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#Post#: 13512--------------------------------------------------
Overheating
By: Snakey Date: July 15, 2025, 7:05 am
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I am in the process of forming cardboard mock-up bodywork on my
almost-rolling chassis and it has really brought home how little
space around the engine (and its exhaust) there is. Yet in all
the build accounts I have read I’ve never heard of anyone having
overheating issues. For me its become a bit of a brainworm that
won’t let go. I’ve adapted an oil temperature gauge sender in
one of the block drain holes and have sent off for a cylinder
head temp gauge. But CK builders have been stuffing air-cooled
engines in tiny spaces for years – am I just over-thinking this?
#Post#: 13513--------------------------------------------------
Re: Overheating
By: jon.pearce Date: July 15, 2025, 7:32 am
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yes !! lol
The engines are fan cooled...well, depending what you do to the
fan vanes !
I did my temp tests with a simple infra red point and shoot type
gun.
#Post#: 13515--------------------------------------------------
Re: Overheating
By: Jimr1999 Date: July 15, 2025, 10:12 am
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Some cyclekarts do overheat especially in warm weather if the
engine is enclosed. Some of our members run fans from computer
systems to aid cooling in the bodywork, some just run with the
boot lid off, some put ducting in to scoop air from below across
the engine, some use perforated alloy for panels. We suggest
everyone vents the exhaust outside the engine compartment and
exhaust wrap helps both the cooling and the performance a
little. We have one kart in our membership that seems to collect
grass around the cooling fan enclosure adding to the problems
and creating the chance of a grass fire. They all behave a bit
differently, what yours will need and what it wont will probably
only be apparent after your first few outings.
JimR
#Post#: 13518--------------------------------------------------
Re: Overheating
By: StefanN Date: July 16, 2025, 1:08 am
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You’re not overthinking it - lots of people have overheating
issues if they don’t remove the back of their ck when running.
I have 2 holes in the top of my tail that are made to look like
the twin fuel tank fillers. Below that are two computer fans.
They assist the natural convection. These make all the
difference between the engine overheating and it staying hot but
stable.
I’ve also got an oil temp gauge fitted and it’s very helpful.
Wrapping the exhaust helps a lot as does getting the exhaust run
out of the tail asap.
The engine shrouds and fuel tank help guide the air from the
engine fan over the fins. So if you move the tank for example,
consider adding a plate to force the air over the fins. I’ve no
direct measurements but I suspect this is a significant factor.
Depending on your layout, engine bay temperature can also be a
factor in brake cooling, so worth considering if you are adding
air ducts/scoops. Ie bring the fresh air in to flow over the
brakes.
#Post#: 13520--------------------------------------------------
Re: Overheating
By: jon.pearce Date: July 16, 2025, 3:10 am
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Moving the tank away from the engine bay and fitting a "Top
Plate" certainly improves the situation.
By moving the tank and using a Pulse Pump, you can keep the tank
and its contents cool.
(If you have an aluminium tank the fuel stays really cool).
These engines run best when hot in my opinion.
If you fit a good quality rev counter, you will see the idle
rise and stabilize after a few minutes of running from cold on
the stand.
#Post#: 13521--------------------------------------------------
Re: Overheating
By: DavidandCarolynne Date: July 16, 2025, 3:14 am
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What is the ideal operating temperature?
#Post#: 13523--------------------------------------------------
Re: Overheating
By: StefanN Date: July 16, 2025, 4:38 am
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[quote author=Jon Pearce link=topic=1782.msg13520#msg13520
date=1752653407]
These engines run best when hot in my opinion.
If you fit a good quality rev counter, you will see the idle
rise and stabilize after a few minutes of running from cold on
the stand.
[/quote]
What temperature do you mean by "hot" Jon? I've had a quick
look for technical specs for the engines and not found anything
yet. There's a few specs for max temperature for different
types of oil.
#Post#: 13524--------------------------------------------------
Re: Overheating
By: jon.pearce Date: July 16, 2025, 5:01 am
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I will do a little video at the weekend and post it here.
I always use 0W-20 Semi Synthetic, but I dont use the standard
quantity of oil either.
To be honest, I am only concerned with the head temperature and
not the temp of the oil.
#Post#: 13526--------------------------------------------------
Re: Overheating
By: DavidandCarolynne Date: July 16, 2025, 5:38 am
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I found this. It's from the usa, so temps are Farenheit.
It seems cylinder head at around 375F (190C) is optimal. But
then the thread degenerates into heated duscussion...
HTML https://4cycle.com/karting/threads/clone-temperature.35811/
#Post#: 13529--------------------------------------------------
Re: Overheating
By: jay pratt Date: July 16, 2025, 7:38 am
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Mine decides its had enough playing once the temp under the
spark plug hits 160°c and starts spluttering, then if you let
off throttle for too long it cuts out, not figured out exactly
why, but it doesn't hit 160 without the lid on. My fuel tank is
in the front with a pulse pump mounted under a pro kart engine
plate so should be cooled with the flywheel fan, which can only
draw cold air in from outside.
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