and are 30+hp

We have a event going on out here and all the motors are stock size making 20hp.

I need to take a closer look at what you are doing.
There are 20 hp motors up here but they aren't as reliable as your discribe.

 

[minidragbike]

I need to take a closer look at what you are doing.
There are 20 hp motors up here but they aren't as reliable as your discribe.

There is about 12 out there making 20hp, and about 15 making around 14hp.. They pull start and run all day long on pump gas.

But these are not budget motors, they will cost someone about $600, more if you know nothing about engines.

 

[oldfatguy]

Wooden wheels suck on a minibike.

I was a big improvement over the older log or stone wheels

 

[texasfabguy]

You didn't read the thread in that link I see. ut:

READ, and remember this is test done without the stock parts on the head, so it flows less with them on.

4 Cycle Karting Forums - Stock Head vs Big Valve Modified Head (Flow Numbers)

I failed to see a stock head with just a cam,only ported head with bigger valves...

 

[minidragbike]

I failed to see a stock head with just a cam,only ported head with bigger valves...

Your still missing the point
The point is, more lift and duration allows more air to enter. While just milling only allows the same exact air as before. But more TQ gain, but the added air with the cam produces more TQ and HP.

You did see what a stock 22cc head flow, and the 14cc flows 2cfm less.

 

[texasfabguy]

Your still missing the point
The point is, more lift and duration allows more air to enter. While just milling only allows the same exact air as before. But more TQ gain, but the added air with the cam produces more TQ and HP.

You did see what a stock 22cc head flow, and the 14cc flows 2cfm less.

I'm not missing my point,just yours. Are you sure your not missing mine?

 

[texasfabguy]

I was a big improvement over the older log or stone wheels

Lol

 

[Oldsalt]

Black mamba cam being the cheapest performance getter, if only one engine modification is made, I'd be interested in some numbers if installed in an otherwise stock engine. Would some one offer up some performance specs? Like for instance the RPM that we could expect the greatest torque out put and the advertised RPM range. I know this is asking a lot but a newbie like me needs to get some learning.

If at all possible don't give HP numbers. Horsepower is, as everyone knows, is a function of a physical force acting on a lever over time and distance. That 'time' factor is why the the 'constant' of 5252 is used in the classic formula. Which, as everyone knows, requires the torque AND the HP curves to ALLWAYS cross at 5252 rpm. Really dumb and almost meaningless as a gauge of actual engine performance. Torque and rpm numbers will be sufficient.