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oscaryu1

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I luv this thread...LOL...
I have yet to see any detrimental effects after more than doubling my stock rpm and increasing my HP by 23.5% (roughly).
I do not buy (figuratively OR literally) the billet bull**** and never will.
Billet flywheels are nothing more than a money making scheme. It is pure BS as far as anything we are involved with goes.
An improperly torqued flywheel will destroy itself...as will a rod, cylinder head, or anything else you can think of.
On 2 occasions was I able to destroy flywheels. Neither one of them were related (ultimately) to excessive rpm.

Happens with cars, don't see why not with small engines. Buncho guys from 4cycle sent a clone flywheel (or was it a Honda?) anyways, stock flywheel, to an independent lab for research. At bit more than 11k the flywheel magnet flew off (epoxy + screw). Flywheel was still intact..

I buy into it anyday... lots of factors to consider... fatigue, casting defects, ect..
 

devino246

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HOW BOUT THIS

If you are that scared of blowing up the flywheel

1. Keep it governed
2. Take some steel plate and make a blast shield so If the fly wheel blows up (99.99999999999999999999%) chance it wont, It will block the shrapnel.


I got a 3hp briggs on my go-kart and its got an aluminium flywheel from a pushmower any I hold it out till the valves float all the time down the road. Never had a flywheel burst, never will.

Now theres an idea, 1/4 armor around your flywheel.
 

devino246

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Happens with cars, don't see why not with small engines. Buncho guys from 4cycle sent a clone flywheel (or was it a Honda?) anyways, stock flywheel, to an independent lab for research. At bit more than 11k the flywheel magnet flew off (epoxy + screw). Flywheel was still intact..

I buy into it anyday... lots of factors to consider... fatigue, casting defects, ect..

Like I said, cars have crap bolted to their flywheels, they do more than just rotate.
 

anderkart

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I believe most all the reported flywheel failures can be directly linked to either defective manufacture, or being somehow modded, damaged or incorrectly removed/re-installed.

Most all the credible sounding 4-cycle go kart-engine Flywheel failure Info I've ran across were regarding 6.5hp clone engines, and hardly any genuine-Honda or Briggs/Tecumseh. I've only heard of a couple 2-cycle flywheels exploding, and that was usually after lightning/modding.

I think most all 6.5hp clone flywheels are a direct copy of a Honda GX200, that were over-engineered and probably designed to safely spin up to 10,000+ rpm.

In the past I've seen Harbor freight selling Greyhound engines for as low as $77, and I'm guessing they were still making a profit... I'm also guessing that means those clone flywheels must have been manufactured at a cost of no more than $5 each. At that price-point, I believe a genuine Honda GX200 flywheel would have had much higher quality control when manufactured and installed.

I also believe approximately 99% of billet flywheel purchases were probably not necessary, and only a small number of the stock ones would have actually ever failed. But I dont think any of you guys calling this a Myth have ever actually raced 4-cycle/Industrial engine karts, or even had 4-cycle engines on your karts that turned anywhere near 6000 rpm.
I have, and I can tell you that until you've competitively raced on a track you just dont any Idea how intense it is to have a 7000rpm engine screaming away only a foot away from you. If you ever experienced that I think you guys might be a little more concerned about this possible safety issue too.

Guys that race karts do all kinds of extra safety improvements that may not always be necessary, just in case. My kart has all the Important nuts and bolts safety wired. It also has a metal guard over the top of the Brake Rotor to protect my neck and back just in case my seat ever breaks. These safety Items were instituted because of the very small percentage of the time when people were injured when things went wrong. I believe It's the same deal with aftermarket racing flywheels, and that there has been a few stock ones that DID indeed explode. Although I've never found any proof of any related deaths.

I've ran across several racers that recommend using genuine Honda flywheels to others that couldn't afford a Billet for their clones. I think that's good advice too.

There's a good reason so many guys on heymow, vintageminibikes and bobs4cycle forums recommend upgrading flywheels, Its because a small percentage have indeed failed in the past, not all of them.

Some of you guys give the impression that all the racers are totally wrong about this matter, when the truth is they know a lot more about this subject than you.

___________


As far as proving myth's go:

I've seen several guys here recommending that ALL Governor gears must be removed or they will come apart and catastrophically damage engines spinning over 3600rpm. Do any of you guys have any absolute proof this is true? If so, please post that proof because I haven't been able to find any.

I do believe this is is good advice, and it's probably came about because the Governor gears in some engines did in fact fail and damage the engine at higher rpm, just the same as I believe some stock flywheels have exploded...

I've got a 1977 Honda G400 flathead engine I raced at a track extremely hard at 5000+rpm for a whole season. Back then I never removed any of the internal governor components, I simply removed the external linkage and connected my throttle cable directly to the carb. This was when I first got into karting and didn't know any better.

So does this prove that Every ones been spreading a total Myth about anyone ever needing to remove their governor gear?
No, I think it just means I was lucky got away without mine never coming apart. I think its kinda the same way with stock flywheels, I just happen to have less trust in the quality control of the flywheels used in these clone engines that were manufactured to be sold at these ridiculously low prices.
 

syko120

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wow this thread as turned pretty useful guys thanks for the piece of mind...

I might just opt. out for a genuine honda flywheel. But with that a simple question just to clerify. If any karter were to buy a clone and not just switch out but properly install a genuine honda flywheel and remove the govener, they could safely run the engine at higher rpm? and the stock valve springs which im guessing are around 8lbs correct me if im wrong around what rpm should they float? 5500-6000?

again guys thanks for the info
 

Doc Sprocket

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I believe most all the reported flywheel failures can be directly linked to either defective manufacture, or being somehow modded, damaged or incorrectly removed/re-installed.
Exactly what I have been saying.


regarding 6.5hp clone engines, and hardly any genuine-Honda or Briggs/Tecumseh... I think most all 6.5hp clone flywheels are a direct copy of a Honda GX200, that were over-engineered and probably designed to safely spin up to 10,000+ rpm...
I believe a genuine Honda GX200 flywheel would have had much higher quality control when manufactured and installed.

This is undoubtedly true, between metallurgy, QC, and manufacture process. There is also a truth that some clones (based on "brand") are built better than others. That said, we do not typically hear of near-stock clones blowing at 5000 RPM on a regular basis. This leads to the whole point I personally have been pushing. If an engine has not been modified in such a way as to allow insane RPM, odds are even you're safe. This, of course, is based on a few fundamental assumptions;

*That the mechanical work has been performed by a competent person
*That the flywheel has not been previously damaged or defective
*That the engine is operated responsibly. This means that if you remove your clutch, and stand there watching while the engine free-revs itself into oblivion, you're an idiot and that doesn't count against the "myth".
*That we all recognize that under the right (wrong) circumstances, anything can happen. There are always exceptions to any rule. S**t happens. A new, stock flywheel could frag at 3000 RPM. Remember that.

But I dont think any of you guys calling this a Myth have ever actually raced 4-cycle/Industrial engine karts, or even had 4-cycle engines on your karts that turned anywhere near 6000 rpm.

I've been above 5K, not above 6. However, my argument regards near stock engines that simply CAN'T turn above speeds like that, due to performance modifications that have NOT yet been done. Most folks around here will have noticed by now that I personally suggest keeping the valvesprings stock when degoverning an otherwise stock engine. Think of it as insurance.

I have, and I can tell you that until you've competitively raced on a track you just dont any Idea how intense it is to have a 7000rpm engine screaming away only a foot away from you. If you ever experienced that I think you guys might be a little more concerned about this possible safety issue too.

Absolutely- but at that point, in for a penny, in for a pound. Not like you're going to build a race engine with every high performance part sold.... And a stock 'wheel.

I've ran across several racers that recommend using genuine Honda flywheels to others that couldn't afford a Billet for their clones. I think that's good advice too.

That can't be a bad idea. See above metallurgy/QC comments.

Some of you guys give the impression that all the racers are totally wrong about this matter, when the truth is they know a lot more about this subject than you.

Again, I'm referring to lightly modded engines, and use the term "race" in an amateur sense.

Now- regarding the governor internals-
I've been inside an engine or two, but since we're mostly discussing clones, I will comment regarding the Honda GX-seires clone. I CAN tell anyone here firsthand and unequivocally the following- The governors internals on these engines are not designed in such as fashion that the "button" will stay on at higher RPM. The "button" I refer to is retained between the governor's flyweights and the governor arm. SINCE most folks would be inclined to simply disconnect the governor arm and run the throttle directly to the carb, this leaves this button in a very good position to simply be pushed off the shaft by the flyweights. This plastic button PROBABLY won't funk up your engine TOO badly if it flies free but- I can also tell you that if the governor arm swings out enough, it WILL strike the reciprocating assembly. THAT will cause you a fair bit of damage. I have not SEEN it happen, and I have not HAD it happen but,

You don't have to SEE someone insert a grenade into their rectum in order to very safely extrapolate the fact that it will do some damage.
 

redsox985

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What's with TS and funny sayings about explosions. Killing the fly with the RPG, now grenade suppositories.
 

oldbikerarlo

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IMO, I don't see anybody spending the money on an engine, that is NOT going to be raced, to cause a grenaded flywheel.

The boxstock racers turn upwards of 6000 rpm and must run a stock unmodified flywheel. Even this class of race engine, has a couple hundred $'s added in parts. The carbs are worked on, rings, cam, springs, head gaskets, and anything that can be run as close to the rules as possiable. It is more than just removeing the govener.

My point being it's not easy to make the engine turn the RPM's required for the fly wheel to explode. So I would think if you get your engine turning these higher RPM's you have done some homework, and have some clue as to the safety concerns. Againe IMO.
:devil2:
 
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