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#Post#: 13124--------------------------------------------------
Engine stalling
DIR By: PredHughes
Date: May 4, 2025, 12:51 pm
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Hi guys,
I have a brand new Hyundai Engine, I have replaced Carb with
same but it has a fuel filter and mixture screw, changed jet to
a 0.38"/96mm and emulsifier to one with bigger holes, has an
open air intake to outside, it starts great, idles great, revs
and runs fine. But after a few 100 yards it splutters/stals as
if it was running out of fuel, it re starts with just one or two
pulls, no problem.
I've taken car bowl off, lifted float and fuel runs out fine and
clean.
I've changed and tried many jets and this one sounds and runs
better than the others, set mixture screw to what I think sounds
sweet.. I had this issue at Stretton played with mixture screw
at home and thought it was better, had a good location today at
an old Airfield but kept going off after a stretch.
I'm Stumped as what to try next, any suggestion greatly
appreciated. Regard Pred
#Post#: 13125--------------------------------------------------
Re: Engine stalling
DIR By: jon.pearce
Date: May 4, 2025, 1:03 pm
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re-check the ignition system...and plug, cap, wiring, etc.
Sounds like a fault that only occurs when the kart is moving?
chaffing ignition wire to earth, etc.
96 main is big in my opinion...my Hyundai has a 17mm bored carb
and an 86 jet.
#Post#: 13126--------------------------------------------------
Re: Engine stalling
DIR By: Ian F
Date: May 4, 2025, 3:00 pm
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Hi Pred,
I have a set of chinese jets off E-Bay and these are marked as
31 to 38. Like you I assumed these were Imperial measurements
in thousands of an inch, and like you assumed a 38 would be
0.96mm. However, on checking with drills it is way smaller
(less than 0.8mmand think about 0.75mm). Therefore, I now think
these are either just chinese rubbish or maybe its a flow
(rather than bore diameter) measurement like some Mikuni jets.
I have still used these jets but have drilled them out. I was
successfully using 0.8mm drill for a standard bore carb and
0.9mm for a bored out carb.
My theory on your issue is that the emulsion tube sits in a
"well" which is supplied by fuel from the main jet, as you put
the engine under load the well progressively empties till your
just pulling on the main jet. Therefore, I reckon yours runs OK
till the well is empty at which point the jet (possibly much
smaller that the 0.96mm as detailed above) cannot supply enough
fuel.
Good luck
#Post#: 13128--------------------------------------------------
Re: Engine stalling
DIR By: PredHughes
Date: May 4, 2025, 3:25 pm
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Jon, Ian thank you both for reply, I will check out all above,
Ian my set of jets were also Chinese ones numbers same as you
had, and your theory makes a lot of sense as to what happens to
mine
Fuel starvation would make perfect sense.
Thank you both
#Post#: 13129--------------------------------------------------
Re: Engine stalling
DIR By: NewbieNick
Date: May 4, 2025, 11:47 pm
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Hi Pred I had a similar problem with a BSA C 15 many years ago,
I had inadvertently blocked the fuel filler cap vent hole with
chrome cleaner. May be worth checking. Have you removed or
disconnected the oil sensor? If not that could be the issue.
Good luck .
#Post#: 13131--------------------------------------------------
Re: Engine stalling
DIR By: jon.pearce
Date: May 5, 2025, 2:44 am
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Ian makes a really good point here....
I had assumed that you had original Mikuni jets !
However, if you have been lean on the main jet all this time of
running, what does the plug look like ?
Cheers,
Jon
#Post#: 13132--------------------------------------------------
Re: Engine stalling
DIR By: Ian F
Date: May 5, 2025, 3:44 am
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Hi again,
I've just been checking back through my notes and a 0.65mm
diameter sewing pin wouldnt pass through those chinese jets. I
dont remember if I tried it on the 37 and 38 jets before I
drilled them, but as you can see they are very small diameter
holes.
#Post#: 13149--------------------------------------------------
Re: Engine stalling
DIR By: PredHughes
Date: May 11, 2025, 4:03 pm
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Tomorrow I will be running round a karting track, with a drilled
out jet and another 3 in hand of different bores, will report
outcome and I do hope I will find a sweet running one.
Thanks for the above replies
Pred
#Post#: 13152--------------------------------------------------
Re: Engine stalling
DIR By: jon.pearce
Date: May 12, 2025, 2:41 am
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Best of luck today Pred,
Give me a call during the day if you need phone support !!
07833 917962
Jon
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