I just got a 1981 CB750K and the carbs were in pieces. Not only did you address every piece of the carb, but you also explained the purpose. Got them back together thanks to you. This was a big help. Thank you!
Thanks for a terrific video. It appears that you video camera needs a little more light so viewers can see better what you are addressing in your discussion.
This is by far the best explanation that I've ever seen about a carburetor disassemble. Thanks a lot, I recently bought an Honda Cb1100f super bol'dor and I'm trying to learn about everything, this helps a lot (I hope the carbs of the 900f and 1100f don't differ so much...) Thanks again!
Thank you , great video. I've had my carbs apart 5 times now, cleaned, ultrasonically etc. New Carb kits, etc. even got new carb bodies. My problem is at around the 3000 rpm range, the power cuts out, if I pull the choke it lights right up again. Any suggestions? I've even pulled them apart again and put the old components back in thinking I got a faulty carb kit. Any help would be appreciated. Thanks for the great videos!
Hi Garr. It sounds like you have a jetting problem. When you open up the throttle, the carb runs off the pilot jet and although the slide moves up, it only lets in extra air, not extra fuel (the parallel section of the needle is in the main jet at this point). As the throttle is opened further, the slide moves up, more air comes in and at around 2500-3000 rpm, the needle should be on the tapered section, allowing more fuel in through the main jet. It sounds like you are not getting enough fuel into the engine (as you say it resolves itself if you open the choke, which is a way of restricting air and adding more fuel). So what you can do it try to move the needle up a notch or two, and/or increase the main jet size. Good luck !
They are tough to get out because the thread is quite long and gets furred up - the slot for the screwdriver is not enough in a lot of cases. I use plenty of penetrating oil, lots of time to soak, and then a left handed drill on a low RPM combi driver. Good luck !
The ring that fell off when you shook the carb at 18:09. What is that? That looks like a gasket for the top valve, but I can't find it anywhere... All the carb rebuild kits only offer the float gasket..
Hi. If you fast forward to 20:42 you can see the big gasket that fell off when I shook the carb. It is the seal between the top hat and the carb body itself. I think the part number is 16010461003 but that may be the full set of "hard" gasket parts. Type that number into www.davidsilverspares.co.uk or www.CMSNL.com and you'll see the exploded diagrams.
Thanks for the answer!! I hope i can find it. The absence of that rubber ring may be the reason why my CB900 gets too much air, and farts sometimes during deceleration!
Is it possible to replace the overflow pipe in the float bowl? I have one that has had a very poor repair done and is now blocked and is beyond further repair but I cant tell if it's a push fit or screw fit into the bowl or if it is in fact replaceable?
Hi Rob. That brass pipe is soldered into the float bowl (some variants have it pressed in) and is not designed to be removed. However I have had the same issue as you and had to drill it out and press in another pipe. The key here is to make sure the height is correct to prevent flooding the engine.
@@RobAiki A new bowl is a better idea because any failure of this pipe will pour neat fuel all over your engine! Make sure you get the right bowl because they are different for the different cylinders. Good luck.
Thank you, great video. I have a question. I have Honda cb 900 bol d'or 1982 starts, runs on the 1st, 3rd and 4th cylinder. Fuel runs out of the drain hose of cylinder 2. Is the float stuck? I have removed the automatic fuelcock. Carbs have been ultrasonic cleaned and fitted with a new Dynajet kit. Original carburettors with new rubbers.
Fuel running out of the overflow means you have a float valve problem. Either the float is not operating the valve, or the valve is leaking. Problems with the float can be: HOLED (i.e. it doesn't "float"), BENT (the float moves but the actuator arm doesn't close the valve fully), or STUCK (the float doesn't move with changes in fuel level). More often than not it is a valve problem and these can be : WORN (unlikely if you've fitted a new dynajet kit), MISSING PARTS (different kits have different areas for the needle to set against. Some seat on the carb body but others have a separate seal element. If you don't fit the seal element then the needle valve near seats and it always flows), or MISFITTED (the valve may not be properly attached to the float or the valve seal may not be pushed fully down into the carb body). Hope that helps! G
@@aldermarsh6776 I changed the float valve of carb 2 and cleaned the drain screw. Now out of all the 4 overflow lines is running fuel. What's wrong? Is it because I have removed the automatic fuel cock?
@@gustaaf22 it is nothing to do with the automatic fuel cock. The carbs should be able to shut off fuel flow when the bowls are filled to the correct height irrespective of what is upstream. When you fitted new float valves (and seats), did you check to see if the valve sealed?
Hi Arthur. Do you mean this slow jet (images.app.goo.gl/rtYER3kS1ZbutWPa9) ? If so, you just remove it using a screwdriver, but the head can often shear off. If it does, you can either cut a new screwdriver slot in it, or carefully drill it out. If you do drill it out you'll need to strip the whole carb to clean any swarf from the body. Good luck !
Hi. It is similar as it is a VB model fitted to Hondas in the early 1980s. I think the VB11 was fitted to the single cylinder FT500 (VB10 for the US market?).
You're right, it is a complicated carb for a single, but providing the secondary nozzle is clean and you can get the pilot jet set right first, the main jetting is relatively straight forward. Good luck!!
I just got a 1981 CB750K and the carbs were in pieces. Not only did you address every piece of the carb, but you also explained the purpose. Got them back together thanks to you. This was a big help. Thank you!
You're welcome !
Great video mate, really appreciate it. The only video I've seen the clearly outlines what each part is and what it does.
Glad it helped
I just cleaned mine today 1981 first time cleaned and the pilot jet was 7 tuns as well.
Thanks! You are the only one who mentions the accelerator pump and what it does!
Kudos very good video 👍greetings from Curaçao, Dutch Caribbean.
Honda CB1000C
Thanks for a terrific video. It appears that you video camera needs a little more light so viewers can see better what you are addressing in your discussion.
Fair point Richard. It was just filmed from my iPhone. Thanks for the constructive feedback though - I'll make sure I do better in future work!
This is by far the best explanation that I've ever seen about a carburetor disassemble. Thanks a lot, I recently bought an Honda Cb1100f super bol'dor and I'm trying to learn about everything, this helps a lot (I hope the carbs of the 900f and 1100f don't differ so much...)
Thanks again!
Thanks. Glad it helps!
Please can you do a video of the complete strip down with them all together?
Thank you , great video. I've had my carbs apart 5 times now, cleaned, ultrasonically etc. New Carb kits, etc. even got new carb bodies. My problem is at around the 3000 rpm range, the power cuts out, if I pull the choke it lights right up again. Any suggestions? I've even pulled them apart again and put the old components back in thinking I got a faulty carb kit. Any help would be appreciated. Thanks for the great videos!
Hi Garr. It sounds like you have a jetting problem.
When you open up the throttle, the carb runs off the pilot jet and although the slide moves up, it only lets in extra air, not extra fuel (the parallel section of the needle is in the main jet at this point). As the throttle is opened further, the slide moves up, more air comes in and at around 2500-3000 rpm, the needle should be on the tapered section, allowing more fuel in through the main jet. It sounds like you are not getting enough fuel into the engine (as you say it resolves itself if you open the choke, which is a way of restricting air and adding more fuel).
So what you can do it try to move the needle up a notch or two, and/or increase the main jet size.
Good luck !
many thanks great video just starting on a Honda cb 750 custom exclusive and the carburettor is very similar,thanks for the help
Hope your rebuild goes well !
Anything like a prelude dual side draft Canadian model carb?? Can't find anything at all and mine are over flowing onto the floor
Hey I hope you respond to this, im rebuilding my 81 cb900c and cant get the primary nozzle out. Would you have any tips to get it out?
They are tough to get out because the thread is quite long and gets furred up - the slot for the screwdriver is not enough in a lot of cases. I use plenty of penetrating oil, lots of time to soak, and then a left handed drill on a low RPM combi driver. Good luck !
@aldermarsh6776 thanks for the response i hope to get this project moving along!
Hi Alder, where do you buy the new things to the carburator?
CMSNL in Europe, David Silver spares in the UK and OldSkoolCarbs in the US
The ring that fell off when you shook the carb at 18:09. What is that? That looks like a gasket for the top valve, but I can't find it anywhere... All the carb rebuild kits only offer the float gasket..
Hi. If you fast forward to 20:42 you can see the big gasket that fell off when I shook the carb. It is the seal between the top hat and the carb body itself. I think the part number is 16010461003 but that may be the full set of "hard" gasket parts. Type that number into www.davidsilverspares.co.uk or www.CMSNL.com and you'll see the exploded diagrams.
Thanks for the answer!! I hope i can find it. The absence of that rubber ring may be the reason why my CB900 gets too much air, and farts sometimes during deceleration!
Is it possible to replace the overflow pipe in the float bowl? I have one that has had a very poor repair done and is now blocked and is beyond further repair but I cant tell if it's a push fit or screw fit into the bowl or if it is in fact replaceable?
Hi Rob. That brass pipe is soldered into the float bowl (some variants have it pressed in) and is not designed to be removed. However I have had the same issue as you and had to drill it out and press in another pipe. The key here is to make sure the height is correct to prevent flooding the engine.
@@aldermarsh6776 - thanks for that, I'll give it a go but may be looking at a new bowl looking at the bodged previous repair!
@@RobAiki A new bowl is a better idea because any failure of this pipe will pour neat fuel all over your engine! Make sure you get the right bowl because they are different for the different cylinders. Good luck.
Thank you, great video. I have a question. I have Honda cb 900 bol d'or 1982 starts, runs on the 1st, 3rd and 4th cylinder. Fuel runs out of the drain hose of cylinder 2. Is the float stuck? I have removed the automatic fuelcock. Carbs have been ultrasonic cleaned and fitted with a new Dynajet kit.
Original carburettors with new rubbers.
Fuel running out of the overflow means you have a float valve problem. Either the float is not operating the valve, or the valve is leaking.
Problems with the float can be:
HOLED (i.e. it doesn't "float"),
BENT (the float moves but the actuator arm doesn't close the valve fully), or
STUCK (the float doesn't move with changes in fuel level).
More often than not it is a valve problem and these can be :
WORN (unlikely if you've fitted a new dynajet kit),
MISSING PARTS (different kits have different areas for the needle to set against. Some seat on the carb body but others have a separate seal element. If you don't fit the seal element then the needle valve near seats and it always flows), or
MISFITTED (the valve may not be properly attached to the float or the valve seal may not be pushed fully down into the carb body).
Hope that helps!
G
@@aldermarsh6776 Thank you so much for the answer! I'm sure this will help.
@@aldermarsh6776 I changed the float valve of carb 2 and cleaned the drain screw. Now out of all the 4 overflow lines is running fuel. What's wrong? Is it because I have removed the automatic fuel cock?
@@gustaaf22 it is nothing to do with the automatic fuel cock. The carbs should be able to shut off fuel flow when the bowls are filled to the correct height irrespective of what is upstream.
When you fitted new float valves (and seats), did you check to see if the valve sealed?
@@aldermarsh6776 I just replaced the float valve of carb2 which gave the only leaking problem. Now all 4 leak. I did not check if the valve sealed.
Добрый день ! Для чего закрывают канал резиновой заглушкой в поплывковой камере ?
Sorry ! I will have to improve my editing ! Thanks for watching.
Hey, I'm just wondering do you offer a rebuild service for this carb?
Hi Luke, Where are you based? I'm in the UK and may be able to sort something out for you.
How to remove slow jet mines are clogged & need to remove .
Hi Arthur. Do you mean this slow jet (images.app.goo.gl/rtYER3kS1ZbutWPa9) ?
If so, you just remove it using a screwdriver, but the head can often shear off. If it does, you can either cut a new screwdriver slot in it, or carefully drill it out. If you do drill it out you'll need to strip the whole carb to clean any swarf from the body. Good luck !
Hello. do you now if this is the same carb as the cb900c?
It is the same carb from the C (custom) bike of the early 1980s.
is the carb similar to a keihin VB11
Hi. It is similar as it is a VB model fitted to Hondas in the early 1980s. I think the VB11 was fitted to the single cylinder FT500 (VB10 for the US market?).
Alder Marsh yeah I have an ft500 so a useful video for working out how they come apart and the jetting setup as it's a complicated Carb for a single
You're right, it is a complicated carb for a single, but providing the secondary nozzle is clean and you can get the pilot jet set right first, the main jetting is relatively straight forward. Good luck!!