Spacer plates cranks and port timings

[hercalmighty]

Slo. If your doing a long rod 4mil you need new pistons. You can't use the stockers. No, I don't think you need a whole new topend every time you pull the topend. But usally if I'm pulling the cylinders I'm doing the topend.

As far as the math, have you read any porting books? Once again its not just lowering or raising a port a little. To get the most out a motor you do need to find the optimum port timing and angles.

You keep talking about the port roof angles but that's only a fraction of making a motor run good. You have to angle the ports back to the correct dimensions to make sure the mixture isn't going right out your exhaust.

As far as the money goes I saying for a guy sending out just the cylinders to get ported and doing all the disassemble and assemble yourself. So that cuts out a lot of money. My 4mil dune port cost me 700 from HJR with a new topend and bore.

[SLORYDER]

Slo. If your doing a long rod 4mil you need new pistons. You can't use the stockers. No, I don't think you need a whole new topend every time you pull the topend. But usally if I'm pulling the cylinders I'm doing the topend.

As far as the math, have you read any porting books? Once again its not just lowering or raising a port a little. To get the most out a motor you do need to find the optimum port timing and angles.

You keep talking about the port roof angles but that's only a fraction of making a motor run good. You have to angle the ports back to the correct dimensions to make sure the mixture isn't going right out your exhaust.

As far as the money goes I saying for a guy sending out just the cylinders to get ported and doing all the disassemble and assemble yourself. So that cuts out a lot of money. My 4mil dune port cost me 700 from HJR with a new topend and bore.

 

Maybe you're so persistent on defending the builders is the fact that you already shelled out the money for yours.

 

I'll admit, most people would rather send their cyls off to get ported because of the ease and peace of mind of it all.

 

And yes, I've read jennings book and bells book several times each.

 

You speak of these discharge angles as something that must be altered to keep the charge in the cylinder...

I can assure you that the stock angles are sufficient, UNLESS you widen the exhaust or main transfers too much toward each other. This is why many builders go wide w/ the exhaust port above the main transfers (smiley face port).

Other than that, you are changing the roof angles to a more flat angle to allow for more port area.

I'm sure some of the seasoned builders have their little secrets of changing an angle here and there to get a few more hp, but this takes serious time. It's that last 10-20% that makes the builders experience worthwhile.

 

 

On a 4 mill build, (other than full drag)80% of your gains will be in the exhaust port. The rest will be intakes transfer runners and maybe a little on the port roof, as well as widening.

On a stock stroke build, you have to work the transfers more, UNLESS you know a shortcut, aka raise the cylinder.

I wouldn't suggest going more that a .060" base gasket, because you won't be able to get your squish anywhere near optimum.

If you are doing a stock stroke and you want to go ore radical then that, then you might want to call a builder unless you are comfortable cutting your pistons.

[hercalmighty]

It has nothing to do with defending the builders. Like I said earlier, I have been doing some research on porting so I can do it myself. When I had my porting done I wasn't as familiar with all the durations nor the tools to do the best job I could. So at the time it was better to send my topend off to get it ported. I'm going to tackle my 125 cylinder myself and see what I get.

[SLORYDER]

It has nothing to do with defending the builders. Like I said earlier, I have been doing some research on porting so I can do it myself. When I had my porting done I wasn't as familiar with all the durations nor the tools to do the best job I could. So at the time it was better to send my topend off to get it ported. I'm going to tackle my 125 cylinder myself and see what I get.

I highly recommend you subscribe here for assistance in your build

http://www.macdizzy.com/forums/index.php

I am gonna port my blaster jug (stock pipe).

I thought about porting my go kart but it is too fast already lol.

I might just bump the compression to get some more grunt.

[dirtjumper]

I have a question what should i do all mine is on the top i have 4+5 and the spacer was on top then i had domes cut to take place of spacer. I have about 65 horse at the back wheels with no porting at all with only 185 psi on compression. what kind of porting will i need

[SLORYDER]

I have a question what should i do all mine is on the top i have 4+5 and the spacer was on top then i had domes cut to take place of spacer. I have about 65 horse at the back wheels with no porting at all with only 185 psi on compression. what kind of porting will i need

 

First you need to print out a degree wheel and degree your cylinders.

 

You will be raising your exhaust port and widening it, to what extent depends on your riding style.

 

You will also need to lower your ports to be even with the timing edge of your piston at bdc.

 

Raising and widening your intake ports will also be needed to take full advantage of the port work, as well as opening up the transfer runers, being careful not to touch the roofs, then blend in your cuts.

You have to try to understand how the air flows through there, where the restrictions are and alleviate them, realizing if everything is not smooth you are cutting for nothing.

 

You should not have to worry about raising the transfers unless you are going for a full drag build.

Edited June 26, 2010 by SLORYDER

[AKheathen]

just to clarify- you don't want polished intake/transfers, just exhaust. what porting will depend on what you want, and are setup for.

[firebanshee]

I have a question what should i do all mine is on the top i have 4+5 and the spacer was on top then i had domes cut to take place of spacer. I have about 65 horse at the back wheels with no porting at all with only 185 psi on compression. what kind of porting will i need

What kind of riding do you want to do?185 is the perfect amount of compression in my book,you will need to run race fuel or methanol with that compression.You also have your motor ported to the pipes you are running and the carbs you are running.

[AKheathen]

oh, and i also have some info you might be interested in- the long rod and short rod cranks will change the port timings quite a bit too, because of dwell time. i don't remember exact timing off the top of my head, but i do know that the transfer time is increased with the short/stock rod on a 4mill, and basically, the minimum rpm biased porting is higher than long rod. i was also looking at some stock transfers, and they can definately use some cleaning up on the top side, but not necisarily getting into the roof, just at the sleeve, where you can feel a step-down. it can be done with an egg-bit on the strait tool, if you are interested in playing there.

[SLORYDER]

oh, and i also have some info you might be interested in- the long rod and short rod cranks will change the port timings quite a bit too, because of dwell time. i don't remember exact timing off the top of my head, but i do know that the transfer time is increased with the short/stock rod on a 4mill, and basically, the minimum rpm biased porting is higher than long rod. i was also looking at some stock transfers, and they can definately use some cleaning up on the top side, but not necisarily getting into the roof, just at the sleeve, where you can feel a step-down. it can be done with an egg-bit on the strait tool, if you are interested in playing there.

 

Yeah the long rod mellows out the powerband, gives you more bottom end.

[SLORYDER]

Anyone want to post their experience as far as stock transfer timing?

[donkeypuncher]

Note that obtaining these durations using a spacer would obviously not yield the same hp numbers as if you had it ported properly; however the "bang for your buck" factor would be high.

 

 

if using a spacer plate means you dont get the same amount of hp as you would without, i would think using your stock crank and a $300 port job would be a better bang for your buck then buying a 4 mill crank ($450 ish). a good port job should be able to get you around 60+ hp depending on other mods and type of port. maybe im wrong?

[SLORYDER]

if using a spacer plate means you dont get the same amount of hp as you would without, i would think using your stock crank and a $300 port job would be a better bang for your buck then buying a 4 mill crank ($450 ish). a good port job should be able to get you around 60+ hp depending on other mods and type of port. maybe im wrong?

 

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.

[donkeypuncher]

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.

 

 

how come when you have a builder doing the work you throw in a cool head and v-force reeds? if you are gonna use a shaved head and boysen reeds in one scenario then you should use the same in the other.

 

so how about:

 

builder- shaved head, dune port, boysen reeds 60+hp and about $450-$500.

your way- 55 hp and $120 plus a 4mill cranks so......$570? (

 

 

im not tryin to knock you for doin the work yourself, which i truthfully think is pretty cool. i just dont agree that this set up has all that great of a bang for buck. is it a more cost effective way to run a 4 mill crank? yes. does it provide a better bang for your buck? compared to another 4mill maybe, but compared to a ported stock stroke bike, no. personally i would rather send my cylinders off to have them ported correctly to run without a spacer plate and get 75+ hp then run a spacer plate then have a 4mill that has the same amount of hp (maybe less) as a stock stroke bike with ported cylinders. but maybe thats just me.

[Pasi S.]

i don't really agree with pasi in the statement that you should do buisiness with a sponsor to have the right to use the site, but i understand drunken posts,lol.

 

LOL! Don´t take my statements too seriously. It´s my bad english that can make more detonation than my actual thoughts.

My intend was -> It´s awesome that this site is free for us. It´s awesome that we have great builders and/or site sponsors and other professionals that can help me with my Banshee problems.

 

I´m in that 90% with my wet ears! So I just love to read and learn more about Banshees. LOL!

 

-Pasi S.