rubber on engine mounts slows you down.

[Deleted member 25783]

Redneck,
Post the results of your suggestion, curious minds need to know.

 

[Deleted member 25783]

Once my Sportsman Flyer build is complete...... (long pause ) I want to re-think and redo the engine mounting system used in my Huffy -Davidson (see my avatar ) rubber blocks to isolate the engine. Logically motor mounts as used in vehicles provide vibration isolation and dampen drivetrain torque relief. But empirical data from major MB builders and my own experience restoring vintage Harleys tells me that a hard mounted engine, firmly attached to the frame is if not perfect survived and were used for decades . I may have to make my own engine mount for the Huffy-Davidson as it gets reworked, I promise to give you all a comprehensive evaluation.
Forgive my digression, I have no empirical data to verify rubber mounting an engine could slow or impair motive force. Might be rough on the drivetrain as I think I am experiencing
Tom from Rubicon, WI

 

[bcredneck]

I'd rather stay light with my bike
But you ever see the brace that connects the top and down tube on a motorcycle and creates a triangle right behind the head tube that's there to cancel out frame harmonics

 

[Deleted member 12676]

rubber allows the engine to vibrate more which can froth the fuel in the carburetor which affects how it runs

best to balance the crank. Two 3/8" holes in the crank wheels will change night to day!

 

[Deleted member 25783]

rubber allows the engine to vibrate more which can froth the fuel in the carburetor which affects how it runs

best to balance the crank. Two 3/8" holes in the crank wheels will change night to day!

Great suggestion Jag,
Do you put the crankshaft between centers ? I did a crankshaft turning job for a guy. It was a engine from a log splitter which was mated a hydraulic pump via tapered keyed shaft. My customers application was for a Go-Cart so I turned the out-put side to fit a centrifugal clutch. I spun the crankshaft to 1000 rpm for a fine finish with no imbalance. Do you weigh the con rod piston assy. and the remove the same from the counter balance?
Jag., forgot to ask, 2 stroke or 4 stroke?

 

[Deleted member 25783]

I'd rather stay light with my bike
But you ever see the brace that connects the top and down tube on a motorcycle and creates a triangle right behind the head tube that's there to cancel out frame harmonics

Frame harmonics? Never would have given it consideration till you mentioned it. Learn something new every day and live a long happy life. Thanks.

 

[Deleted member 12676]

look at my page http://www.dragonfly75.com/motorbike/vibes.html and download the balance calculator

 

[Deleted member 25783]

look at my page http://www.dragonfly75.com/motorbike/vibes.html and download the balance calculator

Thanks for the quick reply Jag, I will do some serious study.
Regards,
Tom from Rubicon, WI

 

[gary55]

After all the various methods I have seen so far nothing has convinced me of anything other than solid mounting. I get a lot of guys saying the bike speeds up then dies down then speeds up then dies down. They think I'm crazy when I tell them it's loose motor mounts allowing the motor vibrate enough to create bubbles in the carb, but tighten them up and there believers. On the large frame mounts I double the frame where the mount attaches so the flat engine mount won't stress the frame where they connect.

 

[john morrow]

Jag. Has the best solution to stopping engine vibration. I drilled the 2 hole's at 3/8 and like magic vibration gone.