blowit

http://www.factorypro.com/images/dynochart...%20adv_comp.gif Here ya go! Please note that the power NEVER falls below the stock power curve anywhere in the RPM range. The reasons for the power increase are sited above. Brandon

Wrong, simply stated, the Banshee has a lazy ignition curve (retarded). Yes, if OEM ignition is dead on from the factory, you boost bottom end and lose some top but the Banshee needs advanced ignition just to get power back where it needs to be. On the dyno, we see boost across the board until around 4-5 degrees advanced and then top end we start to fall off. This is assuming stock ports and 21cc heads. OEMs hardly ever put timing right at the edge because of assumed liability. Most OEM products will benefit by simply moving up the ignition slightly. Please look at Factory Pro timing goods. They have made a business by simply bumping ignitions a couple degrees and it works! This is always true for all machines but in the case of the Banshee, it is. Brandon

You are chasing your tail on this. You should not even look at milling the head until you get it running. That is not the problem. Warped heads are very rare because of the annealed state of the head casting. It would leak water like mad as well. An easy way to see if you are leaking is slowly kick it over with the radiator cap off and watch for air bubbles. As, try another comp gauge. You still think you have something silly happening. Brandon

You are chasing your tail on this. You should even look at milling the head until you get it running. That is not the problem. Warped heads are very rare because of the annealed state of the head casting. It would leak water like mad. An easy way to see if you are leaking is slowly kick it over with the radiator cap off and watch for air bubbles. As, try another comp gauge. You still think you have something silly happening. Brandon

The Banshee will gain both in top and bottom end with the correct ignition advancement. Top end will start to decline when max advance is approached. brandon

We have never experienced detonation on the dyno while using 20cc domes on stock porting. 175lbs is absolutely in the window for pump fuels. Depending on what type of porting you are looking at, your comp can drop by as much as 20lbs. Any engine builder that knows how to make real power will want head mods to match the porting. This is because of the drastic pressure drop. Domes are very relative to elevation. You may need 18cc domes just to run pump fuels properly at higher elevations with your porting. Brandon

It is entirely possible that something is out of adjustment slightly and you are farther advanced than you think. An over advanced engine will generally detonated but will also decline on having "long legs" on the big end as we call it. Your engine just fights against itself. You may just need to bust out a timing light to get this figured out but the plate ain't always dead on. Go with what runs good. Over advanced engines will wear out faster due to increased head pressured and will damage rod bearings. Not saying you are over the sweet spot but sure sounds like it. Are you sure you don't hear a new little sound at WFO in 5th? Detonation? Brandon

I do think that your mains might be a little lean just by the setup but DO NOT go swapping main jets because your bike will not start. They have ZERO effect on jetting at zero throttle. Sounds like plugged pilots. Pull them and clean them. Before you do, back the drain screw out at the bottom of the bowls to ensure they drain indicating the bowls have fuel in them. When you pull the bowls, you migh just throw in some 300 mains if you are around sea level. That should be closer. Brandon

Um, you are aiming right at an electrical CDI or stator coil issue. Try a quick swap with someone on the CDI and give it a try. electrical goodies love to fail when they get warm. Brandon

I would not buy a thing just yet. Rain would not cause component failures in this manor. Even if, somehow rain got to the coil, It may or may not even short to an alternate ground. Rain water is NOT much of a conductor. I would dry things out and look at the handle bar switches and such. Sounds like a pretty basic problem. Brandon

Some axial play is normal since a radial ball bearing is designed for primarily radial loading. It will be very hard to detect or measure radial clearance without proper gear. I would say that if you pull up and down on the crank ends and can actually get verticle movement, you have a problem. I would sure think something is out of balance if that is the case. You would reall want to check those cases too for an oversized bearing bore. If the center bearings are in question, the crank needs taken apart and trueing and welding should follow. Like fire guy said, if there are any grooves in the crank shafts, you may have an issue there. The LH side can sure be testing with flammable gas around the sealing area while running to test for air leakage. Of course the safest method is the leakdown tester. Brandon

Kinda wondered on that. We have had plenty of customers do the same thing. I am sure the right pistons will get you back up to speed. Brandon

You can generally get about .040 off with acceptable clearance but .030 is genreally max without considering race fuels. The major changes really come into improving the specs on the head, not just cutting the deck. The squish angle is criticle for proper performance. You would still be fine with -.030 with stock porting at sea level. More people are more conservative with the compression but we use knock sensing here and have pushed the banshee over 200 psi on pump fuel without detonation. Generally speaking though, 170psi would be max recommended compression for pump fuels and only 4degrees ingnition timing. We have plenty of happy racers using our stock sleeper heads. PM us if interested. Brandon

Don't know your setup buy sounds like incorrect porting on the exhaust port, or your pistons are wrong. By chance, are you running long rod pistons in a stock rod motor? Check your squish clearance and that will help. The banshee should be a zero deck motor meaning the piston comes up to the top of the cylinder at TDC. There is not question that something is very wrong. Even if you comp test a new engine with no break in, ti will pump within 10lbs of run in comp. I would look for welded rings in the pistons as well. This is very common if you have higher comp with pump fuels and some detonation occurs. These really are very few things this could be but rest assured that 60 psi is not going to work. I would also be looking at that comp tester to make sure it is good. Just because it says Snapon, does not make it immune to damage. Just gotta check everything. Brandon

Just let us know. Thanks Brandon

We are looking for stock banshee heads. We pay 20 dollars shipped to us. We offer 15 dollars shipped for ones with light pitting. If you have one or even 10 of them, we need a pic of each head, bottom and top, and we will pay via paypal. We generally will not buy anything older than 98 but if yours looks nice, send us a pic. We prefer to buy in bulk. Thanks Brandon

Sorry, we are only looking for the banshee heads right now. Thanks Brandon

We are looking for stock banshee heads. We pay 20 dollars shipped to us. We offer 15 dollars shipped for ones with light pitting. If you have one or even 10 of them, we need a pic of each head, bottom and top, and we will pay via paypal. We generally will not buy anything older than 98 but if yours looks nice, send us a pic. We prefer to buy in bulk. Thanks Brandon

As Jeff said, the 1211 is the stuff. The 1104 is the replacement or equivalent for the yamabond. The 1211 is silicone based and seals very nice. We prefer it over the Yamabond. It is not cheap but well worth it. Brandon

Yes, both HP and torque are increased by advancing timing. The port timing is not relative. What is relative is the rod angle vs ignition timing. Or as most people look at it, degrees of crankshaft rotation. By comparing rod angles and timing, you can determine when rapid bearing wear might occur As well as detonation. There are many factors in the timing game but mostly, you would push the ignition right up to the point of detonation and thats it. The reasons for different timing with different fuels has to do with a given fuel's flash point and burn rate. Higher octane fuels need more advancement . Alky requires more advance than about any fuel. The reason a fuel detonates under high ignition advance is due to you basically starting the fire early enough that the piston has to force through the counter acting force of the ignited gases, resulting in very high combustion pressures causing spontaneous combustion in the form of multiple flame fronts. This is called also called knock. Knock is BAD! Brandon

Actually you have 'er basackwards. The screws you are refering to are called air screws and adjust a fine stream of air bypassing the throttle slide. They primarily affect idle and have an effective range of 0-1/4 throttle. There is zero relativity to the screw and your main jets. DO NOT adjust your mains based on this setting. You are fine with your screws set at 1.5 out and that just indicated your motor is needing a little more fuel on the bottom. The condition your are experiencing sounds like lean pop and I am not sure which way you are going on the needle but if you are lifting the needle and it is getting better, that sounds like the ticket. If it ran fine before and just started this, jetting does not just get off so there is something going on. If not, just keep tuning those needles until you hit the sweet spot. We always refer to the needle positions as needle up or down, not clip position. I don't know why people like to use clip positions, very confusing for our customer. Raise the needle to richen and drop it to lean. Hope that helps Brandon

I sent you PM regarding your issues. Brandon

www.mullengineering.com We have been doing this custom head mod with great results. It does work when done correctly. There is a bit more to it than cuts in the squish band. Velocities and pressures must be carefully tuned. We have many very happy racers using our heads. I cannot speak for trinity because our design is far different. All bikes especially alky and big bore bikes really show a difference with the head. We have been doing this mod for about 5 years now.

and best of luck to you. We just will not do it to a customer bike. The same as saying " i only put a 1/2 quart of oil in but it has not blown up", super, but we don;t gamble on other people's investments so simply conveying this. Do what you wish, but don't ask us to do it. Brandon