blowit

Now I feel old. The big trend in stroker banshees hit in the mix 90s from Trinity. The biggest stroke for a while was an 8mm. Then 10-12mm was tested with other big bore sleeves. I know they bad a bunch of setups but none of them were ever real hitters. The stock banshee cylinders, as is, are restricted to a 6mm over stroke to keep porting within max HP timings. The hindering factor becomes the transfer port timings that, if allowed to become excessive, with not allow proper blow down and reverse port flow occurs. You cannot pop a piston out of the hole more than 3mm so you would have to raise the deck which would also raise port timing. Many motors were made in the day that were NOT within the max HP window but still made some power just because of displacement. If you were to get sleeves to allow for more stroking, you must add material to the cylinder ports to allow for proper port matching. When big bore sleeves are used with the stroking, this reduces port volume thus flowing less when the engine really needs more. Not good for the GO factor. All in all, a waste of time IMO. The cheetahs with PVs are the way to go. MUCH better port layout, more volume, just better.

Sounds like someones party is getting kinda expensive for a flywheel pull. Ouch

Have you considered just backing the timing off a hair and running pump fuels? Brandon

Your limiting factor really becomes porting timing with the OEM jugs. Long stroke engines require different port locations to make max HP. B

I for one would never park anything in your ass, verbally or otherwise. You can take that to the bank.

For general riding do NOT remove the air box. This serves a good protection for that filter and a splash of water on any dirty filter will cause a matted mess of crap that will not flow air. I only say this because of your riding areas and the couple extra ponies with pods are estimated only with "clean" filters. Once dirty, it does not matter. You need to use the right setup for your riding conditions and boxes save HP in very dirty condition by keeping the filter cleaner. Brandon

I would say those pistons look pretty damn normal. You might putt around in some places or your low end is slightly rich or something but I don't see anything that would indicate a lean condition. No detonation but maybe the pic is not close enough. I would sure be checking tolerances about now, ring gap, bore taper, all things will tell you what is going on. I am thinking you might have a poor port chamfer causing excessive ring wear. The pistons skirts look fine. Mic things and let us know. I am just betting you have a huge number for the ring end gap. We see a bunch of engines with trashed rings at the exhaust because of poor porting and it grinds the ring thin in no time. look under the crown of the piston for color. tan brown is all and good, black or carbon build up is a sign of overheat and may indicate a lean condition. Brandon

Yeah, it's a bolt up deal but if you have never been in an engine, probably good to have some experienced eyes to watch over. Yes, I would highly recommend carbs. The stockers will run but your HP will be down. 35mm will be minimum for good power out of that setup. You might bolt up and run for now and upgrade carbs later. brandon

Yep, just get ahold of it from the outside and pull it out. Make sure the site is clean when doing this of course. Should really be a 5min job. if your shift shaft bearing is toast, it will still leak though so you might check that. brandon

Mine was not a crank killer, but a piston killer. Detonation and nasty. Now, I was also pushing the timing at the time so that did not help. I never did any numbers at the time but I know it needs ROOM because it pops very fast and can get down right forceful on parts. Maybe that is why I went through a wrist pin every few hours. I was making nice power but nothing NOS would not out-do. However, getting the right amount and not having to mess with a bottle would be nice. We have never probed out combustion pressured but I know that will be a must to tune for that stuff. I will have to look into that again. Brandon

One thing we really push here is thermal coatings because it causes heat reflection and reduces convection of heat into the head so the heat is reflected back into the charge where it is better used and the overall engine temp is reduce drastically. We use coatings on much more than just the head though. By doing this we ensure that the dome is not super hot when the charge enters the chamber because the heat is carried away with with exhaust and not absorbed by the head. This allows for more compression without detonation. Flame head, that reminds me, have you played with nitro yet or what????? I used to play with it but at a rate of about 3oz per gallon. I know it pops fast and I did kill a motor with it but that was before some good testing equipment too. I can't help but love the stuff. Brandon

We have not actually run testing just on cooling with an aftermarket billet head but we run most of our guys with digital temp gauges and I will say minimal temp drop. Also, where are you taking a temp reading from? Yep, the head may be able to drop "head" temps a little through better flow and volume of fluid BUT, putting the DA thermodynamics to it, basically, it would take longer for the bike to get hot but still would if there is a real dissipation issue. And there is on the banshee. More air flow, better radiator, better coolant flow pattern. You have to think that as you raise the HP in an engine, you have more HP in heat to dissipate. Also, do you want an ice cold head? I will let flame head take that one out in depth but cool cylinders and warmer head are much better for efficient burn. We feel the key in the two stroke head is to super atomize the fuel charge just before combustion thus helping everything to lite up upon ignition thus reducing a chance for detonation. We actually run motors over 200psi static with pump fuel in detonation testing. Anyway, coolheads have there place but not in drastically reducing engine temps. Brandon

There is no question I would check it out but honestly, if they dumped sand in the fill hole and put the stick back on, there would be sand on the stick, threads, and all that. If you clean it all off BEFORE cracking open the stick, and find that a stick check reveals no sand, I would drain the oil to be safe and run it in a strainer to verify and kinda inspect the oil for crap. The absolute worse thing for an engine is glass bead but sand ain't far from it. I doubt there are any "strange liquids" that would kill a motor faster than sand. Also, if these are younger punk kids, you can bet this is there local hang out as they may not have any wheels so I would roll the area around that time of day for a week or so until you found them. They will show up, and I would use my smarter side and would lock them down, call the pigs, make a report, and make mommy and daddy buy you a new engine. I had a similar incident with some teens knocking my son down. You bet I caught them in 3 seconds (ran college track), and when one said "you can't touch me", he got my knee in his throat. That was a "protective" beating but if you jack those kids up over it, you may get some time for it. Not worth it IMO. New engine sounds better. Brandon

Can I have your old coil and wires? I guess I am an electrical guy so I LOVE to fix electrical issues. I just think you might have something like a coild wire that needs re-terminated or something simple. I am saying this because if one side is strong, that kinda leaves wires and plugs and thats it. the simple swap I mentioned above would find this fast. Could save you some coin in a new coil. Unclip those wires from the coil and see if the cores are rusty. Just chop .25in off and reterminate and you are all set. Brandon

The easiest way to sort that out is swap the plug wires wide to side and install brand new plugs to rule that out. You plugs wires can be installed either of two ways. If your problem does not follow your suspected wire, I would lean on the carb. Very common, do a detailed carb clean and balance the carbs. When the carbs are off, you should look at and feel the reeds to make sure you do not have a split reed or something of that nature. Just sounds like a carb but I am not there either. The way the coils are made, if you have spark only on one side, it is either the plug cap or wire. I have installed countless plug caps. Brandon

You make it sound as the CDIs fail all the time. I am just curious who all has replaced theirs? We rarely see them fail here for some reason. I tell you, to be honest, this is our busy season and we are just trying to get people taken care of right now. We try not to R&D in the spring. One thing worth noting is if we could tear apart a few bad CDIs and determine the failure point, that would help a bunch but those CDIs are potted so goodluck on that one. You will destroy the whole thing trying to get it apart. Now---If I could get my hands on the PCB layout of the CDI, we could develope a test for it and maybe reverse engineer it. Either way, at this point, even if I do tell you how to help the power situation, how would we ever know if it is helping the CDI live longer? Well, if you want to play, you will not hurt anything by adding a 470uf in the circuit from radio shack. make sure to purchase a film and foil or metalized cap. They typically have a metal case. These are designed more for this application. They are also called run caps in motor applications. The ceramics would fail in short order. The voltage on the cap is a rating of its break down. I would get the highest voltage you can find because that just means it will be bigger and be able to tolerate more voltage. You would install this cap in the AC+ line from the stator going to the CDI. This needs to be installed in series and if the cap is polarized, make sure flow is shown correctly. If you have any issues, the cap will just fail and it will go open line or closed line, either way, it would not hurt anything if it failed. If it boils the resin in the cap, you might need a higher voltage cap. I would say 100V should get you taken care of. Now testing it, well we use DAQ equipment to log that data so I guess it might be one of those things you install, leave it alone, and if the CDI never fails, you can say it works!! Really, this stuff can get technical fast but adding a little capacitance in your life will not hurt the system. I just cant offer an easy way to test you improvements. If you can find an oscilloscope, you might be able to track your transients and harmonics but logging data really helps.

Yes, STD is for standard or stock OEM bore size. For the banshee, that is 64mm unless you have some other pistons in it. For instance, the 66mm Blaster pistons used in the long rod setup. The piston will say STD but the bore is NOT 64mm. Just know what you have and you are all good. Brandon

well in inch conversion, that would be 2.519685039 Considering a 64mm bore. Hope that helps. Brandon

I really thought there were a couple other cos but I sure can;t find them. No, the pantyhose will not work since this is for a production product. I was rather amazed with the high pricing right from outerwears and I am betting K&N would be cheaper but still out of our target pricing for the part. If you think of another, let me know. Brandon

Well of course we are trying to stay out if the sewing business We would much prefer to find a company that makes these at a more competitive rate. Let me know if you think of something. Brandon

I feel that a huge amount of testing would have to go into suppressing back talk from the plugs by means of wires and or plugs. many cars today use both. Not because of the misfire concern, but all the sensitive engine management sensors on board. Piezoelectric sensors can be faulted by this back talk pretty easily. Suppressive wire and plugs are a must and all PCMs are STILL heavily protected because they need PC type power. Clean as a whistle. I feel that if too much resistance is used in the banshee (no HEI) you may reduce the effective voltage to the plug. After all, this is one way we buck voltage down, by adding resistance in series in a circuit. Parallel acts as a power absorber. Either way, not good for a bike that already has wimpy spark. I would follow the OEM specs but I would sure prefer suppressive wire rather than R plugs if I had to pick. Brandon

We never had a reason to repair the power issues at hand and I am sure this applies to all constant loss ignitions. I guess if someone is concerned, adding capacitance to the system is the first defense against transients. Those CDIs have to have pretty good guts to cope with the power. The cap will act as a shock absorber and smooth some ripples. There is just no data that I have that would indicate that cleaner power would extent the life of the CDI. This is just a "theory" we have. I am confident, even if we spend the hours of time designing a part to fix it, someone would just duplicate it and call it their own. We just cannot see any marketable reason to pursue a "clean power" module. Brandon

OK, I thought since we have some sharp minds here I would try to get some help. We are trying to find alternative vendors for the polyester nylon mesh filter wraps. Outerwears is WAY to proud of their product but we do like it. We are looking for more economical solutions but would prefer to stay with the same base material. We are looking primarily for a manufacturer or a high volume wholesaler. Brandon

http://en.wikipedia.org/wiki/Engine_knocking I have found this links thing helps get my point across much easier. No detonation and pre-ignition are NOT the same thing. That damage looks like the work of pre-ignition but VERY unlikely because the flywheel key would have to be missing or something extreme. Generally, there is hot spot from carbon build up that causes this and I know this is not the case. Those pits in the piston may collect carbon and at some point, start to cause pre-ignition but we'll let that go for now. Pre-ignition would only have this type of pattern if it has multiple ignition points thus causing multiple flame fronts. One flame front would just diesel and beat the rods to death but would likely not show piston wear. Brandon

Toluene, now we are talking but you really need to do some numbers and study up before attempting "fuel tuning". We don;t have time to mess with much custom fuel here. Alky or nothing for us. We typically will use Acetone in ours to lower the flash point in cold weather but that is about it. Brandon