Topic: "Help Juntjoo fix his CB650!" thread

[Scott S]

 Wait a minute.... those carbs have a PUSH  and a PULL throttle cable. It looks like you have the choke attached where the push cable goes. I think.
 I've only had one CB650, so I'm no expert, but I don't *think* the choke cable goes there.

 EDIT:  watched the video again and I see that you have both throttle cables.
 It definitely looks like the choke is the culprit.

 If you pull the carbs again, can you install the cables without installing the carbs on the bike?
 I'd like to see the choke cable attachment and actuation. I'd like to see the gap on the butterflies from the bench sync at rest, too.
 Try attaching the cables and watch the choke operation before you install the carbs and see if you can find the culprit.

[Scott S]

 Remind me again what part of Florida you're in?

[juntjoo]

Remind me again what part of Florida you're in?

thanks. SWFL, Cape Coral.

[Scott S]

 Again.... I'm no 650 expert. I had those exact carbs only once. But I would think that the choke should only operate the choke and not the throttle. That last video looks better.... I think....

 I had a problem with the accelerator rod/diaphragm.  I had to find a replacement and cut the rod to the correct link. And this little low-speed injector "pipes" in the throats of the carbs are TINY. Took me several attempts to get them clear.
 The good news is, the 650 is a little hot-rod. If you persist, I think you'll be very happy with it.

 I ask your location because I'm a VJMC member and I might be able to find a fellow member that's local to you and willing to lend a hand, if needed.

 **Dang...looked back and, has it really been 5 years since I worked on that 650?! The 650 engine swap starts on page 4. 
 http://forums.sohc4.net/index.php?topic=67907.75. **

[Yamahawk]

Yeah, I think Scott may be on to something, your throttle may not supposed to be opening when you use the choke. Its cable should be hooked to the enriching circuit, and not the throttle. Are your push/pull cables both installed on this bike? I have seen some where the PO removed the push cable from the throttle, and just used the pull cable. Check that your choke isn't hooked up wrong...really not sure if it would even work throttle-wise if your choke cable was hooked to the push side of the throttle linkage..
Charlie

[juntjoo]

I thought we all had same carbs, either the pd or cv like mine. What do you guys have?

Can anyone with cv carbs, can you watch your throttle pulley while actuating your throttle to confirm it moves or not? I can't imagine what that little bendable lead arm is there for.

"Its cable should be hooked to the enriching circuit". Are you talking about the hole the throttle plates uncover with the  black idle adjustment knob or the holes for the pilot screws? I'm pretty sure this adjustment "fork" does something and it's only interacting with the choke shaft

[Yamahawk]

Yeah, the knob pulls a rod, which is linked to a fork that pivots and pulls a plunger on each carb. That is an enriching circuit. (choke) It is different than the manual chokes used on other carbs that physically close off the intake bell of the carb. It adds extra fuel by the enriching circuit, and that's where you get the higher rpm from.
Charlie

[juntjoo]

Yeah, the know pulls a rod, which is linked to a fork that pivots and pulls a plunger on each carb. That is an enriching circuit. (choke) It is different than the manual chokes used on other carbs that physically close off the intake bell of the carb. It adds extra fuel by the enriching circuit, and that's where you get the higher rpm from.
Charlie

well I dont have this plunger you speak of, must the pd carbs, but okay, that hole my throttle plates  uncover would be this "enriching circuit".

[Flyin900]

There are a few holes in the carb venturi floor that you are referring to and yes that is part of the slow speed enricher circuit along with that brass tit in the floor of the venturi throat that is part of the accelerator pump circuit.
Did you verify you are getting a squirt of gas out of those brass nozzles in the front of each carb throat when you pump the bell crank after you cleaned and rebuilt them. This isn't part of your issue presently, yet will be a problem if those circuits are not all clear when you do get it running and ready to ride.

[juntjoo]

There are a few holes in the carb venturi floor that you are referring to and yes that is part of the slow speed enricher circuit along with that brass tit in the floor of the venturi throat that is part of the accelerator pump circuit.
Did you verify you are getting a squirt of gas out of those brass nozzles in the front of each carb throat when you pump the bell crank after you cleaned and rebuilt them. This isn't part of your issue presently, yet will be a problem if those circuits are not all clear when you do get it running and ready to ride.

yes thanks. just about everything engine/carb related has checked out as far as I can tell. Just on my brakes now so I should be off and riding soon

[juntjoo]

does the path from the fuel tank petcock to the brass fuel tube over the carbs have to be slanted downwards to allow fuel to drop?

petcock to carburetors https://imgur.com/a/u2zvA

what I did to it was rebuild the petcock, and remove the vacuum operated one that no one likes, then connected a tube there but it's mostly horizontal and maybe a bit vertical before it curves downward onto the brass tube and Ive put a lot of fuel in the tank and confirmed it makes it to the bowl at the bottom of the petcock. So what could be blocking it's path beyond that bowl? Did that evil petpock I removed have a particular function that must be substituted somehow that I missed?