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Loosing power at full throttle 4-5 gear 50mph

617 Views 1 Reply 2 Participants Last post by  Critter
Hi Everyone,

New to the forum, I'm no mechanic and don't have much experience but i understand the basics

I'm having an issue with my Daelim Daystar 125, when I get to about 45-50 mph in 4-5th gear and I pull the throttle all the way the bike starts to choke up and looses almost all power (doesn't cut out completely) i then go down a few gears as I'm slowing down which doesn't seem to help until i come to complete stop and the engine cuts out.

I then start the engine back up again with no problems at all until i get to the same situation as above - my question is why is this happening?

Just as an FYI i had a spark plug blow out last week which took the threads in the cylinder head with it, so I took the cylinder apart (with help) re-tapped and fitted a helicoil (couldn't find any inserts online which fit) put a new spark plug in and it was up and running again beautifully- the problem is i dropped the spark plug before fitting it and the outside thread casing caved in a little and was very close to touching the ceramic part inside the plug - could this be causing the spark plug to ark incorrectly or overheat?

Another issue is I didn't tighten up the crankcase cap but as far as I'm aware this shouldn't matter at all anyway as it's not under any compression and doesn't have any oil etc in.

I'm going over to the bike where it broke down tonight to fit a brand new undamaged spark plug but I just want to ask you lot if there's anything else I should be looking for,

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Each spark plug requires a specific gap according to it's application. Dropping one and reducing that gap definitely will not help it run better. I would do a compression test and see if that helicoil is solid and not leaking.
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