Topic: favorite cam?

[BLUE71TURBO]

 My favorite cam .........?   The " TOP SECRET "  Special turbo profile from WEBCAM.       

[Sam Green Racing]

In a perfect world...     the biggest cam......... however you forgot the most important part of the equation, the rider, how good is he ( you)    I always use the cam to suit the rider / driver when ever they let me talk them into it.  Get better results.................data loggers are good, gives the engineer a more reliable feedback, sometimes riders have a bad case of chinese whisper, you know forgetting what they are really doing with the throttle.   Not many riders can get on a pro stock bike and hold it flat till the end, in that case new rider I would be starting on a more controlled cam until the rider come back complaining he wanted more. ( cams are cheap)
This is in reference to the biggest of everything of course.
ciao Johno

I rekon he might pass Johno.

Hello guys . I'm an old guy who used to race a sohc 750/970 back in the day . For the last few years I've been racing a Nitrous Hayabusa in Land Speed and quarter mile events but I've recently started the process of building a retro 70s sohc 750  pro stock bike . It's something I've been meaning to do for a while now and I figure this is the place to meet people with the knowledge and enthusiam to help me complete my project .

Sam.

[johno]

  Sam on Jims agent orange back of tank he had " put your nuts here"  on the tank, ( loved it)
I reckon on a nitrous Hayabusa it would pay to put a sign on the back of the tank " bet you cant keep your nuts here"   
ciao Johno

[johno]

  Greg ,lucky I got Sam the man as a mentor,I reckon he is the moderator cos to me he seems to know every Honda cb rider in the world 
The previous thread is my way indicating  my humbleness with an average attempt at humour.

My personal favourite race is the IOM TT ( speaking of big nuts), my personal favourite bike to look at is a 70's pro stock bike,  I hope you get the project up and running and get some pics to excite us.

I promised to post some numbers for different megacycle cams so here goes.
I chose a 70mm bore so MikeR can compare numbers to what hes got, I'm sure he would have done so      I guess its not so much what the numbers are but the change between the cam only changes.   I chose some good numbers for the ports, would have loved to put in yours Mike. Started with a stocky just to see how the numbers compare.    All numbers are engine only not back wheel.

Stock cb 750. K2    Max HP 55 @7,750........ Max Torque 36ft/lb @7,000.
Highly modified with 70mm bore: 
125-25........ Max HP 128hp @8,000..... Max Torque 87 ft/lb @7,750
125-35.........Max HP 135hp @8,000......Max Torque 90 ft/lb @7,750
125-65........ Max HP 130hp @8,000......Max Torque 88 ft /lb @7,750
                                                               Torque curve flat 6,200 - 8,000
125-75........Max HP 145@9,200     HP 130  @ 8,000 ... 90 ft/lb @ 7,750
Flat torque curve 6,200 to 8,200
125-95........Max HP 149@9,200    HP 133 @8,000.....89 ft / lb @7,750
Flat torque curve 6,200 to 9,250
125X 12 .....Max HP 150 @9,250     HP 138 @8,000....91 ft / lb @7,750
Flat torque curve 6,600 to 9,200

Thinking dont hone in on the numbers but think in terms of percentages with cam only changes.  If you have some bench marks to compare would be good, although most dynos are rollers not engine, throw it out there baby,
ciao Johno

[Sam Green Racing]

Hey Johno, I was talking to a mate last night and mentioned Greg to him, he told me I know him
I even have his cell number

Sam.

[Greg H]

This is a really interesting read , so o.k guys which cam would you recommend for an all out drag motor , you know , big bore ,big carbs, big valves, in fact big everything .

Aye aye Wigan pie, you slipped in rather quietly
Welcome to the forum, your in the right place to have the time of life.
We have members in here with every combination that you might like to try.
We have street K and autos knocking on the 11s, F and autos in the 10s, 200mph fuelers that run 7s and we even have a member with a single engined turbo nitrous bike that has run well over 200mph, where would you like to start.
Start your own thread Greg, tell us what you have and what your plans are, you'll get all the info that you will need. I'm just a few miles south in Warrington if I can be of any help.

Sam.

Hi Sam and thanks for the welcome . I'm in the process of building a 70s style sohc Pro Stocker . Although I want to keep the authentic 70s look I now realise that there have been  quit a few superior engine components developed for the old sohc motor since I last used one .Consequently I'm concentrating on the rolling chassis at the moment and just researching the engine set up . I'll take some pics and start a thread as you suggest . Regards Greg "H".

[NitroHunter]

Johno awesome job.

As Jim Dour of Megacycle told me when we were developing our 7 time Daytona F750 winner...your going to like this cam.....I do, best one out there  and you don't need that much compression. Less than 11-1 works great.

And so the numbers indicate.

Since it's where most guys start, I would like to see this comparesons done for an average 836cc 10.5 cr, without ported head flow figures (55cfm stock); something the average guy could reasonably expect (comparison wise) from an inexpensive piston kit + cam only upgrade.
Then maybe a re-run with ported head flow numbers (75 cfm) and see which grinds come alive...

[Don R]

It looks like I'm going back with the stock head and cam for now. I traded an extra E-bay 836 kit for my brothers Kenny Harmon f grind welded cam. I have a drop out frame kit on the bike so after I get my ported head done this winter I can switch it out.

[bear]

Greg ,lucky I got Sam the man as a mentor,I reckon he is the moderator cos to me he seems to know every Honda cb rider in the world 
The previous thread is my way indicating  my humbleness with an average attempt at humour.

My personal favourite race is the IOM TT ( speaking of big nuts), my personal favourite bike to look at is a 70's pro stock bike,  I hope you get the project up and running and get some pics to excite us.

I promised to post some numbers for different megacycle cams so here goes.
I chose a 70mm bore so MikeR can compare numbers to what hes got, I'm sure he would have done so      I guess its not so much what the numbers are but the change between the cam only changes.   I chose some good numbers for the ports, would have loved to put in yours Mike. Started with a stocky just to see how the numbers compare.    All numbers are engine only not back wheel.

Stock cb 750. K2    Max HP 55 @7,750........ Max Torque 36ft/lb @7,000.
Highly modified with 70mm bore: 
125-25........ Max HP 128hp @8,000..... Max Torque 87 ft/lb @7,750
125-35.........Max HP 135hp @8,000......Max Torque 90 ft/lb @7,750
125-65........ Max HP 130hp @8,000......Max Torque 88 ft /lb @7,750
                                                               Torque curve flat 6,200 - 8,000
125-75........Max HP 145@9,200     HP 130  @ 8,000 ... 90 ft/lb @ 7,750
Flat torque curve 6,200 to 8,200
125-95........Max HP 149@9,200    HP 133 @8,000.....89 ft / lb @7,750
Flat torque curve 6,200 to 9,250
125X 12 .....Max HP 150 @9,250     HP 138 @8,000....91 ft / lb @7,750
Flat torque curve 6,600 to 9,200

Thinking dont hone in on the numbers but think in terms of percentages with cam only changes.  If you have some bench marks to compare would be good, although most dynos are rollers not engine, throw it out there baby,
ciao Johno

Johno,

Could you factor in my 69mm stroke into those figures.

Cheers,
Brian

[bear]

The cam on the right is the Megacycle 125-75 that we run in our "A" motor.
The cam on the left is our "OH SH!T" cam that we run in our "B" motor. (not worth a crumpet under 6'000rpm but then it gets real ugly).
I think it's one of your mate Ivan's creations Johno.

Cheers,
Brian

[johno]

Nitro,
For 836cc some head and cam options.
Just reminding you dont stress on the numbers , just the change.

For base cam I didnt use a stock cam, used the megacycle stock replacment 125-05 (.340 lift,246 duration, 104 lobe centres, .004 lash.

For the hotter cam I used Megacycle 125-65 based on their recomendation for 836.(.375 lift, 257 duration, 103.5 lobe centres, .004 lash.

65mm , 10.5 comp
Stock head stockish cam.........Max HP 105 @ 8,000.........Max TQ 80 f/lb@5,500.   both curves drop off 7k
Good head stockish cam .........Max HP 108 @7,000........Max TQ 84@ 5,500,      both curves drop off 8.2k

Stock head good cam............Max HP 114 @8,000........Max TQ 84 @5,500.     flat curve 7k to 9k
Good head good cam...........Max HP 117 @9,000........Max TQ 80 @7,000.     flat line 4k to 8k

The last torque curve confused me but I think its to do with the port info I used,  I had trouble balancing the average port diam , length, volume and flow figures because I guessed a couple.

 Re cam; The big change is the RPM of max torque and how flat the curve is.
Re head; allows more HP  at lower RPM with mild cams .... and big cams at higher RPMs with longer flat curves .

ciao Johno

[johno]

  Hi Bear ,
re your stroker, did you use 3mm shorter rods or space up the barrell, is it 70mm bore or 73mm bore.
I just need to know the conrod length , stock or shorter
ciao Johno

[johno]

  Too late mate !     this is  70mm bore with  shorter rod.

Cam is mega man 125- 75
STD stroke... Max HP 144 @9,250      ..............Max TQ 89 @7,000   ( flat curve 6k to 8k)
69mm stroke Max HP143 @9,250     ...............Max TQ 97 @ 6,250  ( the horsepower curve shows 10HP more from 2k up to 8k then levels to same HP.  The torque curve is awesome , dead flat from 5,500 to 9,200 and how low is the max torque. This combo in chair would pull like a train from 5,500 on.

Maybe baby , Bear how does this sit with your experience with your engine.
ciao Johno

[bear]

Hi Bear ,
re your stroker, did you use 3mm shorter rods or space up the barrell, is it 70mm bore or 73mm bore.
I just need to know the conrod length , stock or shorter
ciao Johno

Johno,

The "A" runs a 72mm bore and it has a 5mm spacer.
We have gone back to using DOHC 1100 rods.

Cheers,
Brian

[bear]

Too late mate !     this is  70mm bore with  shorter rod.

Cam is mega man 125- 75
STD stroke... Max HP 144 @9,250      ..............Max TQ 89 @7,000   ( flat curve 6k to 8k)
69mm stroke Max HP143 @9,250     ...............Max TQ 97 @ 6,250  ( the horsepower curve shows 10HP more from 2k up to 8k then levels to same HP.  The torque curve is awesome , dead flat from 5,500 to 9,200 and how low is the max torque. This combo in chair would pull like a train from 5,500 on.

Maybe baby , Bear how does this sit with your experience with your engine.
ciao Johno

Jeez Mate!

Your that close to spot on it's uncanny.
My change point is @ 6000rpm but I don't usually run it past 8/8500rpm, rev limiter is usually set @ 9000rpm
It will be interesting to see how the other cams affect the model now we know we have a pretty accurate base line.

Cheers,
Brian

[NitroHunter]

Johno this stuff is awesome fun, thanks.
Yeah I get you about the numbers, they're "FOR REFERENCE ONLY".
Interesting that only .035" lift and 11 degrees of duration makes such a dramatic change.

My first RC 836 cast piston, RC 240 reground cam would flat run away from my other Navy pals stockers in low & mid-range roll-ons. Of course having 240psi cranking pressure (!) - and using 108 octane booster - certainly helped.

[johno]

  cheers Boys,
Speaking of cams I purchased a few goodies last month for the small 750 engine and the cam I purchased was an RC 315, Buzz talked me into it to suit the hi comp 62mm pistons.

I run it on the software and compared it to the two mega cams 35 and 75. The HP and TQ curves were almost exactly the same , one (1) hp difference at 9,000 rpm.  The software said the RC 315 had to much duration on the inlet compared to the other cams but I advanced the cam and run a bigger inlet ( from 33.5mm to 34mm inlet) valve and increased the port diam one mm and it was happy so I'll give it a go.

Wether it becomes my favourite cam remains to be seen.

I'm not planning to do much tuning on the bike other than, fuel ratio, sprockets,  as a last resort I will take an alternate cam just in case the air wall loads the bike too much and I need more torque.

Hey Bear where did you get the groovy barrels from and what sort of $ ?    I,m looking at these 73mm barrells I've got for the big motor with loads of aryldite in the guts and thinking YUK might get my new leathers dirty. ( dont worry there blue not white )
Let me know , cheers Johno   

[bear]

Hey Bear where did you get the groovy barrels from and what sort of $ ?    I,m looking at these 73mm barrells I've got for the big motor with loads of aryldite in the guts and thinking YUK might get my new leathers dirty. ( dont worry there blue not white )
Let me know , cheers Johno   

Sorry Johno we had a mate that sand cast the solid barrels for us ages ago and I'm sorry to say he passed away some time ago.

Cheers,
Brian

By the By,
If you would like one of our stroker motors for Gardner I'm happy to oblige. What a great excuse for a beer.
They may not be able to rev like the std cranks but you would be able to run some pretty good gearing.

Cheer,
Brian

[NitroHunter]

I had personal experience that the RC 315 cam worked great all-around in a motor with lots of static cylinder pressure. It will pull the motor way past the safe numbers on the tach on just about ANY combination. 
However, not so good below 5500rpm in a F-2 915cc with 9:1, probably because (with overlap blowing down some cylinder pressure) that thing only had about 160 psi cranking pressure. I initially experienced valve-to-valve clearance issues too, (34mm intake vs 31mm exh), it came that way as a used bike. Milling, grinding, and degreeing cured that tho.

[Doctor_D]

Johno:

What are you using for VE?  I generally specify 105% volumetric efficiency for 2-valve sohc's.

Sent from my ADR6400L using Tapatalk 2

[johno]

  Thanks doc, the high numbers were getting to me too.
I,m trying to get used to a new system. I purchased my first performance trends software 21 years ago, ( can you remember 5 !/4 inch floppy disc on the commodore. Then I upgraded to a 3.5 inch disc a few years later and both those used the VE % as a base to get the numbers right.  However in making the big comeback from retirement  I read that the new upgraded software used a different more accurate process based on flow bench figures, cam doctor info to determine the efficiency (VE%) by airflow speed through the port benchmarked by a factor of MACH.

The truth is the old system was a lot simpler to set the benchmarks for me and your comment has prompted me to start reading the 261 page war & peace manual.  The upgrade offers two ways to get numbers, a simple system based on default settings , the other is with lots of detailed inputs and which like most bloke would, I went straight for the hi tech inputs, hopefully after page 261 I can get the benchmarks spot on.

I am stressing about matching the port diam with the cam on the small 750 motor as it will be really sensitive compared the the big motor, this software will nail it, the driver just needs to practice. 

I'm feeling if you get the port too big or the cam too big on a 1/4 mile you can put a bigger sprocket on the back and get  away with it to a degree but if I get it wrong on the salt with small baby sprockets I will get crucified and need trainer wheels itll be so slow.

Thanks Doc you inspired me into action.
ciao Johno

[johno]

  Bear you mad bugger, your humbling me.
Thanks for the info.
Re your offer very generous and extremely appreciated.  I was thinking about it and it may come to something if time beats me.  At this stage I am keen to get these two babies of mine going but being truthfull it has been on my mind while fooling around with the hi port that it would be great to have some stroke.
If I go to the expense of a big port , big lift cam its kind of makes sense to make an all out assault on the fastest sohc in OZ and stroke would be a big part in that.  What would make it special is if we could make it happen with some forum members.   There is a gun 55kg jocky on the forum who is used to piloting big fuellers  ( no Sam not you, not enough corners or instruments for you)  who holds the  salt M/G 1000 class record on his daily 900 hack ( camboy) Would be great exercise if we could get it all together , a great chance for everyone to meet over a bike or two, we could end up with someone from every state and maybe O/S.

Any feedback or interest ?

[bear]

Bear you mad bugger, your humbling me.
Thanks for the info.
Re your offer very generous and extremely appreciated.  I was thinking about it and it may come to something if time beats me.  At this stage I am keen to get these two babies of mine going but being truthfull it has been on my mind while fooling around with the hi port that it would be great to have some stroke.
If I go to the expense of a big port , big lift cam its kind of makes sense to make an all out assault on the fastest sohc in OZ and stroke would be a big part in that.  What would make it special is if we could make it happen with some forum members.   There is a gun 55kg jocky on the forum who is used to piloting big fuellers  ( no Sam not you, not enough corners or instruments for you)  who holds the  salt M/G 1000 class record on his daily 900 hack ( camboy) Would be great exercise if we could get it all together , a great chance for everyone to meet over a bike or two, we could end up with someone from every state and maybe O/S.

Any feedback or interest ?

What the the hell we're in.

Timbo my engine man heads over every year anyway.
There's no way I would subject my much loved Martin/Windel chassis to a salt bath.
But I,m happy to throw our two motors on the ute and bring them along.(Just on spec.)

Cheers,
Brian

[bear]

.  The torque curve is awesome , dead flat from 5,500 to 9,200 and how low is the max torque. This combo in chair would pull like a train from 5,500 on.

 Bear how does this sit with your experience with your engine.
ciao Johno

We run the cam with about 5deg. more advance whats on the timing card so you could probably pull the max torque a little lower even.

Cheers,
Brian

[scottly]

There's no way I would subject my much loved Martin/Windel chassis to a salt bath.
But I,m happy to throw our two motors on the ute and bring them along.(Just on spec.)

Cheers,
Brian

That's the way I feel about my Seeley, Brian, especially after seeing all the salt encrusted into every nook and cranny of that guy's Rickman after B-ville.