Honda CB350 Carburetor Rebuild Part 3: Setting Float Height, Jet Installation, Sealing Float Bowl
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- čas přidán 26. 08. 2024
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In part three of our Honda CL / CB350 carburetor rebuild series the focus is on setting the float height and installing the main & secondary jets. We button the carb up by installing the float bowl with a new o-ring gasket and drain plug. This covers most of the carburetors used on Honda CL / CB350K series motorcycles, however early versions as well as SL350 slide carbs have a slightly different float height setting. Float height can vary on the high end at 23mm an low end at 26mm. The height will vary based on float needle spring back force and the condition of the floats and hanger.
Honda CB350 Carburetor Rebuild Kit: www.common-moto...
Honda CB350 Carburetor Diaphragm: www.common-moto...
Honda CB350 Intake Manifold: www.common-moto...
Honda CB350 Float: www.common-moto...
So I’ve been pulling my hair out with my carbs - especially the right side which kept getting starved of fuel. I found out through trial and error that its probably better to go with the 26mm float height to make a lower fuel level in the float bowl. The fuel bowl vent hole in my right carb kept getting plugged up because the fuel level is too high and when the bike was on sitting the kickstand, the fuel which had little bits of Vaseline in it (from putting that ridiculous circular O-ring in a house shaped groove) would drown the little vent hole and smother it in Vaseline residue in the fuel. This would clog the vent and make it so the fuel just barely trickled in to the right carb because the air in the float bowl wasn’t being displaced properly as it couldnt escape through the vent.
THANK YOU! Just bought a 1970 SL100 and a Clymer manual which listed the float height at 12 mm. I thought I was going crazy. SO glad you mentioned the wacky float height specs!
Brenden is the knower of all things. Glad we could help!
Big help thanks.
Going well now.
Three times on and off the bike with the carbs.
Needed to watch all the videos...
I finished the complete rebuild of my 1972 CL350 a few months ago. Both carbs were fully rebuilt using the kits from CMC. I have never attempted this before but followed these 3 videos to the letter and the result was perfect. I have done a few rides since the rebuild and just had to adjust the idle screw to get the tick over at about 1000rpm when she is warmed up. I live in the UK so had to pay a stupid amount of import tax etc on what are relatively cheap parts but it was worth it. Even if I could have purchased in the UK I wanted to support CMC as the video tutorials are like gold. If anyone is interested I just made a video of my bike, there are a number of other parts on it from CMC, the most obvious are the rear shocks that are 1" longer than stock and help give my build the stance I was looking for. Check out Vipers 365
These are really nice instructional videos. I have a 71 CB350 that I'm getting back together after a mild restoration and I have to get the carbs set. It starts perfect but it only runs with the choke on. If I turn it off even slightly it starts to die. I believe my manual said 17mm for height but people on forums said it should be 26mm. I believe my bike is running too lean at 26mm so I should probably try the 23mm float height and see what happens.
I learned a trick for setting float height though and it makes great sense. I learned a method where you put a piece of hose on the fuel inlet to the carb and blow throw it, lower the float and when it stops the flow of air, measure at that exact point. It makes good sense and worked great for me. I just need to try a different float height.
23 mm was too high for the early 1970 3D. It overflowed on both carbs. Went with 26 mm, not overflowing anymore. Thanks for the vids! Very helpful.
I am trying this today. Hopefully to the same result
Hi, great videos.. I was wondering if you could make a comment on using (brand new) engine oil on screws before putting in vs using Mystery Oil (in crank case and elsewhere). Any thoughts? Thanks for the efforts in making videos. Much appreciated.
Perfect, this video series is just great, well done & THANKS!!
They make kits with pre-formed bowl gaskets. it's a lot easier to deal with.
I am rebuilding carbs on a CB350G. The manual says 26mm which mine is and yours was at first, but you then altered to 23mm though. Is this because of changes to fuel now or just you find they run better like that?
I have the factory addendum book for the SL350, Its float level is stated at 26. plus or minus .05 . its the exact same carbs , Do you think the bumped it up because the bike is " susposed" to be off road a bit and it gets knocked around. i know the SL had slide issues where guys jumped around or popped wheelies and the slides would slam shut due to weak springs and throw guys over the handlebars . I was thinking of stretching the diaphram springs maybe an inch and trying it. And experience with either issue
Okay so I’ve been battling my cb350 for awhile now and we just can’t seem to figure out what the problem is. The bike starts up and idles but the left cylinder seems to not be running at full power. The left side is considerably colder than the right but it’s still has some warmth. The bike will take off but at the next stop the bike does not want go. But after you get out of 1st gear it runs perfect. We’ve cleaned and then rebuilt the carbs the spark plugs and coils are all new and we don’t know what to do. Our assessment is that the carb bowls are filled with gas when the bike starts but by the time you get to the next stop they’re empty(or don’t have a enough gas) and it doesn’t want to get going. We’ve adjusted the floats many times but to no avail, any suggestions?
any idea when you'll get these floats back in stock?
if you have the option, at the same price buy the house shaped gaskets
I would recommen rotating the carburetor on a 45 degree angle until the tang of the float bearly touches the float needle and adjust the float to 25mm found this was the best setting for me.. I have a Honda cl350
Great info
they really should be measured with the carb tilted where the float just barely rests on the float valve. but still great vids.
I’ve got a 73 cl350 I’m building into kind of a stripped cafe/brat and I actually bought a set of valves for it from y’all about a year and a half ago. However my carbs don’t have that choke flap connector so when I flip my choke only one carb chokes. I haven’t been able to find one ANYWHERE. Any places I could find one or would y’all maybe have one to sell??
What size jets were used
I have two questions about the needle.
1. What is the spring for? Other types of carbs don't have that, it's just the needle without a spring.
2. In my case, the spring goes in and out when I'm pushing on it with my finger, but it seems to be too weak. The float's weight pushes the spring all the way down, there is absolutely no play. Is that a problem? Thanks a lot!
reach out to our support over at common-motor.com and they can answer a more technical question like this. We also have tech support calls you can schedule over there too!
Hey, I do have a question about jet sizing, I have the late style keihan carbs off of a 72 cb350, but I can't find any conclusive metric to find out what the jets should be at except to try them all, I bought the angled pod filters to replace the old busted ones, and cannot figure out which ones I need. I have the 115 mm main jet and the 89 mm other one in it now but I am still working on other parts of the bike, how do I know what jets I need?
If you indeed have the 72 carbs, your jet sizes are 68 and 105. The pilot jet is a 35. Float height should be 26mm. I'd be cautious about setting it at 23mm per this video. That's a little too high for my comfort level, but use your own judgement.
I'm seeing a lot of folks online set their float at 26mm. How will I know if a float is too high or too low?
26 works. Too high the carb will flood. Too low and it will starve for gas when coming to a stop.
I wish my o ring was as easy to fit, the ones supplied were far too big, origonal equipment alledgedly
Yeah - Tell me about it! I had just the opposite! o-ring was too small and kept slipping off the corners. Tried using gasket sealer to hold the o-ring in place but it popped off as I replacing the float bowl and consequently leaked after EVERYTHING was reassembled. GRRRR! You can't remove the left carb without removing the gas tank and exhaust pipes (CL-350) I shoulda checked the carb BEFORE I put everything back in place.
BTW! Thanks for the video! Well done and really helps.
@@paulwhite555 you need to stretch them out a bit before quickly putting them on. After they are on for awhile they'll stay
That o-ring took me half a damn hour to put in
The float bowl? Thats rough! I've struggled with it for similar lengths of time. Usually the saving grace is using some vaseline to hold the corners in place. If it's new I also give it a bit of a stretch. If it gets wet with gas, let it dry for a while in the sun because it will have expanded.
23mm on the float height is like... whoa... You are really close to hitting the overfill tube. Me thinks you're going to have a very smelly garage.