Inside A Motorcycle Carburetor - Float Bowl Height | MC Garage

[@billmackey8388]

Near the end you mentioned bending the float adjustment tab a "slight" bit. Wish I'd heard this in 1973. I bought a nearly new 1968 Kawi 500, not running that had gone through 3 owners while not running. I knew very little about trouble shooting, but learned a bit. (As it turned out, it had a bad distributor rotor) But, of course, I rebuilt the carbs first thing. And the float spec in the Shop Manual was way off what my carbs had, so I bent the tab a mile, expecting that to fix the bike, but it didn't. When I finally realized that I got a hot spark from the coil, but a very weak one at the plugs, I bought a new rotor ($12) instead of a cap ($13), put it in and YES! - hot spark! But it still didn't run. But when I squirted gas into the carbs, ran fine. FINALLY figured out that the float spec in the manual was wrong. Fixed it and had a very sweet running, screaming hot rod bike, until I loaned to a 'friend' Another lesson learned.

[@uofa85]

Great information! The one thing that might help is to show the proper way to measure the float height. I think this may help because of the accuracy needed to get the fuel level correct. Thanks guys and keep up the good work.

[@ralphwaters8905]

I've had a number of problems with "sticking" needle valves over the years, both in cars and motorcycles. The single most common issue involving adjustment (not dirt or water) is IMHO a factory spec that opens the float valve a bit too far. The problem usually occurs when a vehicle sits long enough for the float bowl to dry out from evaporation. The float drops to its full-down position, and the tab that pushes on the needle ends up at an angle far from the ideal 90-degrees. You can see this in the video around 1:08. The lateral thrust is often enough to jam the needle at an angle in its bore and flood the engine. Polishing the needle and seat bore is not enough to fix this. (Yes, I tried that too.) It's usually impractical to bend the float tab enough to tune this angle without destroying the fuel level adjustment in the process. However, the next best thing is to reduce the float travel limits from the factory spec a bit so that it doesn't drop down quite as far before hitting the stop. This will help keep the float tab pushing straight on the needle and avoid the flooding problem. Yes, you need to be sure the needle is opening enough for fuel demands at WOT, but it's usually quite a bit less than the factory spec calls out. This simple adjustment has fixed the "stuck needle" problem every time for me.

[@riveraluciano]

Maybe I'm going a bit over myself here, but here goes: Can you make a diagnosis tutorial? Basically how to quickly diagnose when something is off on the motorcycle (brakes, carb/injector, suspension, maybe basic electric system). I'm not talking about pre-ride check of integrity of parts, but rather their functioning on a daily. I'm not necessarily asking for myself, but I do wonder just how easier would my life had been if I could have recognized what's the issue when my front brake "pumps", when I lose power while accelerating or when I hear the chain rattling after downshifting or letting off the throttle.

[@billmackey8388]

The concept of a carburetor float and valve is very similar to the float and water inlet in a toilet tank.

[@its_a_revvolution]

was just thinking that myself

[@ChopperFisher]

Outstanding video, production value is admirable!

[@sibiar600]

Great video. Some drawings or diagrams could be helpful in visualizing what's going on here.

[@CajunGreenMan]

Nice! Never heard of the 45 degree angle thing. That will come in handy, thanks!

[@dm0ney743]

I cant wait for jetting because fuck me its tedious and difficult.Great video guys super helpful

[@GETUPANDGO]

I was always taught to hate carbs...but the more I've gotten into working on my own bikes, the more I like them

[@CollinMac96]

I love my carbs but lately I’ve been enjoying the ease and maintenance free hassle of efi

[@GETUPANDGO]

@@CollinMac96 Yes, I definitely agree

[@davidhein7439]

thanks for the info, it will definitely be of use. Looking forward to upcoming video.

[@sennest]

In agreement with all, excellent series and an awesome episode! Thank you!

[@mmohd6x]

Good info... Next subject on the sprocket ratio.

[@davidbrierly2453]

This is an eye opener. Love it . Just rebuilt my carb and will fine tune if i have to using these new info MC inFo's ;)

[@DavidReuschJr]

great videos guys! And that framed peg board art at the end... so beautiful! lol

[@jonas5759]

great video! Really interesting!

[@dbwindhorst1]

Just learned that hard way that the float can stick on a brand new Mikuni TM40, too. Apparently this isn't unheard of, and may be traced to residue from the oil used to coat the valve.

[@mrikomediana1509]

Please make a video on how to read spark plug colors. Thanks!

[@Shkvarka]

Hi Justin! Thanks for the nice tutorial! Could you please make a video about ignition coils and CDI boxes? How they work together and how to troubleshoot them?

[@knifemaster8]

its not so hard. What do you have problems?

[@Shkvarka]

@@knifemaster8 I have Geon Tossa 250cc (this is kind of Ukrainian bike, but it's just Chinese complete clone of Honda CBR250R). It is used, I bought it two month ago and this is my first bike=) It has some floating issues with the ignition, for example, for the entire last week it starts perfectly, but before it was a pain to start the engine. So I want to figure out what hidden problems do I have inside. I downloaded electric diagram and I can't believe it works, there are no connection between CDI and ignition coil! Ignition coil connects to the ground, spark plug and to kill switch o_O (according to this diagram), there are some very weird connection to some "coils assembly" (so I think this is stator), but if this is stator it MUST be connected to REG/REC, isn't it?

[@knifemaster8]

​@@Shkvarka I dont know the nature of you'r bike but i have among others a 71" Moto guzzi ts 250. So as far as i know: the coil provides AC ac current with the help of a magnet Thet goes to the regulation circuit thet turn the 30-60V AC to 13.4V DC wich powers evriting. And at the magnet there is a pick up sensor, which puts the signal when the spark needs to kick in, the sensor needs needs about 150 ohms resistenc. Thet all goes to the cdi unit. so the cdi unit needs power from the power regulator and a signal when to kick in from the pick up. then the cdi puts out the signal to the ignition coils. the signal form the cdi comes to the ignition coil and gets transferred to a high voltage so the spark can kick in. You can check the coli with the ohm meter: Primary coil has 0.75-1ohm of resistance the sec coli has 10k to15k of resistance depends on the type and brand. and if i am not mistaken your coil as you said goes to ground ignition and kill swich, but the kill swich has 3 wires one to coil one to ground and one to CDI so whe you hit the kill swich the signal gets short circuit and goes to the ground and not the coils so the motor will not run. in between the kill switch and cdi the circuit goes to the ignition lock, with bettery and other wires. you can also have electrical gremlins like i have on my ts 250 the wires are intakte but are broken inside took me a week to find why the turn signal will not work You can also check youre spark plug color. Black to rich to much fule white to lean not enuf fule. Dark chocolate brown just right. And the spark pluh heat resistance. i went one plug colder on my derbi dxr 250 so that it will not have problems when the engine is a little hotter. Sory if english is bad.

[@TheFLUFFless]

I have been searching for the first video in this series. you haven't linked them very well. why aren't they a playlist? or at least link them in the description numbered! I watch a video to tell me if you haven't watched another video to go and watch that. What's the first video called?

[@chris-dn2cl]

I want moorree videos more knowledge i love the mc garage tips keep doing videos thank you guys

[@DM396SS]

Good video but I was looking for how to make sure the float was set correctly, how to measure it once I had the specs

[@mickeypopa]

Great video! Now I just need to spend the next 5 years waiting for the other 748 parts of this series, each 0.47 seconds long and covering 1 miniscule piece of a small engine part that could, in reality, be explained entirely in one 20 minute video.

[@JM-sb4nb]

Thank you for your video. What is the height of the fuel in the bowl? My manual has spec saying 21mm from float top to the carb frame. That is fine but where is the fuel in the bowl level? Should the slow jet and main jet be xx millimeters in the fuel to work correctly? Thanks for your thoughts.

[@fromex2lsturbo]

I have a transparent bowl on my keihin pwk 38 carb.. I just want to know what the level of fuel should be!! Shit is driving me crazy bc I can’t find this info anywhere!

[@angrycapsicum6027]

When I hold mine at 90's, it doesn't seem to depress the needle. The spring load also is much shorter that on your demonstration (could be bike specific), so I'm not sure how to tell if the needle is being depressed or not. I have been having overflow issues, where if fuel tap left off fuel runs throug the overflow, and after sitting in traffic not moving my engine starts drop revs and still if I don't add acceleration.

[@erickson26]

HI , I've watched all the MC GARAGE videos and i just need help on one thing. Why does the wheel bearing becomes loose inside the hub? it's like i can effortlessly pull out the bearing and put in new ones without breaking any sweat. Yah i knew that i have to replace my hub. But this is will be the 3rd hub that i had.

[@blipco5]

And make sure the seat can be removed, some seats are built into the carb body and can't. If you screw them up it's time to buy a new carburetor.

[@sufisoul8640]

Good content.

[@kieranJo70]

Thanks again....

[@joshbullers14]

You forget about float hang, that's usually what causes em to stick

[@someone46018]

The pin holding the float can get loose sliding out the hole, making the float loose and get stuck. Have this happened to me 2 times on different bikes.

[@JakobTheDane]

could use an explaining of carburator synchronizing :D

[@vishnusimba6136]

My idle setting changes within a few days of adjusting it properly. What might be the issue? 🤔

[@WILLY52368]

Why would gas flow from my overflow when I turn my gas on just a little but stop when I start my bike? It wont do it again after that though just during my initial assembly when I first put it back together after I adjusted the float height, please help? Also it's surging at about 1/4 throttle with a 68S pilot and a 55 main I moved the needle to the very top thinking it was to richen according to a post I saw but now I understand i to richen it needle clip needs to drop to a lower slot?

[@baazigaj9125]

What is the reference point to measure of the float

[@ceesklumper]

Great video, I didn't quite get how to measure the float height, by holding the carb at a 45 degree angle? What does that show me? How do I then see the level of the fuel in the bowl?

[@MyMGBJourney]

Are there differences between a 2 stroke and 4 stroke carb? Is there such a thing as oil injection?

[@Roger_Ramjet]

No difference between two and four. Yes - oil injection (by virtue of a separate oil tank/metering system) eliminates the need to mix oil and gas in a two stroke motor.

[@debasisdash6252]

Nice Video brother....

[@scottcoffman3248]

om my Hitachi carbs on my 85 yamaha virago the needle component has spring loaded button on it. If i set float to where it just contacts and does not compress the button completly down. It will create a extreme rich condition. Can someone explain to me what function this type needle design serves. Use to have solid needle design but nobody supplies them any more i think.

[@andreuserna]

My carb squirts gas when i turn it off and when it's on there is a lot of white smoke out of the exhaust. I cheked the float level but it's correct...

[@andreuserna]

The bike don't have oil problems it was working fine but the gas squirts trough the airbox

[@andreuserna]

@Justin Dawes i can't close the petcock only has open, prime, and reserve. When the bike is off the petcock must be closed. It works fine becouse i take out the gas pipe and the peacock don't lose gas

[@andreuserna]

@Justin Dawes yeah the seat looks full of shit but it's not removable. I must handle with care if i don't want to buy a new one...

[@31mayank]

can some one review a royal Enfield bullet 500.... i am been asking this for generations

[@6Twisted]

Carbs seem like such an over engineered nightmare of things that can go wrong. As much as I like 90s sports bikes, I don't think I could own one and deal with carbs.

[@SuperYertleTurtle]

Once you know what does what and especially whot it does it it's actually really simple. And very simple to work on. I'm thinking of all the crap EFI brings with it that you can't fix on the road or with just a few screw drivers. That of course comes from a mechanics stand point. If you don't work on your bike and don't want to EFI is propably the better choice.

[@CollinMac96]

Stick with efi. It’s not as easy to take and fix a carb issue on the side of the road as people make it out to be. Fuel injectors *rarely* fail. Would you rather have something that you can fix “easily” or something you’ll never need to touch?

[@michaelfiorina]

What happened to the Niken review

[@Abel-e003]

You could talk about 2 stroke

[@koyval22]

2nd in this carb vid

[@siddharthbatra7380]

Well Carburators are a nightmare I have experienced it 😵😵😵

[@CollinMac96]

Stick with efi. Rarely fails and you never need to touch em

[@rajdwiproy18]

You're doing a great job, but missing Ari 😣😣

[@STruple12]

Well no one can replace Ari and Zach but most of the time when a show changes hosts it just goes super downhill. But not here, quality level is pretty much the same. You are doing great, guys!

[@CollinMac96]

*Go Pay The Fee At MotorTrend If You Miss Them So Much* !

[@STruple12]

Collin Mac yeaaah .. well ... there are students and poor people watching. Sorry but no.

[@CollinMac96]

STruple12 it’s 5 dollars. Their internet bill would cost more...

[@JTTofficial]

2:39 "That's a pain" ? Bullshit.

[@maicito123]

would be better to have graphics and or explain with a real carburator. Just talking wont cut it

[@morkrau]

first?

[@zeeshannaeem5331]

2nd