Topic: Big Bang camshaft configuration

[mystic_1]

Over on Hondachopper.com there's a thread discussing the "Big Bang" firing order, apparently this involves a replacement cam and timing gear to fire 1+4 as a pair and 2+3 as a pair.  Seems this has some advantages in controlling/recovering from wheel slip in corners during racing.  Anyone have any experience with this?  I'd never heard of this particular mod before.

http://www.hondachopper.yuku.com/topic/27605



Some relevant info I found via Google:

http://en.wikipedia.org/wiki/Big-bang_firing_order

http://www.perthstreetbikes.com/forum/f16/making-big-bang-engine-77160/

http://www.crash.net/british+superbikes/feature/3632/1/exclusive_virgin_big-bang_secrets_revealed.html

mystic_1

[mlinder]

It's also great for major wear and tear on the engine, with frequent rebuilds, from what I've heard.

[OldSchool_IsCool]

I think it's mainly for dirt/hill climb.  Massive low-end torque, not much on the top end.  Instead of Bang-Bang-Bang-Bang, you get BANG-BANG-rest-rest.  The rest-rest phase is the re-grip which works kinda sorta like anti-lock brakes.

[Tnutz]

sounds like one giant paralell twin in that configuration

[Syscrush]

Big Bang is so 20 years ago!

Crossplane's where it's at, dude.

[mystic_1]

I bet it makes one hell of a sound, and therefore the "Big Bang" moniker   I can also see how this configuration would wreak havoc on all the internal parts in a very short time.  The staggered impulses and increased torque must be hell on the primary chains.

Syscrush, "crossplane" eh?  Anyone ever done that with a Honda SOHC that you know of?

I'm continually amazed at the things people do to these bikes.

mystic_1

[IHWillys]

...
Syscrush, "crossplane" eh?  Anyone ever done that with a Honda SOHC that you know of?
...

I think it's Yamaha only at this point, as far as inline fours go.

Ken

[Syscrush]

Syscrush, "crossplane" eh?  Anyone ever done that with a Honda SOHC that you know of?

It would require more than a cam & ignition change - it would require a custom crank, and ideally a balance shaft, too.  I've never heard of anyone changing a production screamer or big bang I4 to a crossplane.

[mystic_1]

One of the guys over at Hondachopper.com had this to say re: the Big Bang setup:

Neal is right, there were some called a Big Bang Cam. Mine was called Twin Fire, and was labelled APE. APE is still in business, and might be able to give you more info on it.

I sent a PM to Big Jay, maybe he'll have some comments.

mystic_1

[Big Jay]

We only made one of those cams. It fired two cylinders at a time, not a cross plane like the 09 Yamaha.

We gad to move some cam lobes around on the cam. We did it for a drag racer. He stated that the motor ran as planned, but was no faster than a conventional firing engine.

[mystic_1]

Well you must have done a great job on it then, seems it's still out there in a running bike

I did put it in a motor, and did notice differences! It sounded like a bumble bee, a big one! Best guess would be a big cb350 twin, and a noticeable lower end grunt! That is all i can remember about it!

http://www.hondachopper.yuku.com/topic/27605?page=1

mystic_1

[paulages]

Syscrush, "crossplane" eh?  Anyone ever done that with a Honda SOHC that you know of?

It would require more than a cam & ignition change - it would require a custom crank, and ideally a balance shaft, too.  I've never heard of anyone changing a production screamer or big bang I4 to a crossplane.

would not require a new crank. 1-4, and 2-3 already rise and fall together. it essentially makes it a 360 degree "twin," like most british twins of the 60's and '70's.

[Terry in Australia]

Dammit, now I want a big bang cam!

[turboguzzi]

nothing wrong with trying that but essentially you will be multiplying loads on all transmission gears/chains X2.

with stock firing order, torque load at any given time equals the force of only one cyl, with a big bang I-4 you will get two bigger torque peaks rather than four per engine cycle.

the yamaha crossplane is not a real big bang, the idea there is to keep crank speed more stable to improve drive control. By the way, Helmuth Fath tried it way before yamaha in the 60's in his 500cc GP sidecar motors.

[lordmoonpie]

I had a crossplane crank in my TVR sportscar too! (way before I got married  )

[MRieck]

We only made one of those cams. It fired two cylinders at a time, not a cross plane like the 09 Yamaha.

We gad to move some cam lobes around on the cam. We did it for a drag racer. He stated that the motor ran as planned, but was no faster than a conventional firing engine.

I know a hill climber who used that setup in his CB750 powered unit. He has a lot of trophies.

[mlinder]

Syscrush, "crossplane" eh?  Anyone ever done that with a Honda SOHC that you know of?

It would require more than a cam & ignition change - it would require a custom crank, and ideally a balance shaft, too.  I've never heard of anyone changing a production screamer or big bang I4 to a crossplane.

would not require a new crank. 1-4, and 2-3 already rise and fall together. it essentially makes it a 360 degree "twin," like most british twins of the 60's and '70's.

He's talking about crossplane, not big bang, Paul. Crossplane would require a new crank and cam.

[MRieck]

Syscrush, "crossplane" eh?  Anyone ever done that with a Honda SOHC that you know of?

It would require more than a cam & ignition change - it would require a custom crank, and ideally a balance shaft, too.  I've never heard of anyone changing a production screamer or big bang I4 to a crossplane.

would not require a new crank. 1-4, and 2-3 already rise and fall together. it essentially makes it a 360 degree "twin," like most british twins of the 60's and '70's.

He's talking about crossplane, not big bang, Paul. Crossplane would require a new crank and cam.

And ignition ECM

[mlinder]

That too

[MRieck]

I'm sure it could be done with points Mark....my mistake.

[Sam Green Racing]

Syscrush, "crossplane" eh?  Anyone ever done that with a Honda SOHC that you know of?

It would require more than a cam & ignition change - it would require a custom crank, and ideally a balance shaft, too.  I've never heard of anyone changing a production screamer or big bang I4 to a crossplane.

would not require a new crank. 1-4, and 2-3 already rise and fall together. it essentially makes it a 360 degree "twin," like most british twins of the 60's and '70's.

Nearly right Paul, it wouldn't need a new crank but it would be like a big 180 degree twin like the CR93 and CB72/77s.
The 360 British twins are like the CB92 and C72/77s, both pistons rising together but one firing while the other is exhausting.

Sam.

[mlinder]

I'm sure it could be done with points Mark....my mistake.

That sounds messy....

[paulages]

Syscrush, "crossplane" eh?  Anyone ever done that with a Honda SOHC that you know of?

It would require more than a cam & ignition change - it would require a custom crank, and ideally a balance shaft, too.  I've never heard of anyone changing a production screamer or big bang I4 to a crossplane.

would not require a new crank. 1-4, and 2-3 already rise and fall together. it essentially makes it a 360 degree "twin," like most british twins of the 60's and '70's.

Nearly right Paul, it wouldn't need a new crank but it would be like a big 180 degree twin like the CR93 and CB72/77s.
The 380 British twins are like the CB92 and C72/77s, both pistons rising together but one firing while the other is exhausting.

Sam.

yeah, you're right.

[mec]

the big bang firing order is not worth a thought on our weak vintage bikes.
big bang or screamer, it seems it is more a yearly trend made by commercial experts.

big bang is a must have, it does good to the rear tire and is better controllable out of corners.
screamer is the way to go, gives more power and is controllable as well.
big bang .......the way to go.

the motoGP ducati with 1000ccm was a big bang.
the GP09 ducati was a screamer.
the GP10 will be a big bang
..............
what more to say.

mec