motor question

[oil-lamp]

Ok Guys here's a question? How much do these engines vibrate? I been having some bad vibrations while running the motor. Last night I ran it a minute or two without the tyranny and it just about took the bike apart. There was a time or two it tuned to where it didn't vibrate as much but had to stop before things started falling off. Any thoughts? 

[Ricks]

Something is out of balance,.  These motors are pretty smooth running.

[oil-lamp]

Ok what should I look for. I was thinking about swapping the flywheel to see if that helps. What else is there?

[kartjockey]

It would seem logical to blame the flywheel. Have you seen  that  flywheel run on another engine. I don't know if Simplex balanced their engines 'internally' or not.  I would assume they did. An engine that was externally balanced would mean that the flywheel is specific to that engine or at least that specific kind of engine. For example, a smallblock 350 chevy is internally balanced and a 400 smallblock chevy is externally balanced.  Although the harmonic balancers will fit each other they aren't to be crossed up.  A 400 balancer will shake your teeth out when put on a 350. This does raise the question of what would happen if a flywheel from a "G" lets say was installed onto an "M" since we know the cranks are different.(actually I'm not sure if they fit each other).  I used to have 5hp briggs stuff balanced but had to supply all the fixtures and etc. to have them done. No one had a shaft to mount the flywheels on. I would definitely try switching flywheels.

[Ricks]

I am with Tom on this one.  I would think these engines are internally balanced.  I have switched flywheels between 2 motors, and did not notice any difference.

If the flywheel doesn't fix the problem, I would look at the rod bearing next.  If that seems OK, I think I would take the crack out and check it for straightness.

[oil-lamp]

Well this motor was already a running motor when I received it. I never had it running long enough to notice the vibration till now. So seeing its been years from childhood when we did ride I've not notice it. Shoot it could be that wasps have filled some holes that could affect it. So it should be the flywheel not bearing or crank?

[Ricks]

Reese, we responded at the same time.  See my above post.

[oil-lamp]

Ricks I will check that also. Just trying to get all the info before I get back home. I don't want to loose my temper getting this bike going. 

[Mike Sal]

Do you have your upper motor brace in place?  If it's not there, it will affect the harmonics.  Other than that, I agree that you should pull the cover & take a look at how true the flywheel revolves and if it looks good, pull it anyway to see if a magnet has come loose or if a mud dauber has left a gift in there.
Mike Sal

[oil-lamp]

Well I cannot use my spare flywheel till I get the bolt holes heilx. All three are bad and will not be a quick fix. I did not find anything ad-be-normal with the flywheel that is on there even filmed it for later viewing. It seem to still vibrate but not as bad as the last time. The motor bracket is in place mounting bolts are tight or at least they were tight. Now how do I check the rod without disassembling the motor? Any thoughts. 

[admin]

Reese, take off the motor side cover and compression plate and check the rod bearing.  If the bearing is loose, I would think that could cause a hell of a rough running motor.

Also, are you running a stock compression plate or do you have one of those solid aluminum ones?  Check to see that the rod is not rubbing on the compression plate.  I know with those aluminum ones, that can be an issue.

Rick

[oil-lamp]

Rick,
I do have a solid cover on it and a large scar on my left hand to prove its not hitting the rod. Well at least not hard enough to cause trouble. Could something be pushed off center if the compression plate was install deep enough to press on the crank to hold it from turning? I will check the rod tonight when I get back home. 

[Ricks]

I'm thinking you might not have enough clearance between the compression plate and rod screw.  Maybe as motor turns it is hitting the plate. Should be easy to tell if the plate is nicked up on the inside.

[oil-lamp]

There is some contact to the plate but only a gentle rub no hitting is taking place.

[pd]

That gentle rub might be enough to throw the balance off .