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

[bigblockbanshee]

I was planning on just putting it together and running it as is with Toomey filter and T-5s and some better reeds but the longer I take the more the mod-bug starts to bite. My purpose is trail riding with good performance but good fuel economy. I'm about 400 miles away from any decent sand so I'm sticking with trail. I don't wanna get stuck out on the trail with no gas because I sacrificed fuel economy for a little performance. That's like driving a top fuel dragster back and forth to work IMO. Also my crank has too much side clearance on the rods so more than likely it will have to be rebuilt and I have no clue how much this costs or if it would be better off in the long run to just do a 4 mil stroker now and be done with it. So here are my questions:

 

1. How bad are the 26mm carbs? I'm talking about restriction specifically. Do the stock carbs restrict even a stock motor? I've just rebuilt my carbs with a TORS eliminator kit, idle kit, rejetted for T-5s, and all new internals.

 

2. Since my crank will need fixed should I just sell some stuff off and buy a 4mm stroker kit?

 

3. I know it's probably not recommended but could you run a 4 mil kit with stock/unported jugs and still see good gains?

 

4. Is a 4 mil too much for trail riding?

 

5. Given the fact I'm gonna be running stock cylinders what would be most beneficial, efficient, and reliable, porting my jugs and staying stock stroke or leaving jugs stock and going 4 mil stroker?

 

I know to get the absolute most out of it there would have to be sacrifices made and lots more mods done. The debate between no porting/4 mil and porting/stock cc is unfortunately an "either-or" situation due to finances. If I had my way I'd do a 4 mil cub with 34mm carbs or something like a lot of members on here have. I also have no reason to do 100 mph or even 80 on my Banshee so I'll probably re-gear as well. Or when it all comes down to it should I just leave it stock and ride it? I just want a good running/efficient trail machine. Thanks in advance for all of your answers and intelligence. I come from the V8 world and I build my own engines and do my own tuning but I'm mostly a newb to Banshees if you couldn't tell from my questions lol. Chris

[bigblockbanshee]

Also I must state that I have a Top Notch Design cool head with 22cc domes that will be going on as of now. If anyone has any suggestions as far as dome size please tell me. I'd like to keep it on pump gas though. Race gas is so expensive around my area that it takes the fun out of it.

[papa_smurf49319]

Stock carbs are really underestimated, they will work well on most setups.

 

Do the 4 mill for sure for the woods it will help out with the torque for sure, also save the money till you can have the cylinders ported for the 4 mill.

 

Basically theres two ways to build a 4 mill, one is with a spacer plate which is the shitty way. The other is to have the cylinders ported for the 4 mill and the head cut and rechambered for the added stroke, piston will pop out of cylinder a bit, or stroker domes in your case with the cool head.

 

You want 4 mill 5 mill long rod

 

 

 

Cody

[SLORYDER]

 

I am not a builder nor do I claim to know everything about banshees buut...

 

I was planning on just putting it together and running it as is with Toomey filter and T-5s and some better reeds but the longer I take the more the mod-bug starts to bite. My purpose is trail riding with good performance but good fuel economy. I'm about 400 miles away from any decent sand so I'm sticking with trail. I don't wanna get stuck out on the trail with no gas because I sacrificed fuel economy for a little performance. That's like driving a top fuel dragster back and forth to work IMO. Also my crank has too much side clearance on the rods so more than likely it will have to be rebuilt and I have no clue how much this costs or if it would be better off in the long run to just do a 4 mil stroker now and be done with it. So here are my questions:

 

1. How bad are the 26mm carbs? I'm talking about restriction specifically. Do the stock carbs restrict even a stock motor? I've just rebuilt my carbs with a TORS eliminator kit, idle kit, rejetted for T-5s, and all new internals.

 

2. Since my crank will need fixed should I just sell some stuff off and buy a 4mm stroker kit?

 

3. I know it's probably not recommended but could you run a 4 mil kit with stock/unported jugs and still see good gains?

 

4. Is a 4 mil too much for trail riding?

 

5. Given the fact I'm gonna be running stock cylinders what would be most beneficial, efficient, and reliable, porting my jugs and staying stock stroke or leaving jugs stock and going 4 mil stroker?

 

I know to get the absolute most out of it there would have to be sacrifices made and lots more mods done. The debate between no porting/4 mil and porting/stock cc is unfortunately an "either-or" situation due to finances. If I had my way I'd do a 4 mil cub with 34mm carbs or something like a lot of members on here have. I also have no reason to do 100 mph or even 80 on my Banshee so I'll probably re-gear as well. Or when it all comes down to it should I just leave it stock and ride it? I just want a good running/efficient trail machine. Thanks in advance for all of your answers and intelligence. I come from the V8 world and I build my own engines and do my own tuning but I'm mostly a newb to Banshees if you couldn't tell from my questions lol. Chris

 

I think your best bet, if you have to take out your crank anyways, is to go ahead and get a 4mill crank (RDZ sells tham with a TZ bearing for 425) and get 2mm base plate spacers. NOW, some people (mainly builders or nut swingers) will tell you to not run tha spacer and cut the dome and re-port. This is good if you want to have loads more bottom end to midrange, due to having a much longer power stroke...However if you use the spacer, you will make your port timing more radical (essentially adding a more top end oriented cam) and gain a lot of midrange to top end. If you do this you will need a dremel with a 90 degree but to lower your transfer port windows to the top of your piston at bdc (not completely necessary but you will get a big bump in port area) and lower your exhaust port floor to the top of your piston at BDC (necessary because the gasses trying to escape will catch that lip and cause all kinds of turbulence.

 

So which way you go depends on whether or not you want the more agressive bottom end.

 

I'd send the stock crank to get trued and welded and get them to send you back both cranks, then sell the old one.

Oh yeah and while you have your jugs off I would widen the exhaust port to 72% of your bore and also raise your intakes a couple or 3 millimeters and also smooth out the entry way.

Do this and add a generous chamfer to the top of the exhaust port and even more so (1/8" on the sides and you will be good to go.

If I had to guess you would gain close to 20 hp by doing this and you could use the stock carbs. Also get your squish (piston to head clearance) to .035 (absolute minimum) to .040" by shaving the stock head. Again not necessary but it will get you close to 5 hp

 

To me this will be your most cost efficient way to bump your power and you will have a 4mill crank for if you ever want to co 421 cub.

Edited April 27, 2010 by SLORYDER

[papa_smurf49319]

If you I think your best bet, if you have to take out your crank anyways, is to go ahead and get a 4mill crank (RDZ sells tham with a TZ bearing for 425) and get a 2mm spacer. NOW, some people (mainly builders or nut swingers) will tell you to not run tha spacer and cut the dome and re-port. This is good if you want to sacrifice your ability to ever-rev and have decent top end power for loads more bottom end to midrange, due to having a much longer power stroke...However if you use the spacer, you will make your port timing more radical (essentially adding a more top end oriented cam) and gain a lot of midrange to top end. If you do this you will need a dremel with a 90 degree but to tower your transfer ports to the top of your piston at bdc (not completely necessary but you will get a big bump in port area) and lower your exhaust port floor to the top of your piston at BDC (necessary because the gasses trying to escape will catch that lip and cause all kinds of turbulence.

 

So which way you go depends on whether or not you want the more agressive bottom end.

 

I'd send the stock crank to get trued and welded and get them to send you back both cranks, then sell the old one.

Oh yeah and while you have your jugs off I would widen the exhaust port to 70% of your bore and also raise your intakes a couple or 3 millimeters and also smooth out the entry way.

Do this and add a generous chamfer to the top of the exhaust port and even more so (1/8" on the sides and you will be good to go.

If I had to guess you would gain close to 20 hp by doing this and you could use the stock carbs. Also get your squish (piston to head clearance) to .035 (absolute minimum) to .040" by shaving the stock head. Again not necessary but it will get you close to 5 hp

 

To me this will be your most cost efficient way to bump your power and you will have a 4mill crank for if you ever want to co 421 cub.

 

 

Have you even ran your bike yet? Just because you read a couple books doesnt make you a expert, and not everybody wants to port there own cylinders!

Basically by saying not running the spacer plate sacrafices power, your calling all the builders that recommend this which is everyone dumbasses.

 

 

Cody

[blowit]

If you I think your best bet, if you have to take out your crank anyways, is to go ahead and get a 4mill crank (RDZ sells tham with a TZ bearing for 425) and get a 2mm spacer. NOW, some people (mainly builders or nut swingers) will tell you to not run tha spacer and cut the dome and re-port. This is good if you want to sacrifice your ability to ever-rev and have decent top end power for loads more bottom end to midrange, due to having a much longer power stroke...However if you use the spacer, you will make your port timing more radical (essentially adding a more top end oriented cam) and gain a lot of midrange to top end.

 

 

 

Not trying to be an ass here but that is just poor advice. I will put any of my 4mil builds against a spacer plate job any day. Indications above are that without the plate, the bike will only perform on the bottom end. Simply NOT the case! I have several drag ported 4mils with OOFs out there. Not one uses a plate. I can prove my concepts on paper rather easily why I do not condone the use of a plate. This plate is simply offered as a bandaid for people that want to just assemble something in the backyard without grinding on any ports.

 

NOTE: A plated bike WILL out perform a stock port 4mil without plate. Neither will touch a properly ported, non-plated 4 mil.

 

Mull Engineering

[papa_smurf49319]

Not trying to be an ass here but that is just poor advice. I will put any of my 4mil builds against a spacer plate job any day. Indications above are that without the plate, the bike will only perform on the bottom end. Simply NOT the case! I have several drag ported 4mils with OOFs out there. Not one uses a plate. I can prove my concepts on paper rather easily why I do not condone the use of a plate. This plate is simply offered as a bandaid for people that want to just assemble something in the backyard without grinding on any ports.

 

NOTE: A plated bike WILL out perform a stock port 4mil without plate. Neither will touch a properly ported, non-plated 4 mil.

 

Mull Engineering

 

 

Exactly!!!! Its been proven time and time again, there is a reason very few still run the spacer plates!

[SLORYDER]

What did I say in my post? A BUILDER WILL TELL YOU TO RUN NO SPACER AND PORT TO THE CRANK. This is ideal if you have unlimited funds, but if you are on a budget you can do it my way, save 250-350 bucks on a port job, and still have a MAJOR increase in power.

 

 

You will need to have someone more experienced than me verify that the port durations will be ok, but I don't believe anyone will disagree that my method is much more cost effective and will probably be the the best bang for your buck.

 

And blowit, I said it would be a bottom end motor due to mellowing out the durations. This is wiithout having to send the jug to a builder.

You guys have peoples minds on here warped into thinking that only a rocket scientist can port an engine.

Ii am not trying to brag simply stating a fact but I went from NEVER touching an atv engine to doing a full rebuild on a 730cc vtwin, including cams, valvesprings, new JE pistons and relieving the valve pockets on the heads as well as doing a full port and polish; all by gathering knowledge on my own and feeling comfortable about what I was doing and then going for it.

 

This site is like an internet tourist trap and you will be lesd into believing that you are not smart enough to do anything yourself.

 

And by the way that 730cc Vforce ran HARD for more that 2 years in the hot southern Louisiana weather and many people told me it was the hardest running Vforce they had ever seen. If I can do it I think anyone can with the right guidance and determination. You will be hard pressed to find the former on this site.

 

Good luck

Edited April 27, 2010 by SLORYDER

[Larry's Shee]

My son's Banshee has a 4mil stroker with no porting but has a 2mil solid copper head "gasket" and stock everything else and it runs. He bought it this way a year ago. I wouldn't have known this if he hadn't flipped it into a deep mud hole. I know this isn't the most powerfull setup, but it's what he has for now. If all you needed and could afford was a crank , you "could" use a 4mil and then port it at a later date. Plus you maybe could have domes cut for your head or maybe recut existing for the stroker and not have to re-do later. JMO , your results may vary.

[SLORYDER]

Have you even ran your bike yet? Just because you read a couple books doesnt make you a expert, and not everybody wants to port there own cylinders!

Basically by saying not running the spacer plate sacrafices power, your calling all the builders that recommend this which is everyone dumbasses.

 

 

Cody

If you do not port you will lose your top end.

If you run the spacer plate plus drop the port floors (which almost anyone can do since these are not c critical area that you must get perfect)you gill gain in the mid-top end which is where the banshee shines.

The spacer plate adds crankcase volume which makes the engine slightly more inefficient, but the added durations will more than make up for it and that's a fact.

 

I'm not advising him to bllindly follow my advice, but with some research and planning I believe he will realize this is his best bet.

 

Your engine is good for what, 80 hp? That's with around $3,500 in work.

I would not hesitate to say the engine I decribed would be close to 65 and he will spend less than 1,000.

You could have sold your bike for say $2500, put that 3 g's in and had a 10 mill cheetah bike with all the goodies.

Please don't blindly attack me sir; I think you need to learn to use your brain a little more.

[AKheathen]

first things first- what kind of trails are you ridding? fast thrails where you can wind it up and use allot of topend, or tight, technical trails, where bottom end and smooth, precise throttle is key? like woods/mud or whatever else? as far as the carbs go, the stockkers will perform good for up to 80hp, but that is speaking strictly performance/flow......the way they were designed for the banshe is different that your average off-the-shelf mikuni vm......among other things, both good and bad, the biigest concern is moisture. not just getting them soaked with allot of water, but the smalles bit, even morning condensation, or a light mist getting in them will make them run up like you are holding it to almost 1/2 throttle, which is why they suck for trail. you can do a few tricks, like packing the cable retainers and other things with grease, and running outterware with whatever filter setup you choose. when it happens to you, though, you can just pull the choke out to make it come back down. now for the stroker and such....when it comes to a trail bike, low-mid will out perform higher powered mid-high setups in the nitty-gritty. you can have a 90hp dune/drag 4mill, but you may not find room to use it, if you know what i mean. you already have the coolhead, so it would be a matter of getting the spacer plate for a more topend orented 4mill, or cutting the domes for a more midrange torquey pull. when you come up with the funds later, you will end up with cut domes on the ported 4mill anyways. i really don't think you should feel pressured into doing the porting yourself, and for good reason. it really takes allot to port a banshee. one of the things is the willingness to accept if you fuck up your cyls and have to buy another set. also, loads of time to do the reasearch first, and more money than a port job cost in tools just to do it. we are not trying to brainwash anybody into thinking that only rocket scientists can make rockets, but more of a warning, that you are doing it as a major commitment, and for the sake of doing it, not just to save a little. now, on the otherhand, there is cookie-cutter exhaust templets to show you how to shape the exhaust, and some measurements that will let you rough out something that will make more power, but the real gains come from the guy not only sitting down to do the calculations and measurements, but being able to see and know how everything is going to flow and when and how it will all interact through every bit of the cyle. on top of that, the extensive experience to know what works, and what hurts. also, forming the transfers is a major 1-up...... well, i digress.....back to the ORIGIONAL issues.......the economy...the 4mill will suck a bit more fuel, no matter what you do, but tthe higer rpm range you tune it for, the more it is going to suck the fuel down. for that matter, the more you build it up, the more it will use. an ims oversized tank is an option, too, and it holds more than 2x the stock fuel tank..........so figure out the main focus on what you are trying to get for performance, and what budget you have to get it done.

[blowit]

What did I say in my post? A BUILDER WILL TELL YOU TO RUN NO SPACER AND PORT TO THE CRANK. This is ideal if you have unlimited funds, but if you are on a budget you can do it my way, save 250-350 bucks on a port job, and still have a MAJOR increase in power.

 

 

And blowit, I said it would be a bottom end motor due to mellowing out the durations. This is wiithout having to send the jug to a builder.

You guys have peoples minds on here warped into thinking that only a rocket scientist can port an engine.

Ii am not trying to brag simply stating a fact but I went from NEVER touching an atv engine to doing a full rebuild on a 730cc vtwin, including cams, valvesprings, new JE pistons and relieving the valve pockets on the heads as well as doing a full port and polish; all by gathering knowledge on my own and feeling comfortable about what I was doing and then going for it.

 

 

 

 

I think I might have misunderstood your post. As I said, if you are not going to touch the cylinder porting for a 4mm, you are better off adding the plate, BUT neither will preform close to optimal.

 

I certainly do not try to make porting any hidden art. However, as an aerospace engineer, I have a pretty firm understanding of air flow, structures, fluid dynamics, and math. I will admit that there are many builders that talk more than they walk but they get sorted out soon enough. Most engine builders have learned from trial and error. Very few have a formal education in performance mods. That does not mean their engines do not haul. They found what worked. Most of them found it through someone else's port work. I think that the reason you find some resistance in getting port info is most builder have put MANY hours in the learning process. That learning did not come over 30 days.

 

Personally, I have been building engines for 13 yrs. My first port job was a drag port Banshee that still runs and makes 65HP with more to go. I have never ruined a set of cylinders in my career. I never stop learning. I always say, if I knew then what I know now. This level of knowledge is cumulative and the only person that will have enough time to gather most of it from me is my son. I guess what I am getting at is trying to get all the info out on the table from a competent builder will take more than a 12 pack....

 

I think I have preached enough on this site about education. 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.

 

Even with all the knowledge, you will still go through a trial and error process. That is part of learning. If you maintain your drive to learn this stuff and read the books, you may be one of the best engine builders in the country in 10 yrs, or 3 if your port every day...

 

K, I have rattled on enough by now...

 

B

[papa_smurf49319]

If you do not port you will lose your top end.

If you run the spacer plate plus drop the port floors (which almost anyone can do since these are not c critical area that you must get perfect)you gill gain in the mid-top end which is where the banshee shines.

The spacer plate adds crankcase volume which makes the engine slightly more inefficient, but the added durations will more than make up for it and that's a fact.

 

I'm not advising him to bllindly follow my advice, but with some research and planning I believe he will realize this is his best bet.

 

Your engine is good for what, 80 hp? That's with around $3,500 in work.

I would not hesitate to say the engine I decribed would be close to 65 and he will spend less than 1,000.

You could have sold your bike for say $2500, put that 3 g's in and had a 10 mill cheetah bike with all the goodies.

Please don't blindly attack me sir; I think you need to learn to use your brain a little more.

 

Blindly attack you, i dont see how you figured that i attacked you, just giving my point of view on your post. 10mill cheetah, i dont want nor need a 10 mill cheetah, what i have is exactly what i wanted and needed for my setup. I love how your so quick to get pissed at everyone and turn defensive, even the people that help you. Ive been following all your post for quite awhile, and well im happy to see you porting your own engine, theres no need to spit your numbers out to everyone that has a question on porting and who to send there stuff to.

 

no hard feelings

 

 

Cody

[AKheathen]

If you do not port you will lose your top end.

If you run the spacer plate plus drop the port floors (which almost anyone can do since these are not c critical area that you must get perfect)you gill gain in the mid-top end which is where the banshee shines.

The spacer plate adds crankcase volume which makes the engine slightly more inefficient, but the added durations will more than make up for it and that's a fact.

 

I'm not advising him to bllindly follow my advice, but with some research and planning I believe he will realize this is his best bet.

 

Your engine is good for what, 80 hp? That's with around $3,500 in work.

I would not hesitate to say the engine I decribed would be close to 65 and he will spend less than 1,000.

You could have sold your bike for say $2500, put that 3 g's in and had a 10 mill cheetah bike with all the goodies.

Please don't blindly attack me sir; I think you need to learn to use your brain a little more.

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.

[bigblockbanshee]

first things first- what kind of trails are you ridding? fast thrails where you can wind it up and use allot of topend, or tight, technical trails, where bottom end and smooth, precise throttle is key? like woods/mud or whatever else? as far as the carbs go, the stockkers will perform good for up to 80hp, but that is speaking strictly performance/flow......the way they were designed for the banshe is different that your average off-the-shelf mikuni vm......among other things, both good and bad, the biigest concern is moisture. not just getting them soaked with allot of water, but the smalles bit, even morning condensation, or a light mist getting in them will make them run up like you are holding it to almost 1/2 throttle, which is why they suck for trail. you can do a few tricks, like packing the cable retainers and other things with grease, and running outterware with whatever filter setup you choose. when it happens to you, though, you can just pull the choke out to make it come back down. now for the stroker and such....when it comes to a trail bike, low-mid will out perform higher powered mid-high setups in the nitty-gritty. you can have a 90hp dune/drag 4mill, but you may not find room to use it, if you know what i mean. you already have the coolhead, so it would be a matter of getting the spacer plate for a more topend orented 4mill, or cutting the domes for a more midrange torquey pull. when you come up with the funds later, you will end up with cut domes on the ported 4mill anyways. i really don't think you should feel pressured into doing the porting yourself, and for good reason. it really takes allot to port a banshee. one of the things is the willingness to accept if you fuck up your cyls and have to buy another set. also, loads of time to do the reasearch first, and more money than a port job cost in tools just to do it. we are not trying to brainwash anybody into thinking that only rocket scientists can make rockets, but more of a warning, that you are doing it as a major commitment, and for the sake of doing it, not just to save a little. now, on the otherhand, there is cookie-cutter exhaust templets to show you how to shape the exhaust, and some measurements that will let you rough out something that will make more power, but the real gains come from the guy not only sitting down to do the calculations and measurements, but being able to see and know how everything is going to flow and when and how it will all interact through every bit of the cyle. on top of that, the extensive experience to know what works, and what hurts. also, forming the transfers is a major 1-up...... well, i digress.....back to the ORIGIONAL issues.......the economy...the 4mill will suck a bit more fuel, no matter what you do, but tthe higer rpm range you tune it for, the more it is going to suck the fuel down. for that matter, the more you build it up, the more it will use. an ims oversized tank is an option, too, and it holds more than 2x the stock fuel tank..........so figure out the main focus on what you are trying to get for performance, and what budget you have to get it done.

 

 

Great posts everyone. The kind of trails I ride are the low end chugging type of trails. I came from a Sportsman 700 that I had to ride around that way. I'm not the type that likes to race through the woods at the speed of light. I don't mind going fast sometimes but not all the time. I've considered an IMS or a Clarke tank and may end up getting one but for now plans are leaning towards a stock tank. Nothing with this build is set in stone though except my budget. I've been 4 years trying to piece it together and have made a lot of progress in the last month but it won't hurt to take a little longer to save money for something if I can justify the benefits of it. With the carbs, the water/moisture issue gets to me. I didn't know anything about that problem and it doesn't excite me one bit so I'll need to at least get that taken care of. I don't really have a use for 80 hp either, only if it nets me some good bottom end. I'll never be able to really "air it out" on any of the trails I ride. I'd honestly forgotten about the port timing and spacers, etc. so now I'm kinda turning away from the stroker idea unless someone can convince me that it's the way to go. The only reason I'd considered a stroker is because of the type of trails I will be riding. I suppose though that with some extra clutch and throttle the stock cc could more than compensate for the lack of stroke that the 4 mil would have. Am I treading into the right territory here? How do you eliminate the moisture issue with the carbs?

Edited April 27, 2010 by bigblockbanshee