from four to two

JR wrote:

A few year back a member here - biquetoast I think - put a single carb on a 650.

Nope, it was The Milkman - here´s a link to the original thread:

kzrider.com/archive/viewthread.php?tid=23259#pid202597

LLC wrote:

Ive seen a CB750 run the same setup with an SU it worked real well.

I wont be using an Su but most likely stayin with the mikuni, or possibly a Bendix.

Nah, don't be a wimp! Here's the carb you need:

Holley 750 CFM

OnkelB wrote:

JR wrote:

A few year back a member here - biquetoast I think - put a single carb on a 650.

Nope, it was The Milkman - here´s a link to the original thread:

kzrider.com/archive/viewthread.php?tid=23259#pid202597

Ah yes, The Milkman !!!!
Told you my memory was hazy. :laugh: I did;nt even get the carb right. It was a stromberg.
Thanks OnkelB.

I should bookmark that thread.

650ed wrote:

LLC wrote:

Ive seen a CB750 run the same setup with an SU it worked real well.

I wont be using an Su but most likely stayin with the mikuni, or possibly a Bendix.

Nah, don't be a wimp! Here's the carb you need:

Holley 750 CFM

Thats retarded...

LLC wrote:

650ed wrote:

LLC wrote:

Ive seen a CB750 run the same setup with an SU it worked real well.

I wont be using an Su but most likely stayin with the mikuni, or possibly a Bendix.

Nah, don't be a wimp! Here's the carb you need:

Holley 750 CFM

Thats retarded...

True, but you gotta consider the source.

Holley can be made to work on anything....except sidedraft:(

loudhvx wrote:

Different length intake runners will pull different vacuum on the carbs. It is important to remember that the vacuum comes in pulses and the air pressure tries to accomodate these pulses. But air has momentum.

It would not be an issue if the vacuum was constant.

I did small scale modeling of the effects of port volume here. It also shows why a tuned port will get you more CFM with equal vacuum pulses from a cylinder.

I also did an electrical anlog model of it to confirm. (Electricity has many analogs in fluid dynamics.)

It's a lot of reading, though. Scroll down past the manometer stuff to the "further discussion".

home.comcast.net/~loudgpz/GPZweb/Manomet.../ManometerNotes.html

Interesting tests you did..... We should have a discussion on that in a new thread. There are some things I'd like to point out but I don't want to hijack this guys thread...

seanbarney41 wrote:

Holley can be made to work on anything....except sidedraft:(

Why wouldnt it work on a side draft? Ever heard of a straight six? All the fords chevy and dodge straight six's used downdraft carbs. Thats just angles in the intake manifold. that doesnt matter. Providing youre not working against gravity there is no reason why it wouldnt work.

larrycavan wrote:

loudhvx wrote:

Different length intake runners will pull different vacuum on the carbs. It is important to remember that the vacuum comes in pulses and the air pressure tries to accomodate these pulses. But air has momentum.

It would not be an issue if the vacuum was constant.

I did small scale modeling of the effects of port volume here. It also shows why a tuned port will get you more CFM with equal vacuum pulses from a cylinder.

I also did an electrical anlog model of it to confirm. (Electricity has many analogs in fluid dynamics.)

It's a lot of reading, though. Scroll down past the manometer stuff to the "further discussion".

home.comcast.net/~loudgpz/GPZweb/Manomet.../ManometerNotes.html

Interesting tests you did..... We should have a discussion on that in a new thread. There are some things I'd like to point out but I don't want to hijack this guys thread...

Please, buy all means. Who knows we all might learn something.

I frequent the Honda boards too because i have a cb750 and have seen all sorts of opinions on this topic. Cycle x makes great stuff and ken is a super nice guy to deal with and will lead you in the right direction. i have heard that those twin carbs run awesome but can be a real pain to tune. i have talked with guys about log manifolds and didnt hear too many people saying a lot of good about them. i did work on this guys suzuki samari one time that had a single carb off a harley with an aftermarket manifold that lookes like it would work great but it was long. i will try to find a pic.

www.zuksoffroad.com/MY-SIDE-2-Harley-Car...it-wintake_p_16.html

this had to runners out of each side that turned 90 degrees, then split into two more, it seemed to distribute air and fuel well between all cylinders, which was everyones complaint about the log. i want to build one for my cb750 if i ever get the time.

55fbomb wrote:

I frequent the Honda boards too because i have a cb750 and have seen all sorts of opinions on this topic. Cycle x makes great stuff and ken is a super nice guy to deal with and will lead you in the right direction. i have heard that those twin carbs run awesome but can be a real pain to tune. i have talked with guys about log manifolds and didnt hear too many people saying a lot of good about them. i did work on this guys suzuki samari one time that had a single carb off a harley with an aftermarket manifold that lookes like it would work great but it was long. i will try to find a pic.

www.zuksoffroad.com/MY-SIDE-2-Harley-Car...it-wintake_p_16.html

this had to runners out of each side that turned 90 degrees, then split into two more, it seemed to distribute air and fuel well between all cylinders, which was everyones complaint about the log. i want to build one for my cb750 if i ever get the time.

That would be a very good way to do it But not every bike has a frame that will allow that. Mine certainly does not. from 1.0L to 3.5L engines have been using Log type intakes for over 20 years now. This isnt something new that needs to be studied. Its a very simply concept. Providing IM not 6 feet away form the engine i will have no vacuum problems.

the outside cylinders starve with a single carb log. why not use a twin carb log?