1981 CB750 Super Sport

[Johnnylevi]

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[TOOLS1]

Unless, you have a lot of experience tuning carbs, you should stick with the stock airbox on the DOHC bikes.
The collar, for the exhaust should slide right past the frame. Maybe it just needs rotated?
TOOLS

[pat english]

let see some pics of this...

[Johnnylevi]

 Here she is when I first got her.  And here's what she looks like now. So far it seems like I've just made things worse.I'll be putting the airbox back on when I get a chance. I took of the exhaust because it was so rusted and had holes in it. Thinking of upgrading to a 4-1 M.A.C exhaust. The goal is eventually have this thing as Cafe'd out as I can get it, as properly as I can get it. I've cleaned out the carbs since the last time i posted. They were pretty gunked up! Lots of (I think) gas deposits. Last time I had it running it was only firing on 2 cylinders at idle and 3 cylinders at 8k. Is that just a carb problem or should I be warry of anything else?

[Johnnylevi]

I've tried rotating the collar every which way and it still hits the frame. Have any suggestions TOOLS?

[pat english]

that thing looks pretty sweet as is..you should check for spark..you may have a bad coil..as for the flange,you just gotta wriggle and turn it untill it comes loose..you might try to get all the others off and loose first then go back to the one thats giving you trouble.

[Hellbilly429]

Pull the plugs and make sure they aren't just fouled out.

Also if you washed the bike.... pull the cover off of the left side of the motor and make sure you didn't get water into the ignition system, I had gotten water in there pretty easily and eventually the bike would not run anymore. Cleaned out moisture and it ran. Oh, and don't freak out as there is supposed to be oil in there, so make sure you have bike on the center stand when you pull the cover off.

[Johnnylevi]

The other day it was firing on all four after it warmed up. Could that still be the coil or is that a carb issue?

[pat english]

i really dont know,but its not hard to check for spark real quick..you might need someone to help you though.

[shinyribs]

If the problem is intermittent,it could be a loose wire feeding the coils. Hellbilly and Pat are right,though. The first thing to do ,and the easiest,would be to check your spark. Plus,it's free to do yourself.

First,do what Hellbilly suggested and check behind your ignition cover for water or corrosion.

Then a pull a plug out of the head and put it back in the plug wire. Crank the bike ,making sure it is neutral, and see what sparks and what doesn't. If the spark is a good bright blue ,then it's strong. A yellow spark is a weak spark. If you pop all 4 plug wires off you know the bike won't try to start,probably a good idea.

[Hellbilly429]

also wear or glove on the hand that you hold the plug in, lol, if the boots leak any electricity (which means they should be replaced anyways) you will get a pretty good jolt since you will probably be touching your other hand or laying your arm across the bike and grounding yourself. unless of course you're into being electricuted then have at it...

[Ghost-Flame]

That's a sweet looking clean bike. I don't think a 20 yr old should be messin' with such an old and obsolete bike... too many problems for a young guy to handle, just give me a call and I will take it off your hands I'm closer to 60 than 20. JK. Have fun and good luck w the project!

There's a young guy, in his 20's, near me that I run into at the gas station occasionally he has more than a dozen old bikes... BMW's and Japanese. They all run great and look like shit and that's the beauty. Anyone can finance a new bike it takes someone special to appreciate the older bikes!

[Johnnylevi]

My friend just gave me a set of Mikuni's. They came off of his 1983 Suzuki GS750E. Does anybody know anything about these? Where i can find the model?

[Lucky 1]

Just use a clamp on  timing light on  any spark plug wire it will tell you if it is firing.

[Johnnylevi]

Hey guys, a little update on whats going on:
The bike is with my grandpa about two hours away  ( moved and didnt have a place to store it) Good news is is I'm getting it back within a few weeks ( owners of my place were kind enough to clear out a place for me to park it)
secondly! I'm trying to figure out how to change the name of this thread to just 1981 CB750 F as i would really just like to get this thing going and start riding. I don't know enough to make this thing into a Cafe anyways!
New passenger plugs on the way for stock carbs ( others were falling apart) Dunno if that will help with the poor idling?
I will try out all of your advice on the spark tests and everything once i get a chance, but like i said its about 2 hours away and my grandpa insists that he doesn't need to do that. (mechanic for about 45 years)

Thanks all!
- Johnny

[Johnnylevi]

Quick question. Figured out i have the push in idle jets for my carbs yesterday. Guess my bike is from early 81  does anyone have a good way of taking these out to clean them?

[Hellbilly429]

Quoting Tools here

The best way to remove those pilot jets is to use a 4-40 tap, 4-40 screw, nut, washer, and a short piece of metal break line tubing. The idea is to tap into them about 1/4 inch, then slide the break line tube over the jet, and screw the screw into the jet. Then by tightening the nut down, you pull the jet right out. However sometimes the jet will come out while you are tapping it. Also the threads will not hurt anything in the jets.
TOOLS

Now this wasn't for an '81 but it was for pressed in jets.

[Johnnylevi]

Thanks for finding that for me Hellbilly! Just got done dismantling my carbs and soaking them in pine-sol . Pics to follow.

[Hellbilly429]

No problem, the search function is your best friend here, and Tools is like the budha of these bikes

[Hoosier Daddy]

 Just getting acquainted here and found your thread...
To answer a previous question. That carb rack off the Suzuki should be Mikuni BS32's I believe.