Topic: Riddle me this, riddle me that, a four into one carb could it do that!!

[oldhondarider]

I'll snap some pics of it along with it lined up to a rack off an "F" I have..

Thanks mate!

sorry for the delay..  I'm trying to get prices for shipping to AUS.... but christ it's expensive... I'll give you the options and their prices on the next post.

[Terry in Australia]

That looks fantastic mate, wrap it up and let me know the total with shipping ASAP, I'm flying out to deepest darkest  Tasmania to do some Army training next Tuesday and I won't be back until the end of April, nor will I have access to a computer, so I want to pay you before I go. Thanks again mate, I'm really looking forwards to trying it out! Cheers, Terry. 

[camelman]

So, how's the 1-4 intake coming?

[Terry in Australia]

So, how's the 1-4 intake coming?

Ha ha, yeah, like this thing was ever really gonna get off the ground..................

[camelman]

Yeah, I didn't figure this project was going to get very far.  I'm surprised to hear about Rotortiller's bike though.  That at least points to partial success.


However, I did get to thinking about a 2-4 intake system.  It would really be more about aesthetics than performance, but it would suffer the same power robbing issues that a 1-4 would run into.  I wonder if there is a way to isolate pressure waves from ganged cylinders through intake geometry to eliminate or reduce the "cross talk".  For instance, the longest expected pressure wave could be sized so that a raised ridge in the intake runner (possibly coupled with a very porous screen) just after the carb could isolate the pressure fluctuations from entering the carbs or transferring between cylinders.
I also wonder if turbulators (internal ridges in the intake runner) could act as rebound locations for shorter wave forms.  I know this concept is heavily used in large diesel engines all the way down to small gas engines (variable intake runner technologies using active valves inside the intake to vary runner lengths), but this concept would use flow characteristics and fixed surface features as opposed to active valves.

Oh well, I doubt I'll build it... unless I get the bug to really change the looks of my next 350f custom.

Camelman

[Pinhead]

Yeah, I didn't figure this project was going to get very far.  I'm surprised to hear about Rotortiller's bike though.  That at least points to partial success.


However, I did get to thinking about a 2-4 intake system.  It would really be more about aesthetics than performance, but it would suffer the same power robbing issues that a 1-4 would run into.  I wonder if there is a way to isolate pressure waves from ganged cylinders through intake geometry to eliminate or reduce the "cross talk".  For instance, the longest expected pressure wave could be sized so that a raised ridge in the intake runner (possibly coupled with a very porous screen) just after the carb could isolate the pressure fluctuations from entering the carbs or transferring between cylinders.
I also wonder if turbulators (internal ridges in the intake runner) could act as rebound locations for shorter wave forms.  I know this concept is heavily used in large diesel engines all the way down to small gas engines (variable intake runner technologies using active valves inside the intake to vary runner lengths), but this concept would use flow characteristics and fixed surface features as opposed to active valves.

Oh well, I doubt I'll build it... unless I get the bug to really change the looks of my next 350f custom.

Camelman

CycleX sells a 4-2 intake system and claims increased performance.

New carburetion system for Honda 750 SOHC-4

[Goldbug]

I think we sometimes forget WHY OEMs do things. Mass production automobiles were meant to be relatively maintenance free without the need for many adjustments by the owner. Motorcycles... well these were always performance machines. If you have to adjust the valves on something then it's implied that there's going to be the need for some tuning and tinkering and mechanical ability. Single carbs worked on cars and provided good drivability with minimal headache for the owner. Some even made quite a bit of power. But take a closer look. In 1970 your average hydraulic lifter 7 liter engine made around 400hp with a single quad carb (or more like 365-390 actually). Or around 57hp per liter. In 1970 a CB750 was making around 90hp per liter. Think about that a second.

All else being equal you'll lose efficiency going to one carb in the name of less maintenance and adjustment. Given the nature of naturally aspirated engines you'd have to do A LOT of work to make up for that loss. Increasing displacement, increasing RPMs (read: maybe better internals and valvetrain), bigger cam, bigger valves, head porting, more thought into the exhaust than just buying a MAC... In other words, if you're looking for performance and have half a brain you WOULDN'T be doing that.

If you're looking for Grandma's 1968 Olds wagon that made 40hp per liter but was rock solid, never in the shop and started easy on a cold Wisconsin morning then by all means switch to a single carb on your CB750.

Or perhaps maybe a Camry beckons.