blowit

Lower needle one position and see what that does. Likely rich 1/4 throttle

Agree with Zilla. Pilot is the first place I would go if you know the carbs are synced decent enough. Remember there are windows on the side of the stockers to help. Where people get in trouble is realizing the slides set down on the idle screws. You really need to back the idle screws all the way out to do it better by eye. Then you can start it and hold the throttle near the idle position and listen. If RH drops out, pull the carb. Brandon Mull Engineering

This is where an oscilloscope is your friend. You might be able to catch the pulse activity with an analog multimeter but won't know the voltage. You want to test the coil primary leads right off the CDI or the wires right at the coil. The CDI VERY MUCH SO could do what you are describing. I have worked on electronics for years and broken solder joints are very common on boards. Hell, take a look at the Chevy windshield wiper drill board recall!!! I found and was fixing those suckers for years before Chevy finally recalled them. Anyway, it is a safe bet you are losing power FROM the CDI so you would want to test to see if power is lost coming from the pulse coil or source exciter coil. Sort of sounds like a CDI but I would be the last guy to recommend replacing parts without knowing for sure. Brandon Mull Engineering

Why not! I will see if I can help. Another thing to do is put the bike in gear with the clutch in and lets see if the noise changes. Typically if it is a clutch issue, just pulling the clutch will change the sound.

You know, trying to give that another listen on a better sound system, I might get an experienced ear on that before tearing it down. It does sort of sound like the old clutch cushions too. It would be obviously quieter on the left side of the bike. Use the old stethoscope trick to try and isolate the noise.

More detail this time. In a constant loss CDI, the source magneto coil is coupled directly to the ignition coil through the CDI. The Pulse generator typically has one lead to ground reference, the other goes to an SCR or TRIAC which acts as an AC switch. As the voltage rises from the pulse generator, the voltage meets the threshold (turn on) voltage for the switching device and that device couples the other side of the ignition coil primary to ground reference. As the voltage sine wave from the PG rolls back down or falls, it meets the turn off voltage threshold for the SCR and current no longer flows. The modern CDI is a bit more sophisticated than that due to timing and includes a chipset and crystal to vary timing but in each case, the PG is totally isolated from the output voltage to the ignition coil. This can be further proved on the bench with an oscilloscope and varying the PG gap. Why a Banshee would seem to hit a rev limit with excessive PG gap does not hold water BUT I guess there are possible other reasons for this. As stated, if the PG is right at threshold, something as simple as vibrations from the crank could cause unreliable performance. Anyway.

Let me explain a touch. The pulse generator is a magnetic pickup coil that will send a sine wave of voltage to the CDI upon coming close to and away from something ferrous. That wave or peak voltage is relative to how close or strong the magnetic reaction is. The closer the flywheel gets to it, the stronger the pulse. This does NOT affect spark energy though!! This is merely a trigger voltage for the CDI. But, if you are right at the threshold of required voltage to the CDI, the spark output could be unreliable. HOWEVER, in no way shape or form would you experience troubles that are RPM specific. The problem would seem almost at random. If you get to a certain throttle position or RPM before the problem occurs, that ain't the issue. You may wish to reduce your spark plug gap from the factory .028 to .020. It is common for heavy breathers to snuff the spark, then you think it is rich, lean the jets, and toast the engine chasing the wrong issue. Try that and report back.

1. You need to verify that you used the correct series of piston. You may also want to check the squish clearance for the piston/head. Check on this site to learn how. 2. Do NOT use your cranking compression values for decision on fuel type!!! That will get you in trouble. Indeed, with 19cc domes, you will need about 100oct thought I have run them on premium. It should dial in fine with your fuel. 3. It would be great if we knew the exhaust duration. Is this new porting? Who did it? I do agree that 125psi is low BUT what gauge are you using? Does it have a schrader valve in the tip? If not, ignore the value, you are not testing correctly. 4. Please remove air filter devices and look up the back of the carbs. Slightly open the throttle and see if the slides are opening together. Sounds like you have carb balance issues. There are also glass windows on the sides of the carbs to check slide height. Read the manual on this.

If money is tight, you likely will not want to pay someone. Doing a topend in these is SIMPLE! One bit of advice, WASH YOUR BIKE beforehand and push compressed air between the cylinders before taking apart. There is always crap caught in there that gets in the bottom end. As I said though, one of my biggest peeves is people boring engines just because they don't know how to mic an engine. In most cases, we don't bore engines. Get the book, work your numbers. Knowledge is FREE! You have to inspect the bore for imperfections, first. believe it or not but grooves below the transfers is rarely a problem. You check for taper, out-of-round, and overall dimension. We wrote a quick sheet in Excel for this for our techs to follow. They have to record each measurement, then the taper and roundness is calculated. Then we enter the piston data and the clearance is calculated. With a knock that bad, I would expect to see a skirt hanging on by a thread or rings welded up. It does NOT have to cost much. You DO NOT need to buy Wiseco pistons. Research my threads and you will find that I am a strong supporter of hypereutectic pistons like Namura coated pistons. The high silica content and casted design gives a harder piston (less wear), more uniform expansion, thus a tighter clearance. I have seen stock engines last 15yrs! A piston kit might cost you 150 bucks. I don't buy into forged pistons unless they are required. They are softer thus take a little more abuse but that does not mean they are better for all applications. If you wait until the pistons break, you are pulling the engine and likely get to buy a crank. Now you are in for at least 500 in parts.

No way would I recommend to ride one with a noise like that ever. Hard to define in a video but sounds like good old piston slap. Ride it until you finally break the piston skirts off and you will not like yourself. I would highly recommend taking it apart and having an experienced pro check things. If this pro does not have the tools and skill to mic the bores and pistons, you found the wrong guy. Wrist pin failure is very rare in Banshees. Piston wear and crank failure is more common but usually cranks just pop, they don't develop too much knock before locking. Also, when you rev it, I hear a pfffttt sound in the exhaust. That is either lean condition, carb balance, or improper tuning of the TORS system. Lean condition could certain have created the problem you have there. People go ride a Banshee when they are not right and the good running cylinder kills the other one. Case and point, plugged pilot jet on ONE carb. This can lead to overheat in one pistons, weld the rings into the piston, more overheat due to lack of ring seal and blowby, and the grenade pin is pulled. Brandon Mull Engineering

In a Banshee, I always recommend premium even though it sounds like you have a box stock engine and could get away wtih 87. Premium is a higher grade of fuel and will resist oxidation better and will give you some safety margin against detonation on really hot days or when your engine might be extra hot. Premium also has much reduced Ethanol which is creating quite an issue lately with fuel quality. Brandon Mull Engineering

I know some guys have been needing one. Still needing some packaging but will be able to ship next week. Available on our site and ebay. If you want to save, use our site though. Ebay makes us do an ankle grab anymore!

Nope. Some here probably remember that we originally designed our pump head to mate to the factory shaft because we acknowledged the OEM shaft was just better. The OE shaft has a spline end. Unfortunately we started getting a flood of calls wanting a shaft because their PD pump was grooved beyond belief. We had no choice but to make a total replacement deal.

Thanks for the nudge to get these out. I had the guys working things out today to get these back in stock ASAP. had a few growing pains earlier in the year but I will have to shoulder the blame here. Yes indeedee, our shaft is nothing like the stainless shafts in other pumps. We identified all the issues with the factory pumps and other aftermarkets and set out to build a superior product. I feel we did that but gotta work harder to keep them in stock. IMO, our pump is better, our shaft is stronger harder, and has an infused surface treatment to lubricate the seal. We also discussed some test procedures for our pumps that we can televise the performance. Sometimes you just need to see them in action to see the competitor's product eat crow. I will admit every pump on the market will move water, but how much and at what head pressure? How much power to run it? Pumping water ain't free. It certainly sucks a little off the tit! I will push on this harder to get you guys going. Brandon Mull Engineering

Sorry, listing was update.

Bike is a runner. Friend bought it to build up but lost interest. It is not a cream puff and needs a few things. I just did the valves and leakdown. Engine is ok. Tank is still off from doing the valve job. 1. water pump cover is leaking. Oil is not contaminated and believe to be the cover only. 2. Rear brake caliper is missing 3. Clutch cable just broke, clutch works fine. 4. Will need a battery. Firm at $1350. Would make a great parts bike throw a few parts at it and have as an extra. Bike is near Wichita, KS

Engine was blown and parted out. Before I part the rest of this machine, I thought I would offer it as a donor for anyone wanting to do a big engine hybrid. These chassis are a little bigger and should make a good builder. I need 850 firm for it. Bike located near Wichita, KS

Whether you have us rechamber it, or someone else, I firmly believe it is worth doing right. We offered the simple "decking service" for about 5 minutes. I decided it was not worth putting our name on. The key to our heads is in the fact that when we machine the face and the domes, we can get precise on the clearances and performance characteristics. We also do some unique work with the squish area to improve the combustion rate. They have worked well in a wide range of apps from mild 350 pump fuelers, to big super cubs. You will see some gain with just decking the head, but not near the same as with proper rechambering.

Are you sure you are not confusing the ring clearance? Probably a small error but I did not want someone thinking of using 8-10 thou for clearance on a Banshee. She might slap a bit.

In all seriousness, if you do reassemble and still find slipping, please do check the rear tires for slippage on the wheels. I have seen it in the shop and it will feel just like clutch slip. Brandon Mull Engineering

Impressed you see you actually measured your engine to determine what was going on. However, that level of scuffing was leading me to look for "4 corners damage" or a tight engine which causes cold seizure. It is possible someone bored for stock cast pistons but Seizecos were installed. Forged pistons get funky with heat. You could possibly go back with good WSM or Namura pistons or hone a bit and run Seizecos. Nice job finding the cause before a rebuild! URCH: Hell no on reusing those pistons. One of the big things with pistons running on cast iron bores is oil retention. No oil grooves, no run. You WILL overheat them again and lose them. Start over on pistons, touch up the bores, and be happy. Brandon Mull Engineering

You just waisted your money. Your tires are slipping on the wheels. Go put marks on your wheels/tires and go ride. Your welcome Brandon Mull Engineering

If you are close on a top end or at least what to know what is going on, usually cranks will separate as they go out of phase.so you can simply inspect the thrust washer clearance on the crank journals if you pull the cylinders. The banshee engine is inherently balanced well as a 180* phased twin so imbalance is a concern. It my also be worth while to remove the LH side cover and put a dial indicator on the flywheel and determine the TIR or totoal indicated runout. It is rare there would be an issue but if magnets breaks down, it will certainly cause this. Personally, I would find the cause BEFORE it is too late. I remember looking at an engine for a member after he went through a crank or two. flywheel imbalance will break a crank right off. Brandon Mull Engineering

If you can find someone in the USA that still hand rewinds them, THAT will be your best stator. one of the problems with most stators today is they are wound by machine and it only takes one small issue in the wind process to ruin it. I used to have a guy wind all of ours but that was a few days ago. Aside from hand winding, asking the question of what wire they use and the dielectric breakdown of the wire is sure to enlighten them that you care about what you are getting. Personally, I feel that due to the skimpy wire and coatings today, flipping the Banshee wind to a 3 phase would sure cut down on problems but not exactly a DIY rewire for most. Brandon Mull Engineering

I think most have this covered. A divergence angle in the head would effectively trap unburnable fuel at the outside circumference of the piston. It will also cause a pressure spike at TDC which likely is the reason for head seal failures. The idea of design in the modern squish band 2 stroke head is in an effort to increase the volatility of the fuel/air charge before combustion. Two things do that, pressure, and heat. Physics laws dictate that the "rate" of compression of a gas has an affect on the heating of the gas. It is just a numbers game but I have explained many times that there is a reason yur ignition system timing has a "curve" and is not linear to flat. PIston acceleration and rate of gas compression have a large affect on the burn rate of the charge thus the reason to change when the combustion event starts thus optimizing when max cylinder pressures are obtained.