[jakec]

Found this snapshot from a manual online.

I have one of each, #306A and #653A. I'm wondering which one my bike was supposed to come with, and if I should try and get a replacement so I have two of the same, or if I can run it with the current set up. It states different settings for the two different carbs, so if I were to run both of them would I use two different settings/jets? Someone here already told me that the carb bodies are the same, which seems right (the bowls are definitely different, I can tell). If the bodies are different, then why would the manual settings be different?

Any help would be appreciated, as I work toward getting this bike running I think getting these carbs tuned will be one of the challenges. I've been looking at this 4into1 rebuild kit that would have all of the jets required to run either set up.

Ultimate Carburetor Rebuild Kit - Honda CB175 CL175 - 1968-1973

 

[Richard_Pitman]

You can work this out by going to the CMNSL website, and looking up which main and pilot jets are fitted to each model.

I know for sure that my CL175K7 engine has 653A carbs, with 92 mains and 38 pilots.

CMNSL lists the CLK4 main jet as 90, with 38 pilot, which equates to a 306A. CB175 K6 ( US spec ) has this jetting, according to CMNSL.

306B are CB175K4 carbs, so far as I can tell, too dark to go out and check mine tonight.

Differing jets are matched to different exhausts, and to different markets, height above seal level and ambient temperatures, also the advance and retard mechanisms differ according to engine. Internally, engines are all the same, and in practice it doesn't seem to hurt too much to mix and match parts, although you obviously need same jetting on both cylinders.

I'm running UK spec CB200 carbs, which have 88 mains and (from memory) 35 pilots, mounted on 653a manifolds, on my CL175K7. Bike runs fine, stock air filters with paper replaced with foam, and a Triumph Speed Triple 1050 end can mounted on a 2-1 adaptor. Easily as quick as a stock bike, I'd say.

 

[jakec]

Thanks for the reference. CMNSL says the CL175K4 Jets should be #90 and #38. That would mean 306A would be the correct carb.

I'm going to be running everything as close to stock as possible, stock exhaust, stock air filters (they look pretty good so I'll be trying to clean them).

I guess there's no use guessing in how this bike ended up with two different carbs, but if the bodies are the same and I can run them together, I will. So you're saying that the jetting differences in the manual have more to do with the locale or model the carb was in/on, and that if they're both on the same bike in the same place then they can be jetted and tuned the same and they'll work as if they're the same carb? Encouraging.

 

[7TheDude2]

Found this snapshot from a manual online.
View attachment 207401

I have one of each, #306A and #653A. I'm wondering which one my bike was supposed to come with, and if I should try and get a replacement so I have two of the same, or if I can run it with the current set up. It states different settings for the two different carbs, so if I were to run both of them would I use two different settings/jets? Someone here already told me that the carb bodies are the same, which seems right (the bowls are definitely different, I can tell). If the bodies are different, then why would the manual settings be different?

Any help would be appreciated, as I work toward getting this bike running I think getting these carbs tuned will be one of the challenges. I've been looking at this 4into1 rebuild kit that would have all of the jets required to run either set up.

Ultimate Carburetor Rebuild Kit - Honda CB175 CL175 - 1968-1973

Yes I am replying to a 5 year old post because I am having the same type of issue. I have a 644A and a 7A (?) stamped manifold on my '73 CB175. The 7A is about 4mm longer than the 644A and I actually have a spare set of the 644A carbs/manifolds in a basket. Also in my basket of oddness, I have a complete set of carbs/manifolds, theoretically for the same bike, that are stamped 306B and these are the same length as the longer 7A.
Should I use the ong or short manifolds?