tfaith08

We're waiting on details so that we can give an accurate answer, or at least a relevant one. Faster? Does he mean gearing? Engine mods? Tire selection and suspension setup? Tuning? How to shit out 10lbs for the sake of acceleration? Until we get details or even a few more replies, the fuck-fuck games will likely continue.

Use the tube that comes with the can of carb cleaner. It fits either in or right up next to most passages in your carb. When you spray, you can see where the passages flows and you can clean it with pipe cleaners accordingly.

http://www.macdizzy.com/1989ihopup.htm

I think that's what needed to be clarified the whole time. If these are a set of custom pistons, who has the rights to them? Has the owner made the design public? Wiseco has a very strict privacy policy. They won't allow you to buy someone else's design if they ask to keep it private. In most instances, they require a run of 8-10 pistons or so before they'll even make them for you. I haven't seen this personally, but I have heard of an instance where a guy got his hands on another builder' piston, derived the dimensions, and called Wiseco to have some made. They wouldn't accept his order because it showed up in whatever system they use as a private design.

Aword of advice is that you rephrase things like "these pistons are the best" to "this is what I tried, this is what I found." It goes over much better that way. Until then, you're going to end up being viewed as just another guy thinking he's made a huge bound in engine development and really hasn't or either can't convey what he's done. I'm not being rude, that's just how it is. You'll be called the 10hp piston guy or something along those lines. It happens on Blasterforum, sevenstring.org, NICO, thumpertalk, E2S, and every other forum that I'm a member of and you better bet like hell that it'll happen here.

Also, it should have been "piston against piston, not engine against engine."

Well isn't that a gem. I'll tell you what. When you provide quantifiable evidence that proves that these work, let us know. The only way that I can see these making 7-10 more hp is if the engine is turbocharged or if you're running pipes that are designed for an extra 200-300cc per cylinder larger than what you're actual displacement is. Again, I want to see these in action because I doubt that either is the case. Well, I can see where the latter would be the case. "Blah blah, I'm running 800cc pipes on my 370 4 mil." Also, how about we discuss things in a logical, thought out manner that isn't riddled with miserably failed insults and that actually has some sort of punctuation so that we don't confuse your attempts to tell someone that they can't use a CNC machine with you actually conveying that you just watched someone use a CNC machine this one time and you came up with a cool idea (which has likely been tried and dis-proven), which is giving you the piss-poor reason to act like you're basically at the level of a formula one senior powertrain engineer. Oh wait... I'll be waiting for you to either logically explain your reasoning or to show us proof, such as a dyno run video that also shows you taking the pistons out. Surely the face of south street speed shop can disassemble a Banshee engine in what, 30-45 minutes? Oh, and props for the next level of professionalism. No uppercase letters in a 4 word company name screams attention to detail. Good thing that this engine building stuff hasn't started demanding things like precision, professionalism, correct piston selection, or even a reason to pick this piston over that one.

I'd like to work with some of those pistons on a long rod 4mil setup. My first thought would be to deck the cylinder base and get a PD head and run some domes that can take the extra deck height. Pistons that have the pins close to the crown have always been a plus in my book. Also, agreed on dropping the port floors. When at the transfers, an increase in 2mm height will produce much more duration than 2mm added to the exhaust port height. You'd end up with a wide, garbage powerband.

A long rod will produce different durations for the same port heights. Keep that in mind.

Don't start that steel clutch basket shit again. Cotton Branch Racing described the way I'd go if I did it. Any machine shop that has any sort of capability can machine anything that's symmetrical (which a flywheel weight should be) without having to balance it.

Floats valves very likely just need to be cleaned. I literally just worked on a Racher 420 today and the owner was tapping the carb bowl to get it to stop leaking gas. I cleaned the valve and it stopped. Backfiring means lean 95% of the time. That could be caused by your valve being dirty and not actuating as it should. Again, the fix is to clean the float valve. Whatever you do, DO NOT block that tube off. It will not fix the problem and your bottom end will fill with gas if the floats are stuck and the gas has nowhere to go. When you try to crank a 2 stroke that has a crankcase full of gas, you will destroy the reeds. You can fix your problem for free, granted that you brush your teeth and clean your ears.

Clutch problems, you say? Someone go get Thacker...

Well, you'll run like a monster with 18s for a minute or so, if that long. What'll happen is that the mixture begins to burn under it's own accord (hence the term detonation) because the lack of available octane within the gas. Octane is very stable and takes much more coercion to get it to ignite with pressure alone, but it only exists in gas in small quantities. Since the rest of your gas is more chemically unstable and the octane required to keep it from igniting before you want it to isn't present in the amount that you need, the mixture will burn anyway. Since the mixture takes time to burn, it begins to burn before the flame front from the spark plug burns all of the contents within the chamber. Those 2 flame fronts meet and a great deal of heat and pressure are forced into a much smaller spot than they normally would be confined to. This is more than enough to get most aluminum alloys past their melting point. After the aluminum from the piston or dome start to melt and fly all over your chamber, it sticks all over your dome and piston top. When this happens, those aluminum beads start to get really hot because they have more surface area that the flame can touch. They get so hot that they begin to cause the surrounding aluminum to melt and separate. Then, the AFM begins to ignite from the heat of these beads and hot spots. This is called pre-ignition. By this point, you only have a few seconds before you're stranded with a partially molten piston with a huge hole in it. In small quantities, you can get away with detonation, but it is very, very highly recommended that you take all measures to prevent this from happening. I tore my head off yesterday and found one small pit on the right cylinder and will be backing my timing off by 2 degrees. Jetting and cooling capacity also affect detonation. Lean mixtures can greatly increase the risk of detonation. A radiator that isn't sufficient will be unable to pull enough heat from the head and have the same result. Keep it under 150psi, jetted properly, cool, and set the timing to a reasonable setting and you should be fine with your setup.

Even if you kept it together with 18s, you'd still have to run race gas. 92 octane will not cut it. Do you have pipes yet? I didn't see any listed in your list of mods. If not, I'd go with that before anything else. That money could get you a set of good used ones and the jets you need. The difference between a piped and non-piped Banshee is significant.

Are those U.S. Army stickers on the back? Did you buy this Banshee used?

+1. I've been on a Banshee with the same mods as mine except the domes. His were custom (idk where from) at 155psi and mine were PD 21s at 150psi and his was noticeably stronger. He would pull about a bike length over mine on an asphalt drag by the time we hit 70mph. I'd call one of the site sponsors. If I need a head cut, I go to a local guy. If he can't help, I'll call Noss Machine, but that hasn't happened yet. If you're spending money to do an aftermarket head, do it right. A Chariot Performance head w/ stock PD domes will run you about 210-230 shipped. Go ahead and spend the extra $50 to get even more power and response.

21s at your elevation should be fine with 92oct. However, a lean condition will amplify the likelihood of detonation. Best make sure you're fine there.

Snap On sells them. They're high, but that's what we have at the shop. I'd recommend not doing the Snap On route and going with what everyone else has posted. Craftsman Pro Series used to have them IIRC.

Well, I've decided not to buy a ported set of cylinders because I know I'll look inside them and take ideas. It's stealing work in my eyes. If I ever stop working on other people's stuff, I might do it then so that it can only be applied to my stuff. I can't bring myself to make money off of someone else's design, which is what it'd ultimately be doing. Lately, I've sort of gone through and started re-thinking all of what I know with porting. I'm not a master and I don't think I'll ever come up with a design that'll hang with what the site sponsors build unless I come across some insane amount of money and have nothing to do all day long. In that case, I'd have about 50 cylinders and a dyno to test with. In that scenario, I'd be chasing a better design much more effectively. For now, it's just one piece at a time. Recently, I've started putting a lot more thought into port shaping and it's a subject that requires a bit more thought than I've imagined before.

I think you'd be safe with 21s. I'm pretty close to sea level and my pistons and plugs show no sign of detonation.

That's a really unimpressive hot saw. I've seen some that run in the stock appearing class that are faster than that. It also has to be a backup/failed test saw because he's running it for so many cuts. I've never seen a hot saw race that went for more than 3 cuts because most of the guys run billet heads that have no cooling capability and will absolutely fry an engine after 15 seconds of use. I get your point though. Those saws are incredibly powerful when built properly. I've witnessed a few of the 3ci (50cc) saws pick grown men's rear foot up off the ground when they cut top-down. Imagine the 120cc limited hot saw class.

A 4T is more susceptible to increased flywheel weight. Accounting for exhaust cam duration, only about 70-90 degrees out of 720 experiences combustion force. That's a ratio of an average of 1:8, combustion to other . A 2 stroke sees about 60-80 out of 360, so it has a much better ratio of about 1:4. 20% more weight added to a 2T rotating assembly will affect it much less than 20% added to a 4T. However, it is still there. A Banshee will see about 120-160 out of 360, so that's a ratio of 1:2.5ish. Dependability of any clutch will be largely dependent on setup, type of use, traction, weight, and TORQUE, not HP. Clutches and transmissions are rated for torque. That's how some of the 1000hp+ civics that make power at 9krpm are holding together with transmissions and clutches that only take 600 lb.ft. This is the same as on the cars we used to build. The 2JZ that we had made 456hp and would stand up to anything in the world while it was in the snow and on wet asphalt, but the first day out on dry pavement resulted in a fried clutch within minutes. After the owner stripped the car and added a lightweight flywheel with a clutch of similar quality, it stood up much better. I think it lasted for a few weeks IIRC. Now, he uses a heavier flywheel with a dual plate clutch that's good for 500lb.ft and it's taking all the abuse he can throw at it. His car spins less as well, but you can't call that more traction. A lack of acceleration will result in less tire spin, but that's not to be confused with traction. A pro class FD drift car has tires that have more traction than you'd ever imagine, but you can't say that a bicycle has more traction because it doesn't spin. I've never tried it, but I'd bet my Banshee that if you lined 2 Banshees up, one with 50hp and a heavy flywheel and one with 50+ and a lightweight flywheel and the latter was throttled to accelerate at the closest rate possible to the other, tire spin would be nearly identical. If I had the exact dimensions, I could calculate the exact loss in power. Since horsepower is a measurement of torque over time and torque is the measurement of twisting force in distance and weight, an increase in weight will absolutely reduce torque. The vector arm length, the radius from the axis of the twisting piece that is being measured for torque to the point of force, is a required figure for torque, hence the "foot" in lb.ft. The figure for force can be, much like the vector arm length, measured in any given applicable unit of measure. Pound is chosen because it is an easy figure for those who understand what's going on to comprehend. 1 lb.ft. = force required to move one pound in a circle at a distance of 1ft. from the source of power. Now, if your clutch assembly has say, 2lb, added so that the weight is centered at 3" from the axis (3" for easy figuring) and it is turning at a ratio of .35 the speed of the crank (source of torque), you should lose about 0.175 lb.ft, Again, that's very rough figuring, but it's there. The loss of acceleration and power is derived elsewhere. When something rotates, it is measured in rotational inertia, which is a derived figure. There is no such thing as rotational inertia, but it can be explained as the measurement of 2 forces and their effective relation to one another while an object is spinning. It's kind of like one kid has 9 cents and the other has 16 cents. Neither has 25cents, so no quarter exists, but it does in essence. Now, the rotational inertia is 2 things. It is nearly instantaneous velocity (since there is no such thing as true instantaneous velocity) accelerating forward while the object spins and the outward force, counteracted by tensile strength. Those 2, or more inaccurately stated, rotational inertia, eat up A LOT. Put a clutch basket of the exact design as I described above and you will lose more than .175 lb.ft., but that's what it calculates to with just that aspect. As for engineers, they tend to fixate on just one idea because they aren't allowed the latitude to focus on a project as a whole until they grow and gain experience. Engineers get a project like a clutch basket and try and calculate one thing until they've exhausted it. Then, they move on slightly and still cherish the thought put into the first calculations, so their every thought isn't it's own; it exists as a relation to the "pet-idea". Then, everything becomes centered around that. Once it fails and they learn why, they start to grow as an engineer.

I run stock bore and stroke on 21s at 100-200 asl with +4 timing on 93 and I'm doing great.

Put bigger wheels on back so that you're always rolling downhill.

That's a blanket statement in my book. Don't get me wrong, I like when people create their own stuff. I do all the time. Hell, it'd blow your mind what kind of stuff we have to make for customers who buy brand new Honda stuff from the store. It's very evident that you have a lot of thought behind everything that you're saying; I won't try to deny that. Keep in mind that to have been misguided doesn't reflect negatively on anyone. Presenting your thoughts, misguided or not, in an ineffective and close minded fashion does reflect negatively, however. Flow of information, whether by hard data, pictures, or by conveying trains of thought, is what forums are for. However, it proves to be a problem when you try to push it on other people when they question it. To make matters worse, you tried to justify something that you didn't have to justify, and did so in a poor manner. Stating that you had a degree in applied science (which is a great thing for this sport) makes every miscalculated thought stand out more than anything on the thread. The motivation for and the rudeness in my post was in response to your 99% statement. That kind of stuff basically translates to "pick everything that I have to say apart and make me look like an asshat".