Motorized Bike Carb Adjustment Tips & Tricks 

This worked like a charm getting my bike going. Thank you!

One thing I like to do, on those black punisher air filter covers is drill a hole dead center between the two screw holes "with it off the carb and the round foam out of the way " so in the winter time you can spray in a quick blast of starting fluid if need be. I know you could spray it up from the holes on the bottom but most of it drips out

good tip for the carb to intake mounting! esp like the pedal with full choke to oil up the cylinder on first start up. never heard that before. most ppl just recommend squirt a little 2 stroke oil into the spark plug hole. maybe both? break-in is very important with these little 2 strokes

Thank you so much, ThunderHead!!! My bike build was giving me a headache, it's my first build on my own. Did every single thing you said including a tight seal, I even used an electrical tape too! LOL and she runs likes a beauty now when before it wouldn't start! Yay! Thank you again! Liked and Favorited, and subbed! :D

Thank you thunderhead! Great tips very helpful!

Lightly turn in the idle adjustment screw til it bottoms. Stop. Turning in to tight will damage the screw. Turn the screw out (counter clockwise) 2- 2 1/2 turns. This should put you in the ball park. Adjust your cable with the filter assembly removed. Look inside or place a finger inside the carb opening. Twist the throttle to fully open. The slider should reach top of bore. If it doesn't adjust the cable accordingly. Begin adjustment at top of carb and finalize at the upper adjuster. Try not to use up more than half of the threads of either. Too few threads and you will eventually strip them lose from stress as you continually use the throttle. Start the bike. If it doesn't idle, turn the adjustment screw in until it does. If it idles to high, turn the screw out til you have reached proper idle. Before starting your bike for the first time, remove the spark plug and add a tablespoon or so of oil into the plug hole. With the plug still out, push the bike forward a few feet to pre lubricate the cylinder. Reinstall the plug and ride on.

great background i love the datails

Nice bike man. I recently gave my motorized bicycle engine to my friend (got paid well) and it runs pretty good after cleaning the carb with carb cleaner. Though now it has one issue. Motor sat for a few months and the engine seems to be breaking up at high rpm only when it's warmed up (when the engine is cold it hits 30 mph. When warm it only goes 23 mph and sounds like it's breaking up) Before I took the engine off motor ran great all the way to the max rpm even at temp. I cleaned the carb and the spark plug (gap is the same but runs rich). The story from start to end. I swapped the engine over to his bike from mine, I attached it to the bike with zip ties as I did not have a way to safely secure the front engine mount. #becauseroadkill I got the bike running for a few minutes and then the engine sputtered bad enough that it ran. Once I cleaned the carb and the spark plug (then duct taped the choke lever which was loose to the open position and it ran great all the way to max rpm. (Until it warms up). Once it warms up the engine starts breaking up and it's running rich. I did put way too much oil in the first tank but the next tank will be 32:1. Went 23 mph in it. Before i swapped it it went 30. I'm guessing the ignition box (also ziptied down) is dying or there is a short in the connection.

Still waiting on my 66cc Gt7 from Gasbike. Thanks for the tips

Thank you for these awesome tips Thunder Head

Thanks a lot the tips really helped.

thanks so much. i just bought an hp carby but the performance was shit. i did all these tips and itsbetter than it was before. great vid 😊

11 turns plus a quarter was just what I needed thanks for the vid was helpful

you have good taste in music

the "mix screw" (idle set screw) stops the barrel from going below a set position ie. slightly opens the throttle as if you were pressing on a gas pedal, the other two (top of carb & throttle adjuster) are for any slack in the cable once it stretches out. Nothing needs to be balanced you just don't want anything fully backed off where it could come apart and cause the throttle to stick open.

The screw on the side is the idle adjuster screw NOT a mix screw. It simply opens the throttle slide and lets in enough air and gas to idle. The adjuster on the top of the carb simply tightens the throttle cable. It's important not to have any play in it. It needs adjusting so you get instant response when you twist the throttle. There is NO mix screw. The ONLY way to adjust the mixture is by altering the needle setting. There are videos that show how to do this.

took the end cap off my 48cc motor exhaust canister today and WHOA, much more speed, loud, but in Russia nobody cares.. She sure was restricted.

put an 0-ring in the carb intake. also the side screw should raise or lower the throttle slide to set idle

I have 2 49cc's, newly broke in. Now they will only run whilst priming the carb. Suggestions please.

What altitude are you at? I'm 528ft above sea level, so I'm wondering how your settings would compare.

Wow so great!

Do these carbs have an air/fuel mixture? I think my bike might be running lean cause at high speeds/loads it sounds like it's misfiring and not getting enough fuel to combust. Although after watching your video I think I might have a slight vacuum leak and am gonna try spraying around carb cleaner

My engine started to sputter and run really rough. It will start, but backfires around the carb area. Just when it seems to clear and rev up again it backfires again and runs rough. Any ideas?

There a push primer button beside the turn screw on the carb . Push it a few time if you have not started it in few days.

Some needles have 5 notches and some have 4 and mine has 4 but for my combination the 3rd notch is where it runs best

I just bought one of these bikes and it was already put together and I don't really know how the clutch supposed to work it don't seem to work properly I'm not sure how to start it. I would appreciate your help by the way I paid 200 for it and it does run but I don't know how to operate it.

Is your gas filter turn the correct way. i have an arrow on my filter . check it.

Okay I took off the end part of the exhaust and 1. It got loud 2. it went fast but only for a quick minute like 15 seconds and then back to slow how it was when it was on so why does that happen

Where can I buy a new carb screw I can't find one anywhere or I might be asking for the wrong thing

should I use one of those cool looking filters that come with the HP carbs? What about taking out the baffle in the exhaust? Which jet do you recommend? You should start charging but not me...lol Thanks

Where can I buy a new screw for my idle

Your vacuum leak problem describes what i am having issues with exactly. Idles fast when not under load, and revs down slowly. Thank you so much. Is there any other places that often have this same issue?

I will try you recommendations insomuch as I've been struggling for a while because after replacing my head gaskets, the bike will not idle down. I also tried a new carburetor and throttle to no effect, because right now she's just wide open.

ever notice some motors have the plug angled toward the intake and some toward the exhaust? wonder if that makes any sort of difference at all.

Proper procedure would be to screw the throttle handle adjustment all the way in, screw in the carb throttle cable adjustment until there is some slack in the cable and then adjust your idle speed with the idle speed screw on the carb side, then adjust the throttle cable carb adjustment to take up any slack in the cable...the throttle handle screw can then be conveniently screwed out to take up slack from stretch as time goes on.

How about those HP carb!, are they much better! thanks

another problem!!! :D my bike is under performing. i made sure there isn't a vacuum leak or and gunk in the carb.

Where can I buy mudguard like yours?

I try start mine up for the first time with full choke it started up fine but soon as I clothes the choke it shuts right off? Thank you for your help if you can.

Fuel filter direction ?

So my bike won't start at the middle notch on the pin, only on the bottom one or the one above it, but at those two spots it pretty much revs uncontrollably and gets extremely hot(keep in mind we just had a huge winter storm so it's pretty damn cold out) in like a minute and eventually just stalls out or stalls as soon as I engage the clutch. While it's running I've essentially moved the screw in and out in every position, as well as adjusted the throttle cable, which has a slightly too short casing so if the screws aren't basically all the way out more than half of the throttle travel is just pulling up the slack, but I still tried it and no dice. I'm wondering if having cut the intake like half an inch shorter could be the cause, so the air filter would fit while I wait for an offset manifold, or maybe something else? I also noticed some fuel on the engine that is seeming to drip out of the air filter 0_o any ideas would be greatly appreciated!

Mine stumbles a bit at first. Just popped a new carb on today. Fired right up. Just need to understand the tuning.

There is NO MIXTURE SCREW on a NT carb! The screw on the side just limits the lowest position of the slide, thus determining your idle rpm (if the cable is not too tight). The idle RPM must be adjusted from the screw and after that the cable must be adjusted so there is just a litle bit of free play when you start twisting the throttle.

Hi,good explanation body, you did very good, I think this guy when I bought this new bike w. 80cc doesn't know like you explained. Question?? my bike at first I drove in the Ally only, it was fine but when I got home I smells gasoline, is licking all around under the top of the carburetor, I don't know why? I think this guy does not understand much about the all information like you explain very well, now I am trying to put an other carburetor in the bike but I don't know much about this bike S.......any idea why is licking?? thank you.

and my throttle needle thing in carb is 1 before the bottom should I raise the c clip up

i just got my bike to start & run but it wont stay running on its on so im gonna try this tomorrow n see if she sTAy running

did you buy this kit from 99motor on ebay too? I'm looking to put one of these together this summer and trying to find the best motor kit. Thanks!

Hey I put a thrust muffler on my stock carb with high performance head it bogs out some what should I do

Hey I can't make my motor bike idle new engine and stuff any suggestions

i just installed an 80cc motor on a mongoose 29inch the frame was a very tight fit but i was able to get it in with some modifications but the carburetor i had sitting in there sideways and it was leaking gas by the primer. does it matter which position the carburetor is ? i apprecaite all your videos . thank you

Are you telling me the adjustment you make on the throttle cable adjusts the idle speed. and the screw on the side is the fuel mixture.... BECAUSE I'VE BEEN ADJUSTING THE SIDE SCREW TRYING TO GET THIS THING TO IDLE CORRECTLY

Well, so I took the screw all the way out, screwed it in ten full turns and it stopped right there. It is seated. I would imagine that it should be screwed out a few turns? Say, oh two and a half...? Something? I can't imagine it wants to be left seated down tight. Any suggestions?

hey thunderhead. i just got my motorized bike going she runs smooth. only thing i seem to notice is after i get her going whenever i squeeze the clutch in to stop the engine revs really high it seems. after a good 10 minutes of riding this seems to go away its usually only the first few stops after i start it.

Dear Thunder, On the idle adjust, do you mean ten FULL turns? Also, what does the little spring loaded pump on the side of the carb do?

hi guys, can you please tell me if you can.......I have a new 80cc 2 stroke engine kit on my bicycle, went together well but now the engine won't rev much, not enough to propel the bike & me on it! I checked/cleaned all the usual stuff carb/plug/throttle cable/vacuum leaks etc. All seems fine, I live in Ireland and used your fuel mix as close as possible in litres/ml, (16:1) again mix seems ok, a mechanic friend of mine thought it was the carb at fault as he took the barrel/needle out of the carb while keeping his thumb on the opening while engine was running, he said the engine should be screaming/revving it's brains out at this stage, but still only revved a bit kinda like a fast idle, so I again dismantled and cleaned the carb. It looks fine and you'd expect it to work when I put it on, but no! Please send me any suggestions you can. Regards P.S. it's a NT carb...........

Song in beginning is?

Hey quick question. I haven't ran my motorized 80cc bike in about 10 months. Started it yesterday and it's rev at what seems to be full RPM and it's blowing a lot of smoke any ideas on what to look for? Cheers mate.

Fucking awesome information man thanks!

hay my bike is running rich and i have it set to the top of the needle is there anything i can do?

What do I do if , I have to open choke to start every time.??what does that mean ??

When you say 10 or 11 turns in on the idle screw do you mean full 360 degree turns?

hallo chief,,i have problem with the spark plugs.after 3-4 kilometres are black..i have given 600 euro for repair but nothing..it has rich gasoline mixture i think..also there is a leak of gasoline in the switch even ..

moi j'ai déja 648 km , a mon vélo 80 cc , je roule tous les jours avec démarre au car de tours, vitesse maxi 26 pouce 46 km/h , 28 pouce 55 km/h

My carberator does leak fuel when in push the button on the carberator does that mean I'm not getting fuel to the engine

Thanks

Good

If my pin has 4 notches which do you suggest to put it on?

The air/fuel pin with the flathead slot fell off my carburetor. Can I screw a new one in or does this require me to disassemble the unit?

My bike was running great but now it barely runs and only with the choke on? Any ideas?

Have you put a 56 sprocket on your bike

Is ur fuel filter on backwards?

thnaks man! i tryed this today and now my bike stays running. only problem im having now is thAt its idling real high and wont stop. what do u think? vaccum leak inbetween the carb n engine?

Hello it's me again :D i'm just having some trouble with the carb, when I push the choke down, then get going and fire up the engine, the choke goes upwards and the motor just dies. (sometimes it keeps going but slower) if I put it all the way up the bike doesn't work. so I have to keep pressing the choke down to get it going. (when I want to keep going after it was going) I hope you know what I mean. please help and thank you soooooooo much for the help so far. you're the best! also it wont start with the choke up. I have to physically push it down to make it work.

Im getting ready to do my first build and have the same 29 inch bike, is an easy build? seems like everyone builds 26 inch bikes. any tips for me? thanks

I believe I have the same engine but it won’t fit on my bike 😪 now I’m in search of another bike

set your camera focus to spot instead of centerweight

My motor revs like a runaway diesel when I pull the clutch in?

i have a high idle problem. any idea to seek out the problem

My discover bike problem. When I start the bike it starts and remain in idle, but when I accelerate a bit the engine shuts off. What is the problem?

What altitude are you at

Word. Ty

Any tips if my fuel is coming out the intake?

Dude wen my gas valve is all the way on like it should be to run gas is pouring out of the back of my carb..I dont understand why

For the idle adjustment screw, I’ve found that taking the screw out completely and making 3 1/2 complete (360 deg) turns in is a good starting point. Altitude will come into play for some riders, but this should put most engines close to where they need to be.

Hey man, just a question, I have good spark and compression but my bike just won’t start... any tips??

Is your engine 80 cc

or use plumbing tape! its better than black tape! good info but every motor runs different for real!

Like your vid but is that 10 - 11 complete turns or half turns?

what car and is that in the end?? ford falcon?? Chevy??

What's the intro song

I was always taught to "Loosely Hand Tighten" the screw and then "Back it Out" the Required amount. Not remove it and then put it back in "Some Amount". What am I doing Wrong???

Everytime I start my bike the engine runs but it doesn't give any power. Last time it did that i bought a new spark plug and it worked fine, but now it just runs until i stop but doesn't give power. Any idea what it probably is?

My bike started bogging so I thought maybe is a stock carburetor so I bought a little better one and it still bugged and stuff I got the a new stock carburetor put it on and still bogging and not getting power wont idle at a new spark plug got a new CI thing change the gas change the lines got spark to the spark myself anybody got any ideas

hi my throttle cable is loose how do i fix it ? soon as i started it max speed by it self

I jus got mine does anyone know how to make it faster? Mine goes only 12 mph

here's my situation my bike starts fine but it has hardly any power whatsoever anymore and everytime I come to a stop I can't keep it running with the clutch in. basically it just keeps on stalling out and running like crap

Are you still answering questions here?

hiya thunderhead simple question for you have an 80cc bike ran great for about a month and then died will not start , i've tried new plug and the fuel is mixed correctly ? any help

When I full throttle, my engine doesn't get super high on rpms like it should (not a ton of power). My bike can barely move on a flat... Could that be a loss of compression or what? One of my piston rings might be broken. I will do what you did in this video, but would it be the piston rings? I am kinda sure I broke when when assembling the top cylinder, but I haven't ran the engine too much. It maybe has a mile and a half. The engine still seems to run fine and I will fix the piston ring like asap and I won't run the engine, but is anything damaged possibly?

which way do the rings go on the piston? dose the grooved side of the ring go up or down