DWMS RACING CB550F SUPER REVERSE PORT! NEW ENGINE COLORS AND PHOTOS!

[joeyputt]

Re: DWMS RACING CB550F SUPER REVERSE PORT! NEW PHOTO!

Brother Swagger most cam cards will not show it but this one does. See on the intake side at the bottom where it says EZ - START 51.5 ABDC and EZ - STOP 85 ABDC, this is the range on a degree wheel where the intake valve is open during the compression stroke, so with this particular cam the intake valve would be open for 33.5 degrees during the compression stroke.

 

[Swagger]

Re: DWMS RACING CB550F SUPER REVERSE PORT! NEW PHOTO!

So it's a built up portion of the base circle then....correct?
Interesting.

 

[joeyputt]

Re: DWMS RACING CB550F SUPER REVERSE PORT! NEW PHOTO!

So it's a built up portion of the base circle then....correct?
Interesting.

Yes, and if you file it off the intake will close completely and the piston will build compression full stroke, most all engines have it yet almost no one knows about it.

 

[Swagger]

Re: DWMS RACING CB550F SUPER REVERSE PORT! NEW PHOTO!

I imagine one would want to pay pretty close attention as anything over what.....270psi is pretty rough on air cooled cylinders. IIRC my autocrosser is close to 300psi but it's a water cooled car engine with nice thick liners.

Thanks for the heads up Joey, I'll have to delve deeper into this.
Any ideas how much extra compression one will gain? Different for different engines?

 

[joeyputt]

Re: DWMS RACING CB550F SUPER REVERSE PORT! NEW PHOTO!

I imagine one would want to pay pretty close attention as anything over what.....270psi is pretty rough on air cooled cylinders. IIRC my autocrosser is close to 300psi but it's a water cooled car engine with nice thick liners.

Thanks for the heads up Joey, I'll have to delve deeper into this.
Any ideas how much extra compression one will gain? Different for different engines?

Yes different engines will vary but it is a lot of compression, If you take the whole ramp off you will barely be able to turn the engine over and most of the time you will not be able to use the stock electric start.

 

[tWistedWheelz]

Re: DWMS RACING CB550F SUPER REVERSE PORT! NEW PHOTO!

WOW, I just learned something that I was completely oblivious too prior to reading this, you two cats just made my night! Cheers gentlemen!

 

[joeyputt]

Re: DWMS RACING CB550F SUPER REVERSE PORT! NEW PHOTO!

WOW, I just learned something that I was completely oblivious too prior to reading this, you two cats just made my night! Cheers gentlemen!

Brother Twisted you know I am full of all kinds of useless knowledge! Hahahaha!

Seriously though almost no one knows about this, it was taught to me by the greatest man I have ever known or even heard of, my Father.

 

[joeyputt]

Re: DWMS RACING CB550F SUPER REVERSE PORT! NEW PHOTO!

Brother revheadgl there are lots of little racing mysteries out there!

 

[FunJimmy]

Re: DWMS RACING CB550F SUPER REVERSE PORT! NEW PHOTO!

Brother Joey

This is very interesting stuff and I appreciate you posting it for all of us to learn from. You mention that most all stock cams have that EZ Start ramp and most performance cams do not. Do you know it the WebCam profiles have this limitation or not?

BTW, could you post the stock 550 cams specs?

Thanks again.
FJ

 

[joeyputt]

Re: DWMS RACING CB550F SUPER REVERSE PORT! NEW PHOTO!

Brother Joey

This is very interesting stuff and I appreciate you posting it for all of us to learn from. You mention that most all stock cams have that EZ Start ramp and most performance cams do not. Do you know it the WebCam profiles have this limitation or not?

BTW, could you post the stock 550 cams specs?

Thanks again.
FJ

Brother FunJimmy most performance cams will not have it or it will be partially removed depending on the application of the particular engine and camshaft. I am not sure what the webcam has but for a street engine, if it has it, you would not want to totally remove it as it would normally be too much compression. Do you have the cam card for your webcam or a degree wheel and a lift type micrometer so that you can read the numbers off of it?

I can post the stock cam specs for you but the readings would be directly off of the cam not off of the rockers.

 

[teazer]

Re: DWMS RACING CB550F SUPER REVERSE PORT! NEW PHOTO!

OK guys settle down. Is it April 1 already?

That must be it. It's all a joke. Yes??? If not I want some of whatever you are smoking.

What on earth are we talking about with ez start lift on intake cams changing compression and all sorts of mumbo jumbo.

Cams have what is known as a Closing ramp. They also have an opening ramp. The closing ramp is there to allow the valve to slide gracefully to a halt rather than banging down on the seat. I have plotted lift curves on dozens of motorcycle cams - stock and race and all things in between and none of them has any weird EZ start ramps.

I have even gone as far as to plot valve speed and acceleration rates and calculated rate of change in acceleration aka Jerk trying to understand why one particular cam grind was so hard on valve stems.

Let's talk about the compression effect for a moment. The average intake valve closes somewhere around say 60-80 degrees after BDC. We tend to think that a valve closes at BDC and then the gas gets compressed, but in reality, the intake flow is still moving in and you get better cylinder filling and a higher effective compression ratio at running speed. Race cams frequently do not fully close until 90 degrees ABDC/90 BTDC.

For example Honda CB77 stock cam closes at around 30 degrees ABDC, the Race kit cam at 38 ABDC. Our race cams close at 80 and 92 ABDC from one cam grinder and 63 ABDC the way we run the current hot high lift cam. With that cam it's a PIA to start on rollers because the head and barrels are milled to get that 13.5:1 CR for alky.

One might rationalize that if the intake valve closed earlier the CR would be higher but in the real world it would be lower. In simple terms, the higher an engine revs, the longer the valve has to stay open (within reason) so for a slow revving motor it's desirable to close the valve earlier.

It's all about gas flow and pressure waves. I'd love to get a Cam Doctor and associated software. For now I'll plot every few degrees and input that to spreadsheets to do the analysis. It's slower and cheaper.

 

[teazer]

Re: DWMS RACING CB550F SUPER REVERSE PORT! NEW PHOTO!

Brother Swagger most cam cards will not show it but this one does. See on the intake side at the bottom where it says EZ - START 51.5 ABDC and EZ - STOP 85 ABDC, this is the range on a degree wheel where the intake valve is open during the compression stroke, so with this particular cam the intake valve would be open for 33.5 degrees during the compression stroke.

Not exactly. That cam card says that the intake closes at 76 BTDC that's 76 degrees before top dead or 19 degrees AFTER that EZ B/S figure.

EZ start is available in some HD cams and it is a hydraulic cam that actuates when starting to keep the valve much more open that it would normally be. That's what you are looking at. It's not part of the stock cam profile.

Come on guys. Stay awake. This isn't rocket science. Then again, neither is most rocket science.

 

[teazer]

Re: DWMS RACING CB550F SUPER REVERSE PORT! NEW PHOTO!

I imagine one would want to pay pretty close attention as anything over what.....270psi is pretty rough on air cooled cylinders. IIRC my autocrosser is close to 300psi but it's a water cooled car engine with nice thick liners.

Thanks for the heads up Joey, I'll have to delve deeper into this.
Any ideas how much extra compression one will gain? Different for different engines?

Swagger - to what are we making reference here?

Engine cranking compression or What? I missed the reference and didn't see where those numbers were coming from.

Cold cranking will be in the 120-150psi range as a rule. Much more than that on street gas would be a problem.

 

[joeyputt]

Re: DWMS RACING CB550F SUPER REVERSE PORT! NEW PHOTO!

I am going to have to take a moment before I respond to this...

 

[teazer]

Re: DWMS RACING CB550F SUPER REVERSE PORT! NEW PHOTO!

That's OK Joey. I have been messing with this crap for decades. Those EZ start cams were a new one to me though, so I did some research and that's what I found.

The oldest book I have on cam design came out of Iskendariam when the old man wasn't so old. That book is probably 30 or 40 years old. I learn something new every day and those S&S EZ cams were just one thing I learned today.

 

[Swagger]

Re: DWMS RACING CB550F SUPER REVERSE PORT! NEW PHOTO!

Teazer, that would be me attempting to thumb-type on this phone. Should read 200 and 170psi.

I gotta be honest Teazer, I'm getting pretty tired of the holier than thou condescending tone evidenced in most of your posts. You may be Joey Chitwood and Carol Shelby rolled into one chocolate treat, but frankly being talked down to, even by the elderly pisses me off.

edited for enhanced civility

 

[joeyputt]

Re: DWMS RACING CB550F SUPER REVERSE PORT! NEW PHOTO!

Teazer I see what happened you searched ez spin and the s&s cams came up however this is not at all what I am referancing...almost all camshafts have an easy spin ground into the lobe or a centrifugal half moon pivot which opens the intake valve slightly again before top dead center to release compression, this is where the ez spin start and end are on the cam card I showed.

Almost all motorcycles, atv's, even lawnmowers and tillers have them so I am unsure as to how you have never heard of them if you have been studying camshafts for decades, they are actually very old technology and have been around for over fifty years that I know of.

It is very disappointing that you would write the replies that you did simply because you are unfamiliar with something and did a quick search.

 

[teazer]

Re: DWMS RACING CB550F SUPER REVERSE PORT! NEW PHOTO!

Teazer, that would be me attempting to thumb-type on this phone. Should read 200 and 170psi.

I gotta be honest Teazer, I'm getting pretty tired of the holier than thou condescending tone evidenced in most of your posts. You may be Joey Chitwood and Carol Shelby rolled into one chocolate treat, but frankly being talked down to, even by the elderly pisses me off.

edited for enhanced civility

Swagger,

No worries. That makes more sense now.

As to your comments, I assure you that I am neither of the above and I'm really not trying to be condescending though it may come over that way sometimes. I just don't have the same chatty communication style. When I try to be lighthearted and funny it does tend to come across all wrong, so maybe I should avoid that.

 

[teazer]

Re: DWMS RACING CB550F SUPER REVERSE PORT! NEW PHOTO!

Teazer I see what happened you searched ez spin and the s&s cams came up however this is not at all what I am referancing...almost all camshafts have an easy spin ground into the lobe or a centrifugal half moon pivot which opens the intake valve slightly again before top dead center to release compression, this is where the ez spin start and end are on the cam card I showed.

Almost all motorcycles, atv's, even lawnmowers and tillers have them so I am unsure as to how you have never heard of them if you have been studying camshafts for decades, they are actually very old technology and have been around for over fifty years that I know of.

It is very disappointing that you would write the replies that you did simply because you are unfamiliar with something and did a quick search.

Joey, let me try that again.

I thought that card said EZ Start which is a starting hydraulic cam technology. If I understand you correctly, you are referring to the EZ-Spin on a Briggs cam. EZ spin is a B/S feature where the valve lift is temporarily held at the same lift for 30 degrees on the closing ramp and is then allowed to finish closing. It would be circular at that point and would appear as a slight bump in the closing ramp.

* Easy-Spin Starting - This was introduced in 1961 as a means of cutting in half the effort of manually starting an engine. This had replaced all means of starting on all B&S engines except for electric start systems.[6]

But in 1982, as new U.S. federal safety regulations required every small engine manufacturer to add emergency shut-off switches to lawn mower applications, company engineers discovered that engines with the Easy-Spin intake were unacceptably difficult to restart. The Easy-Spin was moved to the exhaust valve, but this move presented mediocre power output. Where that was an issue, a mechanical compression release was used. The intake valve Easy-Spin had continued to be used on B&S's larger engines, but was then shelved in 1997 due to new emission regulations.

Most motorcycle cams that I have looked at do NOT have that feature. It was a B/S feature which is probably why you are familiar with it. AFAIK no other manufacturer used it and no motorcycles use it.

P.S. when I say B/S I mean Briggs and Stratton , not the more colloquial expression.

 

[teazer]

Re: DWMS RACING CB550F SUPER REVERSE PORT! NEW PHOTO!

That explains something to me. A few years back we sponsored a rider in the 600cc class, we got partial factory support for him. Speaking to the factory team boss, I asked him about whether we should grind the base circle of the cam. I got a very guarded "that would be a good place to start". I couldnt get any more out of him on the matter.............

The simplest way to get more lift and duration is to grind the base circle. Superstock rules are usually very tight on cam lift but less so on duration so if you grind the base to get more duration, then the rest of the cam including the nose also has to be ground to get a new cam shape with more duration and the same lift.

Might have been what he was careful to avoid saying out loud.