Wheel-Horse
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I also never said it will happen to every engine turning over 4000. But it is still a possibility that it will and I just dont want to see anyone get hurt.
Exploding Flywheel?
- Thread starter Orange Krate
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Doc Sprocket
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Sure- it can happen. Anything can happen. It's too bad it did, and I hope the guy's okay, but I gotta ask-
Was he free-revving it with no load? A load goes a long way toward keeping the harmonics in check.
Also- we have no idea where that flywheel's been. Could have bee defective, could have been dropped. Whoever built the engine could have removed it in a damaging way. There are right ways to remove a flywheel, and wrong ways.
In the grand scheme of things, 4-5000 RPM isn't particularly fast. Think about the grinding wheel I was using immediately before posting this response- it was turning over 10K. And it's not steel. It's a composition that we hope stays glued together. I have used literally hundres of these wheels in the years past, and have had one detonate on me. Why? Defect. The exception, not the rule.
Flywheels are manufactured with quite an error margin built in. So, barring defects, that explosion was the exception, not the rule.
Was he free-revving it with no load? A load goes a long way toward keeping the harmonics in check.
Also- we have no idea where that flywheel's been. Could have bee defective, could have been dropped. Whoever built the engine could have removed it in a damaging way. There are right ways to remove a flywheel, and wrong ways.
In the grand scheme of things, 4-5000 RPM isn't particularly fast. Think about the grinding wheel I was using immediately before posting this response- it was turning over 10K. And it's not steel. It's a composition that we hope stays glued together. I have used literally hundres of these wheels in the years past, and have had one detonate on me. Why? Defect. The exception, not the rule.
Flywheels are manufactured with quite an error margin built in. So, barring defects, that explosion was the exception, not the rule.
Russ2251
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Link depicts what appears to be a highly modified engine. I've seen it before.
As I have pointed out (2007 ?), I consistently run my engines at near 6500 rpm with nary a hiccup.
I have more than doubled the factory governed setting of 3000 rpm.
Am I worried ? Not even a little bit. Perhaps my engines have stronger flywheels than garden tractors.
Engines are torn down often enough that I would have noticed anything out of the ordinary.
My firm belief is that a flywheel will not let go unless it is either defective or was improperly assembled to engine to begin with.
Never assemble an engine without a torque wrench.
As I have pointed out (2007 ?), I consistently run my engines at near 6500 rpm with nary a hiccup.
I have more than doubled the factory governed setting of 3000 rpm.
Am I worried ? Not even a little bit. Perhaps my engines have stronger flywheels than garden tractors.
Engines are torn down often enough that I would have noticed anything out of the ordinary.
My firm belief is that a flywheel will not let go unless it is either defective or was improperly assembled to engine to begin with.
Never assemble an engine without a torque wrench.
Wheel-Horse
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I guess, it might be OK in your guys's circumstances. In our tractors, we have the clutches running directly off the flywheel, I personally believe that this is one major cause to our flywheels exploding. But in a kating situation, I think it probably will be OK. I was just adding some personal thoughts and my $0.02.
Most of our motors are rebuilt every year and yes they are highly modified. My Kohler v-twin turns 10,500rpm and makes 120+hp on alcohol.
Most of our motors are rebuilt every year and yes they are highly modified. My Kohler v-twin turns 10,500rpm and makes 120+hp on alcohol.
Doc Sprocket
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Those are some pretty amazing specs! What's the stock output on that Kohler, and what sort of clutch are you referring to?
Wheel-Horse
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Stock Kohler specs are CH20, 20hp started at 38Ci. Now at 45.5Ci. Stroked, pop-out pistons, roller cam/lifters/rockers, Severly ported and polished heads. Too much to list.
The types of clutches we use are similar to a car type clutch. The have a driver (bolts onto flywheel) and it then drives the clutch disc. And it has two pressure plates that grab onto the disc.
A couple of webstes for garden tractor pulling are
http://gardentractorpullingtips.com/index.htm
http://midwestsupercub.net/
The types of clutches we use are similar to a car type clutch. The have a driver (bolts onto flywheel) and it then drives the clutch disc. And it has two pressure plates that grab onto the disc.
A couple of webstes for garden tractor pulling are
http://gardentractorpullingtips.com/index.htm
http://midwestsupercub.net/
Doc Sprocket
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Okay, an automotive-type friction driven mechanical clutch. Interesting.
120+hp? Spooky. And NO, I wouldn't run a stock flywheel with specs like that, that's just stupid.
EDIT- In the example of an exploding flywheel that you posted, why the he// would the stock 'wheel still have been on such a modified engine???
120+hp? Spooky. And NO, I wouldn't run a stock flywheel with specs like that, that's just stupid.
EDIT- In the example of an exploding flywheel that you posted, why the he// would the stock 'wheel still have been on such a modified engine???
Wheel-Horse
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Yeah, thats why I was a bit concerned when I first saw the post. My motor was built by Midwest and this is a video of a motor 95% the same. The only differences are: I have a newer cam grind, I am running two 56mm Mikuni's and I have a different chassis as them. The motors run very similar. Also, he started as a 25hp, and I just bored and sleeved mine up to the 25hp bore.
http://www.youtube.com/watch?v=BTmb3OxT31k
http://www.youtube.com/watch?v=BTmb3OxT31k
Wheel-Horse
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To your Edit--From what I have heard (from the owner of the website) he was new to the sport and was too anxious to hear it run, rather than to wait the couple of days to get a steel flywheel shipped to him.
Doc Sprocket
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Well, when it all comes down to it, it kind of works like this. Around here, we tend to use smaller displacement engines, very commonly 200cc. Modifications are pretty mild in comparison, bringing RPM up in the 4-6k range, and hp up a few points. Often, we continue to use the stock 'wheel, with no problems.
That said- if one was to put a bunch of money into a race engine with all the high-zoot goodies, mutiplying horsepower and bringing revs well past 6k, there's absolutely no excuse for the last dang stock part on the engine being the 'wheel. There are realistic expectations, and there are fantastical ones.
The advice I generally tend to hand out is along these lines- IF you remove the governor for increased engine RPM, #1, keep the stock valve springs. It is a very solid bet that the valves will flutter and cause a power loss well before the 'wheel or rod grenades, and #2, avoid free-revving the engine as there is no load to absorb and cancel excess harmonics.
That said- if one was to put a bunch of money into a race engine with all the high-zoot goodies, mutiplying horsepower and bringing revs well past 6k, there's absolutely no excuse for the last dang stock part on the engine being the 'wheel. There are realistic expectations, and there are fantastical ones.
The advice I generally tend to hand out is along these lines- IF you remove the governor for increased engine RPM, #1, keep the stock valve springs. It is a very solid bet that the valves will flutter and cause a power loss well before the 'wheel or rod grenades, and #2, avoid free-revving the engine as there is no load to absorb and cancel excess harmonics.
Kaptain Krunch
Pro Junk Collector
Heres my personal experience. a few months ago, i went through 2 or 3 5hp flatties, right after all the flooding in vt i was riding my go kart every day, and holding it wide open 90* of the time through sand, 1 wheel drive cart, so essentially no load at times. threw rods 2 out of 3 times, third time seized up from lack of oil. Used the same block for all 3 motors, same flywheel, same crank, just cleaned it up and put a different used rod in.
What it all comes down to is, do you trust your work? if you torque your flywheel properly, and make sure your coil is on tight, the chances of that flywheel exploding will be slim for the most part. I'm a firm believer that my connecting rod will go long before my flywheel.
What it all comes down to is, do you trust your work? if you torque your flywheel properly, and make sure your coil is on tight, the chances of that flywheel exploding will be slim for the most part. I'm a firm believer that my connecting rod will go long before my flywheel.
Doc Sprocket
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j.concepcion54321
Rebuilding KTM, Need Kart
i think more dangerous is a clutch explosion.
when i was riding my kart the bolt holding on the clutch fell off and so the clutch housing flew off. so the clutch expanded and flew out of its thingy. So i luckily had a helmet on and that saved me from a burning hot chunk of solid metal flying at the back of my skull at around 4000 rpms. Needless to say it left a battle scar on my helmet, and the car that was next to me when it exploded.....
when i was riding my kart the bolt holding on the clutch fell off and so the clutch housing flew off. so the clutch expanded and flew out of its thingy. So i luckily had a helmet on and that saved me from a burning hot chunk of solid metal flying at the back of my skull at around 4000 rpms. Needless to say it left a battle scar on my helmet, and the car that was next to me when it exploded.....
kendelrk
redneck engineer
now you can be like "hey you see that scar? yeah my clutch exploded"
Doc Sprocket
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No doubt! I had exactly that happen on an old Sears snowblower a few years back. The parts missed me (thank goodness) and I recovered the shoes. With a new set of springs I was able to rebuild the unit and return it to service, but not before a massive dose of Loctite 242!
AceEngineer
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Typically the valves will float before the flywheel explodes. Stiffer valve springs could prove this observation wrong.
Russ2251
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We've been through this. It will not.
Maybe in the majority of cases, but not all.
Russ2251
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Yes, in all.
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