69cc vibration cure?

[Deleted member 12676]

I just did a search for "vibration" and almost all the gripes were about the 69cc(80cc) vibrating excessively, to the point of not even wanting to rev the bike up which is when it starts vibrating. I have the 48cc bottom end and 3 cylinder sizes (48cc, 55cc, 60cc) and before I lightened the wrist pin and installed the Jaguar CDI the upper rpm vibration was bad but not as intolerable as people were saying in their posts. I would like to hear of other peoples experience, hopefully from someone who tried the same cure on their 69cc and what the outcome was. Here are a few of the posts I found:

Is the 2 cycle [69cc] motor known for a lot of vibration? I have some rubber pads between the mounts and the frame, but anything over about 15mph is just about unbearable.

My seat seems to be vibrating a little too much to comfortably ride long distances at full throttle. It seems to have gotten worse recently. Any idea how I could figure out where it is coming from? The engine mounts are solid I wrapped the frame in thick leather under the mounting hardware. I'm running the Chinese 66cc 2 stroke on a mountain bike.

I just finished my first motored bike build- a "Black Stallion" 66/80cc from Kings Motor Bikes. ...at the end of yesterdays ride I cranked it wide open to see what it could do. As it built RPMs, it passed a certain range and the entire bike began vibrating like the engine was totally mis-balanced! The gas tank loosened and shifted, and I had trouble keeping my hands on the handlebars! I dropped RPMs, and the vibration went completely away. I tried doing this several times, and each time I crossed that certain RPM barrier, the bike would go into wild vibration!

I have a huffy panama jack bicycle, with a 80cc engine on it. I have such a bad vibration in the bike, its terrible.Ive tried rubber motor mounts, does anyone have any ideas? please help!!!!!!!!!!!!

 

[Deleted member 12676]

ps- please I don't really want to hear about motor mount mods to help with the vibration. I know some people have been semi-successful doing that but that is not what this post is about. thank you. I am only asking for reports from people who have tried using a lighter wrist pin (sources are listed on my site) and the Jaguar CDI. Reports on both engine sizes are welcome.

 

[Skyliner70cc]

The only engine vibration issues I had were with the original bushing engine HT engines. They would make your hands go numb after 10 minutes of riding. Today's engines are significantly better and thick foam grips have eliminated the issue for me.

 

[Florida_Trail_Rider]

I have a 80cc real 80cc and alot of rubber in the mounts with jack shaft so I do 40 and it is not Unbarible for me at all..Although I like the vibration

 

[Jbomb]

vibration solution?

ps- please I don't really want to hear about motor mount mods to help with the vibration. I know some people have been semi-successful doing that but that is not what this post is about. thank you. I am only asking for reports from people who have tried using a lighter wrist pin (sources are listed on my site) and the Jaguar CDI. Reports on both engine sizes are welcome.

Hey Jag,
I will be taking the measures you recommended including the lighter pocket bike wrist pin and Jag CDI. Will update when parts arrive.