Carburetor Rebuild and Checking Valve Lash | 1981 Honda CB900 Custom

Step by step description of replacing old, dry carburetor gaskets from this classic motorcycle. This beauty has been sitting for 3 years and has only recently been brought out of storage and put back to the road. Topics covered include removing, installing and resetting the CV carburetors to factory specifications, plus an overview of checking the clearance on the valves.

[@mrrtwig]

Just got exact same bike but blue, similar exhaust as well. Informational, clear, and straight forward with no unnecessary commentary. You are a God send. Thank You!

[@mytube3358]

What a breath of fresh air. He said exactly everything that needed to be said and nothing more. You manage to pack more into 15 minutes than most do in 40. Thank you. May I recommend providing links to your new internal parts in the description? That would make this absolutely perfect.

[@jasonselinger]

Thank you! That’s exactly my intent. I hate it when channels start talking about their lunch choices or trying to sell merchandise while rebuilding a carb. I want to accurate, thorough and to the point! As for the links, I’ll try that in the future. Your feedback is appreciated!

[@jamesb_53]

So glad I just found your channel. I just got one of these from a friend. It’s my first ever motorcycle and I’m a tradesman but not that great of a mechanic. This was awesome. Thank you.

[@jasonselinger]

Take your time and pay attention. Like most things, it is more intimidating than it is difficult. You’ll be fine. It’s a great bike to start with.

[@C.F.C.GARAGE]

This is an excellent tutorial! I am getting into my 82 900C that has been sitting for 7-8 years. Already have the carbs off. One thing about screws. JIS- Japanese Industrial Standard. Screws get mangled by people using Phillips screwdrivers.

[@TheNsxdude]

WOW !! I am building a Cafe racer based on a CB900 custom... You just saved me hours !!! What an amazing video !

[@handyfix2952]

I’ve never seen this channel before. It only took me about 4 minutes into the video and I’m hitting the like button and subscribing to the channel. What a great presentation. This channel will grow.

[@jasonselinger]

Thank you so much for the positive vibes! I hope you keep enjoying the content as it comes out!

[@saulloyola1161]

Thank you 💯

[@waiheke109]

Awesome skills on all fronts.

[@glennatchison9034]

Boy, I wish I had this video when I did my carbs. First time. I think it took me 2 hours to get them out and longer to get them back in. After doing them a dozen times it gets pretty easy. They are complex and not easy to get back in, but one key trick is to make sure your cables are all connected before you get your carbs back into place, as it makes it easier. Easier. Great job on this video.

[@mexicanorespondon1223]

The best carburetor manteinance that I have seen !!! You are very good mechanic ! Greetings from Mexico

[@stancoleshill8925]

First thing not to do in most cases is to take the carburetors off the bike then disassemble a whole bunch of small parts and moving shafts with parts mounted to the shafts. Most people do not have the patience, knowledge or mechanical skills to be able to put everything back together once they get past a certain point. If you DO NOT remove the carbs, you do not risk losing any of the small parts or misalignment of the shafts etc. because in most cases there are not issues with these parts and they have been set up properly at the factory. In most cases, dirt, lint or foreign material in the tank or fuel system is the cause of poor running / no starting. THE MAIN CAUSE IS that the motorcycle has been left for a long time without draining the fuel for long term storage. The fuel will deteriorate and sometimes will turn to a hard varnish deposit that will plug the jets, usually the idle jet. Remember that the bike was running fine when it was left or abandoned for other things. Nothing much mechanical has changed since it was stored / left. The jets and passage ways can be cleaned properly by removing the float bowls / jets and confirming when spaying cleaner through the passage ways that it comes out the other end. Most important is to clean ALL of the holes in the emulsion tubes of the jets and that the idle circuit and jets are completely free of debris. The tank must be removed to be completely cleaned of any sedimentary debris, using a siphon hose together with a flashlight. The tank must be shaken and tilted so that ALL debris can collect at a low point on one side of the tank which can be accessed using the flashlight and hose.

[@bignasty3274]

Paragraphs, my friend Paragraphs!

[@monkmoto1887]

Nice classic and awesome video dude!! Hope you keep putting these out because this was well done

[@jasonselinger]

Oh I will! My projects jump all over the place, but there's a lot of bikes in my future!

[@sheldog012]

I just bought my 3rd 82 cb900c. Its 40 years old with 6900 kms on it. Bike is in mint condition. I will tear down the carb this winter as per your video. Awesome video, very helpful. Thank you!

[@codybrooks2696]

Beautiful bike

[@roborat]

Perfect video, im getting one soon

[@webchez69]

I owned this bike when new. I am still drooling looking at this bike now. Those yellow coils are not stock. Considering the speed capability and weight of this bike, I feel luck I sold it in 1986 for only $1400 without injury. Seeing all the tiny parts in the carbs makes me glad I never needed to have the bike serviced.

[@yomommaahotoo264]

When replacing like pnuematic valve o rings on equipment I work on, I've shyed away over the years from using silicon because it has reacted/hardened here and there...same with those type of diaphrams (in case someone thinks those need sprayed). If I have to use anything at all I use smallest dab of synth food grade grease possible. Great content!

[@jasonselinger]

Thanks for the tip! In the case of a seal, I think I’d replace it if it was that much trouble to get off. Older equipment is getting harder to find parts for though, so maybe not too. Thanks for watching!

[@ScottDLR]

Thanks for the vid and nice job. I bought one of these new back in 1981 and absolutely loved it in every way. I had faster bikes later, but if I could have any bike back, it would be my 900C. BTW, you will absolutely need to sync the carbs now and it will run and sound much better afterwards. Also want to adjust the cam chain (easy).

[@du-rronburton7731]

Loved it.

[@ChrisR57]

That is a job I will have a professional do. Luckily, the carbs on my CB1100F have never been off the bike since I've owned it. I've owned the bike since 2008, it had 30K kms on it when purchased and now shows 450 kms on the ODO. My carbs do not leak, and the bike runs strong up to redline in the 1st 4 gears. I've never pulled redline in 5th!! Great video BTW!!

[@OfAHigherClass]

Tip: I use a steamer on old Hondas to remove the carbs when the rubber boots are holding on the the carb or engine

[@tomburdett6639]

👍👍👍😁

[@dab-pre-ss-ionaustin1986]

My dream bike i got a frame roller of one looking for a motor for it been wanting to bring it back to life for awhile

[@grassrootslawncareservice2846]

My brother just gave me a 1982 cb900c for free. He is crazy lol. I love the bike already. I came here to this video because this bike i got the carbs are flooding out or all the fuel isnt burni g. You can smell fuel everywhere when running

[@charlestomasino9161]

Stuck floats

[@leifsutherland3475]

I have an issue where number 4 seem to be running cool? lots of sapork carbs are clean .Any advise will be good .thanks from vancouver island.

[@SternDrive]

Which shifter is the Overdrive? The top one or the bottom one? How much does it lower the RPM? Great idea.

[@cadeng8168]

What other adjustments would one have to be prepared to make after the video ends? Would I need any special tools? I'm just trying to replace all the rubber without touching the jets

[@OfAHigherClass]

You didn't show the most difficult part. The tiny spring that connects the 2 choke rods.

[@mik2marty1]

Great video! Needing to rebuild mine, this answer made the task look manageable. What is your cleaning mixture? You mentioned Dawn and Pine-sol, but not quantities.

[@jasonselinger]

Hi Mike, I put about an ounce of Dawn and two ounces of Pinesol into the 10L tank. I’m my opinion Dawn is about the best all around cleaner there is.

[@adventuresonwheels4966]

Thanks for the video, do you mind sharing where do I adjust the idle on the bike, mine is idling to high. Would like to lower the rpms a little. Thank you.

[@jasonselinger]

You need small hands to reach in below the carbs. There is a thumb screw there that you can turn to adjust. Best done on a warm engine, a little at a time. Tweak it after after a few rides and you'll find the sweet spot. Careful, it's hot down there!

[@JimWycoff]

Wasnt there another part on those carbs that the fuel line hooks to and a vacuum line that went to the number two carb that has something to do with the fuel . The gas tank ties into it and then it goes to the carb two. I didnt see it in your video. Yet its on my bike. Thats the information i was looking for. Because my vacuum is really high in the main carb . I was wonderind if it was because im not using the what looks like accelerator pump.. i was just letting it gravity feed. I needed to know if not using it is why im having trouble with the syncing or why its making popping sounds.

[@Ordrock7]

You need to get some JIS screwdrivers, great work by the way

[@jasonselinger]

I just ordered a set!

[@gabyB25]

Salut Il semble que les étincelles ne se fassent pas au bon endroit et qu'elles sont mortes ,pourtant, tu n'en parles pas. Et,à la toute fin,tu parles et on entend pas si ton moteur tourne bien 👌 Dommage😢 Merci quand même de nous faire cette vidéo par laquelle, on peut voir qu'une membrane est déchirée et qu'un joint est défecteux. 👍

[@Adm7869]

Great video ! Quick question, can I check valve clearances on each cylinder by turning the crank to TDC on the cylinder I’m checking ?

[@jasonselinger]

Yup, that's exactly how you do it.

[@bradgt5130]

I just did a rebuild, and now I can’t get my engine to crank and stay idling, and if it does crank it’s very rough and only 1 cylinder is running hot now. Can you tell what I did wrong?

[@Jdubsgarage74]

Why did you not remove the plugs that cover the air screw and remove and clean that as well?

[@rodofsteel6662]

I have an 81 cb900c, Once it’s warm I can ride it about a mile and when I pull the clutch in the bike revs at 5000 rpm then it does it in neutral as well. The longer I ride the worse it gets i don’t know what’s wrong. Carbs are rebuilt so im thinking possible air leak or maybe the timing??? Even if I lower the idle adjuster all the way out it still happens. Running lean too my pipes are blue. if I wait it might start to go down slowly but barley. 17,000 miles on the bike.

[@jasonselinger]

Check the valves.

[@ianmachiz8461]

I need to rebuild my carb I bought a 1980 cb900c that hasn’t run in 9 years where should I go to buy a rebuild kit?

[@tommac9119]

Hi there great video, do you rebuild these carbs for others ? thanks

[@jasonselinger]

You know, I've thought about doing customer work, but I have so little spare time these days. I have a few friends and relatives that need little jobs like this done every now and then, which is good enough for me!

[@paulwenzl1711]

I have the same bike. Could I send you my carbs for a rebuild. Seeing is believing. I'd trust you.

[@seanfritz5068]

hello great video, would you be so kind as to provide the part number for the o-ring kits needed for these carbs? I could only make out one. Thx

[@jasonselinger]

18-4619, 18-4634, 18-4638

[@seanfritz5068]

@@jasonselinger Thank you very much!

[@roborat]

My engine side boots are super tough, do you just keep working at it?

[@jasonselinger]

Spray the mating surfaces with silicon lube and they should slip together much easier.

[@ryanfogt4273]

What are the part numbers on all the k & l o rings. I can pause and get two but not the third

[@jasonselinger]

18-4619, 18-4634, 18-4638

[@matthewmartens446]

Is the sealing ring on the hat of the carb supposed to be hard? When I take apart my carbs, the sealing rings are very hard, and I'm wondering if I should get softer ones. When you took these off, did you notice if the sealing rings were hard? Thanks

[@jasonselinger]

I’m not exactly sure which ring you mean, but in general sealing rings should not be hard. If you have the carbs out, I’d replace them to be safe.

[@matthewmartens446]

@@jasonselinger the ring is visible from 6:00 -> 6:10 in your video. The big black one that surrounds the hat of the carb(s). I have a funny feeling those are plastic and shouldn’t be replaced (also because it’s almost impossible to find a replacement part).

[@roborat]

I can't seem to get my choke mechanism to work right, I'm wondering what I did wrong any advice?

[@jasonselinger]

Check it over carefully. It's a pretty simple thing, most likely the cable not hooked up properly? It can be a bit tricky to get the linkage between the left two and right two carbs when putting it all back together. Get it working on the bench before hooking it up in the bike.

[@user-rv2ih1bd8b]

What’s the mix on the solution for the cleaner?

[@jasonselinger]

An ounce of Dawn dish soap plus an ounce of Pinesol in the 6L U/S cleaner. For whatever reason, Dawn dish soap is a far better degreaser than the other dish soaps. Not sure why, I have no affiliation, it’s just the truth.

[@robbie123robbie123]

I think you mean .08mm not .8mm for the valve lash

[@emiller412]

you didn't clean the slow jets

[@MerlinZener]

5:09 they're not philips screws, they're JIS. You're meant to use a JIS screwdriver on them, not a philips. Of course they're going to get "deformed really easily" if you carelessly go around using the wrong tools on them. Just use the right tool.

[@jasonselinger]

Thanks, I made the switch a while back, the JIS are wonderful tools!