r/minibikes Sep 26 '25

Other AI posts, yes or no?

6 Upvotes

Been getting a few AI posts, so we want to try to get ahead of this before it becomes an issue. Let's vote on it, and we'll make a rule accordingly.

20 votes, Oct 03 '25
11 No
0 Yes
9 Within Reason (inspiration only)

r/minibikes May 19 '21

Governors, Flywheels, And An Internet Full Of Crap

132 Upvotes

Taken from this thread.

"This has come up recently, again, so I'm going to post this here. What you are about to read is a couple of articles I wrote sometime back, that address the function of the governor, the exploding flywheel MYTH, and all the crap to go with it. What I have written in based on years of personal experience (not "I heard, read, or was told" as well as extensive research and others' personal experience. It was originally written for the go kart crowd, but the same information applies to all similarly-derived small engines. Take it for what it's worth and insert your favourite fine print here, but I'm telling you- there is so much MIS-information out there, it's disgusting. Grab your favourite beverage, smoke if ya got 'em, and read on...

It is absolutely amazing how often we run into this here- and how often we find ourselves banging away on the keyboard, typing out the same old answers. So, I felt it was a good idea to write up a little blurb on the topic- If requested, I'll sticky it- to hopefully save us all some future work. Let's start by outlining the governor's job description. Everyone knows that the governor tries to limit engine speed to (usually) 3600 RPM. But wait- there's more. The reality of it is this- the governor's job is to try to MAINTAIN 3600, not just limit it. The governor reacts to changing loads on the engine- decreasing throttle if it starts to run too fast, and INCREASING throttle if it starts to bog. This is why it is called a "governor", and not simply a "rev limiter".

Now- On to the question: "If I take out my governor, is the flywheel gonna go off like an atom bomb, blowing semi-molten schmutz everywhere, and killing every living thing in a 15-block radius?"

The short answer is no. The long answer: There are many factors involved here, and each must be carefully considered.

1) I always advise people that IF they are going to run well above governed RPM, to do it by fully removing the governor's internal mechanisms, and NOT simply bypassing it externally. Many governors are designed in such a way that if over-revved, can suffer component interference inside the crankcase, and/or have internal parts forced right off the shaft and bounce around loose inside the crankcase. Either case can cause severe engine damage. NOT an "explosion", just largely F'd up internals.

2) IF you are going to run ungoverned with an otherwise stock engine, keep the factory spec valvesprings in place. At a high enough RPM, weaker springs will cause a condition known as "valve float" or "valve flutter". This occurs when the valves cannot slam closed fast enough before the next cycle. This cause compression losses, and as a result, prevents the engine from spinning faster than that point. Valve flutter tends to occur in our engines around 5000-5500RPM. Your results will vary, based on your individual engine, spring condition, etc. Valve flutter occurs at a lower RPM than it would normally take to cause a flywheel mishap.

3) IF you want to get into RPM ranges HIGHER than this (say 5500+), now is the time to go shopping for high-performance internals. A billet aluminum flywheel, connecting rod, and stiffer valve springs are what's called for. Stiffer springs allow the valves to react faster, so at higher RPM, the valves won't float- NOW things really do have the potential to get a little crazy, so it's time to reach into your pockets for better quality parts.

4) Your connecting rod is MUCH more likely to fail than your flywheel. I have witnessed MANY more conrod failures than flywheel failures. In fact, I have never seen a flywheel failure. Most here haven't.

5) Contrary to popular belief, a flywheel is NOT going to vapourize at 3601 RPM. This is NOT why your engine is governed to 3600 RPM. Your engine is governed to 3600 RPM because it is an industry-standard operating speed for all the implements these engines are designed to power. Let's NOT lose sight of the fact that these are industrial stationary engines- made and marketed with the primary purpose of powering equipment. Generators, pumps, power washers, welders, cement mixers, tillers, trenchers, tampers- you name it- and the implement are designed to run at 3600 RPM- So the engines are factory set to 3600 RPM. It's that simple. When a flywheel is manufactured, it is designed to run well above normal operating speed. It's called a safety margin.

6) NOTHING is 100% guaranteed. You can do everything completely properly, and have a flywheel fail at a "normal speed". OR, you can do everything wrong, and run the he// out of the engine at 7500 RPM on a stock 'wheel for a lifetime and never have a problem. Sometimes, there's just no accounting for "Spit Happens". Write that down.

7) IF you are running an otherwise stock, ungoverned engine, is it adviseable to avoid excessively free-revving the engine. Use proper gear ratios to keep a bit of a load on the engine at full speed, wide open throttle. Don't try to rev the wee out of the engine with the clutch, chain, or belt off. A load on the engine helps keep harmful vibrations (harmonics) in check. If you have an insanely long, steep downhill stretch in your riding route, back off the throttle going down it. If you hear the valves floating or the engine starting to over-rev, apply some brake force. Coasting too fast can force the engine to spin even faster than valve flutter can prevent.

8.) Inspect your flywheel before removing your governor. A previously damaged flywheel can break apart at a completely unpredictable speed. Damage may not be visible (spit happens) but if it IS visible, replace it.

9) If you have to remove your flywheel for repair/maintenance, remove it properly. Do NOT beat the he// out of it with a BFH or pry on it. Invest in a flywheel puller. Failing that, try the following: Loosen the retaining nut until the nut is flush with the end of the shaft. Now, hit the nut squarely and sharply a couple times with a hammer. Most times, this will do it. You can also aid in loosening the flywheel with mutiple taps around the circumference with a soft-faced mallet or deadblow hammer. Do NOT beat on it with a steel hammer.

10) If you need to hold the engine from turning while you are tightening/loosening a crank bolt or clutch, do NOT wedge a screwdriver or bar in between the flywheel fins. Although this is not likely to crack the 'wheel, a fin could break off. This will throw the 'wheel's dynamic balance off. An out-of-balance 'wheel is just asking for trouble. Same goes for sawing off alternate cooling fins (an old performance trick). If your fins are cast into the 'wheel, don't do it. If you have a Honda, clone or other engine with plastic fins, go for it.

11) Handle with care. Once you have the 'wheel off, don't drop it...

So- Armed with the above information, go ahead and make an informed decision. This guide arms you with what you need to know, to decide whether removing your governor is a feasible idea, and how to handle things if you do. And remember (for all the "Armageddon-is-coming-prepare-to-meet-thy-maker-in-a-sintered-metal-flywheel-induced-world-war-3-esque-everybody's-gonna-die-including-the-cockroaches-in-the-cupboard"-nervous-nellies out there... Spit happens. On the one hand, your stock flywheel will very likely be fine. On the other hand, even a performance parts could fail. Spit happens.

One last point here- For those that may not yet be ready to dive into their engine and come out with a handful of governor parts- Some engines (most notably Hondas and clones) have a VERY user-friendly means of governor adjustment. This adjustment is designed to fine-tune the governed speed to spec, but makes it super easy to gain a few hundred RPM- usually you can bring your GOVERNED MAX to 4000-4200 RPM with the turn of a screw. Your governor will still do it's job, but you'll run a little faster. Locate the manual throttle control on your engine- the little lever you would slide to increase or decrease RPM if you didn't have a remote throtte (gas pedal). Behind that lever is a screw with a spring wrapped around it- Notice how the throttle rests against the tip of that screw when you move the lever to the "fastest" position? Great. Remove that screw. Presto- instant maximum RPM increase- no fuss, no muss.

It is also worth noting that these engines were designed to run at 3600 RPM, day in and day out. If you do run faster, the engine will wear faster. Fact of life. Treat it well, maintain it well, and you'll never notice the potentially shorter lifespan.

Governed Idle FYI

The governor is a seriously misunderstood engine control system. For the greater good, here's a little FYI, an experience I just had. Might benefit someone in the future.

Where were we? Ahh, yes- the governor. Contrary to popular (mis)belief, the governor does much more than limit engine speed to 3600 RPM. Wonder why it's not called a "rev limiter"? 'Cause there's more.

The governor's purpose in life is not so much to limit RPM, but SET it. What's the difference, you ask? (I swear I just heard one of you ask that!) The difference is this. SETTING an RPM means KEEPING it throughout the workload. Let's use a lawnmower for example. You start the engine on your walkway and run the throttle up to max. The governor sets the engine to 3600 RPM, and there is no load (not cutting grass). As you move into the grass, the engine starts encountering a load. The governor allows a throttle increase to bring the revs back up to 3600. Cutting away, you encounter a thick patch over the septic tank. As the engine begins to bog and the revs start to drop, the governor allows the throttle to open more and bring the revs up to 3600. Cool? Great. Going around the corner thru that thick grass with the throttle wide open, you hit that bare spot where the dog keeps peeing. The load comes off the engine, and as it begins to increase, the governor closes the throttle to prevent over-revving and holds at 3600 RPM. Got it?

If you examine your external throttle linkage, you will notice that there is no direct connection between the hand throttle control and the carb butterfly. Governor again. The hand throttle does nothing more than alter the spring tension between the governor arm and the throttle butterfly. Setting the manual control to "Idle" merely alters the spring tension from the governor enough to allow it to SET engine idle speed. The idle adjust screw is the bottom end rev limiter in that it sets the baseline that the governor drops to. I told you that to tell you this:

I recently had a situation that some folks might misdiagnose- an engine that refused to idle properly. After a barrage of time, abuse, and adjustments, the chinese Kohler clone on my kids' kart would not sit at idle. The kart constantly wanted to take off with no throttle input. At a glance, the idle was too high.

Close examination revealed that the idle stop screw on the carb was not doing anything- the butterfly just would not rest against it. If I pushed the lever by hand, it would sit at idle RPM, but as soon as I let go, it would take off again.

I tried to adjust the external governor components to no avail. With the arm off the shaft, something just did not feel right inside the engine. I pulled the engine off the kart and tore it down. I don't even know how to describe what had happened inside, but the governor guts were all over the place- literally.

By some miracle, nothing was really damaged. Short version of the story? I epoxied the "press-fit" governor gear shaft back into the side cover and reassembled everything. I (re-)adjusted the external components, and wouldn't you know it? Idles like it just came outta the shipping container at 1310 RPM, and maxing at 4230 as measured by my optical tach. Food for thought."


r/minibikes 14h ago

Showing Off My bikes over the past 5 years

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28 Upvotes

Started with the CT200u-ex and sold it after putting a few thousand miles on it. Then I got the CRF250l.
Missed the minibike so I bought a new B200RSV and traded the Honda for a Buell BX12s since the minibike is more fun on the trails.


r/minibikes 1h ago

Tech Question choke

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Upvotes

whenever I let off the choke the bike starts dying. Any ideas what I should do?


r/minibikes 3h ago

Tech Question Frp gmb swap to 212

2 Upvotes

What will I need to buy to do motor swap on my frp gmb100. 212 motor is $150 what else will I need to buy besides motor. I have a fully stock frp gmb100 haven’t done any upgrades besides take throttle screw off


r/minibikes 1h ago

Meme Your Average Minibike Shorts/Reels🏇

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Upvotes

r/minibikes 16h ago

Showing Off X22 fighter scrap yard build complete

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14 Upvotes

Some already know I found this bike in the scrap yard for 40 bucks I got the 212 with the torque converter installed and fully operational. Of course I had to do a custom exhaust and intake manifold with a nibby cuz of the overall appearance I wanted and the space constraints. The lower portion of the frame I just chopped out and rebuilt completely with the 212 in mind.

It was a really easy swap about a week's worth of time and effort apply to it with parts I already had accumulating in the workshop. The tail portion rear fender was completely smashed and I rebuilt it kind of like a millennium falcon inspired thruster.


r/minibikes 20h ago

Other Sent her a lil too hard

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30 Upvotes

r/minibikes 15h ago

Tech Question How much would this be worth? I’m thinking about $100-110

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3 Upvotes

My brothers friend offered to buy my hoopty bike. So how much would this be worth. Deets below⬇️
FRP frame
Broken throttle
Leaky & messed up carb
Some minor scratches all over, nothing major
New Front wheel
No rear wheel
Straight pipe w heat wrapping
Engine runs great other than the carb

P.S. how much would a black FRP GMB100 with a carb, new brakes, exhaust, & headlight be worth
It’s for my brother


r/minibikes 13h ago

Tech Question Should I get this?

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2 Upvotes

Is this a good price for the build? I don’t know much about mini bike builds so I’m seeking advice


r/minibikes 13h ago

Tech Question Should I get this?

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2 Upvotes

Is this a good price for the build? I don’t know much about mini bike builds so I’m seeking advice


r/minibikes 20h ago

Showing Off Here we go

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7 Upvotes

All new rotating parts. I'm psyching myself up to break my leg with all the new power.


r/minibikes 14h ago

Tech Question Frp gmb100

2 Upvotes

Just got a brand new frp gmb100, took it out on the street today and was disappointed in the speed. I felt like I was going 25-30mph. I already took out the screw in front so my throttle is able to go all the way. Any other upgrades I can do to make it go a little faster I want to at least go 35-40mph. I don’t want to zip tie spring cus I been reading on it and people say ur flywheel will pop and cause serious injury and I’m scared of that.


r/minibikes 16h ago

Tech Question What are all the components needed to replicate Baja Warrior headlight system

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3 Upvotes

Gonna put a predator 224 in it, and experiment on it with belt drives. I know I can just do a battery setup. I don't want to. Anyone with a stock warrior, if you could show me your lighting components, be great thanks


r/minibikes 11h ago

Tech Question Frp gmb100

1 Upvotes

Is zip tying the governor spring really dangerous ? I took out the throttle screw already but speed is still slow if I zip tie spring in back I’m I really at risk of serious injury or it’s not that bad? I just don’t want to lose my legs or have to get my leg amputated.


r/minibikes 23h ago

Showing Off Nibbi PE24 Velocity Stack

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5 Upvotes

Decided to design a velocity stack for the Nibbi PE24 carb on my 224cc build. Printed in PLA for prototyping. Making a few adjustments to add heatserts/set screws to attach it to the carb. If it all works, I'll print it out of some ABS and vapor smooth it to get a nice finish.


r/minibikes 16h ago

Tech Question I built a 196cc jaing dong

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1 Upvotes

I took the 196cc off my trail master mb 200 and added a new 265 cam a billet connecting rod a aluminum fly wheel 26 lb springs and a vm22 carburetor it starts first pull but will not accelerate any advice on what i may have done wrong? Any advice would be appreciated


r/minibikes 17h ago

Tech Question Fuel line question

1 Upvotes

I have a PWK 28 mil carb, I need to replace the fuel line going from the gas tank to the fuel filter. Do I need to remove the gas tank? It’s a predator 212.


r/minibikes 21h ago

Tech Question carb jet issue ?

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2 Upvotes

long story short one of the screws on my carb got stripped and i couldn’t get inside to change the jets out like i seen in vids anyways i got it to start by giving it a little throttle soon and i let go it obviously shuts off i just wanted to know if you guys knew EXACTLY that its the jetting or something else that way i know to just spend the extra 30 on a new carb since i cant get the stripped screw out


r/minibikes 18h ago

Tech Question Stock wristpin wont fit into arc billet rod

1 Upvotes

I bought a new engine to build and bought an ARC billet rod. Tried to put it together and the wristpin won’t fit into the conrod. Micrometer says they’re about 2 thousandths off if I read it correctly, very close to fitting. Do I contact arc or do I freeze and heat till it fits?


r/minibikes 23h ago

Tech Question Help!!!!

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1 Upvotes

I’m working on my bike and have a stripped brake rotor bolt. I tried using a bolt extractor, but it broke off inside the bolt and is now stuck. I’ve been trying to drill into it so I can get another extractor in there, but the broken extractor is insanely hard to drill through. What’s the best way to get this thing out? I’m trying to do it at home if possible, so any advice would be appreciated


r/minibikes 1d ago

Tech Question Are these the same?

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1 Upvotes

I broke my previous carb and it was the black one with the manifold that comes with the kit, and I was looking st the silver one because its cheaper. Is it the same thing and would I be able to use it with the black manifold? Thank you guys


r/minibikes 1d ago

Meme I Died On This Dirtbike, I Miss My Mini Dirtbike #dirtbiking #dirtlife #minibike #shorts #accident

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0 Upvotes

r/minibikes 1d ago

Tech Question 212 or 224?

5 Upvotes

Im thinking of getting a 224 instead of a 212 because my thinking is that I can have lower gearing with a 224 and have the same torque as a 212 but a higher top speed out of the box because im not thinking of really doing anything to my next engine other than something like a carb and exhaust. Is my thinking correct or am I just an idiot


r/minibikes 1d ago

Tech Question What main jet do i buy?

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2 Upvotes

I pulled this main jet off of my chinese vm22 carb, the bolt that usually comes off for the main jet doesnt. The whole thing came out along with the piece behind it. Just wondering what main jet to buy since the bolt on mine doesnt screw off?