Small Engines (Lawn Mowers, etc.): overheating engine, small engine warehouse, snapper rider

Question
QUESTION: I replaced a blown engine on a a 1991 Snapper rear engine Model 3312X6S rider. The original engine was a:
1) 12hp B&S model 281707
         Type  0162-01
         Code  88082431
I called Small Engine Warehouse and ordered the engine they recommended to replace it. The replacement engine was a 2) B&S 13.5 HP Model- 28R707
         Type   1120-E1
         Code-  030531ZE
It came with an electric starter.
When it arrived the only change I made was to place a recoil starter on top of the crank. I reused the muffler off the old engine. I matched up the drive disk to the transmission and filled it to level with Penzoil 30W. It ran fine. Initial run time was about 20 minutes. I shut down and noticed the block was extremely hot this included the base and the frame of the mower. I have not encountered this type of heat on my 9hp B&S on another Snapper rider even after a couple of hours run time. I dont beleieve the engine suffered any damage but I am concerned it will if i ran it longer. The engine oil does not appear to be burned. The mower ran fine in all gears and it does not appear that the engine was bogged down due to any type of friction from the disk drive on the Snapper transmission. This is the third re engine job on various Snapper riders I have owned over 20 years so I feel fairly mechanically competetnt on these units. Just wondering if I'm missing something. I'm Stumped.
PS- I didnt monkey with the flywheel just removed the shroud to thread the adapter shaft into the crank end to accept the recoil starter. Screen replaced and no binding seen or heard.

ANSWER: Hello John:

Sorry for the Delay. This Question was Located in the Question Pool. It is Not Unusual for a New Engine to Run Hot Until the Engine Components Seat In. If you Did Not Get the Recoil Starter Clutch Tight Enough the Flywheel Key May have been Damaged when the Engine was First Started and is Causing the Engine to Fire Slightly Out of Time and Causing the Heating Problem. The Starter Clutch or Flywheel Nut is Torqued to 85 Foot Pounds. You can View a Breakdown/IPL of this Engine at this Site Addy, http://www.smallenginepartswarehouse.com/parts.asp and Select the Shop Online Parts Look Up. Then Select the Model Tab. Then Select the OEM and Enter the Model and Type Numbers (28R707-1120). Then Double Click on the Model in the Results Area. Now you can Select the Section of the Engine you Wish to View. Hope this Helps. I am Here if You Require More Assistance. Let me Know What Happens, Please. Thanks.

Good Luck

Respectfully

John

PS: I am Allowed to Answer 10 Questions a Day. If you See I am Maxxed Out, then Try Submitting your Question at or Just After 9pm EST (US). My New Day Starts then. Thanks.

Respectfully

John

---------- FOLLOW-UP ----------

QUESTION: I dont think its a flywheel or key issue. i never took off a nut locking the flywheel down. The shround pulls off an exposes the end of the crank shaft. It is a female end and i threaded an extension shaft into the end of the crank and attached the recoil clutch to this shaft. Shroud was replaced with the appropriate screen and bolted in place. there shouldnt be a flywheel issue.

Answer
Hello Again John:

If the Flywheel Key is a Non Issue, then Either the Muffler is Slightly Clogged with Carbon or the Engine is Simply "Breaking In" and Should Start Running at Normal Temperatures After a Couple of Hours Running Time. Hope this Helps. I am Here if You Require More Assistance. Let me Know What Happens, Please. Thanks.

Good Luck

Respectfully

John