Alright so I have been working on my dad's cb750 1982. The issue I had was that the bike did not respond to the choke being pulled open, the plates where operating correctly. So I tore into the carbs replaced all the diaprahms made sure everything was clean reassembled the carbs put them on the bike now the bike starts when cold and responds to choke, but the idle sits at 3000 rpm and the idle **** is fully backed out. Anyone have any ideas about the problem now. I am thinking ballance issues but just wanted to pick the perpetual brain of the chicken clan to see or confirm. Thanks in advance.

 

Did you check the boots holding the carbs onto the intake runners for cracks?

 

Check throttle cables for correct slack and routing. Sync carbs.

 

boots on both ends are in good shape, the bike runs great just has idle issue that it didn't have before I fixed the choke. So is that a +1 on sync? My theory is that when I fixed the choke issue it somehow has really thrown off my balance. I have balanced carbs a number of times and have previously balanced these carbs. It ran great before it was just a cold blooded beast because the choke didn't work. I just was hoping that I just need to re sync them and was hoping that would be the overall consensus. I will try and sync them later, but since my sync tool broke I will have to wait for my gauges so I can build my own manometer.

 

My first thought was there may be an air leak somewhere on one or more of the carb boots on the motor side of the carbs. I would go through the motions and start checking throttle cables and the choke cable. I've seen the choke cable get a kink in them before.
One place that would be helpful is cb1100f.net. Sometimes they get a little uppity if the bike isn't an F model, but most people are more than willing to lend a hand. I'd poke around there for a while, there's a ton of info for the old hondas.
Why did you replace the diaphrams on those? Aren't they the all aluminum slides without any rubber on top?

 

well the rubber plungers, I think they are called air cut off valves, and I also replaced the accelerator pump, all of them where showing some wear. I am more than sure that there is no leaks and that the cables are operating correctly. I very carefully put the carbs back on the bike. Also I am pretty familiar with this bike I already brought it back from the dead, and my dad put 7000 miles on it this summer. I just didn't like the idea of it being so hard to start when cold so I dug in. Since my ballance tool broke I was just wanting some closure because I can't try until my new parts come in for my sync tool. Problems like these frustrate me because I won't know for sure until I balance the carbs, which I am a week or so away from. Thanks though for all the thoughts and tips I like the discussion and sometime having someone question the simple stuff will make you check and often you will find the problem.

 

so it was balance. I was able to test out my homemade sync tool and it worked awesome. Heres a picture of my setup. All in all it cost me $20 for all of the gauges shipped and $20 in brass fittings. Although if I did it again I could just get the female ended gauges then I wouldn't have had to buy brass couplers, that would shave ten off the cost.

 

So it's running good now?

I love the style of the early '80s CB750F and CB900F.

 

Glad to hear you got it worked out ok. Most people would just give up on it, and say it's too old or something along those lines. I brought a '80 750F back to life last summer. I bought the thing for $49 and it ended up needing new cam chains, a valve, and a whole lot of TLC. It was worth it though.
Here's a pic of it after I got it together.

 

very cool, I like the old cb's too, my first bike was a cb 450 and it got me started well. Ones a 450 and the other is my dad's 750 c, the f was defintly sportier looking.

 

My 2nd bike, bought new, was an '86 CB700SC Nighthawk. Red, white and blue version with blacked out engine and wheels. I put a Supertrapp stainless 4 into 1 on it at 600 miles, and sold it 5 years later with 48,000 miles.

I loved that bike until I discovered big twin torque on a BMW R100RS.

 

my 1st bike was a 1982 cb750 custom, blue & blue in color. i was hooked the 1st attempted down the driveway!!! i should hae kept that bike.
enjoy!!!

 

I am there with you guys, here is my bike i boughjt new while in college in 83. It is a one owber bike and she looks the same today as she did 10 years ago. Here in TN you can tag a bike as an antique at 25, so i did and never have to buy or re-new tags anymore. My plan is to convert her to a SuperF some day. I already have the CBR600 wheels and forks, just got to find time to take her apart and have the tripletree milled out. 17" Radials will be a welcome change.

 

bought my 750F when they came out in 79, worked up to a 900F in 81 and kept that till I got the superhawk. Missed the bike and bought this 2 years ago in need of some work. Thumper, I'm waiting on my triples to come back from the shop and then will start mounting the F2 front end.

 

very cool bikes, heres another bike I brought back from the dead for my friend, a vf750f interceptor 1983 I think alot of people who own soup chickens started out on the older cb and honda's, and its cool seeing some nice examples still floating around in the hands of those who can still enjoy them.

 

Nice, I think you got the last of the F Models in '83, replaced by the 700 Nighthawk in '84. And of course the Interseptor came out in '83.

 

I know, what was i thinking, i could have had an 1100F or an Interceptor for just a few hundred dollars more.

I paid $2100.00 tax and all for mu CBF when i bought her.

 

Hey PM me the contact info on who is doing your triple tree and let me know how good the work is.

Cost too ....

Thanks


Is the same shop making your wheel spaces as well.