in need of help

[Racingrobby]

I have a 1980cb750f ss and Im having problems . Cleaned the hell out of the carbs and have new boots and new iridium plugs . The problems is that Im unable to rev passed 5k ?? It will just cut in and out , Does anyone have any idea's??  Any help would be great...  Thanks

[sgtslag]

Have you checked/cleaned the Main Jet circuit?  Sounds like it might be blocked.  When you say you "cleaned the hell out of" the carbs, can you be more specific?  Did you remove the jets, and/or check them for plugging?  Did you go through the Floats?  Is the gas line clear?  A partial blockage may choke off fuel flow, leaving the carbs sucking mostly air.  Is there a fuel filter?  Is it clean, and free-flowing?  Just some thoughts on what to check.  Cheers!

[Racingrobby]

I removed all jets cleaned them and ran a e-string though them I cleaned the floats and housing my float arent adjustable . Im having the same problem as I did with another set of carbs . I broke the chock spring and couldn't find one . So someone gave other set . So I thinking its not the carbs . ?? Oh I ran ether in with out air filter in and it's still wouldn't get me pasted 5k ..  I looked for the fuel filter in the petcock I don't see one ? And the. Ike came with extra tank and I don't see one in that petcock ?  It's now at a bike shop and the guy said he will check the wires and coils .  And I asked to check the timing and he said he check but that prob not the problem .  Should he check that first?    I hope all this makes sents it's really hard to type with a iPhone . Lol

[Racingrobby]

Oh I did put a inline fuel filter on .

[TOOLS1]

On the timing, it could be the advancer not working. But I would suspect a vacuum leak.
TOOLS

[Racingrobby]

Ok thanks I check. Where is there vac. Lines ? I do know that the rubber T that's just behind the carbs ripped and I black taped it . I think it was for the crank hoes . One rubber line on the left and the right and T back maybe the air box. I can't rember now .  But again where should I check ?

[TOOLS1]

I would check the rubber boots, and the diaphragms on the top of the sliders. You can check the boots by running the bike, and spraying carb cleaner around them. If there is a leak, when the carb cleaner hits it, the engine will speed up.
TOOLS

[Racingrobby]

Ok great . 😃. The boots on the carb are brand new  . But I'll check the box ones . Ok don't want to sound dumb but what are the sliders ? Is that where the top are and a ring in each on are ? Maybe the Plastic ring is bad?  

[Re-run]

Yeah you sound to be running really lean, not enough fuel to keep going. Do as tools said. Check them diaphragms as they can crack. Do you have the manual? It will show all the parts or you can go on to bikebandit.com and they have exploded parts views.

[Racingrobby]

I have cv carbs . Did they have sliders ?

[shinyribs]

Is sounds like you are running the stock airbox,do you have the stock air filter in place,too?Is the exhaust stock or has it been opened up? Your bike is doing the same thing mine did after I went to pods and open exhaust.It was lean and had to be jetted up.I'm not saying that is whats up with yours,just an area to consider.Do the plugs read lean or does the A/F look correct?

[TOOLS1]

If, you take off the tops of the carbs, you will see the diaphragms. The slides are connected to them. Also, you do not need to worry about the boots to the air box, just the ones to the head.
TOOLS

[Racingrobby]

Check everything today everything was fine . Sat there talking the shop guy and thinking that it could and when he said well maybe the exhaust is pluged up , took the header off and started it and it rev right up good. So I well I need a exhaust ?? I would really like a 4 to 1 anyone have any ideas ?  I wish I could even find a good used exhaust .  Just don't want to shell out the cash for a new one ( I'm cheep and poor).

[Racingrobby]

Oh I running all stock . No pods paper filter . And if I do get a 4 to 1 exhaust I still have to rejet on stock air box?

[TOOLS1]

Do, you need to change the whole exhaust? You might be able to replace the muffler with an aftermarket one. For a 4 into one I would go with a MAC. However, you will probably need to re-jet.
TOOLS

[Racingrobby]

I only really need the right side . But for a stock on eBay they are used and cost about the same for a new 4to 1 . Maybe I could sell the left side to For a new 4 to 1 ?? I'm not sure what to do ?
 

[sgtslag]

The general consensus, here, is to re-jet when changing the exhaust.  However, I've read other comments, elsewhere, that it is a myth, that the exhaust pressure change is so small, that it is not necessary.  I guess I would leave it alone, until I saw evidence that it needed to be re-jetted -- why waste money?

Folks have recommended re-jetting if you replace the paper filter with a K&N air filter.  I put a K&N in mine, but I never re-jetted, and it runs just fine.  YMMV.  Cheers!

[LukeM]

If you want a neat sound, and something that may just bolt on, find a Harley Sportster muffler.  My son and I put one on his CB550F, and it went from a straight-pipe rumble to a sportbike purr.  Quite a difference. I think the only "custom" part was fabricating a bracket from some aluminum stock to bolt it to the rear footpeg hole.

Cheap enough on EBay, or maybe your local Harley shop has some sitting around, since usually the first part a new Harley owner changes out are the mufflers.

I'll try and upload a QT movie of my son's bike with the new muffler on it.
Luke M

[LukeM]

I think this will work. Let me know if it doesn't.

High Speed pass with new muffler CB550F

There are 2 more videos, one when he first got it going after the change, and one of me on my Shadow.  Also, please no comments on his license plate.  He didn't have any choice about it. You know how the BMV is.

Luke M

[shinyribs]

It worked. And it sounded nice!.Hey,your bike dont sound half bad either.As far as the tag...i dont have a problem with the number 13     poor guy.That had to suck