Gixxus Christ! Posted March 9, 2015 Report Share Posted March 9, 2015 (edited) Those on here that know me know that I know my shit when it comes to working on bikes...especially vintage bikes. I've been called 'captain carburetor' by a few members on a few occasions. That being said, there are some fucking idiots out there. I'm a member of several bike groups on facebook, one of them being cb 750 four. Someone posted a pic of a rack of carbs off a 1980 cb750 pointing at where the push cable goes and asking what went there. in the pic the butterflies were open and you could clearly see the slide in the throat and the chrome tops that house the vacuum diaphragms. The predominant reply was 'choke cable'. I won't go into details but after clearly explaining not only how cv carbs work, telling the guy where the push and pull cables and the choke cables go there were still people commenting on the page that it was 'obviously the choke'. One guy even stated that he works on cv carbs all the time and that the butterfly valves are the chokes and go on the intake side of the carbs. I wonder how good his bikes run... /rant over Edited March 9, 2015 by CrazySkullCrusher 1 Quote Link to comment Share on other sites More sharing options...
smccrory Posted March 9, 2015 Report Share Posted March 9, 2015 Um no, the butterfly valves are not the chokes nor the slides nor the bystarter valves on a CV carb. I bet those are the same hacks who pull pipes and airboxes, put on short shots and pinecone filters and then dump the molested, shit-running bike on CL with "ran great before winter - will be awesome after a quick carb tune." [emoji21] 1 Quote Link to comment Share on other sites More sharing options...
Gixxus Christ! Posted March 9, 2015 Author Report Share Posted March 9, 2015 Pretty sure that's the condition this dude bought the bike in... lemme get pic... Quote Link to comment Share on other sites More sharing options...
Gixxus Christ! Posted March 9, 2015 Author Report Share Posted March 9, 2015 Pic posted with finger pointing to what cable goes here:Shitbox hack job bike the poor jaggoff bought: Quote Link to comment Share on other sites More sharing options...
smccrory Posted March 9, 2015 Report Share Posted March 9, 2015 Yep, that's where the push-pull cable from the throttle ring goes to the butterfly valves. As you know, CV carbs don't have cable lifters at the top of the carbs - their slides are vacuum actuated to better smooth out fast throttle changes by fueling only according to the actual airflow (though they're still not as good as measured and mapped fuel injection).So, yep, he bought a victim of sexual assault. Lol and it's both a soft tail and a sprung pan seat. Poor thing will most likely never run well now that the airbox is gone. You need harmonic dampening and equalization of the air supply to optimize CV systems. But you already know that! Quote Link to comment Share on other sites More sharing options...
gsxkat1100 Posted March 9, 2015 Report Share Posted March 9, 2015 Oh the stories I could tell you from the things I have found or heard from PO's. RTV gaskets for intake boots? check. Standard threads in carbs, check. Broken parts inside carbs from ignorant jackwagons, check. CSC, you have seen some of the shit I have to deal with. Quote Link to comment Share on other sites More sharing options...
Gixxus Christ! Posted March 9, 2015 Author Report Share Posted March 9, 2015 It's actually looking like I may be wrong... I've never seen one like it before but the carbs appear to have a bellmouth there where the butterflies are....which would indicate the intake side...which would make those butterflies the choke...except I've never seen a mechanical choke on a cv carb before....could I be the internet dipshit? Quote Link to comment Share on other sites More sharing options...
gsxkat1100 Posted March 9, 2015 Report Share Posted March 9, 2015 I looked on ron ayers at the 1980 cb750 c and the linkage and butterflies in that picture are listed as a choke assembly. I learn something new every day. I have never seen one like that either. Quote Link to comment Share on other sites More sharing options...
Gixxus Christ! Posted March 9, 2015 Author Report Share Posted March 9, 2015 So this thread will inevitably become a big collective thumb in my ass lol.... Quote Link to comment Share on other sites More sharing options...
smccrory Posted March 9, 2015 Report Share Posted March 9, 2015 Really? That's not at all what I had on my 85 CB700SC's CV cluster. Quote Link to comment Share on other sites More sharing options...
Bad324 Posted March 9, 2015 Report Share Posted March 9, 2015 I stopped when I got to "Facebook"I knew the collective iq in those groups is 14 1 Quote Link to comment Share on other sites More sharing options...
whaler Posted March 9, 2015 Report Share Posted March 9, 2015 That would be the very definition of a choke. The butterflies choke air making mixture more rich.The plunger type is not really a choke, but rather an enrichment valve...adding fuel to a fixed volume of air. Quote Link to comment Share on other sites More sharing options...
smccrory Posted March 9, 2015 Report Share Posted March 9, 2015 That would be the very definition of a choke. The butterflies choke air making mixture more rich.The plunger type is not really a choke, but rather an enrichment valve...adding fuel to a fixed volume of air. That's true, and maybe we're getting caught up in nomenclature. Regular, non-CV systems have a flat-side slide or round-side slide that's lifted by throttle cable to adjust both the airflow and the fuel mixture via its attached jet needle. From what I've seen, those carbs usually don't have a butterfly at all, but like you said have an enrichment valve. CV carbs on the other hand use the butterfly as the air regulator, but that doesn't directly adjust the fuel mixture - a vacuum-adjusted round-side slide responds to the instantaneous suction and adjusts the jet needle accordingly. In either case, if that guy is using a CV carb with short pipes and pinecones, he'll be lucky to get it to run without sounding like a jalopy. Quote Link to comment Share on other sites More sharing options...
Gixxus Christ! Posted March 9, 2015 Author Report Share Posted March 9, 2015 It'd very possible to get cv carbs to run good without an airbox, you'll have to take my bandit for a spin sometime to see. Just a matter of jetting and tuning the carb to match all that air. Quote Link to comment Share on other sites More sharing options...
smccrory Posted March 9, 2015 Report Share Posted March 9, 2015 It'd very possible to get cv carbs to run good without an airbox, you'll have to take my bandit for a spin sometime to see. Just a matter of jetting and tuning the carb to match all that air. Yea, I have heard that, but it takes a bit of an artist with time on his hands, no? Quote Link to comment Share on other sites More sharing options...
redkow97 Posted March 9, 2015 Report Share Posted March 9, 2015 It'd very possible to get cv carbs to run good without an airbox, you'll have to take my bandit for a spin sometime to see. Just a matter of jetting and tuning the carb to match all that air. Assuming one didn't have ninja carb-tuning skills, would it be moronic to build your own airbox with substantially identical volume to the stock until? Then you'd have to create intake hole(s) of the same area as the stock intakes as well, but the shape of the box itself should be relatively inconsequential, no? (legitimately asking here - not trying to convince anyone or claim I know what I'm talking about) I ask because the katana airbox is ugly, but I don't want the tuning hassles associated with pod filters - I've thought about relocating and reshaping the airbox instead of completely ditching it. It would still be a big project, but if it fails miserably, all I'm out is some time and mock-up materials, and the stock airbox can bolt back on. I might even utilize a pod filter or two in the design of the fabricated airbox, but the air intake hole would still be stock sized, just hidden by the external filter. Quote Link to comment Share on other sites More sharing options...
Tonik Posted March 9, 2015 Report Share Posted March 9, 2015 That being said, there are some fucking idiots out there. could I be the internet dipshit? So this thread will inevitably become a big collective thumb in my ass lol.... HTH. Quote Link to comment Share on other sites More sharing options...
ScubaCinci Posted March 9, 2015 Report Share Posted March 9, 2015 This is why it's hard for me to buy used bikes sometimes. You never know what moron who thought he knew everything worked on it. Quote Link to comment Share on other sites More sharing options...
Pokey Posted March 9, 2015 Report Share Posted March 9, 2015 I love fuel injection. Quote Link to comment Share on other sites More sharing options...
jbot Posted March 9, 2015 Report Share Posted March 9, 2015 you should post this thread to the group for lols Quote Link to comment Share on other sites More sharing options...
Gixxus Christ! Posted March 9, 2015 Author Report Share Posted March 9, 2015 Kow, yeah the kat air boxed are ugly as hell. You could try one off a bandit 600, I think gsxr 600 had bigger carbs. You can make your own, the key is volume. The more volume you have the more easily it will flow it's maximum which is set by the size of the intake hole. There is a tipping point where the intake hole gets do big the volume no longer matters but you won't get there. what materials were you planning on using? I just got some polymorph this weekend; it's a plastic that melts at around 200°f so you can mold it by hand, then it sets very hard once cooled. You can do this over and over again. I'd use something like that and the stock stacks and make something better than the original Quote Link to comment Share on other sites More sharing options...
lowcel Posted March 9, 2015 Report Share Posted March 9, 2015 If it's on the Internet it must be true. Quote Link to comment Share on other sites More sharing options...
Gixxus Christ! Posted March 9, 2015 Author Report Share Posted March 9, 2015 Wow...surprised that guy can spell his own name. Quote Link to comment Share on other sites More sharing options...
claine650 Posted March 10, 2015 Report Share Posted March 10, 2015 Sv650, "it is a 990cc motor" http://cincinnati.craigslist.org/cto/4910784057.html Quote Link to comment Share on other sites More sharing options...
smccrory Posted March 10, 2015 Report Share Posted March 10, 2015 Sv650, "it is a 990cc motor"http://cincinnati.craigslist.org/cto/4910784057.html LOL. And $4k for a 13 year old 650 owned by someone who can't accurately represent the bike? No thanks! Quote Link to comment Share on other sites More sharing options...
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