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#Post#: 14102--------------------------------------------------
Kaboom blown engine
By: Paddy the pilot Date: December 4, 2025, 2:52 am
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I had an interesting morning last week, I installed a 4 degree
ignition advance key, the engine started well and with it warmed
up I decided to see how it revved up, the kart was on a stand
and I got quite the surprise.
The flywheel magnet decided to break loose, nobody hurt but my
wallet took a hit.
I wonder if any other members have experienced a similar thing.
#Post#: 14106--------------------------------------------------
Re: Kaboom blown engine
By: Jimr1999 Date: December 4, 2025, 4:42 am
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Ouch, at least you have a good supply of spares for the new
engine Paddy. A good Scot would keep as many bits as possible,
Crankshaft might swap over if the flywheel is compatible, keep
the head to practice mild porting on. All the performance bits
should swap over (Carb, valve springs etc). I bet your wallet
took a bigger hit getting to the last event :-)
I have heard of the glue letting go before. The stuff I read
that they use is 2 part and sensitive to temperature in cure and
has a short pot life when mixed. Care in preparation and
application necessary.
All the best,
JimR
#Post#: 14107--------------------------------------------------
Re: Kaboom blown engine
By: NewbieNick Date: December 4, 2025, 4:55 am
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Hi Paddy. I know exactly how you feel, my Lifan engine
dismantled itself after about 10 meetings.
Can you tell me what make engine it was.
Hope you have more luck with the next one.
Cheers Nick
#Post#: 14111--------------------------------------------------
Re: Kaboom blown engine
By: Ian F Date: December 4, 2025, 8:11 am
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Hi Paddy, sorry to hear about your magnet letting go.
I did a lot of research three years ago into flywheels
grenading, and whilst there were lots of people saying how
unreliable and dangerous they were, there was not one single
story from first hand experience, just the usual scare-mongering
based on heresay. However, there was one single first-hand
story of someone's magnet letting go!
Do you have any further information of what failed and the
resultant damage, plus also whether the errant parts were
contained within the shield?
#Post#: 14115--------------------------------------------------
Re: Kaboom blown engine
By: Paddy the pilot Date: December 4, 2025, 3:53 pm
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Ian & Nick,
I had the kart up on a stand and was standing over it when it
let go, nothing really went flying part of the coil (with the
broken mount) ended up on top of the engine. The cowl contained
everything else, magnet pieces and the metal plate which covers
it. The cowl was slightly bent and shows a small puncture hole.
As I didn't have a tachometer on it I don't know what kind of
revs it was pulling but quite high, I had removed the governor
and put a 4 degree advance wood-ruff key in place of the
original.
The engine was an old 196cc that had been used on a lawnmower at
one stage if it's checkered life, there was quite a bit of rust
on the surface to which the magnet was attached.
I hope this helps and if you want to chat about it please feel
free to call me.
Paddy the Pilot
#Post#: 14117--------------------------------------------------
Re: Kaboom blown engine
By: Ian F Date: December 5, 2025, 1:27 am
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Hi Paddy, thanks very much for the detailed response and the
photo, its great to have some real-life experience and data ;D
#Post#: 14243--------------------------------------------------
Re: Kaboom blown engine
By: tim.wheater Date: January 15, 2026, 1:47 pm
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I have taken 2 different cast flywheels to 7k and they both
stayed in one piece, 1 Lifan and 1 Kohla. I also did some
calculations to see if the steel cover would contain the bits in
the event of a failure, there were some assumptions made but I
satisfied myself it would. You seem to have confirmed that .
Blowing engines up is all part of the fun , I have done 1 each
season so far 😜
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