muffler vibration issues

[Old Reliable]

Hey guys! It's Old Reliable back from a long break from this site. Took a break from from the morini bc parts are expensive and hard to come by. I purchased a new 66cc slant head ht engine about 2 months ago. I ran 50:1 for the first gallon and now 32:1 for nominal use. My engine was running great yesterday, but blew out my exhaust gasket. I replaced the gasket with an aluminum gasket, and the engine bogs at WOT and vibrates a **** load. I took off the exhaust and that still happens. My spark plug is a dark red. Any help here?

 

[crassius]

maybe motor has gone really rich as it runs in - or maybe the mounts are loose

 

[Venice Motor Bikes]

50:1 is way too little oil for the break in!!

I always recommend 24:1 for the break in & then switch to 32:1.

As for the vibrations... re-torque all the engine bolts & instal the exhaust brace (that should've been included in your engine kit).

 

[bairdco]

i've never had any luck with either an aluminum gasket or the copper gasket manic used to make. they all leaked and would come loose.

i like the stock thick gaskets, but they're usually not reusable if you take your pipe off.

the stock pipe is designed to use another mounting bracket. it's too mu h weight to just hang off the engine.

make sure your engine mounts are tight as well. once things start shaking, the exhaust is one of the first to go...

 

[2door]

Ditto to all of the above advice.
The copper or aluminum gaskets are okay IF the exhaust flange and the mating cylinder gasket areas are absolutely flat. The steel flange on the pipe/muffler, almost without exception will be warped from the welding process and will need to be sanded or ground flat. Use thick, 1/8" is good, gasket material made for high temperature/exhaust applications. Any auto parts store will have it. The kit gaskets are prone to premature failure. Torque the fasteners to about 50 to 60 inch pounds and re-torque after a couple of heat/cool cycles.

And as was stated, secure the muffler with a secondary clamp or bracket. Don't rely on the flange fasteners to hold it.

I too am curious why you would go so lean on your oil for break-in. 50:1 isn't much oil unless you're using one of the super synthetics designed to be mixed at that ratio.

Tom