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Old 07-03-2014, 03:14 PM
JOBAfunky JOBAfunky is offline
Motorized Bicycle Member
Join Date: May 2014
Location: F'n Kansas
Posts: 33
Default Need some help diagnosing.

I'd love to have a pro in town that I could talk to and have listen to my bike, but you guys are pretty helpful so I'll try my best to describe what's going on.

Installed a 66cc Bikeberry kit on an old(and free) murray 26 inch mountain bike.
Was noticing what I think is called "four stroking" except when giving it gas while going uphill.

I replaced the spark plug with a ngk and gapped it up to .04 and I seemed to be not getting this as much, but I stripped out the head in the process.

Got a replacement straight low compression head(Thanks Davezilla and mapbike) and now it back up and running but four stroking most of the time again.(minor worry) Engine seems to pop more (minor worry).

Throughout all of this I was popping spokes, and at first I took it to the bike shop to get them fixed and wheel trued, got the whole thing back together pedaled 2 feet then "ping" so I got good at swapping spokes and truing the wheel, but now the wheel seems to have a wobble at the axle. (medium worry)

The other thing is after the engine gets warmed up and going high rpm I sometimes get a raspy sound like a thin sheet of vibrating metal loosely attached to something. (medium worry) Or maybe the sound of a little gas escaping, kinda hard to tell. Power is less than original, but I expected that going to a low compression head(No worry)

So, what should I keep or toss out of my worry box?
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