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SOHC 750 Crossover pipes

Sprocket

CB750 Enthusiast
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Location
Brighton, MI, USA
I built these pipes for my chop. They are straight drags but can be built with collectors for 4-2 pipes that sound way different than what you're useed to. Cylinders 2&3 and 1&4 are paired together. This changes the firing order you hear from both sides of the bike, and aids in exhaust scavenging when collectors are used.
They look pretty cool too.

I'm making a few changes to the next set and will be fixturing them for production.


CB750 Crossover Pipes1.jpgCB750 Crossover Pipes2.jpgCB750 Crossover Pipes4.jpgCB750 Crossover Pipes5.jpg
 
Need to do a little tuning after opening this motor up to breathe, acting like a lean miss in 2&3, to be expected I guess. I'll see if I can get it sorted with AF screw, if not, time for a crab clean and synch. Getting ready to ride to North Carolina in a week and a half.
 
They look good! Waiting to see what the next set looks like. Will the next set have collectors on them?
 
I'm thinking of putting collectors on these as my bike runs better with 4-2. It came with straight drags and when I switched to 4-2, it picked up notable power. Will still run the collectors wide open though :)

As far as shapes on the next set, they will be close to what they are now, just a few angles I'm not quite happy with. Needed both sides done to see it. Mostly #3 needs to angle more toward center for visual symmetry. #4 needs a slight tweek as well.
I'm looking for a clean X shape when viewed from the front.

Should have another set in early July, time is tight for the rest of this month. WHCM kills 4-5 days and I'm racing a mini-bike (that I still need to build) at Thunderdrome the following weekend.
 
The 750's do run better with some sort of scavenging exhaust. I ran short straight drag pipes before also and even switching back to stock exhaust seemed to make them run better. I do like the look of your pipes, very clean bends.
 
I've been painting my pipes flat blue on thes bike 'cause I'm too cheap and can't deal with the lead time for chrome.

The flat blue was inspired by the late great John Britten of New Zeeland.
The man who built a bike from the ground up in his garage (including engine castings and all carbon fiber bodywork...) and beat the bigs @ Daytona supertwin 200. BEAT Ducati when they were the top of the heap!
Well... didn't win the race, electrical problem in the last lap took him out when he was a couple of laps ahead if I recall.
John Died of cancer back in the 90s, shortly after that race. He is fondly remembered.
http://www.britten.co.nz/
 
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Well, I had one helluva past few days.
Went to visit Phil the Honda Doctor in Waterford, MI.
He's they guy that built my 836... 36 years ago! Still in the same location, still building fast Hondas!
Got the jets (it was running on stock 110s) bumped to 130s.
Button up the carbs and kick it over. Bike runs on 1/4 cylinders but 2/3 are dead.
Checked everything, set everything, points, timing, power to both coils, power @ coils from points, dead coil on 2/3.
Freaking out as it's late Sat evening and where am I gonna get coils over the weekend?
Then I remembered the '78 getting ready for CBR900 suspension/wheels.
Swapped out the coils and she fired on the second kick (Idle was too low on first to hold it)
Bike runs like a raped ape that used tobasco for lube!

Here's the startup
[video]s1165.photobucket.com/albums/q583/choppersprocket/CB750%20Crossover%20Pipes/?action=view&current=HPIM3091.jpg[/video]
 
Tabasco for lube :laugh:

That's great that you got it running well and figured out the coil thing. Is the Honda Doctor Phil's Cycle Shop right off of M59? If so my mom lives just a few miles from there.
 
Ran to the WHCM last weekend and tested the pipes for real! 1300+ miles, no issues at all.
They work great, roll on power is off the hook powering through fast twistys without shifting much at all. Hell, didn't need to shift much in the mountains of West Virgina at all. Pretty much for gas stops and tolls...lol 5th gear and let 'er eat!

Almost got ran off the road by an SUV driving arsehole on the way home, and powered by him between him and the rumble strips in about 2 seconds. Bitch flipped me off when I took my spot back in front of his air conditioned ass. Was doing about 80 when he pulled into my lane watching me. I saw him look right at me and twisted the right grip!

Next set will be on a stock frame for sure, and that set will get fixtured for producton.
I'm gonna try and do some A/B dyno pulls to see what the actual gains are. Local HD wrench has a chassis dyno for reasonable $$.
Hell, the local Stealership has some wrenches that would like to see what my chop will do...lol
Put the 110s back in with the corked up 4-2s for a baseline, and swap the good stuff back on. those 130s did the trick ;)
I might even bring the original drags just to see where it was when I got the bike.

I'll post results when I get them.
Production is planned for early August after BBB and MI Chopperfest.
I'll have some timeslips to post too :buttrock:
 
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