Excellent video, well laid out and logical. Motorcycle industry technical writers could really hone their craft by following your lead when they “attempt” to write and edit shop manuals. Well played, my friend 👍🏻
I’ve watched a TON of Moto how to videos with my multiple vintage project messes and this was one of the very best presentations of info and technique.
thank you very much! got my 69 cl350 scrambler going because of this video. very informative and this thing runs dead on some others say not to use feeler gauges.. I did what you showed here and it worked perfect. my rest plate on one carb right was even a little wore down from idle screw., still got it to get it close enough to adjust thanks again brother!
Thank you for the Video, it helped me tune my 350k. I installed a quick disconnect in the balancing line, was 10 bucks on ebay and saved me a lot of swearing.
Thank you for this nice demonstration, this is exactly the issue I've been struggling with on my CL200. The right cylinder has been constantly fouling the plug. This week I installed an electronic ignition system, points, coil and rectifier. Will run next to determine if the carbs have been the source for the lack of fire in that cylinder. I'll let you know and perhaps we can converse to get my ride right.
good way of doing adjustments ...is how it is done in the service centers ...what we did was to drill and tap 5mm hole into the intake just in front of manifold and that enabled us to fit the vacuum gauges which made tuning 100% accurate and when finished just screwed 5mm screws and alloy washer back into the tapped out holes ...looks the same as the multi cylinder vacuum on intake adjustment screws
Loving the channel! I just bought a 1972 cb 175. Without getting into everything that's been done, the bike idles nicely and does alright in the first couple gears but bogs out around 20-30 (mid range speeds). I have tried adjusting throttle needle heights and carbs have been cleaned. This bike has OEM air filters but aftermarket megaphone style exhaust.
The biggest difference is, their carbs were on the bench and my carbs stayed on the bike. If I was just replacing the throttle cables I would not want to remove the carbs to synchronize them. Common motor collective are a good source for parts. When Honda added vacuum ports to their bikes in the mid 70's it was a big improvement in synchronizing carbs.
Very impressive. I never saw the balance tube being lifted over the rear of the tank. I thought you have to drain the tank each time for tank removal. I have a '72 CL175...different carbs but principle is the same. I'll put a longer balance tube on it like you did here. I wish the local Honda shop mechanics in RI would view this video before working on my bike again..if I let them. All they did last time was to scratch a perfect tank on me; did not run any differently when I got it back, minus $200! My left carb is the continuing problem; it's not getting the gas like the right one. I removed the jets and cleaned them..even swapped them over but still no luck with the left carb...bike had been sitting with gas in it for 20 years. Cosmetically a 9 out of 10. Same paint scheme as your 350. I just put some star brite and some Sea Foam in the tank and will try to run it. It does not idle so that would be a problem doing what you did to the 350. I'll keep at it or find a competent, knowledgeable mechanic like you....they're very scarce. Thanks for a great video.
Had the same problem before. This video explores the problem and provides a simple solution to it. I plumb up all the old Hondas I do now this way and and never have that problem after that. Honda fuel valve fix. th-cam.com/video/4aDDFMd0Ups/w-d-xo.html
Its like mathematics. All about the order of operations taking place as they should. Hopefully my notes don't get misplaced when next I go after my CB-350 twin.
A Motorcycle Nut I will try that in the morning. I would like to get it running as smooth as yours and take it on a lone trip..a week or so..Thanks alot. I appreciate the advice. I posted a pretty lame attempt at a video today if you want to see my bike..a real servivor with some "patina"..I cleaned the carbs , new diaframs and it started right up after sitting for 22yrs! lol
hi - nice vid! Just wondering would that trick with the single cylinder engine running help me find a nice sync'd idle if I suspect my screws are slightly off?
Great video! I have a 1972 cl350 as well. I am having an issue this spring where the bike runs but only on one cylinder. I’m finding that the one carb is not getting gas but the other carb is. Any idea as to what would cause this?
The dummy plug is a extra spark plug that I put in the spark plug cap so it will discharge the coil when I'm running it. It keeps the spark from frying the coil.
Great video! If I turn in the pilot screw all the way in, my idle doesn't change at all. The idle only changes when screwing it outward, which is happening on both carbs. Do you think it needs a smaller idle jet? Thank you!
That means you are Idling on the main jets and not the idle circuit. Your float level could be to high, ignition timing or valves may need adjusting. Before you mess with that stuff I just mentioned, turn the pilot screws out until the engine speeds up. Turn the idle screws down and readjust the pilots screws. You might have to repeat this until you get the proper response from your pilots screw adjustment. Make sure you don't have any vacuum leaks.
I just got my 72 cb350 up and running after sitting for almost 40yrs! anyway rebuilt the he carbs and it idles a lot higher rpms with the choke off, I'm assuming I need intake boots most likely? Any suggestions I would appreciate it as much as this video,bravo to I mean it !
Love your videos, on my cl450 I can get the left side to idle at 1k but the lowest that I can adjust the right side is about 2200 rpms. Even with the idle screw backed all the way off. Any thoughts?
Hi . . . great video on setting up the carbs !! Question please: what are your float levels set at and are they round floats or square type ? Thanks !!
Great thanks, I will try this out next time I take my CL350 for a run. Just curious what a dummy sparkplug is and is there something else I could do instead? e.g. Could I just leave the ht lead off and pull out the plug on the side I'm not adjusting? That way there is no compression on that side to slow the rpm too much and make it stall?
The dummy spark plug is just an extra plug to discharge the ignition when the HT lead is off the spark plug in the engine. It's so you don't overload your coils when your running. The side that's not firing put a small load on the engine so that the adjustment you're making on the other side becomes sensitive and is easy to find the best spot.
Great, thanks for your answer. So would it be fine if I took that plug out of engine, put it in the HT lead and then bull dog clipped it to engine fins? Or is it best to keep that one in the engine with no HT lead and find a spare plug to use? I guess it's important that the spark doesn't ignite the empty chamber.
True, but keep this in mind. The cylinder with the plug disconnected has it's throttle plate completely closed. So very little fuel is actually going into that cylinder and you are only going to run it long enough to adjust the Idle air mixture on the running cylinder. As soon as you hook it back up it will burn any excess fuel up that was in the cylinder if you have good spark plugs in it. More raw fuel goes through the cylinder on a cold start up with the choke on.
I’m a little confused. Are you syncing the carbs and adjusting the cables BEFORE you set the idle mixture and single cylinder test??? Thanks in advance !!
No. I set the Idle mixer first on each carb at 1000 rpm one cylinder at a time so I know my idle mixture is right. Then I sync the carb cables with the butterflies totally closed. That way I know they are the same when I turn the throttle. Then I sync the carbs at Idle with the feeler gauge because the cables do not effect that at idle and it will start easy. Just follow the steps in the video and you'll see that it works.
Thanks for the reply. Oddly, when I adjust the idle mixture, it falls off turning in but when I back it out it just revs higher, never falls off. Same with both carbs. Bike idles and runs good now but backfires a lot. Any insight would be appreciated.
Hi, WhatsApp do you use that spark Plug dummy? Doesn’t it also work if you just disconnect the one spark plug? I am asking because I have not such a dummy. Maybe you can show me how to build one of them? Greetings from Germany
I am disconnecting one spark plug. I don't want to have the voltage in the ignition circuit to get to high and fry the coil or the condenser while I'm doing the adjustments. The dummy plug maintains the proper spark gap in the circuit. Working vintage ignition parts can be expensive and hard to find, so I don't want to over stress the components by having to large of a spark gap. The dummy plug prevents that and can be easily made with a good spark plug, small hose clamp and a big alligator clip.
I've never seen carb tuning done that way, with the spark plug cap undone. Can I do this method with my CB750? I'm assuming the idea is to do one cylinder at a time when adjusting air mixture screws... taking the one's you're not adjusting out of the equation? Having all 4 going at the same time on the CB750 makes it hard to tell how the air mixture screw is affecting the engine. Would I pull three plugs, leaving the one hooked up that I'm adjusting? Does the dummy plug have to be clamped onto the engine block? Where do I get one of those dummy plugs? Or is it just a regular spark plug? Sorry for all the questions. : )
yes , dummy plugs always need to be grounded to the block. You could also just unhook one of the coils at a time with a four cylinder with the plugs left in. just unhook the wire that powers the coil, not the spark plug caps. That will disable two cylinders and you will be able to adjust your air mixtures on the ones that are running.
My idle RPMs aren’t responsive to my idle mixture screw when I turn it back and forth like yours is. And, instead of being 3/4 to 1 full turn out, it doesn’t like anything but about 1/4 turn out from seated. Very confused.
@@Amotorcyclenut Great video - Can you please post a video on how to make and hook-up a dummy plug. I am completely new. Just saying 'use an old one' like the other comment doesn't cut it for someone like me who has never did something like that before. Thanks
No. Once the bike accelerates, the air in the line will come out on the low side of the tank. after that it will siphon by it self and keep the levels even. It works, I have been doing it for years.
Excellent video, well laid out and logical. Motorcycle industry technical writers could really hone their craft by following your lead when they “attempt” to write and edit shop manuals. Well played, my friend 👍🏻
Well said!
I’ve watched a TON of Moto how to videos with my multiple vintage project messes and this was one of the very best presentations of info and technique.
I have a 1970 CL 175. This video really helped me understand how to set up my own bike. Thanks for such a clear lesson
Glad it helped
thank you very much! got my 69 cl350 scrambler going because of this video. very informative and this thing runs dead on some others say not to use feeler gauges.. I did what you showed here and it worked perfect. my rest plate on one carb right was even a little wore down from idle screw., still got it to get it close enough to adjust thanks again brother!
Thank you for the Video, it helped me tune my 350k. I installed a quick disconnect in the balancing line, was 10 bucks on ebay and saved me a lot of swearing.
You're a lifesaver! Thanks for making such a detailed video on the tuning of these old honda bikes. Much appreciated!
Glad to help!
Finally someone showing the precise carburator adjustment! Superb video👍👍,two thumbs up..thank you you rock!!
Glad it was helpful!
Thank you for this nice demonstration, this is exactly the issue I've been struggling with on my CL200. The right cylinder has been constantly fouling the plug. This week I installed an electronic ignition system, points, coil and rectifier. Will run next to determine if the carbs have been the source for the lack of fire in that cylinder. I'll let you know and perhaps we can converse to get my ride right.
good way of doing adjustments ...is how it is done in the service centers ...what we did was to drill and tap 5mm hole into the intake just in front of manifold and that enabled us to fit the vacuum gauges which made tuning 100% accurate and when finished just screwed 5mm screws and alloy washer back into the tapped out holes ...looks the same as the multi cylinder vacuum on intake adjustment screws
Wish Honda had done that originally. I may try that.
Thanks for the great video! Gotta get to work on my 72 cb350
...also.the over the frame balance fuel line saves time EVERY time taking the gas tank off! thanks!
Very good informative video !
I just piked up a 71 sl350 k1, and I've never had anything to do with them, so this has helped a lot
Glad it helped!
Loving the channel! I just bought a 1972 cb 175. Without getting into everything that's been done, the bike idles nicely and does alright in the first couple gears but bogs out around 20-30 (mid range speeds). I have tried adjusting throttle needle heights and carbs have been cleaned. This bike has OEM air filters but aftermarket megaphone style exhaust.
Check the timing and make sure the advance unit is working properly
@@Amotorcyclenut Still have to check timing and advance but the WOT is excellent now.
Appreciating you very much right now as I put the old thing back together, awesome content
That's so different to common motor collective methods but inventive...
The biggest difference is, their carbs were on the bench and my carbs stayed on the bike. If I was just replacing the throttle cables I would not want to remove the carbs to synchronize them. Common motor collective are a good source for parts. When Honda added vacuum ports to their bikes in the mid 70's it was a big improvement in synchronizing carbs.
I had the 250 one these the exhaust 1 each side gold and white colour very good bike very will built compaired to the triumphs i had
Right on
Very impressive. I never saw the balance tube being lifted over the rear of the tank. I thought you have to drain the tank each time for tank removal. I have a '72 CL175...different carbs but principle is the same. I'll put a longer balance tube on it like you did here. I wish the local Honda shop mechanics in RI would view this video before working on my bike again..if I let them. All they did last time was to scratch a perfect tank on me; did not run any differently when I got it back, minus $200! My left carb is the continuing problem; it's not getting the gas like the right one. I removed the jets and cleaned them..even swapped them over but still no luck with the left carb...bike had been sitting with gas in it for 20 years.
Cosmetically a 9 out of 10. Same paint scheme as your 350. I just put some star brite and some Sea Foam in the tank and will try to run it. It does not idle so that would be a problem doing what you did to the 350. I'll keep at it or find a competent, knowledgeable mechanic like you....they're very scarce. Thanks for a great video.
Had the same problem before. This video explores the problem and provides a simple solution to it. I plumb up all the old Hondas I do now this way and and never have that problem after that. Honda fuel valve fix. th-cam.com/video/4aDDFMd0Ups/w-d-xo.html
Great illustration
Check out Amazon for honda CB parts, at the best prices and they will bring it to your door.
Fuel Gas Line Quick Connect Disconnect 5/16" Motorcycle Atv amzn.to/2MzzLhd
Fuel Gas Line Quick Connect Disconnect 1/4" Motorcycle Atv amzn.to/2LYDAM6
Carburetor Rebuild Kit with Floats - Honda 1970-1973 CB350 CL350 Twins amzn.to/2saGyEX
Honda 1972-2007 CB Headlight Unit 33120-333-670 New OEM amzn.to/2J9U3z0
Motorcycle Spark Plug Wire & Cap 7mm x 24 For 12v Coils Honda CB450 CM450 450 amzn.to/2LmoGQh
Metzeler Tire Set - Honda CB450K 70-74 CL450K CB500K - Tires Tubes and Rim Strips amzn.to/2KSaLjM
HONDA CB450 CL450 KEYSTER CARB KIT amzn.to/2KQl8EF
Honda fuel petcock fits CB450K 1968-1974 1968 CB350, 1970-1972 CB350K, 1973 CB350G, 1974 CB360, 1974 CB360G, 1975-1976 CB360T, 1966 CB450, 1970-1971 CL175K, 1968 CL350, 1970-1973 CL350K, 1974 CL360, 1975 CL360K, 1967 CL450, 1969-1974 CL450K, 1970 SL350, 1971-1972 SL350K amzn.to/2x9Q9l1
Its like mathematics. All about the order of operations taking place as they should. Hopefully my notes don't get misplaced when next I go after my CB-350 twin.
Thanks for the video bud.
Is that dummy plug just an old spark plug that you clamped onto the block?
great video! .. I'm restoring a 69' cb350 and this is great to know! It's running good now but popping a bit.
Which ever side is popping turn the idle up on that side and it should stop doing that. If that doesn't fix it. you have an air leak some where.
A Motorcycle Nut I will try that in the morning. I would like to get it running as smooth as yours and take it on a lone trip..a week or so..Thanks alot. I appreciate the advice. I posted a pretty lame attempt at a video today if you want to see my bike..a real servivor with some "patina"..I cleaned the carbs , new diaframs and it started right up after sitting for 22yrs! lol
give me a video link so I can check it out
hi - nice vid! Just wondering would that trick with the single cylinder engine running help me find a nice sync'd idle if I suspect my screws are slightly off?
Great video! I have a 1972 cl350 as well. I am having an issue this spring where the bike runs but only on one cylinder. I’m finding that the one carb is not getting gas but the other carb is. Any idea as to what would cause this?
Check out this video, it might solve your problem because I ran into this problem before. th-cam.com/video/4aDDFMd0Ups/w-d-xo.html
@@Amotorcyclenut Right on!
Very good teaching
Great video. Thanks. What’s a dummy plug? Thx.
The dummy plug is a extra spark plug that I put in the spark plug cap so it will discharge the coil when I'm running it. It keeps the spark from frying the coil.
Great video! If I turn in the pilot screw all the way in, my idle doesn't change at all. The idle only changes when screwing it outward, which is happening on both carbs. Do you think it needs a smaller idle jet? Thank you!
That means you are Idling on the main jets and not the idle circuit. Your float level could be to high, ignition timing or valves may need adjusting. Before you mess with that stuff I just mentioned, turn the pilot screws out until the engine speeds up. Turn the idle screws down and readjust the pilots screws. You might have to repeat this until you get the proper response from your pilots screw adjustment. Make sure you don't have any vacuum leaks.
5 out of 5. Bad ass.
I just got my 72 cb350 up and running after sitting for almost 40yrs! anyway rebuilt the he carbs and it idles a lot higher rpms with the choke off, I'm assuming I need intake boots most likely? Any suggestions I would appreciate it as much as this video,bravo to I mean it !
Could be that the timing advance springs are loose or weak. I would look for vacuum leaks first.
Question… can u tell me if I can apply the same concept to a 1978 cb750k, thank you 🙏
No, you will need a set of manometers to dial those carbs in.
Good explanation
Love your videos, on my cl450 I can get the left side to idle at 1k but the lowest that I can adjust the right side is about 2200 rpms. Even with the idle screw backed all the way off. Any thoughts?
Check the throttle cable to make sure it has enough slack. You might have a vacuum leak, or the timing advance unit is not functioning properly.
Hi . . . great video on setting up the carbs !! Question please: what are your float levels set at and are they round floats or square type ? Thanks !!
Round floats set to factory specs
Great thanks, I will try this out next time I take my CL350 for a run. Just curious what a dummy sparkplug is and is there something else I could do instead?
e.g. Could I just leave the ht lead off and pull out the plug on the side I'm not adjusting? That way there is no compression on that side to slow the rpm too much and make it stall?
The dummy spark plug is just an extra plug to discharge the ignition when the HT lead is off the spark plug in the engine. It's so you don't overload your coils when your running. The side that's not firing put a small load on the engine so that the adjustment you're making on the other side becomes sensitive and is easy to find the best spot.
Great, thanks for your answer. So would it be fine if I took that plug out of engine, put it in the HT lead and then bull dog clipped it to engine fins?
Or is it best to keep that one in the engine with no HT lead and find a spare plug to use? I guess it's important that the spark doesn't ignite the empty chamber.
Keep the spark plug in the engine just unhook the cap and put a different spark plug in it, you want a small load on the engine to set idle speed.
While one spark plug is disconnected, does fuel build up in the cylinder since there’s no spark to burn it?
True, but keep this in mind. The cylinder with the plug disconnected has it's throttle plate completely closed. So very little fuel is actually going into that cylinder and you are only going to run it long enough to adjust the Idle air mixture on the running cylinder. As soon as you hook it back up it will burn any excess fuel up that was in the cylinder if you have good spark plugs in it. More raw fuel goes through the cylinder on a cold start up with the choke on.
Thanks for the vid!
You bet!
I’m a little confused. Are you syncing the carbs and adjusting the cables BEFORE you set the idle mixture and single cylinder test??? Thanks in advance !!
No. I set the Idle mixer first on each carb at 1000 rpm one cylinder at a time so I know my idle mixture is right. Then I sync the carb cables with the butterflies totally closed. That way I know they are the same when I turn the throttle. Then I sync the carbs at Idle with the feeler gauge because the cables do not effect that at idle and it will start easy. Just follow the steps in the video and you'll see that it works.
Thanks for the reply. Oddly, when I adjust the idle mixture, it falls off turning in but when I back it out it just revs higher, never falls off. Same with both carbs. Bike idles and runs good now but backfires a lot. Any insight would be appreciated.
Hi, WhatsApp do you use that spark Plug dummy?
Doesn’t it also work if you just disconnect the one spark plug?
I am asking because I have not such a dummy. Maybe you can show me how to build one of them?
Greetings from Germany
I am disconnecting one spark plug. I don't want to have the voltage in the ignition circuit to get to high and fry the coil or the condenser while I'm doing the adjustments. The dummy plug maintains the proper spark gap in the circuit. Working vintage ignition parts can be expensive and hard to find, so I don't want to over stress the components by having to large of a spark gap. The dummy plug prevents that and can be easily made with a good spark plug, small hose clamp and a big alligator clip.
I’m a little confused. How can you properly adjust one side or the other while you’re dragging a dead cylinder?
The dragging dead cylinder put a small load on the running cylinder making very easy to find the best mixture setting for the running cylinder.
Is there a carb vent on these carbs
yes
Is this the same process for Honda vtwin hawk gt 650?
No that's a different setup.
I've never seen carb tuning done that way, with the spark plug cap undone. Can I do this method with my CB750? I'm assuming the idea is to do one cylinder at a time when adjusting air mixture screws... taking the one's you're not adjusting out of the equation? Having all 4 going at the same time on the CB750 makes it hard to tell how the air mixture screw is affecting the engine. Would I pull three plugs, leaving the one hooked up that I'm adjusting? Does the dummy plug have to be clamped onto the engine block? Where do I get one of those dummy plugs? Or is it just a regular spark plug? Sorry for all the questions. : )
yes , dummy plugs always need to be grounded to the block. You could also just unhook one of the coils at a time with a four cylinder with the plugs left in. just unhook the wire that powers the coil, not the spark plug caps. That will disable two cylinders and you will be able to adjust your air mixtures on the ones that are running.
A Motorcycle Nut
On a 2 cylinders will it also work to just disconnect the wire of one of the coil instead of using a dummy plug? Thank you
How is the dummy plug made
Also, if the level of the balance tube is higher than the bottom of the tank, how can it flow properly?
It will siphon over to the low side.
Where can you get the dummy plug when performing the carb adjustment?
Make one. A good spark plug, Big alligator clip and a hose clamp
My idle RPMs aren’t responsive to my idle mixture screw when I turn it back and forth like yours is. And, instead of being 3/4 to 1 full turn out, it doesn’t like anything but about 1/4 turn out from seated. Very confused.
Could be a lot of things. Pod filters? wrong timing, vacuum leak, valve clearance, float level, plugged jets, wrong jets, dirty carb.
Where can I find the dummy spark plug? Did you make it?
Yes,I made it.
How did you make it?
HAHAHAHA its just a plain old spark plug. use one of your old ones
@@Amotorcyclenut Great video - Can you please post a video on how to make and hook-up a dummy plug. I am completely new. Just saying 'use an old one' like the other comment doesn't cut it for someone like me who has never did something like that before. Thanks
doesn't adding that line over the frame hinder half the tank's capacity?
No. Once the bike accelerates, the air in the line will come out on the low side of the tank. after that it will siphon by it self and keep the levels even. It works, I have been doing it for years.
Your badass. Thanks