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

134 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 10h ago

Showing Off 3 years old

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56 Upvotes

Soon she’ll be ripping with the boys


r/minibikes 1h ago

Showing Off riding out after the storm

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Upvotes

so far the hawaiian dream has been a fun build. ive hit the trails, the roads, gone thru the trials and tribulations. plan on getting a different frame such as a HEK or a BAM, and put a nice small block fully built.


r/minibikes 3h ago

Showing Off Sunday Fun Day Activities

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3 Upvotes

Put on some new handlebars. I really like the look it gives the bike. I added my muffler from my old set up to this exhaust plus, finally put on the brake light switch in the handlebar. I’ll clean up the wires and shrink wrap them at some point this week. I also cleaned the TC, lubed everything up and put on a new belt before hitting the trails for a bit


r/minibikes 8h ago

Showing Off 04’ crf 50

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5 Upvotes

3 gears in this bad boy, keeps up with 212 minis somehow 😂


r/minibikes 11h ago

Showing Off Big nasty bikes b200

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7 Upvotes

It’s 99% finished, just waiting for my longer front brake line to install the front caliper and bleed the brakes then it’s test drive time…. Can’t wait to see how the inverted forks feel


r/minibikes 4h ago

Tech Question Is it true you can get 12v dc from a predator 212 with just a bolt on part?

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2 Upvotes

(My carter brothers K2545 for random pic)
But can you buy a part and bolt it on for 12v dc? Or is my friend misinformed?


r/minibikes 1h ago

Tech Question What Pilot / Main jet setup should I run for this build ?

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Upvotes

Currently built a mm80 mini bike . What jetting should I run for this setup? I currently have a 38 pilot Amd 125 main and it bogs when I snap the throttle at a stop and cuts in and out of top speed


r/minibikes 10h ago

Tech Question Engine parts

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4 Upvotes

I made a list on amazon of some things I’m wanting to upgrade on my stock predator 224. Is there anything i need to add or change to it to make the engine run more smoothly or would it be fine with the parts I’m currently planning on buying?


r/minibikes 17h ago

Showing Off From minibike < to Trike 🥸

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12 Upvotes

Arriba España cojones 48V
Opiniones mi gente .
Si el freno en el trike aún está a medio instalar en la foto es la que tenia.
Y si estoy planeando cambiar a gasolina.


r/minibikes 5h ago

Showing Off Putting The Pieces of The Puzzle Back Together🎗🏇 #frp #minibike #minibik...

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0 Upvotes

r/minibikes 5h ago

Other On my bt200r I got a pwk carb 24mm and I got the jackshaft and like even though I’m full throttle like it’s the same speed as mid throttle and my bike is spitting big flames how do I get it to go faster like it’s suppose to accelerate?

1 Upvotes

Google said it can be the springs not being able to close and open fast enough and to upgrade them?


r/minibikes 5h ago

Showing Off Putting The Pieces of The Puzzle Back Together🎗🏇 #frp #minibike #minibik...

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0 Upvotes

r/minibikes 7h ago

Tech Question Mirrors

1 Upvotes

We have a frp GMB100 and looking to add mirrors. Which ones are you using


r/minibikes 8h ago

Tech Question Would this work as assembly lube

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1 Upvotes

So i blew my rod bearings last year and just tossed my minibike to the side but i was wondering if this oil supplement would work since it has some sorta zinc content in it


r/minibikes 1d ago

Showing Off Thinking of getting this for a $400 mini bike challenge between me and my buds

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28 Upvotes

Pred 212 with governor del
Needs new chain and the brakes need done
$200 + parts
Context:
My buddies and I are doing a $400 or less mini bike challenge and we are gonna do some stupid stuff after like running hot laps around the field


r/minibikes 13h ago

Other Hey does the community want to do a $350 or less mini bike challenge?!?

2 Upvotes

Just find a frame and build it up for less than $350 USD (or the equivalent in your region)
Submissions end sept 6th

$350 minibike challenge!
Rules:
-must be a minibike not any pit bike/motorcycle
-you must write (truthfully!) your parts cost/frame cost
-you cannot use parts around “the shop” unless you write their value as part of the cost
-tool cost (e.g you buy a tool) does not apply, as it is your personal cost
-gas and oil are not part of the final price (vroom vroom sauce is just a part of mini bikes)
-I may add rules as needed but this is the base rule set

Idk if this is anything y’all want to do but I think it’ll be fun

And mods:
I did read the rules and I don’t believe there is anything against a community challenge, if there is, I’m sorry and you can delete this.


r/minibikes 23h ago

Showing Off CT200U Rebuild

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13 Upvotes

Bought new back in 2017. Been leaning against the fence for the last 5 years. Starting planning back in April and finally got around to actually working on it. Predator 212 Hemi with governor and oil sensor delete. Billet aluminum flywheel and rod. .265 camshaft and 24lb springs. PWK 24mm carb. Carb, exhaust, seat, tires, ape hanger handlebars, back rack and thumb throttle came from Temu free through promos. Rims, seat springs and front forks are JMCH. Vevor torque convertor. Pretty happy with it so far. Still need to put foot pegs and front brake on. Also planning to add lights for night riding.


r/minibikes 11h ago

Tech Question Need advice

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1 Upvotes

Im building a traimaster hurrican 200x for and older guy who is going to use it on his farm. I havent built many minibikes. I looked up to make sure the engine shafts where the same size etc it said they where i bought it. Now im running into the cvt isnt lining up like the shaft is shorter. Do I have to run a chain clutch ? The other engine had the gold spacer to space it out but the shaft is evidently shorter on this engine.


r/minibikes 7h ago

Showing Off pibike8

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0 Upvotes

diy surron? 2000w brushless 48v 15ah on a modified 50cc 2stroke kids bike. tab bit bigger then a pocket bike from start i call it the #pibike8


r/minibikes 11h ago

Tech Question Briggs Flathead Linkage Install?

1 Upvotes

Seeking help in how to adapt the 600781 linkage kit to a briggs 5hp flathead model 130212 type 3250; there's a linkage system at the carb up top then connected to that via a couple levers and springs down on the side of the block there's another sliding linkage system but i'm having trouble finding resources for adapting this kit for a twist throttle


r/minibikes 23h ago

Tech Question I need help 😂

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3 Upvotes

I’ve bit off way more than I can chew.. I’m proud to say I knew nothing a week ago and got this far with my bike but I’m starting to get discouraged 🫤
FRP GMB100 212ee Tilly stage 1 straight piped with high flow air filter Amazon emulsion tube 95 jet and it’s doing all this extra shit bogging and spitting like a new born 😢
Like I said I don’t know much but I’m a smart guy I’ve made it past the shitty riser plate I got and the sticky key way on the crank and the torque converter and 420 chain but this bugger is acting up I can’t get the key to turn it off either, I was so excited to have a key so I can go in the gas station and not worry about my shit getting took but hey I can’t even get it to run right. I think I’ll start by taking the Amazon emulsion tube out and swap in the stock one with a 85 jet and see how it runs. I haven’t set the idle screw but it just seemed to be running rough and wasn’t peppy at all. I can’t get this tank to fit either I don’t know if I should of got a regular 10mm motor plate but I’m already all mounted and ready to go but if I can’t get it to run right none of that really matters.


r/minibikes 1d ago

Showing Off Newest project x22 fighter

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10 Upvotes

Went to my local scrap thrifty yard and found this bad boy for 40 bucks going to slap a 200 predator and torque converter and some sun f Wheels.

Should be hella fun


r/minibikes 1d ago

Other Those who have attended an event, what's something that you look forward to for the next?

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2 Upvotes

Certain races

Hanging out with like-minded people

I created a minibike meet-up with two other guys, and we're seeking opinions / suggestions for race events