Author Topic: '79 CB750  (Read 5129 times)

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Offline tennesseebreeze

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Re: '79 CB750
« Reply #25 on: July 30, 2015, 10:16:37 AM »
This is from the manual you linked to. He calls it the Primary Main Jet Emulsion Tube. There was a jet on top of it that screws in separate. Those came out and I discovered the ones underneath are stripped. I guess I'll have to easy-out those suckers and replace them.
'79 CB750F, '73 CB500K2, '78 CB400A, '71 CL100

Offline flybox1

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Re: '79 CB750
« Reply #26 on: July 30, 2015, 10:19:34 AM »
try PB blaster first
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

"This is my CB. There are many like it, but this one is mineā€¦"

Offline tennesseebreeze

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Re: '79 CB750
« Reply #27 on: August 04, 2015, 11:13:57 AM »
I got my carbs back in the bike and lo and behold, the thing is running great (aside from the charging issue I'm working on). Here's what was there:
-stock airbox with oiled air filter, 4 into 1 kerker exhaust with no baffles (it's the 750F, so it originally came with 4 into 1 WITH baffles)
-74 and 96 jets
-floats set to like 6-7mm
-one pilot screw missing
-other pilots missing their o-rings and washers
-needle set to 3 slots below top
-2 stripped main tubes
-all else was pretty clean and in shape
Here's what I put into it:
-kept stock airbox but replaced filter with high flow paper type, same exhaust
-switched out the 96's for 105's, kept the 74's
-set floats to 5.5mm
-replaced pilot screw and all o-rings and washers- set them to 2.5 turns out
-set needle to 2 below top (I did this to compensate for putting a significantly larger jet in)
-replaced 2 tubes and cleaned the others
-serviced the acceleration pump
-polished the slides where they looked like they were abraded and added a very thin coat of lube
-new air box boots (they are attached with zip ties for now until I get the proper clamps)
-cleaned everything I could without taking the carb banks apart

I fired it up and got the idle right and now it accelerates like a freakin' rocket. No popping, backfire, or noticeable lag (it does still have a slight vacumn leak because of the zip ties at full throttle) I pulled the plugs and they look a little rich, but I think with a little tuning it will be fine. Thank you Flybox for your help!
'79 CB750F, '73 CB500K2, '78 CB400A, '71 CL100