tfaith08

For that application, I'd use the stock carbs. Take your boost bottle and destroy it. It has never shown any gain on any dyno in any application that I've ever found. All it is is a piece of junk that can contribute to an airleak = new top end/complete rebuild almost immediately. It was marketed because some of the aftermarket companies that deal in the automotive industry sell spacer plates that increase plenum volume. It supposedly maintains laminar flow into the manifold and engine, but that isn't the case. It keeps flow into the manifold constant and provides a more accurate reading for MAP sensors and can reduce the likelihood of an intake runner being short-charged. For a Banshee, this is infinitesimal. There are more negatives than there are theoretical gains. Get a stock crossover tube. Since the mains are interchangeable, get some in the sizes of 200-330 for both your current application and future upgrades. Accept nothing less than genuine Mikuni jets. I have no clue what stock jetting is since I've never had anything less than T5s and PD Pro Flow and UNI. Choose exhaust based on riding style. At near sea level with T5s and Pro Flow w/ UNI, I was running 280s. Without the airbox lid, I'm at 320 (about to jump to 330 to be safe).

IIRC, (C°x9/5)+32 = F° If zilla freak is right, that would mean (110x9/5) +32 = 222°F. I can't remember what my temps were when I checked mine. I know my cylinders at the tops of the transfers were 7-8°F cooler (Fahrenheit, because who in the fuck deals with Celsius?) with the Chariot head, but my radiator was hotter.

EDIT: Beginning of August

If you still have them around the beginning of July, PM me.

That holds true if there is actually enough juice behind the spark to get it to jump a huge gap. Combine that with the typical engine that won't start (flooding), and the jump is almost completely impossible when fuel is providing a path for the electrons to travel through. Allowing the plugs the chance to let the gas evaporate off of them when you had them out or knocking some carbon off of yours is essentially what happened when you used the screwdriver. Opening the gap is great for low throttle, low rpm, low power response. Not so good for anything else. That's why you see threads all the time that say to gap the plugs to .028. That's also why some aftermarket coil companies advertise that you can open the plug gap up more. The larger the gap, the more power you need behind the spark.

Gap them to what, may I ask? What is your theory behind why a larger than normal gap works? I know the answer to this, I just want to hear an unadulterated version that differs from my ideas before I chime in.

By hang, he means that it doesn't drop back to idle speed right away when the slides drop.

What ever you do, don't block the drain tubes. The excess fuel will drain into your engine. I just worked on a bear tracker that was blocked off and it filled the engine to the brim with gas.

Whenever you get it sorted out, try to come back and post the solution. That's what makes forums work.

Zilla is about right on setting idle. As for your question, I don't know the schematic, but tapping into the spark plug wires won't work since it's a wasted spark system. I'm sure that someone has an answer though.

I saw the effects of it when my banshee ran 96 with the stock head and timing and fresh tires, but ran 83 yesterday with 150psi and +4 timing with less than 1/4" of tread. Thread loss doesn't account for 13mph. I do get there fast as shit though lol.

Ported himself... I'm all for DIY stuff, but of all the mechanics that I work with, not one of them would even attempt to port a 2 stroke. I'd be leery about that... Your idea to tear into it when it needs it is a good one, so long as your crank is fine, it has compression (already checked), it passes a leak test, and the jetting is accurate. At that point, I'd send the jugs to a reputable builder and order domes from the same guy.

Short version of what I was about to say. The effect is absolutely there, but it is incredibly negligible.

Just to tap on setting timing... Back in my car tuning days on standalones, we'd always set timing at TDC across the board. After we got our AFRs in the ballpark, we'd start advancing the ignition. If we saw an increase in power, we'd advance it more. If we saw a drop in power, we'd set it back to the previous setting. On the higher end (especially with boosted cars) we always, 100% of the time, had more timing than the lower RPM ranges. It was very often the case that the engine that we were tuning could make more power with more timing, but we were limited by knock, which was largely limited by the fuel that was going to be used. If we had this table for race gas (made up, but nonetheless within common occurrences): 1k 4° 2k 7° 3k 11° 4k 16° 5k 23° 6k 28° 7k 33° 8k 39° and we switched to pump gas, we may have to set the timing cap to around 25° because knock would limit us. Keep in mind that we could have set the timing to 180° BTDC or ATDC (effectively BDC), but we tuned for maximum power, not a claim of erroneously high timing numbers. There were also instances where more timing did not result in knock, but the engine made less power with more than a certain setting, further contributing to the fact that more timing doesn't always mean more power, even if you have the octane to support it. More timing will always result in more pumping losses. The key is to maximize downward force without excess pumping losses from too much timing. With static timing systems (Banshee for example), you should choose a setting where you will see the most benefit. That being said, advancing the timing will NOT benefit the bottom end range unless the entire combustion chamber is out of whack to begin with. At this point, you are covering up a problem by advancing the timing. If you have aftermarket domes, the builder would be the best person to ask about the timing setting. If you have PD domes, well... you should get custom domes.

A lot of people think that more timing means more bottom end power, but I've never seen evidence of this in any realm of motorsports. More timing means more time for the gasses to burn before the downstroke at higher RPM. That's why the Yamaha DT200 has 8 at idle and 30 at 8000rpm. Timing that high isn't unheard of. When I said 15 over stock, I mean that was the absolute maximum that I would run before he saw detonation on 112 and stock compression (didn't know he was upwards of 170), not what I'd recommend for efficiency and power. With larger bores, the mixture needs more time to burn as well. Add a bad dome to the mix and top end power would scream for more timing. The higher compression packs the mixture into a much smaller area and the charge will burn quicker, reducing the need for more advance. On that kind of compression, I wouldn't recommend anything more than 8 or 9 over stock. That wouldn't be the setting at which the most power was realized, but that's likely the limit of the fuel. The best way to look at timing is in 2 ways, with the first being "what is the limit on timing with my setup and fuel choice" and 2, "what setting makes the most power." All of my answers were aimed at the first question. If the second exceeds the first, you need to alter your setup or go to a higher octane gas or settle for a less than optimal setting. I set mine to around 4 for when I'm in the dunes and around stock for woods, but that's with aftermarket domes. I never did understand why everyone goes straight to +4 anyway. From what I understand, that was the setting that the stock head needed to see maximum peak power, which is why most companies market it as such. IMO, it's kind of like the stage 3 jet kits. Great for marketing, bad for your wallet.

1) What type of aftermarket exhaust do you have? T5 2) What type of airfilter do you have? ProFlow w/UNI 3) Are you a)running a stock airbox with lid stock airbox with NO lid c) Stock airbox with vents d) no airbox at all No airbox lid, 4 vents 4) What is your elevation? (If you don't know, go here: http://www.topozone.com ) 146' ASL 5) What size pilot jets are you using? Stock 6) What size main jets are you using? 330 7) What temperature is your Banshee jetted for? 85F 8) Do you have a port job? No 9) What kind of carbs? Stock w/o TORS - Stock needle, 3rd clip, 2.5 turns out 10) What size carbs? Stock

At that compression, I'd stay under 8 or 9. Is the fuel oxygenated?

I've oiled my UNI with quality oil every time and I still have the factory hone marks in my main Banshee after over 40 tanks of gas. Every time I've pulled my filter to clean it, everything post-filter has been spotless. I've never seen a UNI not perform well. Furthermore, I've never seen any K&N filter more than a UNI in sand or dusty areas. I used a K&N for about 20 minutes with quality oil and no outerwear and the carb on the 250R was spotted with dust. I took it off and used a UNI and have never seen a speck of dust since.

What compression are you running?

More timing will shift the power curve to the right. Your limits here will be fuel and compression. With 112, you can run safely to around +15, but I'd keep it more conservative. More timing doesn't mean more power, it means more upper RPM efficiency. Less timing for bottom end, more power for top end. Just because you make 1-2hp more on peak doesn't mean that you'll have 1-2 hp everywhere. You'll lose power n the bottom end and potentially midrange with too much. If it was mine, I'd go with +6 on the 392 and the 421 and fine tune from there. Just keep in mind that there is a limit where more timing will become detrimental to power production.

Best mods IMO Flipping rear tires around - free and widens it by about 3-4" TORS delete Upgraded front shocks Jets (260-360, 2 of each) - this isn't a suggestion, but rather a huge recommendation if you plan on increasing airflow Porting FROM A REPUTABLE BUILDER Aftermarket head with custom domes Pro Flow adapter with UNI filter Timing plate (if the builder cutting the domes recommends a setting other than factory) Tires to suit riding style By the time you go through these, you'll know where you need to go from there if you stay on forums.

If you don't think that what I'm saying is relevant, stick a piece of sheet metal between your pod filters to completely separate them. In some cases, there will be no change due to equal changes in resonance. In most, however, there will be an alteration of the torque curve. Jetting can potentially be affected as well.

When resonance is a factor, like any situation with a 2-stroke, you have to account for it. If you're a buy and try kind of guy, you can skip this thread entirely. For those of us who aren't financially comfortable enough to buy 20 sets of filters to try and see what makes the most power or can ask someone else to do it for us, calculating a filter size requirement is best. The negative pressure wave from the crankcase that reaches the filter is what pulls air. When that wave hits something or is reversed by turbulent flow, anything beyond that point is useless. Frankly, by the time you calculate to this point, you can select something within 1-2" of what will work best. Say that I generalize an engine that fits sprinkleman's description of 130hp and pulls 325CFM. Of course, this is extremely generalized unless we have the same pipe, porting, rotating assembly, piston profile, reed geometry, carb boot dimensions, carb, and filter. In that case, I could put together a CFD video that would show you how to calculate it, but I don't have anyone paying me to put weeks into creating a functioning Banshee engine and to wait for weeks for the module to process, so I guess generalizing this, unlike like uneducated generalizing anything else to do with any engine ever, has a benefit. Of that 325CFM, we can say that 162.5CFM goes to each cylinder and through a 38mm carb. Until the time that vacuum wave reaches the filter, it has experienced only a small portion of turbulent flow. However, once the vacuum wave reaches a large source of air (filter), the flow becomes almost entirely turbulent. Roughly how and exactly when this happens is largely dependent on the properties of the vacuum wave and the filter dimensions and flow potential. When the wave reaches the filter, air flows toward it from all directions. When that air flows, more air follows it as a result. When the air that is closest to the filter begins to flow toward the vacuum, it naturally pulls from the air that can move with the least requirement of force, which is air inside the filter. When the air has flowed enough to create a pressure differential that is great enough to make air flow through the filter, we see another pressure wave, only positive. This air has overcome the vacuum by sheer momentum and creates turbulence as a result. Generally, this will all happen very quickly and flow will occur in a way that would represent a sphere. This stops when the size of the sphere of flow reaches the filter and begins to pull from air closer to the back of the filter. The air will then begin to flow from outside the filter and fill behind the vacuum wave, creating a nearly symmetrical pattern of turbulent flow in axis around the center line of the filter. The turbulence then pulls air from each direction. Resonance takes effect when these waves are timed and dimensions are altered to compensate. Therefore, filter diameter plays a crucial role in power production. This isn't as great as total filter area, but it is extremely important. The factors that affect this are the velocity of the air, total flow, and filter dimensions. In my eyes, a longer filter creates a constant net direction of flow, whereas the diameter alters the initial inflow. One will absolutely affect the other, so why doesn't someone or their builder chime in on filter diameter for a minute?

I've never seen any effective application for an outerwear, but I clean my filter after every tank so I doubt I would. With longer filters, I just did some crunching on some COMSOL CFD and I'm in agreement that the benefit would come from the straighter air entering the carbs with longer filters as well as the reduction in pumping losses and vacuum associated with pulling from a smaller source. 32mm carb, 3.5 in filter. 32mm carb, 6" filter. From what these suggest, an improvement on the venturi style setup of the carb would benefit these greatly, as would mounting the filter far enough back to allow the carb entrance to protrude into the filter. As you can see, there isn't much net flow difference (color of the flow at the top, which is the engine side of the carbs). There also is a bit of a difference in jetting due to the flow profile at where the main jet would be. The 6" filter will be more turbulent whereas the 3.5" filter will be more laminar, which I completely did not expect. However, a 6" filter will reduce pumping losses around 1.17% over that of a 3.5" filter as evidence by the numbers that I failed to capture. Conclusion, larger filters equate to fractionally more power whereas smaller filters make tuning easier. BUT, that's based off of suggestions by computational fluid dynamics. I'd believe what it says because the software was designed by a group of people who know so much about what they're doing that they were able to produce software that is among the most generally comprehensive in the world. For those of you who know this stuff, know that this was done with laminar flow only. I don't have the motivation to crunch numbers and basically recreate a DM setup that functions over any range, much less a specific one. Furthermore, I am even less inclined to put that much effort into it since this post will likely be overlooked.

For 4 posts, you seem to have done your research. Assuming that you just got it, check these: Airleak. Make sure your leak-down tester doesn't have an airleak. That'll have you running in circles for days. Jetting (rare without throttle opening) Throttle position on both sides - also check to see if the PO put the wrong slide(s) in because I've seen it happen. Carb caps, rubber gasket, Carb boots and carb fitment Leak at crossover tube Check the carb for cracks or chips; I've also seen that happen. It's very unlikely, but it's a possibility nonetheless. The low compression side of things is likely unrelated to the sporadic revving, but it isn't impossible. Take your pipes off and look through the exhaust ports at the back of the cylinder. It helps to tilt the quad on the back end while doing this. Take a flashlight and look through the spark plug holes to check the sleeve around the exhaust port. You won't be able to see everything, but you can see a good bit of your cylinder. Do the same thing looking through your with your reed cages off. Rotate the crank until the pistons rings are in sight from the exhaust port. If you had coolant troubles, you likely overheated the cylinder and fried the rings (and potentially the cylinder). Low compression is due to bad rings, piston damage, sleeve damage or cracks, head damage or warping or cracks, head gasket sealing issues, a bad compression gauge, previously cross threaded spark plug threads, or a lack of available airflow. If those don't get you an answer, get back to us. EDIT: Only a few of these will be related to problems experienced on both cylinders.