old craftsman rider lacks power

[wbt]

Help please. I'm new to the site n need of help with this issue. I have an older craftsman with a 12.5 hp briggs n stratt. It says its an I/c quiet. But to the point. I am no whiz with a mower but I have done all the basics fresh oil, new air filter , new e3 spark plug, n a new fuel filter. It mows fine n seems to go n gear fine but it just seems to be missing power. Any decent incline and I have to drop n to 2nd gear to make it. Its light years better from when I got it but I was just wondering if the drive belt cud b loose n causing it to not have as much umph. Any help on this wud b much appreciated? Thanks for ur time I'll

 

[exotion]

Help please. I'm new to the site n need of help with this issue. I have an older craftsman with a 12.5 hp briggs n stratt. It says its an I/c quiet. But to the point. I am no whiz with a mower but I have done all the basics fresh oil, new air filter , new e3 spark plug, n a new fuel filter. It mows fine n seems to go n gear fine but it just seems to be missing power. Any decent incline and I have to drop n to 2nd gear to make it. Its light years better from when I got it but I was just wondering if the drive belt cud b loose n causing it to not have as much umph. Any help on this wud b much appreciated? Thanks for ur time I'll

I have a murray with the same 12.5 without knowing what model tractor you have. Murray is the same grade as craftsman and mine does the same thing. I've looked through the tranny can't find anything wrong I think that's just the way they are

 

[msaeger]

On my mower it was the drive belt slipping causing this. I didn't get a new belt I just made the spring on the tensioner tighter.

 

[wbt]

On my mower it was the drive belt slipping causing this. I didn't get a new belt I just made the spring on the tensioner tighter.

Hey i appreciate the response. I will try that n see what happens. Ill post back with results. Much appreciated