79cc vibration

donb4103

Member
Oct 7, 2011
167
0
16
74
Chickasha,Oklahoma
I was wondering if anyone else has experienced this. I am building a 79cc bike. I`m using a Micargi GTS frame. Got it running and when ever you take off it shudders and vibrates like crazy until you get it up to a certain speed. It runs awesome after you get it going. But low speeds and takeoffs are really bad.
 

Wickedest1

Member
Oct 31, 2012
687
6
18
38
connecticut
It is definitely the clutch. The engagement is somewhere around 1800-2000 rpm for most of the ⅝" clutches.

Torque converter will smooth out your ride, but may decrease top end by a couple mph.

I have no pedals on my 79 build and I've found that feathering the throttle up slowly will ease some of the shuddering.
 
I built a 79cc on a Macargi Huntington beach cruiser and it did the same thing. To remedy this I put a spring loaded chain tensioner on the drive chain and a fixed tensioner on the transmission primary chain. It now starts off from a standing stop with no problem. It wasn't the clutch in my case. My trusty Stromberg Carlson clipper speedometer says it will do 43 MPH flat out with a 44tooth rear sprocket. The 79cc four stroke will never be as smooth as a 2-stoke because it is firing to far below TDC at low RPM's. Mine smooths out at about 20 MPH.