A few questions for building a trail-ridden Banshee...

[SLORYDER]

I

I really feel before one can properly port an engine and "know" (key word) what they are doing, you need to go buy books fluid dynamics, 101, 201, 301, Aerodynamics 101, 201, 301, Mechanical design 101, etc. I am not saying, go be an engineer, I am saying that when I see someone razor back an intake bridge in a sub sonic air stream, I know what I am dealing with.... I now sound like a cocky asshole but I am trying to convey that as soon as you fully understand how that air is moving through the engine, you will "know" what to do instinctively.

 

I tend to disagree that you need to read all those books to gain the knowledge needed to port an engine.

 

You gan gain much in a two stroke by doing fairly simple modifications if you are properly guided.

 

And I plan on fixing that divider as well as a few other things.

 

Tell me what flaws you see in my theory. I would like to learn.

Edited April 27, 2010 by SLORYDER

[SLORYDER]

Ive been following all your post for quite awhile,

 

Sweet I have a fan club!

[bigblockbanshee]

And before anyone gets torn up about the torque numbers I'm indirectly speaking of, I know the Banshees don't make torque. They aren't made for that type of riding. I got reamed a couple of years ago on a thread that I made about building a "torque Banshee". I understood and decided I'd have to make changes to my riding habits and go from there. I know this isn't a 4-poke with gobs of torque but I don't want one of those. All I want is a good, reliable engine with some good bottom end. Top end doesn' t mean much to me as I'll probably re-gear to bring that top end power down into a manageable range that I can use on the trails. I guess what I'm trying to say is that I just want a dollar's worth of power for a dime, but doesn't everyone? I know I can't get to that but what I think I can get to is a very happy medium while staying on a good budget. I doubt I'll ever see a dune or any sand so as I already stated my riding will be all slow, technical trail with minimum top end bursts. Keep it coming everyone, I'm learning a lot here.

[blowit]

I tend to disagree that you need to read all those books to gain the knowledge needed to port an engine.

 

 

 

 

 

Case and point. Many people can "port" an engine, BUT, who can fully develop a cylinder from scratch??? I will admit that I envy the engineers that do that every day. How do those Cheetahs run?? They did not have a template to work from. They had to "know" what they were doing when they started.

 

I guess my point is there are leaders and followers. If you are only after copying other people's work, buy or borrow a good running set from a friend, copy them to every detail, and you have a port job.

 

 

I am not looking to beat you down for your effort because that is how people learn. I just like to see people learn the right way. Fully understand it and you will be able to adapt your skills to any engine setup.

[SLORYDER]

i don't think you see a major problem here.......you are trying to give advice of an inefficient dune-drag diy port job to a guy that neither expressed interest in doing so, nor trying to gain peak power. the o.p. is looking for an efficient trail setup, and even expressed concerned that it may be too much power. your intentions are good, just not tentative enough in taking perspective of what's going on.

 

Sir I am simply offering my opinion and letting the guy know what I believe would be the most cost effective way to go. A builder would also inform them of the same (although it would be the most cost effective for them)

 

The guy stated that his ideal engine would be a 421 cub with 34mm carbs. I believe that my route will be along those lines but cheaper and obviously less powerful.

 

I bet that 4 out of 5 guys would prefer to do the job themselves and save some money. Problem here is that the majority of people on here don't have enough faith in themselves or others, and only trust what they hear from builders ect. So you end up with a socialist forum that is a mass oppressor of the truth.

 

Two strokes are easy to modify (and equally easy to mess up) IF you have the right guidance. I have been into two strokes for five or so years and only in the past few weeks have I really gotten curious and learned a lot. And I can assure you that I will not touch my jugs further until I feel completely comfortable doing so.

 

I believe I have outlined an ideal diy build for this guy if he decides to do some research and go for it.

 

I was getting ready to dump 5 g's into my banshee, then realized i could sell it as is and use the money to buy a pre built banshee with 125+ hp for the money i was going to spend on mine.

Then I realized I could mod mine myself, still be very pleased with my results, and use that remaining 4500 to buy a sweet 2 stroke ski boat. Which I can become obsessed with and mod.

 

If this guy does not believe in doing things himself I have nothing whatsoever against him and he can disregard my posts.

 

 

 

If anyone has a problem with my plan I would love to discuss it further.

Edited April 27, 2010 by SLORYDER

[SLORYDER]

Case and point. Many people can "port" an engine, BUT, who can fully develop a cylinder from scratch??? I will admit that I envy the engineers that do that every day. How do those Cheetahs run?? They did not have a template to work from. They had to "know" what they were doing when they started.

 

I guess my point is there are leaders and followers. If you are only after copying other people's work, buy or borrow a good running set from a friend, copy them to every detail, and you have a port job.

 

 

I am not looking to beat you down for your effort because that is how people learn. I just like to see people learn the right way. Fully understand it and you will be able to adapt your skills to any engine setup.

 

So I see you refuse to state the flaws in my theoredical build...

[blowit]

So I see you refuse to state the flaws in my theoredical build...

 

 

Are you talking about the 4mm with a spacer?

[SLORYDER]

Are you talking about the 4mm with a spacer?

 

No the 4mm with the spacer.

 

Could you possibly give me some timing numbers with the 2mm spacer since you are so willing to help?

Edited April 27, 2010 by SLORYDER

[blowit]

No the 4mm with the spacer.

 

Could you possibly give me some timing numbers with the 2mm spacer since you are so willing to help?

 

 

This will calculate out the same as having a zero deck 4mm bike with raised port 2mm. Remember that rod angle certainly changes things if you are not at zero deck.

 

^^^^ UH, that is wrong. I apologize for my typo. That should be raised (0)mm.

 

 

The spacer will certainly work to a degree without porting. I would agree with that.

[AKheathen]

good news for you....dare i say- those e-spakin days are not the satandard currently. you can have close to what you are looking for and not have to clutch the shit out of it anymore. the stroker would be an great thing to do, and just making it run for now with cut domes will put a smile on your face. the port timings will drop to a lower rpm power range than stock, and you can get away with a 4mill correction port job for likely allot cheaper, and you won't have to rebuild with new pistons/bore at that time either...just a hone/ring job. do yourself a huge favor and trade off those t-5's for a more "woods" suited pipe. imo, the pro circuits will be the most fun, and net the most torque/power in it's class by far, but they are not the most efficient woods pipe. the t-6, ptr mids, mabey sst and gnarley are good options, with the t-6 being the most efficient, and not just in terms of economy, but utilizing the lower flow rates. stay away from anything 2-1, though, as it's a gimmic, but that is my opinion, and many who run a 2-1 carb or pipe will defend it. you can do some reasearch on this site and decide yourself, but that is all i have seen, and there have been many with info to show it. as for the water issue- like i said, some grease where the cable goes in, and threads, longer bowl vents, make sure the choke tube and boots are still healthy, and run your airbox with a powerlid and outterware. that's what i could think of, but it may still have the condensation issue overnight, and you can just work the choke on-off untill the moisture steams off from engine heat. advanced timing and boysen power reeds will do you some good for torque, and controll. btw, i shread the 4pokes in the woods....

[blowit]

For the record for the OP, my recommendation is to install a 4mm crank, mod the head or domes for the extra stroke, and if you do not want to afford it, leave the cylinder stock ported (no plate) and leave that as a future mod. Your bike will run better, will have improved bottom end from the extended transfer time and added stroke but may hit a little harder when it comes on. You will have about 15+HP hiding in there when you are ready.

 

You can also have the cylinders ported for the 4mm without making them more top end happy. basically improve everything from bottom to top.

 

 

Hopefully that helps.

 

Note: You are going in the right direction if you want improved bottom end on a banshee. Stroking always helps. If you are looking for the "holy grail" of torque, you need a different bike. What you want is 4mm setup for MX. This will provide proper tuning to focus on the low end performance.

[bigblockbanshee]

I gotta get off of my unemployed a$$ for a while. As soon as I get back I'll continue the discussion. I really appreciate everyone's input, challenged by others or not it's still helpful. If anyone can think of anything else I'm eager to hear it. As for the pipes, I don't mean to be stubborn or difficult but for now the T-5s are staying. Yes I know that they aren't the best choice for the type of build I'm doing but it's all I have for now other than a mint stock setup.

[SLORYDER]

This will calculate out the same as having a zero deck 4mm bike with raised port 2mm. Remember that rod angle certainly changes things if you are not at zero deck.

 

^^^^ UH, that is wrong. I apologize for my typo. That should be raised (0)mm.

 

 

The spacer will certainly work to a degree without porting. I would agree with that.

 

OK sweet.

 

So 4mm crank, no spacer custom domes for lot more bottom end due to the longer power stroke and more work being performed at a given rmp. This is of course at the expense being able to rev due to the shorter durations. If tight trails is all you ride, and you already have a shee, this would be the way to go. I would still open up the exhaust port some too. At least to 70%.

 

The spacer will give you close to 10 hp up top due to the increased durations and a bottom end as good as stock thanks to the power stroke being stock.

With the cool head you wil sweeten the bottom end even more and this is why I would recommend the spacer. Good addition of all around power.

You might stay in the trails but one day you'll want get out into the clear and let her rip.I would actually raise the exhaust at least 1mm if the crank + spacer puts your duration back to stock.

 

 

 

And BTW papa smurf I was way out of line calling you out like that and I apologize.

 

Each to his own.

Edited April 27, 2010 by SLORYDER

[firebanshee]

OK sweet.

 

So 4mm crank, no spacer custom domes for lot more bottom end due to the longer power stroke and more work being performed at a given rmp. This is of course at the expense being able to rev due to the shorter durations. If tight trails is all you ride, and you already have a shee, this would be the way to go. I would still open up the exhaust port some too. At least to 70%.

 

The spacer will give you close to 10 hp up top due to the increased durations and a bottom end as good as stock thanks to the power stroke being stock.

With the cool head you wil sweeten the bottom end even more and this is why I would recommend the spacer. Good addition of all around power.

You might stay in the trails but one day you'll want get out into the clear and let her rip.I would actually raise the exhaust at least 1mm if the crank + spacer puts your duration back to stock.

 

 

By your own accord you have never even ported a set of cylinders,by your previous post you are asking other peoples opinions on how to set up your motor, (which is cool),and now you are trying to tell someone to try all your ideas which you have not even tried yourself.What in a weeks time the student became the teacher.I think it is really cool that you want to build your own motor and that it intrests you,but should you really give out all this advice like you are a pro motor builder.Plus in this post you are saying not to listen to a pro motor builder if they pipe in and say you are wrong.

[mikechief]

How bout sum step by step instructions and sum before and after pics cuz I'm a do it yourselfer with more time than money and I wanna Run a 4mm with out a spacer I don't wanna take it into space so I should be able to do it myself