212cc and 420cc exhaust with O2 sensor bungs for tuning.

[chancer]

Bob your final answer sounds like something out of a book or from "Google". Did you cheat. or like Hellion do you always use big words.

 

[bob58o]

Bob your final answer sounds like something out of a book or from "Google". Did you cheat. or like Hellion do you always use big words.

It is the cliff notes version of when you asked for an answer from somebody besides bob about the timing key.

I didn't do the math for flame front propagation speed this time.

But same thing.

I only cheated if you count research from the past 6 months and none today.

Those are my original words from my understanding.

---------- Post added at 12:43 AM ---------- Previous post was at 12:42 AM ----------

What is big???
Coincide or optimize??

 

[chancer]

Just checking! LOL I believe you.
You do normally post like that properly quoting what you have learned.

 

[Jfive]

So the goal is to have ignition as close to top dead center as possible. So as the piston comes up, both valves close the air and fuel are compressed. The spark plug ignites and pushes the piston down, keeping the rotating mass in motion. Messing with timing as people do with the offset key ways. Your bring the firing event closer to the top when the gas is compressed.

If the engine fires too early due to let's say too much timing, low grade fuel for the level of compression, or having the air/fuel ratio too lean. As the piston is going up it actually fire too early slightly pushing back on the rotating mass, called detonation. Often referred to as a tick or knock sound.

By having a forged piston and billet rod, most engine builders are less likely to throw a rod, or lose a piston if this occurs in a high performance engine. But if you can control some of these thing like timing, fuel grade, and the proper fuel to air ratio. You don't have to upgrade these engine parts like you would if you where just guessing.

So now we have people running cheap engines like race engines without the expense of a race engine without them blowing up. But they have to be smart about it. All we are talking about here is finding a way to unlock HP and TQ by knowing a little more about what's going on with your engine.

If that doesn't interest you, fine. If it does okay I might come up with a way to help. Yes a narrow band is less range for you to tune, but has the range you need to do it. Why else would every N/a engine built since 1985 in a automobile have one.

Now I'm taking about a duel purpose header. You don't have to remove it and use another one, so no changing things around like you mentioned. And wires, you mean two wires is too hard to hook up for you? You might as well go back to playing with hot wheels. You could leave the sensor and have a cheap gauge and you not hooking and unhooking anything.

So in reality, you're doing less than you are when you use the spark plug method. And say you had something change like a vacumn leak where the engine started going lean. Unless you noticed the egts going up or something you'd be damaging your engine and wouldn't have a clue. Now if you had a gauge on full time you would and could address any issues earlier.

So not for you cool. But at this point if you don't care about this then just keep to yourself please.

 

[bob58o]

So the goal is to have ignition as close to top dead center as possible. So as the piston comes up, both valves close the air and fuel are compressed. The spark plug ignites and pushes the piston down, keeping the rotating mass in motion. Messing with timing as people do with the offset key ways. Your bring the firing event closer to the top when the gas is compressed.

If the engine fires too early due to let's say too much timing, low grade fuel for the level of compression, or having the air/fuel ratio too lean. As the piston is going up it actually fire too early slightly pushing back on the rotating mass, called detonation. Often referred to as a tick or knock sound.

By having a forged piston and billet rod, most engine builders are less likely to throw a rod, or lose a piston if this occurs in a high performance engine. But if you can control some of these thing like timing, fuel grade, and the proper fuel to air ratio. You don't have to upgrade these engine parts like you would if you where just guessing.

So now we have people running cheap engines like race engines without the expense of a race engine without them blowing up. But they have to be smart about it. All we are talking about here is finding a way to unlock HP and TQ by knowing a little more about what's going on with your engine.

If that doesn't interest you, fine. If it does okay I might come up with a way to help. Yes a narrow band is less range for you to tune, but has the range you need to do it. Why else would every N/a engine built since 1985 in a automobile have one.

Now I'm taking about a duel purpose header. You don't have to remove it and use another one, so no changing things around like you mentioned. And wires, you mean two wires is too hard to hook up for you? You might as well go back to playing with hot wheels. You could leave the sensor and have a cheap gauge and you not hooking and unhooking anything.

So in reality, you're doing less than you are when you use the spark plug method. And say you had something change like a vacumn leak where the engine started going lean. Unless you noticed the egts going up or something you'd be damaging your engine and wouldn't have a clue. Now if you had a gauge on full time you would and could address any issues earlier.

So not for you cool. But at this point if you don't care about this then just keep to yourself please.

I would just like to add that ignition of all the fuel is NOT instantaneous. It takes time. Pressure maximizes when all the fuel is ignited. You do not want this at TDC. IF at TDC, the force pushes the piston and connecting rod at a 90 degree angle to the crankshaft. This does not promote rotation of the crank.

I think somewhere between 10 -20 degrees after TDC is the sweet spot? for optimized piston to connecting rod angle. (which you didn't mention, but is one of the more important aspects of timing or no????)

 

[Poboy kartman]

I would just like to add that ignition of all the fuel is NOT instantaneous. It takes time. Pressure maximizes when all the fuel is ignited. You do not want this at TDC. IF at TDC, the force pushes the piston and connecting rod at a 90 degree angle to the crankshaft. This does not promote rotation of the crank.

I think somewhere between 10 -20 degrees after TDC is the sweet spot? for optimized piston to connecting rod angle. (which you didn't mention, but is one of the more important aspects of timing or no????)

Yes Bob...goes back to your PHD studies on flame travel...spark plug indexing...ect...

Stock Predators are timed at 28° BTDC....modified at 32....8° SOONER!

WHY? does it take 30° of rotation to ignite the charge? No....it DOES take awhile for the charge to become FULLY ignited however....and ..to make it easier to understand...a charge of gunpowder without any restriction simply burns....black powder MUCH faster than smokeless....which is why modern smokeless powder guns are much more powerful than the smokepoles of old....the charge is burning and creating more pressure LONGER...against the restriction of the bullet of the bullet.....again why high octane gasoline and alcohol build more horses....(they burn SLOWER!)

Another facet...is the fact that valve timing comes into play...but that's a different story... but...while it's widely shown as valve and ignition events happening at TDC...It's in reality never the case...and in fact ignition invariably STARTS BTDC...but to change an A/F mix into a fully combusted charge takes a little while...and a fully compressed charge is much harder to ignite...so it should happen BEFORE the charge is fully compressed, but not so soon that the effect of further compressing the expanding fuel charge can build up enough appreciable difference as to offset the benefit by slowing the piston BEFORE TDC....(PRE-IGNITION) ....but much like apples and oranges....what does this really have to do with A/F in a small engine?

Yes...a lean mixture will completely ignite sooner than a rich one....but....just ONE THING MISSING HERE.....

The oxygen sensors....and all the rest of this crap was put into place so a COMPUTER could make "on the fly " adjustments in real time....and implemented due to GOVERNMENT mandate in the interest of FUEL ECONOMY?

So...just how does this apply to a yard kart?

Edit: And yes Bob....10-20° ATDC sounds about right....but keep in mind...as we both said...this is NOT an instantaneous event....so we're looking for that sweet spot that the fuel charge has reached maximum expansion....

 

[Jfive]

having an engine tuned right might have something to do with longer warranty than in earlier years. Egr, catalytic converters, seat belts and air bags, those where for the government. Im gonna do what I'm gonna do your gonna do what your gonna do.

You forget I never tried to sway anyone to doing this that doesn't want to. If your not interested fine if you are fine. sensor and bungs showed up on a side note. Waiting on bender let me post some real time video in weeks from now and then Ebert my ****.

 

[Poboy kartman]

I'm fine....my arse is still in my pants.

 

[Jrgunn5150]

But you asked if we were interested lol, I merely told you no, then defended my position.

It works, I'm sure, like so many other thing's work. Putting wings on a frog would make him not bump his butt when he hop's, but so what?

It's your money, if you want to dump it into making these little tallywhackers, feel free.

If they don't exactly sell like hot cakes, don't be surprised. Although they may wind up in the tanning bed/pool table/weight equipment category of thing's people spend money on and then leave in the basement forever.

Good luck to you with it