1993 70HP Sputter on muffs?

[Fish_This]

Hi all,

Go the engine back together. Started right up on the muffs and as I was reving it up on the muffs it souded like it was sputtering. no a smooth rev. Is this usual?

Thanks in Advanced

 

[chadpcb]

Re: 1993 70HP Sputter on muffs?

It is normal for a engine on muffs to run at a bit higher rpms.
The reason for this is there is no back pressure on the exhuast system.
It is never good to rev a motor that is on muffs. You could get a runaway senario.

 

[jtexas]

Re: 1993 70HP Sputter on muffs?

With no load on the motor, RPMs are slow to drop back down when you let off the throttle, so you get a few lean combustion cycles after the throttles close but before the RPMs drop to match. Some might refer to that sound as "sputtering."

But like the man said, revving on muffs = bad idea.

 

[Fish_This]

Re: 1993 70HP Sputter on muffs?

Ok gonna take it to the lake today and run it, anything else I can check before going?

On a side note tonight I am going to pick up a 55 Gallon tub for it!!