Have you ever broken a connecting rod or flywheel?

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Jimbo

A trial w/o witnesses is like racin w/o tech
Does one also get a certificate of achievement in return or a nomination to the Darwin Awards
 
A better question would be, if you have never broken a rod. I think everyone has broken a few in their lifetime.
But my question would be Where are you going to post this and why.
 

Jimbo

A trial w/o witnesses is like racin w/o tech
Breaking engine parts is not something i would be proud of nor would i want to advertise it.
Call ARC and ask them if they would like to post picture of any of their rods that have broken.
Or better yet one of their flywheels. I'm guessing you might hear the line go dead.
If they would entertain your question i'll bet you would get an ear full of what the guy that put the engine together did to cause such a catastrophic failure.
I'm also guessing the companies whose products are displayed in this compilation would put you on their very special list. I let you figure out what the name of that list might be.
 

KartFab

Member
Let me just back up here so we are all on the same page. I didn’t consider non-stock scenarios where someone screwed something up (eg oil clearance or improper torque, wearing out the babbit bearings by racing too long without checking oil clearances, and other catastrophic failures, etc).
1) video will be informational and will show examples of when stock flywheels and rods have failed
2) video will be on my YouTube channel
3)it is intended to show that there is no “safe” line or stage once you start modifying a stock engine, something will eventually fail if you don’t use a billet rod and flywheel.

I’m sorry if what I wrote was poorly written. No intention of dogging quality aftermarket parts. The opposite really.

This is in response to a growing body of diyers that bypass governors and put in heavy valve springs and think it’s going to run forever at 7k rpm and use anecdotal evidence to say that it’s “ok” because theirs hasn’t broken yet.

I’m talking stock rods without oil clearance and prep, then they fail.
I’m talking stock flywheels throwing the magnet
I’m talking stock flywheel failures etc
I’m talking governor gear failures at high rpm.

It’s all going to tie back into best practices and better safe than sorry.
 

XXX#40

TRUMP 2020
Let me just back up here so we are all on the same page. I didn’t consider non-stock scenarios where someone screwed something up (eg oil clearance or improper torque, wearing out the babbit bearings by racing too long without checking oil clearances, and other catastrophic failures, etc).
1) video will be informational and will show examples of when stock flywheels and rods have failed
2) video will be on my YouTube channel
3)it is intended to show that there is no “safe” line or stage once you start modifying a stock engine, something will eventually fail if you don’t use a billet rod and flywheel.

I’m sorry if what I wrote was poorly written. No intention of dogging quality aftermarket parts. The opposite really.

This is in response to a growing body of diyers that bypass governors and put in heavy valve springs and think it’s going to run forever at 7k rpm and use anecdotal evidence to say that it’s “ok” because theirs hasn’t broken yet.

I’m talking stock rods without oil clearance and prep, then they fail.
I’m talking stock flywheels throwing the magnet
I’m talking stock flywheel failures etc
I’m talking governor gear failures at high rpm.

It’s all going to tie back into best practices and better safe than sorry.

Well that really isn't true, we raced the flatheads for years and never broke a rod nor flywheel, both were stock.
We never even broke one during the fiasco when WKA allowed billet rods for the flatty's, we still ran many more years after that on stock rods and ran against billet rods
 

KartFab

Member
I'm more after the clones, and cheap harbor freight experiences. Briggs are going to get a pass since they were phased out in the 90's.

I'm not sure if its the casting quality being much better, smaller diameter (less inertia) of the briggs flathead flywheels or what, but they are solid! I have heard about the steel bolt on dippers failing though on the cast rods from too much flex and fatigue, so there is something to be said there. I am a big fan of the briggs flatheads, but this really isnt the focus of what I am going for. I'm going for the cheap predator 212 engines that people buy for $100 and try to hop up not knowing what to do.

What I am wanting to avoid is seeing people putting stage 3-4 modifications on a small predator engine, rev till the crank journal is dry, and then the rod seizes to the journal and before you know it knock knock or rod through the block.

Im not out here to say you must use billet if you do any modifications, but I am going to point out that there is a huge gray area once you start modifying. It's not like if you do stage 1 modifications and 18 lb springs that you will see failures, but some have already been submitted with magnet failures at 5500 rpm, others have said no problems at 7000.

I know I am going to be getting differences of opinions as well as experienced and non experienced input. This is to gather and compile information and present it so all can be educated and err on the side of caution rather than hope you don't throw a rod or break a magnet off a flywheel.
 
Let me just back up here so we are all on the same page. I didn’t consider non-stock scenarios where someone screwed something up (eg oil clearance or improper torque, wearing out the babbit bearings by racing too long without checking oil clearances, and other catastrophic failures, etc).
1) video will be informational and will show examples of when stock flywheels and rods have failed
2) video will be on my YouTube channel
3)it is intended to show that there is no “safe” line or stage once you start modifying a stock engine, something will eventually fail if you don’t use a billet rod and flywheel.

I’m sorry if what I wrote was poorly written. No intention of dogging quality aftermarket parts. The opposite really.

This is in response to a growing body of diyers that bypass governors and put in heavy valve springs and think it’s going to run forever at 7k rpm and use anecdotal evidence to say that it’s “ok” because theirs hasn’t broken yet.

I’m talking stock rods without oil clearance and prep, then they fail.
I’m talking stock flywheels throwing the magnet
I’m talking stock flywheel failures etc
I’m talking governor gear failures at high rpm.

It’s all going to tie back into best practices and better safe than sorry.



Actually that thought pattern and activity is pretty self teaching. Plus when you pay to learn, you remember it better and longer.
 

XXX#40

TRUMP 2020
I'm more after the clones, and cheap harbor freight experiences. Briggs are going to get a pass since they were phased out in the 90's.

I'm not sure if its the casting quality being much better, smaller diameter (less inertia) of the briggs flathead flywheels or what, but they are solid! I have heard about the steel bolt on dippers failing though on the cast rods from too much flex and fatigue, so there is something to be said there. I am a big fan of the briggs flatheads, but this really isnt the focus of what I am going for. I'm going for the cheap predator 212 engines that people buy for $100 and try to hop up not knowing what to do.

What I am wanting to avoid is seeing people putting stage 3-4 modifications on a small predator engine, rev till the crank journal is dry, and then the rod seizes to the journal and before you know it knock knock or rod through the block.

Im not out here to say you must use billet if you do any modifications, but I am going to point out that there is a huge gray area once you start modifying. It's not like if you do stage 1 modifications and 18 lb springs that you will see failures, but some have already been submitted with magnet failures at 5500 rpm, others have said no problems at 7000.

I know I am going to be getting differences of opinions as well as experienced and non experienced input. This is to gather and compile information and present it so all can be educated and err on the side of caution rather than hope you don't throw a rod or break a magnet off a flywheel.

The flathead wasn't phased out in the late 90's, the flathead was the main engine in dirt oval karting until about 2010.
 

XXX#40

TRUMP 2020
flathead ceased produciton in 1999 http://www.briggsracing.com/racing-engines/raptor not going to argue a point over vocab words, flathead classes still run today, but you dont see joe blow going to harbor freight and buying one off the shelf for $100. That was the point of what I was trying to say. Thanks for all the input here guys.

They quit production of WHOLE engines, they still had warehouses full of engines, the flathead was still the main engine until 2010.
The clone came on the scene in 2005, it didn't even get a national set of rules until 2010, until 2010 each track that had clone classes made the rules to suit the needs of the local racer
 

Jimbo

A trial w/o witnesses is like racin w/o tech
The best thing you could do is to promote safety.
An exploding flywheel is lethal, even on a small engine. Unfortunately, history has proved this, as well as many other non lethal injuries.
I would be very careful about publishing anything that might imply that you are telling people how to do things safely. The one word that should be of most concern to you is LIABILITY.
Unfortunately, there are plenty of dumb people out there as well as those that have a cavalier attitude that will continue to do unsafe things.
I don't think the people that sell the unsafe engines care if you, your kid or anyone else ends up dead.
I would recommend that all kart engines should have approved flywheels and also blower housings that are designed to contain broken flywheels but to my knowledge the only 4 cycle engine that has those features is the Briggs 206 cc size models. Animal, LO 206 jr, LO 206, WF and 1/4 midget engines

OPEN THE GOVERNMENT BEFORE SOMETHING REALLY BAD HAPPENS
 

KartFab

Member
Jimbo, thanks for the input. The goal here is to promote safety, and thank you for the input on liability.

The goal here is to show real world scenarios of what failures occurred with stock rods and flywheels, and why people should put aftermarket billet parts on their engines if they are going to be removing the governor. Ill talk about oil clearance tolerances, and flywheel torque specs.

What i see are broken stock rods because people didn't even want to open the crankcase, but put high flow intake/exhaust and tied back the governor, and tossed in a pair of 18 lb springs so they could rev high.

What is see are broken stock rods because people bought a generator engine and assumed it would run forever because thats what they are designed to do at 3600 rpm up to a point, and not 8000 rpm.

What i see are spun stock and aftermarket flywheels, and sheared keys because people didnt know how to torque down the flywheel properly.

What i see are stock flywheel magnets flying off because you rev too high

What is see are stock flywheel magnets breaking off the magneto supports because of improper clearance and revving too high.

What i have seen in some instances are stock flywheels breaking.

The video i will make will go over all these scenarios, but the main point will be to put on a billet rod and a billet flywheel, check your oil clearances, and torque everything down to spec.

One thing that I see a lot of people do, even with billet is to have that same cavalier attitude that it will just "run forever" because its billet. I want to drive home the point that there are replaceable babbit bearings in connnecting rods for a reason, and that is because they can and do wear out. These things should be checked and replaced when necessary.

Do you have any good suggestions for rod and flywheel safety beyond what we have gone over so far?

I dont want to get too broad by going into piston to head clearance, and all the other components in the engine that may be the source of other catastrophic failures, but its worth knowing about.
 

XXX#40

TRUMP 2020
Wait your the guy on youtube promoting kids riding karts on the street with no safety equipment on?
 

KartFab

Member
Wait your the guy on youtube promoting kids riding karts on the street with no safety equipment on?

Ya got me man. Cheers.
 

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Really, racing on the street?? No helmets? Racing on the streets?
Darwin was right!
Even wearing a helmet, Racing on the streets? In a kart like that? Not safe even on the race track. A fun kart used at family kart racing venues like Nascar speed park. Governed to 14 MPH. with added bumpers of course. Still people get hurt.
 

KartFab

Member
XXX#40 there are critics, talkers, and doers in the world. I think we can assume what bin you fall into.

Since you are such an astute investigator of all things safety, why don't you look at the plans that this video is about? There is an entire page dedicated to safety when building, PPE use, where to ride, and of course, wearing a helmet. The video was made on closed course under strict supervision only to get the right shots. I'd think you are intelligent enough to understand that, but you resort to taking things out of context with your personal vendetta.

I don't know you, and from the little bit of interaction I have had with you so far, I'm not inclined to continue this conversation as you clearly have a lot of free time to disparage and put down others, something I'd like to avoid in life. I wish you the best.
 

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Bob Evans

Grumpy Old Admin
Staff member
IMO, Jamie has a valid point
I'm not sure if its the casting quality being much better, smaller diameter (less inertia) of the briggs flathead flywheels or what, but they are solid!
It's because the magnet assembly is held in place by two horizontal dowels. Stock OHV magnet assemblies are held in place by one vertical screw and some epoxy (or whatever), and that includes the briggs intek.
there are critics, talkers, and doers in the world.
started this site in 1996, and to this day it still gets over a million and a half page views per month.
I wonder which category I would fall into?
 
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