TurboBanshee420

What is the smallest dome I can run on pump gas for the 421?

ok. i just got done building the rest of the motor. The cylinder is a 4 mil. the piston matches the deck @TDC. I'm leary about using the stock head without any cut for the 68mm pistons. I didn't have any problem with the 66mm bore. I measured the clearance with play-duh...lol... I found roughly.012 clearance between the crown and the head. I can let that slide until I get a new head i suppose. I'm prob going to order tomorrow..... Any suggestions?

ok...spacer or no....???

Not sure what it REALLY is, cause I got it from a guy who bought it from rdz like you saw it. BUT....I was told it is a 4mil 68mm. Already checked the bores. they are 68mm. What is the hieght of a 4mil cylinder? from flange to head surface...

stock

i know I must be a tard right.... Do I use my spacer, they don't look any diff then the stockers on the base flange and i don't want to assemble it to check before I do other shit spacer or not...?

mine made it about 100hrs now and have minimal freying on the corners.....time to replace though. Carbon fiber reeds suck! Sounds like they are slapping the reed box to me... That is one of the reasons why I use reedspacers, but I cut them down to .250 on the mill. No need for a full .500. Just pulling them out a bit helps. Or he can get out the dremel and do some grindage where they are slapping.

fair enough... Is there anyone out there who doesn't dune/drag only these cylinders? Nik cylinders have a perticular problem with heat soaking. I always loved iron liners for this reason. It sure doesn't take long to swell up under full load. Newer sleds are running very wide pston to wall clearances for that reason. Guess I'll just run them and see what I get...

I'd like to end up running 35pwk's with the cub...CPI (*wink*) pipes and maybe even try some of this e85 shit....no race fuel for me since i have a 6gal tank that tends to be empty by 3am everytime...meth sounds fun too, but I'm not crazy enough to ride the trails that way. I like to just kick and burn ass outie...no foolin around with the high end side of banshee-izms...lol I think it's time for bed. goodnight(day) gents. chat on the flip. Thanks!

as this WAS my turbo engine....I have it all already. I was planning for 120+hp.... it will handle the cub easily.... ti-moly chain and sprockets direct drive lockout with 4 washers (pancake too) +4 swinger modquad tubular blah blah...u get me everything short of shift cam mods. btw...not a fan of the pj's though they never did me wrong...still not a fan. My 30's woke it right up when I ditched the pjs...I'm guessing because they were just straight-up too much for a stock cyl 4mil...even with the shearers

ok...don't take this the wrong way either....but are you even reading my posts, well at least the part where I said I'm only running the 2-1 until I can afford some drag pipes? All the trails i ride ARE straight line WOT type riding. Very rarely do I even get into some woods, since there aren't much around. I only want a BROAD power output...well...as broad as I can make it anyways. I know what your saying bro..you said it well. But i still think your misunderstanding my intentions. I want all mid-TOP end. I realize the cub it a different game, but not far from what I have now... considering what else is out there. I wish I could dune it, but the closest thing we have here is the sandy shore of lake Ontario...lol, not that I haven't been there before. If these are only good for all balls drag racing then....BINGO....I'm all about it, since thats all we really do out there anyways. Problem with such a peaky bike is the gearing I run...the shearers I ran for a while would fall out of power before I got to the bottom of the next gear when up in 4-5-6. Not so much that is was a pain...but noticable. Hence why I'm looking for a bit wider, usable power. I had to rev the shithole out of it to get into the power in 5th and 6th so it would continue to pull hard. as for efi cub...sounds fun. It's really easy to do when your pressure range isn't 50-300kpa...lol...however I had some problems getting enough rpm to get the system to register without elec start. I would have to use a haltech or similar. Megasquirt has limits on odd applications like these. No elec start really is a problem there. I could just as easily use the cdi for ign...on a NA engine it would be no prob. The boost blows the weak cdi spark out...hence y I needed an HEI(DIS) ign system...50k volts and 6 amps!!!! Thats enough to kill your ass good!!! but yeah...take another look at it now and see if you can give me some pointers here. I'm not really going the direction your thinking.

I went through 3 rm200w jobbies before I got a good one from them. I had a 260w "electrix" stator that was awesome, but after 3 years of using a shitty stator cover gasket it shit out on me too. going on 3 yrs with the 3rd RM200w...still good so far. (fingers crossed while knocking on wood 3 times)

i would like to keep my 30 pwk's on there if you guys think it will run better...lemme know

Like I said, I'm running the dynport until I can afford some rockets......I like shearer, but they are too short a band for me. Maybe the larger volume rockets will get me what I want.....wide power, not so peaky. I've run the dynoport on lots of different set-ups through the years on this thing and it always has held its own pretty good. plus the sound is sweet. I don't think worrying about "peak" numbers really matters much. So far I haven't touched the windows except for the intake which doesn't matter much really as far as timing goes. If raising the exhaust is a bad idea, then tell me now, before I go and do something I shouldn't.....you guys are the cub pro's....not me by any means. turbo project...yes...that was me. Yes I finished the build, with no luck getting help tuning. I ran into a wall there trying to ride with a laptop sitting on my lap (go figure) so I could get some recordings of what was going on. I got as far as getting it to run and idle, but was WAAAYYY to rich to do much more with. I'm not familiar with how far each adjustment gave me. It's all in a nice sealed tupperware container and waiting for a rainy day. Not so worried about it now. I'm restoring my scarab and have no time to go there...along with tons of other shit. When it catches back up to me I'm sure i'll get pissed it never got "done" and throw it back on. The whole turbo thing has been a god damn thorn in my side for 5 years. Started in 03 when my brother talked me into trying it with carbs....after i failed to get enough fuel in there with carbs I gave up...in 06 I started planning it out again with efi...worked out well so far. Learned more doing that project then I ever did in school! Anyone have a port map I can use? daj...What do you suggest i do with the exhaust? open the small boosters? open the main port? raise lower??? fill me in big guy...You apperiently know tons about the cubs. And what about the transfers? c'mon now, don't tease me lol As far as I'm concerned...making holes bigger isn't where the power is. Timing and shape is where 2 strokes like the work done. I learned that on all the 670's I've done so far. Man what a difference alittle rounding and removal of sharp edges make. Air is pretty flexable from a pressure stand-point...Inside a pump it will do what it's told... to a point The pics don't really do much justice, but all the things I have done so far is only to help push the charge down toward the crank/transfers. I just wanted to get rid of the huge lip on the bottom/side on the intake windows. I feel it shouldn't be channeled more tightly...it should open like a bell going in. (if you know what I mean) look closely at the pics and you'll see what I mean. The first few are before shots (duh). There will be a small pressure drop going in through there, but not enough to reak havoc...The charge will be under vacuum anyhow sooo...

i did the same thing maize did to his on my 670....took alot of money this past year from guys with 800's and this and that...they were mad!

bottom end on a banshee is worthless anyways. I can get back what I lost with higher compression. i just want to get a nice wide band....running a 2-1 dynoport. 34pj's for now. I would like to get a set of rocket pipes eventually. I ride lots of very fast wide long straight trails. mostly railbeds...hard surface. Exhaust changes will give me about 3* more duration. Only to stretch the power a bit higher....I love to hear it scream. The 2-1 pipe does a better job of scavenging the opposing pulse form the other cylinder. They looked ok from rdz, but they needed lots of clean up. I did all the same things to my stocker and got 55.6hp at the wheels. Not too shabby I guess...that was with shearers and 34pjs. Should be much better with a more aggresive cylinder design

Yes I'm opening the exhsut port by 15% by volume, also raising it by 1mm across the window curve. Tranfers are pretty good as far as volume for me, but I want to open the windows on all sides by 1mm or so. And blend the sharp edges into the cylinder. I alwasy start with the intake to give me an idea of what kind of airflow I'm working with. besides, the hardest part is gettin gthe air through the reedbox. Once your in, then the engine will do the work from there as long as it isn't getting back pressure reverberations while pumping it up to the top. Killing all the knife edges with strips of emery when I'm done....round nose cuts air better. If you don't think so then youtube some airflow tests. knife edges will make a pressure "wake" and cause fuel to collect in the wave and de-atomize. read this....This guy made 30+hp off his porting and other small thingsMaize583

i highly doubt that it would be no improvment ...however, I've only had about 2hrs to do anything and I was planning to cover all my bases. For such a "badass" cylinder, it sure needs some help... What is the average output from a 421 without work?

do not use a wire wheel!!! you will imbed steel shavings in the piston crown only to be released later by piston wash and score the walls after it works its way into the the skirt. as said above...don't worry about that shit, It will only return after a tank of fuel. Drop a jet size and re-tune. If it runs good then you should only have about a fingernail sized clean spot next to each transfer port. The rest SHOULD be black with carbon...its NORMAL

building my 421 cub...just thought I'd ask you guys for some pics ideas...yada yada heres some pics of mine as i got it and what i've gotten done so far...only about 2hrs of cutting so far on the one side. BEFORE AFTER, but not nearly done The outside...shiney!

yes that is what I refer to as a diamond ball hone...I bet you can also see y I call it that. All though the difference being one has stones and the other has diamond dust impregnated composite balls on the bristles

"BB hone"??? maybe I'm a bit tipsy, but I'm not following... ring thing is a given, most are too big a gap already though.

diamond ball hone is what you should be using on nik bores. But do NOT over do it. some companies will size the holes for you, some will not. Kustom Kraft will... They did my GASGAS...which is th eonly company who will fuck with GASGAS btw... They skim bored my cylinder and re-nik'd .006 thick and sized a wiseco slug to fit perfectly. Great job too!!! I have no experience with anyone else for nik coatings.

I was wondering.... Since I don't want to waste a set of $1k cylinders when I start putting a hurt on this thing. You guys are just dropping a set of wiseco's in these cubs? No sizing...??? I have heard engine builders tell me that wiseco has a tolerance of +/- .0003 on all pistons. However I have gotten pistons from them for my 670 and they were .0012 oversized. I resent saying this, but should I just drop 68mm pistons in like every other shmo or is this common practice for you professionals too? I have all my motors sized for the slugs....they last longer with hot set-ups. I consider myself a rotax expert now...(from all the times I have roached my 670 over the years). Nik cylinders are different though. They are slightly less forgiving. *shrug*....drop a few pennies. I wanna see what u think.

I ran 148 mains on my old shit I think...ported stockers and dynoport...airboxed 42 pilots