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Author Topic: F2 836 cam recommendations  (Read 3372 times)

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Offline tweakin

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F2 836 cam recommendations
« on: March 18, 2011, 08:05:42 am »
Looking for cam recommendations for my bike.  Currently running a Webcam 41 and want to see what you guys recommend as options.  My understanding is that with the domed pistons and larger valves of the F2/F3 bikes cam choice is slightly limited, but I would like to get the most out of my 836 and head work.

Could I run a Webcam 63a .370" 282 duration?

or APE H-370 H370   .370"   268° Dur. @.050"?
or another cam if I check all clearances and adjust accordingly?

1977 750 F2 with 836
Valve job, new valves
Heavy duty valve springs and Ti retainers

Thanks!

« Last Edit: March 18, 2011, 10:17:22 am by tweakin »

Offline brandEn

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Re: F2 836 cam recommendations
« Reply #1 on: March 18, 2011, 01:11:33 pm »
tagging along hoping to hear some input...

Offline tweakin

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Re: F2 836 cam recommendations
« Reply #2 on: March 18, 2011, 01:31:09 pm »
My understanding is that the issue with the F2/F3 head is the valve intersection.

Offline Doctor_D

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Re: F2 836 cam recommendations
« Reply #3 on: March 18, 2011, 02:34:39 pm »
Tweak:

I have a 125-65 with a dozen dyno runs and maybe one-hour of total run-time on it.  If you're currently running a 41a, it'll give you a little more intake lift with similar duration.

Willing to part with it for either you or BWJ.  Deeply discounted, of course.  ;)
Take care,
David
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1978 CX500
1971 Norton Commando

Offline tweakin

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Re: F2 836 cam recommendations
« Reply #4 on: March 18, 2011, 02:46:34 pm »
Sent you a pm, checking on it.
Tweak:

I have a 125-65 with a dozen dyno runs and maybe one-hour of total run-time on it.  If you're currently running a 41a, it'll give you a little more intake lift with similar duration.

Willing to part with it for either you or BWJ.  Deeply discounted, of course.  ;)

Offline Mandic

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Re: F2 836 cam recommendations
« Reply #5 on: March 18, 2011, 02:59:57 pm »
Wish I could be helpful, I'd like to hear what people say.  I am running a Web 41 cam in my 836 F2 motor as well.

IF you take in what I have read about increasing valve lash to reduce valve lift, you could run an 63a, gain duration and be about the same lift.  However the duration could bring the valves into issues since the timing of when they are close to the pistons is different. 
77 CB750F - Cafe/Daily Rider

Offline brandEn

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Re: F2 836 cam recommendations
« Reply #6 on: March 18, 2011, 03:13:05 pm »
Thanks for the offer D, I have a new cam coming next week from Cycle X. Tweakin, sounds like thats just what you need. I believe that cam is from Megacycle cams?
http://www.megacyclecams.com/

Offline simon#42

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Re: F2 836 cam recommendations
« Reply #7 on: March 18, 2011, 04:24:13 pm »
i have a 125 / 65 in my 836 f2 and am very please with it , better everywhere than the standard cam and you dont have to rev the tits of it to go fast .

Offline tweakin

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Re: F2 836 cam recommendations
« Reply #8 on: March 18, 2011, 05:02:13 pm »
Thanks for the reply simon.  What pistons are you running?  Are they F2 specific 836 pistons?

i have a 125 / 65 in my 836 f2 and am very please with it , better everywhere than the standard cam and you dont have to rev the tits of it to go fast .

Offline Retro Rocket

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Re: F2 836 cam recommendations
« Reply #9 on: March 18, 2011, 05:18:28 pm »
Haven't used mine yet but i have the same cam for my 1000cc engine....125-65
750 K2 1000cc
750 F1 970cc
750 Bitsa 900cc
If You can't fix it with a hammer, You've got an electrical problem.

Offline MRieck

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Re: F2 836 cam recommendations
« Reply #10 on: March 18, 2011, 06:36:48 pm »
Megacycle recommends the 125-35 for the F2 1978 model....that cam is .407 on both both side with 268 duration on the exhaust side. intake is 266 duration. Now if the cam works...... ::) ??? If you have about .150....   .155 between the valves when they are on the seat it's OK. Sam and Dave (Doctor D) have the 5mm conversion kit and that is the valve spacing on those heads. That is spacing on all the 5mm heads I've done and those 2 engines sound OK to me.. They have all worked. All those heads have had the seats cut which requires sinking the intake valve a bit. It doesn't matter what the size of the valves are.....if the valve to valve clearance while the valves are on the seats is that # it is OK. Honda sank the valves making a bigger chamber to achieve the this. Mark McGrew will back this up too. He ran an F2 head at some point and you can sure he didn't run a stock cam or a 41A.
 I'll tell you guys what. I have an F2 head here with new valves, guides...the works. I also have a 125-75 cam and a 125-35 cam sitting on the shelf. i will mock up the head tomorrow morning and see what valve to valve is at overlap and give you the exact # (minimum is .040). I did this quite a while ago when I started using the kits but apparently never wrote the # down. I'll take some pics too.The F2 836 pistons have the large valve reliefs so valve to piston is a moot point.
 I think the biggest testimony is the fact that Simon is currently running that 125-65 with the F2 head and has NOT experienced any problems. That being said your head better have good springs in it because those valves aren't very light
« Last Edit: March 18, 2011, 06:41:19 pm by MRieck »
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Offline tweakin

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Re: F2 836 cam recommendations
« Reply #11 on: March 18, 2011, 07:18:14 pm »
Thanks Mike!  I really appreciate you taking the time to respond to my post.  Springs are good and I will check all clearances for piece of mind.  Hoping to make it up for DoctorD's dyno run tomorrow and pick up the cam.

Offline MRieck

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Re: F2 836 cam recommendations
« Reply #12 on: March 19, 2011, 07:09:21 am »
Megacycle recommends the 125-35 for the F2 1978 model....that cam is .407 on both both side with 268 duration on the exhaust side. intake is 266 duration. Now if the cam works...... ::) ??? If you have about .150....   .155 between the valves when they are on the seat it's OK. Sam and Dave (Doctor D) have the 5mm conversion kit and that is the valve spacing on those heads. That is spacing on all the 5mm heads I've done and those 2 engines sound OK to me.. They have all worked. All those heads have had the seats cut which requires sinking the intake valve a bit. It doesn't matter what the size of the valves are.....if the valve to valve clearance while the valves are on the seats is that # it is OK. Honda sank the valves making a bigger chamber to achieve the this. Mark McGrew will back this up too. He ran an F2 head at some point and you can sure he didn't run a stock cam or a 41A.
 I'll tell you guys what. I have an F2 head here with new valves, guides...the works. I also have a 125-75 cam and a 125-35 cam sitting on the shelf. i will mock up the head tomorrow morning and see what valve to valve is at overlap and give you the exact # (minimum is .040). I did this quite a while ago when I started using the kits but apparently never wrote the # down. I'll take some pics too.The F2 836 pistons have the large valve reliefs so valve to piston is a moot point.
 I think the biggest testimony is the fact that Simon is currently running that 125-65 with the F2 head and has NOT experienced any problems. That being said your head better have good springs in it because those valves aren't very light

 With the 125-35 cam in place valve to valve at the closest point of overlap is .041. That is with .150 between the valves when they are on the seats. That is also with weak testing springs...the real springs will pull the valves tighter to the seats and give about .153 or so I figure. Close but that is what measuring is all about. I'll post some pics later.
Owner of the "Million Dollar CB"

Offline MRieck

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Re: F2 836 cam recommendations
« Reply #13 on: March 19, 2011, 08:30:04 am »
 On a side note...I personally wouldn't go over a 125-75 with it's lift and duration #'s. also...that is the largest cam I have personally used with the 5mm setup using a 34mm intake and 28mm exhaust valve
« Last Edit: March 19, 2011, 08:34:22 am by MRieck »
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Offline tweakin

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Re: F2 836 cam recommendations
« Reply #14 on: March 19, 2011, 08:40:44 am »
Thanks for the extra effort Mike!

Offline simon#42

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Re: F2 836 cam recommendations
« Reply #15 on: March 19, 2011, 12:29:31 pm »
my setup is a bit odd in that i used a 836 kit for a k motor in an f2  , then took  just under a mil off the head to get the compression right . there where no clearance problems at all with the 125-65 cam [ sorry didnt make a note of the figures ] . the cam made a big difference to performance and if i was building another fast road engine i would be pestering mike to supply me with another . have done about 10,000 miles with this cam now with no problems . this could all change soon though as im lending it to sam !!!

Offline luhojs

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Re: F2 836 cam recommendations
« Reply #16 on: March 19, 2011, 01:49:18 pm »
Code: [Select]
then took  just under a mil off the head to get the compression right . there where no clearance problems at all with the 125-65 cam
Really ? only a thou? BTW a thou what? inches or mm's. What is the cc of the "old" comb chamber vs the F2 comb chamber? any figures out there?

Just asking.
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cb750 dragbike

Offline simon#42

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Re: F2 836 cam recommendations
« Reply #17 on: March 19, 2011, 02:45:24 pm »
sorry luhojs when i said a mil i meant a millimeter

Offline MRieck

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Re: F2 836 cam recommendations
« Reply #18 on: March 20, 2011, 05:35:20 am »
Code: [Select]
then took  just under a mil off the head to get the compression right . there where no clearance problems at all with the 125-65 cam
Really ? only a thou? BTW a thou what? inches or mm's. What is the cc of the "old" comb chamber vs the F2 comb chamber? any figures out there?

Just asking.
The stock F2 chamber is 28cc
Owner of the "Million Dollar CB"

Offline kos

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Re: F2 836 cam recommendations
« Reply #19 on: March 21, 2011, 02:15:50 pm »
Megacycle recommends the 125-35 for the F2 1978 model....that cam is .407 on both both side with 268 duration on the exhaust side. intake is 266 duration. Now if the cam works...... ::) ??? If you have about .150....   .155 between the valves when they are on the seat it's OK. Sam and Dave (Doctor D) have the 5mm conversion kit and that is the valve spacing on those heads. That is spacing on all the 5mm heads I've done and those 2 engines sound OK to me.. They have all worked. All those heads have had the seats cut which requires sinking the intake valve a bit. It doesn't matter what the size of the valves are.....if the valve to valve clearance while the valves are on the seats is that # it is OK. Honda sank the valves making a bigger chamber to achieve the this. Mark McGrew will back this up too. He ran an F2 head at some point and you can sure he didn't run a stock cam or a 41A.
 I'll tell you guys what. I have an F2 head here with new valves, guides...the works. I also have a 125-75 cam and a 125-35 cam sitting on the shelf. i will mock up the head tomorrow morning and see what valve to valve is at overlap and give you the exact # (minimum is .040). I did this quite a while ago when I started using the kits but apparently never wrote the # down. I'll take some pics too.The F2 836 pistons have the large valve reliefs so valve to piston is a moot point.
 I think the biggest testimony is the fact that Simon is currently running that 125-65 with the F2 head and has NOT experienced any problems. That being said your head better have good springs in it because those valves aren't very light


I worked with Jim Dour at Megacycle when we went to a F2 head on our CR750 with larger valves than stock, and he told me "I would love that F2 cam" pt# 125-035...and we did. Worked great..just like Mike indicated.

Mark McGrew
M3 Racing
220...221, whatever it takes.

Offline brandEn

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Re: F2 836 cam recommendations
« Reply #20 on: April 01, 2011, 05:58:26 pm »
Just got my Webcam 63A in from Cycle X. Nowhere on the box or cam is the number 63a. The cam and box are numbered CX3. I can't find this number in the Webcam catalog or on any of the online retailers of this cam. Anybody know whats up with that?

Also after getting off the phone with Cycle X I was told I may run into clearance issues on my F3 with my Wiseco 836 pistons, Cycle X valves and  R&D springs. With me not being very knowledgeable in this area any input or experience with my setup and a 63A would be most helpful.

Offline cheapride

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Re: F2 836 cam recommendations
« Reply #21 on: May 06, 2011, 05:34:05 am »
Hey tweakin, just checking to see what cam you got and how you like it.

Brent

1978 cb750f Supersport

Offline tweakin

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Re: F2 836 cam recommendations
« Reply #22 on: May 06, 2011, 05:49:28 am »
I played it safe and went with the webcam 41 and it works well.  That being said I am currently building a 915ci engine to get some more pop out of.

Hey tweakin, just checking to see what cam you got and how you like it.

Brent



 

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