First Banshee Build Questions/Suggestions.

[SeanC7]

What up boys, Im working on my first banshee build and I must say I dont know much about building a banshee. Ive worked on many two stroke dirt bikes and I know they're rather similar but I want to get down to the specifics. So Here I have a bunch of questions. I live down in Miami, Florida so I do a bunch of street riding/racing but I also tend to hit the few trails we have down here. I bought everything needed for a rolling frame, and I wanted to keep all the swing arms shocks and axles stock for now. Now im getting close to looking for a engine. Im wondering if I should buy a stock engine and just bore it out and race port it or if I theres a certain type of way to do this. Im aware of a cheetah kit my neighbor has one on his bike and Im not really trying to get that deep right yet. If I bought upgraded carbs would I need to upgrade other parts of my engine or just jet it properly? Would I need to update my bottom end if I bored out and ported my top end or can I keep that stock? Or is it better to upgrade? What does it mean when people say 4 mil and 3 mil and all of that? Those are just a few questions I can think of at the moment, theres definitely more to come.

 

Also- I want to make sure I put brand new screws bolts and washers on this bike because I hate when assholes strip shit on bikes. What type of screws would I need, I know theres kits and stuff but theres no way that will be enough and I wont know where to put what where for the most part.

 

Thanks for the help!

[Jereme6655]

the banshee is the easiest 2 stroke to tear into (bottom end) in my opinion. 

 

But you have a few flaws in your building knowledge.....

 

First....the stock suspension is terrible.  Try upgrading to at least some Works dual rate shocks up front and have the rear shock rebuilt my So Cal Suspension (matt is a sponsor here)

Second....DO NOT bore the jugs out for more power based on diameter of pistons.....you wont gain power.....only lose the ability to bore larger when failures happen.  4strokes gain power by boring, 2 strokes gain power by porting.

 

After new carbs are purchased you need to upgrade your intake (to fit the larger carb mouth) and a throttle cable. Then jet the carb to your bikes needs.

 

+4mil, +7mil, +10mil and so on.....refer to the amount of longer stroke of your connecting rods due to your crank.  So a +4mil will push your piston up an additional 2 mm and pull your piston down an additional 2 mm.  its early and I don't have enough coffee in me to remember what the stock stroke length is off the top of my head......somewhere around 115 I think. 

-- +4 mil is the only stroker crank that you can drop into stock cases.......if you want to use a larger crank you will need to have your cases trenched out to fit the crank by one of our site sponsors. 

 

My advice would be to look for a ported 421 motor.  Serval motors are more low end grunt all around motors..........cub motors are drag racing motors so their power is top end peaky.  I would suggest finding a motor that is pre-built as you can spend some serious money on a motor and then still want a little more.  Usually it winds up being cheaper when you purchase it already built from someone.........BUT I would suggest tearing into it and going through it with a fine tooth comb after you purchase it to avoid having it blow up because someone overlooked something that shouldn't have been overlooked.

[SeanC7]

Great advice man thanks, now i pretty much understand what the +4 mil means etc. As far as my susupension goes Im trying to get this thing running for as cheap as I can and just upgrading it later. What type of carbs would you suggest? In terms of buying a motor already completed; I definately like that idea the only advantage I have by not doing that is the amount of money I spend. My mechanic down here does alot of work for free so going stock may be better because he can just port it and what not himself. I definately wanna go with a +4 mil crank since I wont have to change anythinf at first. I would like to go bigger then that. When you say getting your chases trenched are you reffering to top, bottom, or both!

[Jereme6655]

the bottom end (cases) need to be clearance internally so that the crank can swing without colliding during its rotation

[SeanC7]

Awesome, at what point is race gas necessary? Would it be a necessity with only a 4 mil?

[Jereme6655]

it depends on a lot more than just stroke......along with the extra stroke, you will need a different head to allow the pistons to go that much farther up.  Your builder would be able to let you know more based on your engine work/porting if race fuel is required.  However you can have them built to run on it, or on just pump fuel.  Hell you can even have it done up to where you need alky to run....

[SeanC7]

Ya i figured I would need upgraded cylinder heads if I got a upgraded crank. I pretty much got everything straight. Just trying to figure out what type of engine build im going to want...which could be the hardest part lol.

[Jereme6655]

believe it or not its the easiest choice......call your a few sponsors and see which one you feel most comfortable with by talking to them.  When you do, ask them what kind of port job they recommend.  They will ask you where/what kinda stuff you ride in and will give their professional opinion on what work they believe you need.

[bansheeryder21]

Glad to see a fresh new build on here. All your questions are good and are standard for someone new to banshee. As far as a motor, I would use a stock 350 and Kevin at HJR do a port job of your choice and throw in a 4mil crank. He can set it up anyway you would like as far as pump, race, e85, or Avgas. He is a great guy to work with and doesn't excellent work at an affordable price 100% satisfaction guaranteed. His turnaround times are pretty quick too. Go to www.herrjugsracing.com or call him at (760) 703-1836. He can work prices with you since your trying to do a budget build. Good luck! Tell him Elisha referred you.

 

 

 

Ya i figured I would need upgraded cylinder heads if I got a upgraded crank. I pretty much got everything straight. Just trying to figure out what type of engine build im going to want...which could be the hardest part lol.

[SeanC7]

Thanks to both of you for the replies. Im going to have to call them soon, only problem is Im all the way down Miami and my mechanic usually does ally work. I dont wanna call them and use them for their advice is im not going to pay them for the job lol, sounds kind of messed up. Either way im definately starting stock and probably gettong a 4 mil in that thang as well.

[Colby]

Thanks to both of you for the replies. Im going to have to call them soon, only problem is Im all the way down Miami and my mechanic usually does ally work. I dont wanna call them and use them for their advice is im not going to pay them for the job lol, sounds kind of messed up. Either way im definately starting stock and probably gettong a 4 mil in that thang as well.

on a banshee, theres about a 90% chance, Kevin will do a better job than your mechanic ...

[SeanC7]

Just checked out his site, sounds like a man amongst boys. Lets say I wanted to go big in the future (7-10 mil) and I trenched the cases got bigger cylinder heads or whatever, would that be a pain in the ass on a trail? Like i said im ablut 50/50 trail and street, I dont want a drag or have to put a wheelie bar or any of that shit.

[Jereme6655]

well here is the problem your going to come about with......going with a 4mil stroker is great.....however if you don't get the cylinders ported (intake and exhaust ports changed) specifically to what a 4mil likes.......you will wind up with a 4mil motor that makes about as much power as a mild ported stock crank bike.  IF you do decide to get a port job done for the 4mil crank....there is a high probability that it will not be able to be ported to a 10mil. (there is no point in going to a 7mil crank....they have been known to not lay down that much more power based on price)

 

My suggestion......call Jeff at FAST racing (farmandsandtoys.com) and talk with him....and think about getting a stock stroke port job done for the time being....and when your ready, get yourself a different top end such as a serval or a cub top end which will really wake that bike up once paired with a 4mil crank.  (serval is all around style power and a cub is more top end drag power)

 

Jeff ported my bike and has a GREAT ability to understand what kind of power you are looking for.  I told him I wanted mid throttle bang as I like to ride wide open trails and get a thrill of being able to force a powerslide......that being said....all that is warranted now on the trails is a flick of the throttle and the bike wakes up and swings wide.  I could have gone larger, yes, however....I still find myself struggling to be able to warrant a larger motor.  Also jeff has the lowest prices I have been able to find when it comes time for a rebuild.....cheapest prices on a set of Wiseco pro-lite pistons that I can find. 

 

Give him a call....he'll do you no wrong.  Ive had him call me WAY after his shop hours to get a feel for what I want and to let me know how things were going with my motor.  Hell.....he even remembers me and asks me how I still feel about my motor (remembering what motor I have) when I call for parts for other motors.  He's one hell of a guy.

 

Jereme

[SeanC7]

So many things to take in my heads going to explode, making me feel like I should just get everything stock and upgrade from there...shits crazy lol

[SeanC7]

If i had a stock cylinder, and put a race port on it, and later got a 4 mil crank in it, would there be room to port it after I have already ported it with a stock crank?