Spacer plates cranks and port timings

[AKheathen]

you know- if you would stop thinking of porting as "mellow" or "radical" it would open a whole new world of understanding. and, when you subtract the cost of a coolhead and vforce reeds from the builder cost, it really changes things. porting is between 3-4 usually, so 120 to try yourself, 3-4 to have it done right, and most likely 2-5 to fix botched cyls with limited option, probably just drag port, if they can. not to mention, a slip into the cyls could mean need for a $100 bore job, and new piston/rings to match. and, the builder will factor bore/hone with the port

[bode1]

Why even send the head out to get milled? Can't the same be accomplished with a piece of sandpaper and a little time. Why send that to someone who knows how to do it and has the correct tools and expertise. I think the reason most people send their stuff to builders is their experiance. I know I want to put my shit together one time and be pretty close on the setup. Builders have through trial and error learned what works and doesn't, so I'd be more inclined to get some info from Brandon or one of the other builders than from a guy who is learning and and still going through his trial and error process., and they seem willing to give you advice, but you keep getting defensive. And most of what you are stating are your opinions, find someone on here with a similar setup done by a builder, and race them. You get what you pay for. But I guess I'm another mindless drone. Why don't you be a sponsor than you can do my 4mil?

[mikechief]

IF You have a dremel and you were on a budget:

 

You could buy a .060" base gasket and run it in place of your stocker. You lower your port floors, widen your exhaust and raise it, at the same time cleaning up whatever you can access with your straight bits.

 

Bring your exhaust up to give you about 33-34bd.

This would be roughly equivalent to a dune port.

Shave your head a total of .065". Port reed cages and run boysen reeds

 

Builder-cool head dune port vforce reeds shipping 60hp and about $800

 

My way-55hp and $120.

 

That's with a stock crank ? 33-34 bd ? Motion pro has a degree wheel it's advertised for 4stroke. Same shit ? There's is something about building a race winning engine vs buying one

[bode1]

That's with a stock crank ? 33-34 bd ? Motion pro has a degree wheel it's advertised for 4stroke. Same shit ? There's is something about building a race winning engine vs buying one

 

 

I agree with that statement, but even having it ported by a builder, you still aren't done. Your whole setup has alot to do with it, unless you send your whole motor to builder, and even than there are still a lot of variables I'd say

[SLORYDER]

Why even send the head out to get milled? Can't the same be accomplished with a piece of sandpaper and a little time. Why send that to someone who knows how to do it and has the correct tools and expertise. I think the reason most people send their stuff to builders is their experiance. I know I want to put my shit together one time and be pretty close on the setup. Builders have through trial and error learned what works and doesn't, so I'd be more inclined to get some info from Brandon or one of the other builders than from a guy who is learning and and still going through his trial and error process., and they seem willing to give you advice, but you keep getting defensive. And most of what you are stating are your opinions, find someone on here with a similar setup done by a builder, and race them. You get what you pay for. But I guess I'm another mindless drone. Why don't you be a sponsor than you can do my 4mil?

 

 

Simple facts

 

1. If you make the exhaust port bigger it will make more power. The bigger the more power bottom line.

 

2. If you are moving gasses out of the engine at a higher rate you need to be letting it in at a higher rate. The transfers are the first bottleneck in the banshee engine. You need to increase the size of the windows and the runners. The runners can be done with a long bit and you have to be sure not to touch the roofs and blend in the cuts.

The windows are tricky. This is why people send theirs to a builder. You can easily screw up the jugs if you cut the sides or roofs of the ports. Buuuuuuuuuuuuuuuuuut the floors are a different story. Raising the cylinder and lowering the floors is foolproof.

 

3. Your next bottleneck is the intake. Open up the intake windows, port the reed cages and add boysen reeds.

 

4. Next handicap is the compression. Shave .020" or .060" if you ran a thicker base gasket.

 

Just doing these things will get you a solid 15hp on a piped engine. If you open your exhaust port more you can prolly get 20hp, but will have to change your rings every 30-50 hours.

 

If you wanted to do a budget drag engine w/ drag pipes, you could run a .080" base gasket on top of the stock one or a .100" if you can find it or any combination.

 

You would then lower your ports 2mm, raise your exhaust port to 34bd and widen it out to 72-75% of bore width using a 1/2" radius on the corners and a 2mm crown on the top. Put a generous chamfer around the whole port, especially at the top and bottom.

open your transfer runners, raise your intake to 70mm from deck and lower it by 2-4mm. Drill boysen ports, widen your boost port, but leave at least 1.5mm clearance from the ring ends. Narrow the intake bridge to 5mm.

 

Port your reed cages, add boysen reeds.

Deck your cylinders. You will need to determine what fuel you wnat to run and determine how much to mill for the right uccr. I can tell you that a safe amount to mill at this stage using the .080" gasket plus the stock .020" gasket is .110" for race fuel, you can probably get away with 50/50 race fuel/ premium unleaded.

Make sure you check the squish before the milling; there should be .150" or more of squish. If it is less than that say by .005", you should only mill .105" ect.

You want at least .035" squish when you are done.

Always check for signs of detonation when done, just to be safe; however I believe if you follow these directions you should definately be in the clear if you run race fuel. Prolly get away with 50/50.

 

Mod your timing plate to +4

 

These recommmendations are somewhat conservative and your rings should last 20 or more hours at this stage. I'd say with cpi pipes and stock carbs you should be at 62-65hp. 34mm carbs closer to 70

 

 

THAT is the best bang for your buck.

[Larry's Shee]

Unless Jennings had a second edition , he recomended NOT going more than 70% of bore for exhaust port width. More isn't always better. I think the ring life would be a lot less than your hour estimate.

[AKheathen]

omg, i'm trying to be constructive, really, i would like to, but the only thing i can't get out of my head tonight, is "i really hope nobody listensto this shit, and sells that motor to someone else......" oh, and 20 hours should be a damn near brand new topend. you know they say repitition is the best way to remember something is through repetition, so i'm gonna re-impress a couple things. time-area is more important to look at at all stages of port opening, rather than the hog-out=power mentality. also- not touching the roofs leaves a real messy opening, sleeve ridge, and all around poor flow well worth the attention.

[mopar1rules]

i'm sure that the roof angles and the rear "hook" on the secondary transfers, could be improved upon, especially for a drag port.

[SLORYDER]

Unless Jennings had a second edition , he recomended NOT going more than 70% of bore for exhaust port width. More isn't always better. I think the ring life would be a lot less than your hour estimate.

 

There have been many advancements in ring materials since jennings book.

 

IF you radius and bevel your port right your rings well last.

I spoke to the owner of cp industries awhile back about spcs on his blaster pipe; he says his blaster runs a 75% exhaust port and his rings last 30 hours or so before they need changing.

 

 

omg, i'm trying to be constructive, really, i would like to, but the only thing i can't get out of my head tonight, is "i really hope nobody listensto this shit, and sells that motor to someone else......" oh, and 20 hours should be a damn near brand new topend. you know they say repitition is the best way to remember something is through repetition, so i'm gonna re-impress a couple things. time-area is more important to look at at all stages of port opening, rather than the hog-out=power mentality. also- not touching the roofs leaves a real messy opening, sleeve ridge, and all around poor flow well worth the attention.

 

Well I think anyone with sense enough to tackle a job like this on their own would have the presence of mind to explain to the buyer the specs of the engine.

 

I agree that the way I described is not 100% efficient. Some people may rather 15 free hp over 25hp at a cost of $350

 

And I guarantee that the ultra high performance drag engines rings do not last 20 hours.

 

 

 

 

 

i'm sure that the roof angles and the rear "hook" on the secondary transfers, could be improved upon, especially for a drag port.

 

I agree that there is a considerable amount of power to be had from grinding on the port roofs and vertical walls; this is something for someone with advanced skills.

Edited July 5, 2010 by SLORYDER

[SLORYDER]

Sorry I can't edit my last post it was the owner of CPI (custom pipes) that gave me the porting specs for the blaster, not Calvin Pollet

[knjlexus]

Thats funny because I just degreed my 4 mill with a .02 gasket and got 90/120. I am in the middle of my build doing research when I came across these said numbers?

 

[PassionRE]

Simple facts

1. If you make the exhaust port bigger it will make more power. The bigger the more power bottom line.

2. If you are moving gasses out of the engine at a higher rate you need to be letting it in at a higher rate. The transfers are the first bottleneck in the banshee engine. You need to increase the size of the windows and the runners. The runners can be done with a long bit and you have to be sure not to touch the roofs and blend in the cuts.
The windows are tricky. This is why people send theirs to a builder. You can easily screw up the jugs if you cut the sides or roofs of the ports. Buuuuuuuuuuuuuuuuuut the floors are a different story. Raising the cylinder and lowering the floors is foolproof.

3. Your next bottleneck is the intake. Open up the intake windows, port the reed cages and add boysen reeds.

4. Next handicap is the compression. Shave .020" or .060" if you ran a thicker base gasket.

Just doing these things will get you a solid 15hp on a piped engine. If you open your exhaust port more you can prolly get 20hp, but will have to change your rings every 30-50 hours.

If you wanted to do a budget drag engine w/ drag pipes, you could run a .080" base gasket on top of the stock one or a .100" if you can find it or any combination.

You would then lower your ports 2mm, raise your exhaust port to 34bd and widen it out to 72-75% of bore width using a 1/2" radius on the corners and a 2mm crown on the top. Put a generous chamfer around the whole port, especially at the top and bottom.
open your transfer runners, raise your intake to 70mm from deck and lower it by 2-4mm. Drill boysen ports, widen your boost port, but leave at least 1.5mm clearance from the ring ends. Narrow the intake bridge to 5mm.

Port your reed cages, add boysen reeds.
Deck your cylinders. You will need to determine what fuel you wnat to run and determine how much to mill for the right uccr. I can tell you that a safe amount to mill at this stage using the .080" gasket plus the stock .020" gasket is .110" for race fuel, you can probably get away with 50/50 race fuel/ premium unleaded.
Make sure you check the squish before the milling; there should be .150" or more of squish. If it is less than that say by .005", you should only mill .105" ect.
You want at least .035" squish when you are done.
Always check for signs of detonation when done, just to be safe; however I believe if you follow these directions you should definately be in the clear if you run race fuel. Prolly get away with 50/50.

Mod your timing plate to +4

These recommmendations are somewhat conservative and your rings should last 20 or more hours at this stage. I'd say with cpi pipes and stock carbs you should be at 62-65hp. 34mm carbs closer to 70


THAT is the best bang for your buck.

 

 

 

 

 

Just for grins, I ran a complete data analysis on this build format, and these are my findings.

 

Keed in mind this is your "average" Banshee cylinder. they vary somewhat in casting accuracy and amounts of casting slag.

 

With proposed ex. area the peak efficiency of ex ports will be right at 9500 rpm... but transfers wont reach peak efficiency untill 11325. This is widening the rear boost port 1.5mm not sure what you had in mind,but it's a good number. This mismatch isn't the end of the world but the engine will be a little slow to build heat, so heavier riders are going to suffer in acceleration and big drag coefficient enviroments are going to tax performance substantially.

Also, the mismatch would NOT like updraft porting, especially near the port roofs of the transfers. Opening up the first 10mm of entrance would be a good idea, but nothing past that on this format. The goal on any updraft is "ever increasing velocity"...so the further you go into the updraft section, the worse things are going to get at this level of tune(BMEP) rating. The stock updrafts will support the BMEP level of this engine with only minor modifications to the very first portions of entry on the updraft.

 

 All in all, the engine will have pretty decent midrange and respectable top-end ...CPI would be a good choice to help combat the port rpm match defficiency, but will absolutely hate the head mod proposal(read below)... 34mm carbs would be needed to match intake velocity for this level of Time/Area.  It would be a decent trail engine in short.

 

 

Combustion characteristics of proposed head mods are a mathematical disaster.. With this suggested modification to the head, Squish velocity's are going to be in excess of 200% of maximum limits. Flame speed is going to be 41% higher than target goals on this engine. Cylinder pressures are off  20% as well ,so your giving up hp due to that format. These issues will cause major upper mid-range power losses and over-all performance of the engine will be way down compared to where it could have been. Compression ratio, squish velocity, squish clearance, and timing specifications will all have to be altered from proposed build to balance combustion characteristics.

 

 

This is not a bash, just the facts. Many are looking for good information on these engines...here you go...Jim

[BANSHEE HP]

what or who are you babbling about?

[nmdesertbansheeryder]

Great info,thanks for sharing jim

[BigRed350x]

Pretty nice of the dude to take the few min and run the numbers for everyone. We can all learn from stuff like this, and its much appreciated any time someone is willing to share knowledge or expertise like this. Thanks jim.

 

Jared