1976 CB 750 carb hell(p)

[legitmw]

So I'm the typical douche that put pods on his bike ya ya. Im also running open headers. I want to get some sort of small baffle or something just to give it some back pressure. I cleaned and rebuilt the carbs and I had 110 mains and 40 slow in and it ran well overall but was pretty lean. I read so many guys that put 130 mains in and it ran great so I did that but it really won't run at all now. I have to choke it to get it started and when I rev it it just bogs. Won't idle at all. So I'm guessing 130's were way too much. Should I try 120's?

What jets are you running with pods and open headers or 4-1? Thanks

 

[gijoe13844]

Trying to tune cv carbs with shitty pods AND open headers is really an impossible task. Anyone who says it runs great with their tuning hasn't ridden something with real power or they'd realize how stupid they are.

Get a real exhaust and start there. Otherwise you will have to retune the pos every time the temp and elevation changes. Don't make a really tough task even more complicated.

Also....why open headers? Why? I don't get that one.


Not trying to sound like a douche it's just stupid to make things tougher. Like saying ....Hey I'd like to build a 50 cal that doesn't kick at all, is dead accurate at 1000 yards and costs me almost nothing. Ummmm...no. Certain things just aren't possible and sound dumb to ask for.

 

[legitmw]

I don't have CV carbs. I'm not THAT stupid. I have a Mac 4-1 and that's the header I'm running. My rear sets are just blocking putting the exhaust on. I've been working on making a small baffle and exhaust just haven't finished.

I'm just wondering what jets people are running with my same setup so I can get some jets in the mail while I finish my exhaust. I'm thinking 120's. Also I might just throw my airbox back on if I can find it. I bought pods before I knew anything and I'm getting to the point where I hate them with all my life.

 

[carnivorous chicken]

Wait, you're 76 CB750 carbs aren't CV carbs unless I'm experiencing a massive brain fart or they've been switched out. Pods will work -- no shame in using em, carbs are easier to take off than with those stock Honda SOHC-4 airboxes. Of course depends on what pods you're using. Advice re exhaust I'd second though, and you're neighbors will be happier. Sounds like you are running rich and you've answered your own question. And you've got some room to play with the needle setting as well.

 

[gijoe13844]

Yeah you are right they aren't cv...i had my own brain fart. I still think you have a tuning nightmare with pods and open headers tho...

Emgo or kn or uni? Maybe consider stacks instead...with filters of course.

 

[gijoe13844]

Just to clarify...I never meant to infer you were stupid. Post was more aggressive than intended. However, I think it's dumb to make a tough task impossible due to stubbornness or laziness.

It really does annoy me tho when I hear anyone say that there "insert motor" runs GREAT with pods and open headers. They are either incredibly ignorant or incredibly stupid. Either way they clearly don't understand the dynamics of an internal combustion engine.

 

[legitmw]

K&N Pods. And don't worry I didn't think you were calling me stupid. I really just need to get this damn exhaust sorted out before I try to do any tuning. I need more beer too :'(

 

[SaltCityCafe]

I asked before but it didn't get much attention so I will hijack a little here. Has anyone noticed any difference or advantage to using oval cone style k&n pods vs just the standard round cone style ones

 

[SrgtBear]

Ideally you should be trying to achieve two things here. Vacuum pressure and back pressure. Truth of the matter is that these older bikes work best with a stock airbox and exhaust the provides back pressure. Alot of your tuning is going to be trial and error with your setup. There is no magic recipe.

My first setup had 2 headers with a very open exhaust. Bike loved to perform with throttle wide open but sucked at low and mid-range. Then I put a 2-1 exhaust on it that made my bike perform way different. It allowed for better response in mid-range and held a consistent idle better. The next issue I had was the slow range. My bike overheats during idle. You can adjust the air/fuel mixture screw but it is only as good as the size of your slow jet and how much fuel your letting into carb. Therefore a bigger slow jet was needed.

I don't think you'll see much of a difference between oval or cone pods. You need a vaccum type pressure which pods don't do.

Here is a chart that I find helpful for tuning