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Discussion Starter #1
sorta like a train wreck but kinda neat just the same









how many NOS pairs of these do you have laying around?
 

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Discussion Starter #3
well for an inline 4 that's a pretty intelligent way to run 2 headers

hook up the companion cylinders

1 and 3

2 and 4
 

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thats what i meant. but they usualy arent that way with 4-2's i thought.

jc
 

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crossover pipes for a cb750 are not unusual. The idea was that you could use the exhaust flow from on cylinder to increase scavenging in the other. I am not sure if they are still made but they come up on ebay all the time.

That being said I have never seen a set like those. They are likely home made. At first I thought they were made from stock pipes but a look at the flange at the collar changed my mind.

I can spot two problems with that design right off the bat: 1) they run too close to the oil filter and probably add more heat than necessary; and 2) Oil filter changes look like a bitch in that you will get oil all over that pipe. Also kick stand clearance must be a real issue but the pics don't show that.

Hack, if you are willing to part with them I would like them just for the novelty of having them to add to my collection or rare, weird, oddball, and NOS cb750 parts.

at first I was curious as to why the inside of the frame was painted red, then it dawned on me - the whole frame was painted red at one point and then someone repainted it rattle can black without pulling the motor.
 

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Discussion Starter #6
they aren't mine but if the whole scary bike comes up for sale I'll get it

I've never seen that bend before but I don't think they are homemade in any sense of the crude manner one generally associates with the term

my guess is "somebody" that knew how made them and did as fine a job as Santee or anyone else making pipes for CB's

production........ I don't think so but I suppose these aren't the only ones out there

the sidestand is a non-issue

the only problem I see with them, I can't say the heat from the pipes being that close to the oil filter is great but I felt and didn't really see any problem..... however I didn't whip out my laser pyrometer......

but the fact the head pipes aren't equal length is the only real turn off for me

they really did sound good and the only reason I snapped a pic of them is they are the only pair I've ever seen
 

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A CB750 is "2" 360 degree twins paired together right?
Any two cylindes that would make up a 360 twin by themselves you'd think would work with 2-1 pipes for those cylinders, and another set of 2-1 for the other cylinders.

The two pipes exiting left look like they'd work nice...the two exiting right...yeah, quite a difference in length (can't tell that well from the pics). 2-1's are pretty forgiving....bet it would make some nice mid-range power if the lengths were ideal.

Hehe...looks like a simple set of F1 pipes all tangled up to get the right pipes into the right collectors.
JohnnyB
 

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I'm armed with a sandblaster and I have a itchy trigger finger...
 

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Discussion Starter #10
I was thinking, and I've been wrong before, that the CB has a 180 crank and the companion cylinders are as I listed them earlier

pretty sure, seems like 1 and 3 share a coil as do 2 and 4

most inline 4's have 1 and 4 along with 2 and 3 as companions

maybe the cb isn't 1 and 3 and my brain is rattled

one of you dingle berries should have caught that if that is the case so I won't feel bad regardless

maybe that's why it sounded kinda cool

ok so now I am doubting myself

is the inline cb different than most normal inline 4's?

he wouldn't come off the boots either, I tried
 

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Discussion Starter #11
oh wait...... it is indeed 1 and 4 along with 2 and 3 just like most every inline 4 out there

none of you goobers caught that momentary retardation!
 

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quote:Originally posted by HackAsaw

oh wait...... it is indeed 1 and 4 along with 2 and 3 just like most every inline 4 out there

none of you goobers caught that momentary retardation!
I caught it. but cb750 4into 2 pipes are usually 1-2 and 3-4 unless they are the cross over types. It makes sense that 1 and 4 would be linked in those cross over pipes becase when 1 is firing 4's exhaust valve should be just closing (1 and 4 fire off the same coil and the ignition system is wasted spark).
 

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Since I know nothing about fours....how does that work....if two paired cylinders are 180, wouldn't that mean that mis-matched pairs would be 360 degrees?

Meaning that 2-1 pipes...one pipe one come off one cylinder/one coil, the other pipe would come off one cylinder/the other coil?

I was thinking that on a four cylinder 180 degree crank...that two cylinder would always work 360 apart...and those you would pair into a 2-1 system. A 2-1 system usually works best on a two cylinders that fire one revolution apart.

Does the honda four fire two cylinders at the same time 180 apart? If so...then yeah, a 2-1 system wouldn't seem ideal.

I was just assuming from the layout of the pipes that it was collection two cylinders firing 360 apart...else what would be the point of crossing pipes.
I'm just feeling verbose...I seriously don't know anything about honda fours.
JohnnyB
 

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quote:Originally posted by jbranson

Since I know nothing about fours....how does that work....if two paired cylinders are 180, wouldn't that mean that mis-matched pairs would be 360 degrees?

Meaning that 2-1 pipes...one pipe one come off one cylinder/one coil, the other pipe would come off one cylinder/the other coil?

I was thinking that on a four cylinder 180 degree crank...that two cylinder would always work 360 apart...and those you would pair into a 2-1 system. A 2-1 system usually works best on a two cylinders that fire one revolution apart.

Does the honda four fire two cylinders at the same time 180 apart? If so...then yeah, a 2-1 system wouldn't seem ideal.

I was just assuming from the layout of the pipes that it was collection two cylinders firing 360 apart...else what would be the point of crossing pipes.
I'm just feeling verbose...I seriously don't know anything about honda fours.
JohnnyB
don't worry I know a few things about them and I am confused too. Mostly because I am at work and not in the work shop.
 

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Discussion Starter #15
1 and 4 are both up on the same time as are 2 and 3 are down

the collector scavenges the exhaust and causes a depression (suction) on which ever companion cylinder is on it's intake stroke which helps it fill more completely

that's the idea anyhow in sorta laymans terms

a 4 into 1 works better

multiple crossovers totally rule but will give you a head ache trying to figure them out only to learn afterwards that when the math, somewhat bogus for various reasons, actually works

you simply got lucky

and for sure the more common 2 into 2 pipes you see on many inlines do indeed have 1 and 2 together as are 3 and 4
 

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Anyone notice that sweet MadMax highway/crash bar? It reminds me of the spoke/infantry destroyers that mount on the hubs of chariots.
 

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not really a crash bar but a bar for mounting hihgway pegs that looks like it was broken off and welded at the end.
 
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