Author Topic: favorite cam? (Read 27049 times)

sohc boy · « **Reply #75 on:** July 04, 2012, 03:07:36 AM »

Johno...yea i'm up for it , i'll give the double nocker a miss , either build an run a sohc ,or a 55 kg pilot on someones bike ,or both , just velcro or cable tie me on anything over 150mph,i tend to start flapping in the breeze . forgot to mention at the lake we took water filled fire extinqishers (,take compreser an plenty of water, t refill)at night we hosed em down, then wd40 ,didnt have a real problem with salt on bikes

754 · « **Reply #76 on:** July 04, 2012, 10:05:26 AM »

Before you give away "the ride of a LIFETIME" to some lucky flyweight bastard that get offered fast bikes to ride..
Remeber this.. on the salt..one of the few places weight is not alawys a disadvantage.. may 200mph bikes are WEIGHTed on the rear... food for thought..

sohc boy · « **Reply #77 on:** July 04, 2012, 02:24:06 PM »

thats true 754,weight on the salt is here nor there , an yea we had wheelspin problems , weight on the rearend is good idea

johno · « **Reply #78 on:** July 05, 2012, 03:11:17 AM »

No such thing as traction problem Pete, what do you think Bear is coming for

Bear is a cave man version of traction control, evan if his legs are #$%* we can sit him on the back and strap him to you

In fact he has lost so much weight you would probably fit into his leathers with him and noone will know.
cheers Johno

johno · « **Reply #79 on:** July 05, 2012, 03:21:20 AM »

Graph of CB750 with 62mm bore and magacycle cam 125-75, its the combo I,m settling on for the 750.
I will post the engine detail next post ( I,m a one post one :)pic man)

johno · « **Reply #80 on:** July 05, 2012, 03:29:07 AM »

Results of engine specs

CB 750 K2 head
Johno

johno · « **Reply #81 on:** July 05, 2012, 03:35:56 AM »

This graph is of two cams the RC 315 and the Mega man 125-75

I reckon I purchased the wrong cam with the RC 315 as on this combo it dips badly around 7,000 RPM on both HP and TQ and I couldnt tune it out. When I put in 900 cc the graph went normal, same for 1,000 cc.
I figure it just doesnt like he 750 thing. I put in the 125-75 and presto normal graph with no power dip, I'll have to buy one of those babies.
cia

sohc boy · « **Reply #82 on:** July 05, 2012, 03:40:32 AM »

interesting Johno.........yea thats may be a good idea with bear,...i like it

johno · « **Reply #83 on:** July 05, 2012, 03:42:22 AM »

These are the engine specs CB 750 , 62mm bore , race version
ciao Johno

Don R · « **Reply #84 on:** July 05, 2012, 12:18:21 PM »

I wonder why the dip is there, then it seems to go past it. Too much cam and it looses vacuum? Larger displacement can move enough air?

bear · « **Reply #85 on:** July 05, 2012, 08:54:00 PM »

I think its time you started a build thread Johno.

Cheers,
Brian

johno · « **Reply #86 on:** July 06, 2012, 03:35:11 AM »

Bear your a mind reader, I was thinking about it last night, whats the drum, in the hi performance threads or the projects section ? Sam

?
Bloody cold in the shed last night , was minus 5 and just up the road at Renmark was minus 9.
I can see why it took 9 years for project moonpie. speaking of that, hes going to have a real blast doing a IOM tt lap. Imagine listening to the 4 pipe exhaust, his marriage will never be the same after that, she wont cope with being second best.

Ciao Johno

johno · « **Reply #87 on:** July 06, 2012, 03:57:40 AM »

Agreed Don, Buzz ( dynoman) said RC 315 was only good for the 750 hi comp pistons if the bike was light, if normal road weight the pistons / compression would need the RC 295. After looking at the simulator I wont evan try it. You never know Don if I,m a good boy the tooth fairy might visit me and swap it for a 125-75.

Johno

mick7504 · « **Reply #88 on:** July 06, 2012, 07:07:54 AM »

Johno

I've got a new 12575 Meg here in Darwin mate if it can help.
It's been installed for spec data but never fired.
Let me know if your interested mate.

Mick

Doctor_D · « **Reply #89 on:** July 06, 2012, 07:15:04 AM »

Quote from: johno on July 05, 2012, 03:29:07 AM

Results of engine specs CB 750 K2 head
Johno

Well, look at that - VE of 105.5%

Doctor_D · « **Reply #90 on:** July 06, 2012, 07:33:43 AM »

Quote from: johno on July 05, 2012, 03:42:22 AM

These are the engine specs CB 750 , 62mm bore , race version
ciao Johno

Very nice, thanks for sharing. I think you might be able to smooth that power curve even a bit more than you have.

On the intake side, try 249.7mm for combined port and manifold length, 3rd harmonic.

On the exhaust, your primaries look a bit big and a bit short. Try 25.4mm diameter, and 881.1mm long. Your collector is close to one of the numbers I got at 305.6mm, and the next harmonic is 611.1mm. I have a best collector diameter of 54.8mm.

johno · « **Reply #91 on:** July 07, 2012, 04:32:16 AM »

Cheers Doc,
you were spot on with the VE.

What software do you have? I couldnt change the VE seperate cos its locked into the flow bench numbers and just shows on the summary screen.

With the intake I'm lumbered with the RC manifold and webbers, so the intake distance is locked in.

With the exhaust I tried optimise function and man the diameters were sooooo small, I reckon they were for a 6 cylinder 250 honda. Your right Doc the 36mm I had is too large , I was being lazy as I planned to use the standard exhaust spigots but now you have revved me

up I'll fabricate some a bit smaller. I'm thinking same as the RC 750 pipes at 32mm. At the top of the exhaust pipe I might try something fancy and offset the pipe up high as the head exh outlet is much bigger and it might help with reversion.
Thanks mate..... Johno

Doctor_D · « **Reply #92 on:** July 07, 2012, 02:55:12 PM »

I use PipeMax. It's header software, but it has some built-in dyno functions.

For header ID, non-stepped design, I'm showing .990" to 1.115". Best length for max HP, not best torque curve, is 20.4" - 22.8". Best HP has a mega that uses a 1.659" 2 to 1 collector opening to 2.159", 12" long.

For your Webers, aren't there longer velocity stacks available? I seem to recall using longer stacks on both my Celica and my RX7, but that was decades ago.

johno · « **Reply #93 on:** July 07, 2012, 04:39:27 PM »

Doc

Ram tubes on your RX7 ! you are a serious petrol head D. I read through your project bike thread last night was a great read, exceptional in fact, well done.

Re exhaust, See what I mean sooooo small, it hurts to look at the numbers. BUT i,m interested as your software is specialised exhaust and you have my full attention. I had a play with the RC size last night and it wasnt happy at the top end at all, both TQ and HP, it was the old game of smaller pipe / longer length better mid range but less up top.

Just for a laugh D I might bend up a set of rough arsed pipes in your baby size and see what happens.
Re the intake I will post some pics of the ram tubes tonight on my new thread build " Salt racer OZ style"
ciao D

754 · « **Reply #94 on:** July 08, 2012, 08:36:37 AM »

FWIW I ran turbo 4-1 on a 836cc, with a midpipe and megaphone.. and it seemed very torqey.. I think smaller primaries on the turbo-pipe may help the midrange, athough top-end may suffer. Ran an RC 315 cam and Webers..... Could be wrong but I am MORE than satisfied with the midrange feel on the street

Jerry Rxman Griffin aka MuthaF'er · « **Reply #95 on:** July 08, 2012, 09:11:20 AM »

Frank,

How did you run a turbo with the Webers? I can't imagine you ever running "regular" carbs.

754 · « **Reply #96 on:** July 08, 2012, 09:24:56 AM »

I ran a 4-1 turbo headpipe (same as Cavebears), into a midpipe running parralel to the ground left side of bike. at the left sidecover it goes down at a 45 degee angle, exiting ito a huge slash-cut megaphone..
This allows me to run at least3 inches lower to the ground, sidestand bracket is cut oof and relocated. great ground clearance, nice slammed bike

johno · « **Reply #97 on:** July 09, 2012, 04:05:10 AM »

For the cam enthusiasts, I hopefully will have a cam soon that might be interesting,

a cam coming in 2 to 3 weeks time with four (4) different inlet cam lobes on the one camshaft. How cool will that be , cant wait.
, wonder what it would run like if I could get it to go.
Dont worry it wont be running, its just to try some geometry stuff.

ciao johno

bear · « **Reply #98 on:** July 20, 2012, 06:11:06 AM »

Quote from: johno on July 01, 2012, 03:48:31 AM

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

Better late than never.

At the moment we are using 117.5mm rods.
Would you be able to model 112.5 as well?
This is for the 72mm motor that's using the 125-75 cam.
The reason I ask is that we will be putting the little motor back together shortly and I intend to use a new set of "made to order rods" from Ridgcrest Enginering in Melbourne.
I'm seriously considering the shorter rods, but if the modeling tells us that there would be no significant gains in the toque figures than it's probably not worth the risk keeping in mind the extera load it would place on the pistons.

Rod / Stroke ratio,
117.5 @ 1;1.7
112.5 @ 1;1.6

As MRick has mentioned before, I don't mind walking a fine line occasionally.

Cheers,
Brian

By the by, package will be posted on Monday.
Sitting on the kitchen bench now.

mick7504 · « **Reply #99 on:** July 20, 2012, 06:26:59 AM »

Quote from: bear on July 20, 2012, 06:11:06 AM

Quote from: johno on July 01, 2012, 03:48:31 AM
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

Better late than never.
At the moment we are using 117.5mm rods.
Would you be able to model 112.5 as well?
This is for the 72mm motor that's using the 125-75 cam.
The reason I ask is that we will be putting the little motor back together shortly and I intend to use a new set of "made to order rods" from Ridgcrest Enginering in Melbourne.
I'm seriously considering the shorter rods, but if the modeling tells us that there would be no significant gains in the toque figures than it's probably not worth the risk keeping in mind the extera load it would place on the pistons.

Rod / Stroke ratio,
117.5 @ 1;1.7
112.5 @ 1;1.6

As MRick has mentioned before, I don't mind walking a fine line occasionally.

Cheers,
Brian

We don't need reminding thanks very much Mr. Williams

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Author Topic: favorite cam? (Read 27049 times)