Cams 254deg

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StormyRob
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Cams 254deg

Post by StormyRob »

Right

Excuse my lack of knowledge here. If I found a set of cams which had been reprofiled so they were all 254 deg as opposed to stock 245.....should I buy them? No other details known unfortunately but lets say they are cheap.

I was trying to understand how it would affect the bike if at all by comparing to the numbers for yoshi and mori as well as kent cams but I just dont know enough about it
If you don't try you never know if you can do it.
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8541Hawk
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Re: Cams 254deg

Post by 8541Hawk »

About the only thing you can take from this info is that they stay open a bit longer.
Without any lift numbers its hard to tell much more about what you would be getting.

With that here is a pretty good write up (or at least better than I can do with the explanation) of what changing the duration will do for you:

http://www.hughesengines.com/TechArticl ... ngacam.php

:thumbup:
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tony.mon
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Re: Cams 254deg

Post by tony.mon »

One of the common ways to increase duration is to lower the base circle, which simply leaves more "meat" to reproduce.
You can get longer duration as well as a lift height gain.
However the clearance gap becomes larger and requires thicker shins, which also adds weight to the valve assembly.
This unsprung weight is what causes the rev limit, "valve bounce" is the term used to describe uncontrolled movement as opposed to opening and closing controlled by the spring or springs.

You would be alright with a reprofiled cam using the standard springs.

See if you can find out what they have done to get the increase.
They will either have had the base circle group d down, in which case ask if they have been rehardened, or alternatively they might have welded a small amount of material onto the standard ramps and reground it.
The only other possibility is that they have used a new blank, but I'd also want to know if that was the case why they haven't also increased lift and lobe height.

I had some reprofiled by a local cam company.
They were cheap enough, but that was because they were not rehardened after grinding.
The hardness is usually only on the cam surface, because hardening the whole cam would make it too brittle.
So mine worked well but after a year I remeasured and found that the lift had worn down to little more than standard.

Hope this helps.
It's not falling off, it's an upgrade opportunity.
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StormyRob
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Re: Cams 254deg

Post by StormyRob »

Thanks guys both comments help. Unfortunately he dies not seem to know much about them at all. Asker if he can ask the guy that did it and for some reason he can't. He certainly wouldnt know if they were hardened
If you don't try you never know if you can do it.
tony.mon
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Re: Cams 254deg

Post by tony.mon »

When Benny Hedges died I was in the process of buying a set of high lift cams from him.
I had sent the money a couple of days before he had his accident... but then he had his accident and they didn't arrive so he hadn't posted them, as far as I can tell.

The people that helped clear up his garage and effects didn't find them.

It's possible that this might be that set resurfacing.
It certainly seems odd that a person selling them can't tell you anything about them.
It's not falling off, it's an upgrade opportunity.
Roger Ditchfield
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Re: Cams 254deg

Post by Roger Ditchfield »

I know of no cams using 254/254, The nearest are Moriwaki ST1 cams at 255/249 measured at 1mm lift.
How reliable is the information you have been given?
If these cams are Moriwaki's then you have a decent street cam set.
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VTRDark
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Re: Cams 254deg

Post by VTRDark »

You have Lift, Duration and Seperation to take into consideration. You need more info and it's amazing how complicated a simple egg shape can be. Just look at the elliptical paths of the planets and how they interact with each other and involves a lot of mathmatical equations.

http://www.lunatipower.com/Tech/Cams/CamSpecTerms.aspx

http://www.compcams.com/Pages/413/cam-t ... angle.aspx

It's actually quite difficult to get reliable info online and something else to take into consideration which confuses things is how the numbers are measured as different manufacturers / builders use diffrent methods and scales of measurment to confuse folk so they can't be copied. It's like they use some form of cryptograpghy and basically make things up that have to be converted but they are the only ones that have the key. So the reality of it is that you could have two cams from two different manufacturers that give the same specs. But when you pysically have them in your hand and take measuremnets there are differences.

There's some some seriously closely guarded secrets amongst cam manufacturers. They keep secrets as well as British intelligence or F1 teams all in the name of keeping their profiles secret so they can't be copied by another manufacturer. A good industry for bit of industrial espionage. A good comparrison would be like trying to measure 180 Keihin main jet versus a Dynojet 180 main.

Do your research because it's not as simple as buying some cam's, sticking them in and off you go.

For some seriously headbanging sh1t see the following pdf :eek2
Cam Design Handbook
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StormyRob
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Re: Cams 254deg

Post by StormyRob »

tony.mon wrote: Mon Jul 02, 2018 7:19 pm When Benny Hedges died I was in the process of buying a set of high lift cams from him.
I had sent the money a couple of days before he had his accident... but then he had his accident and they didn't arrive so he hadn't posted them, as far as I can tell.

The people that helped clear up his garage and effects didn't find them.

It's possible that this might be that set resurfacing.
It certainly seems odd that a person selling them can't tell you anything about them.
The fella is in greece and actually had them done. I find it strange he can't find out more.
If you don't try you never know if you can do it.
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StormyRob
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Re: Cams 254deg

Post by StormyRob »

Roger Ditchfield wrote: Mon Jul 02, 2018 7:24 pm I know of no cams using 254/254, The nearest are Moriwaki ST1 cams at 255/249 measured at 1mm lift.
How reliable is the information you have been given?
If these cams are Moriwaki's then you have a decent street cam set.
I have to take him on his word roger. Unfortunately I can't get enough info from him and as sucham weary of it. Thanks for that roger
If you don't try you never know if you can do it.
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StormyRob
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Re: Cams 254deg

Post by StormyRob »

VTRDark wrote: Mon Jul 02, 2018 8:39 pm You have Lift, Duration and Seperation to take into consideration. You need more info and it's amazing how complicated a simple egg shape can be. Just look at the elliptical paths of the planets and how they interact with each other and involves a lot of mathmatical equations.

http://www.lunatipower.com/Tech/Cams/CamSpecTerms.aspx

http://www.compcams.com/Pages/413/cam-t ... angle.aspx

It's actually quite difficult to get reliable info online and something else to take into consideration which confuses things is how the numbers are measured as different manufacturers / builders use diffrent methods and scales of measurment to confuse folk so they can't be copied. It's like they use some form of cryptograpghy and basically make things up that have to be converted but they are the only ones that have the key. So the reality of it is that you could have two cams from two different manufacturers that give the same specs. But when you pysically have them in your hand and take measuremnets there are differences.

There's some some seriously closely guarded secrets amongst cam manufacturers. They keep secrets as well as British intelligence or F1 teams all in the name of keeping their profiles secret so they can't be copied by another manufacturer. A good industry for bit of industrial espionage. A good comparrison would be like trying to measure 180 Keihin main jet versus a Dynojet 180 main.

Do your research because it's not as simple as buying some cam's, sticking them in and off you go.

For some seriously headbanging sh1t see the following pdf :eek2
Cam Design Handbook
I basically saw that handbook as a picture book mate 😂😂 no idea!

I am steering clear I think as there is just not enough info
If you don't try you never know if you can do it.
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Stephan
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Re: Cams 254deg

Post by Stephan »

I am running reprofiled 256 deg cams. If these cams have profile suitable for bikes (which is important as bike cam profiles are designed for higher rpms), and have lift about 1.2 mm, you can expect similar performance to mori stg1 cams. Cam lift be easily measured by substracting the longest and shortest profile of the cam.
But there are more things to consider. These cams are probably not simple bolt on. You will need to set correct in/ex valves timing and correctly install the cams via adjustable cams sprockets. Not easy to do.

Personally I would not buy without more information.
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