Author Topic: 70cc upgrade, bike cutting out when revving  (Read 912 times)

CobraStream

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70cc upgrade, bike cutting out when revving
« on: October 25, 2019, 05:47:48 PM »
Hi all here is my story and issue.

I purchased a cheap 2013 Kymco Super 8 2T (i think its a 2T), I paid £250 for it with no mot and a box of bits that had been removed.

The fella I bought it from had given up on it after not getting it to run right.
I do know a bit about bikes (own a Vulcan 900) so cracked on with sorting it.

Got the engine back together and it starts 1st time every time, however even after running for a while it kept cutting out if i revved it high.
I figured fuel starvation so I bypassed the vacuum control fuel tap and replace with a proper fuel tap.
Now getting fuel to the carb the bike ran a little better but still dies when revving high.
I put my hand just over halfway over the air intake and tried again and it revved its tits off..
So I figured choke the K&N filter by fitting a plastic disc with a hole cut in it to restrict airflow.
This worked great but after riding it about 250 yards it dies again just like before.
So now i think it must be that the carb needs a bigger main jet, trouble is I do not know what size to get.

So my question in short is what jet size do i need to fit to get this bugger revving right without the airfilter choke disc I fitted?

Also the starter does not work - where is it? I cant find it lol

eamartin

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Re: 70cc upgrade, bike cutting out when revving
« Reply #1 on: October 25, 2019, 07:46:40 PM »
So...you installed a 70cc upgrade?  Is the current main jet stock?  What size is it?

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