Jump to content

Unofficial Home of Old Simplicity & Allis-Chalmers Garden Tractors

Bnrober2

Simplicity 728

Recommended Posts

Bnrober2

Hello everyone, new member and first time poster here.  I recently bought a really well maintained Simplicity 728 Broadmoor, it had a blown engine and i assumed it would be easy to find a replacement, turns out I'm struggling.  Does anyone have any advice on repowering? Id like to keep the old school look and i don't want to have to use a pull start but i'm struggling to get one that actually fits.

155778F9-290C-40B5-B22E-3A983093EBF8.jpeg

  • Like 2

Share this post


Link to post
Share on other sites
Chris727

Too keep from modifying the hood you will have to locate another 7-8 hp vertical shaft Briggs ideally with the 3" x  1" crank. When you put a different engine on it I would suggest removing that exhaust pipe as it will stress the exhaust threads in the aluminum block. 

  • Like 3

Share this post


Link to post
Share on other sites
dhoadley

What exactly blew on the old engine? It may be possible to rebuild it. A repower will require you to either remove or modify (cut up) the hood and grill. They look to pretty to hack up like that. Good luck, Dave

  • Like 2

Share this post


Link to post
Share on other sites
Bnrober2

Im not exactly sure what blew on the old motor, but there is a hole in the side of the crankcase.  I found a "new" 9 HP briggs from a 1999 craftsman rear motor mower.  Fits like a champ, plus a gain a single HP!  Just got to get some electrical figured out.  Mine has a belt driven starter generator this one has a normal starter/magneto set up. 

9615588A-AFB7-46C3-992D-3414511136FD.jpeg

  • Like 5

Share this post


Link to post
Share on other sites
Bnrober2
3 hours ago, Chris727 said:

You can install the starter generator on this engine to keep it looking factory and to keep the wiring simple. 

 

That what I decided to do.  The original motor was in pretty good shape, and had been running very recently, so everything I pull off of it should work.  It's wild to me that every single screw hole matches between the two motors that are nearly 30 years apart.

  • Like 4

Share this post


Link to post
Share on other sites
AC716
14 hours ago, Bill725 said:

THAT PIPE!

Yep except its pointed the wrong way for me! I have a pair of 1100 Goldwing chrome pipes im considering modifing to go on my Allis 716

Share this post


Link to post
Share on other sites
Bnrober2

Okay, I might have messed something up. In the process of checking the starter generator and the wiring the regulator fell off the top of the motor and sparked now it won’t spin the starter anymore. What did I break? 

Share this post


Link to post
Share on other sites
rbstuartjr

Unfortunately it sounds like something shorted when the regulator hit the ground. I’m not familiar with what style regulator that is, but would check the wiring inside the regulator to see if anything looks amiss. Inside there are usually points that will engage due to battery power, which will send power to the starter to start and then reverse to send power back to the battery for charging. Those points have to be air gapped and are held by springs. Someone more familiar with that particular set should help you.

Share this post


Link to post
Share on other sites
Chris727

Fortunately Those regulators are inexpensive to replace. To check the starter you can jump the “A” terminal with 12 volts and see if it spins. Do not put any power to the “F” terminal or it will damage the field. 

  • Like 1

Share this post


Link to post
Share on other sites
Chris727

I would disconnect the battery anytime you are removing, installing, or have a part of the electrical stuff system disconnected. Would also not hurt to remove the two wires from the A-terminal when jumping the starter. Once verified that the starter will crank and the cranking issue is resolved, then you can proceed with checking for charging operation. 

Edited by Chris727
  • Like 1

Share this post


Link to post
Share on other sites
Bnrober2
1 hour ago, Chris727 said:

Fortunately Those regulators are inexpensive to replace. To check the starter you can jump the “A” terminal with 12 volts and see if it spins. Do not put any power to the “F” terminal or it will damage the field. 

Crisis averted I blew a fuse and missed it in the dark last night. 

  • Like 4

Share this post


Link to post
Share on other sites
Bnrober2

I got everything installed and running! Question, how do I polarize the generator correctly?  The video I found on youtube says to jump a wire from the BATT to the GEN on my voltage regulator but that doesn't seem to be working, it also blows the above mentioned fuse.  Any help would be appreciated.

 

Share this post


Link to post
Share on other sites
PhanDad

I believe that's the correct procedure, but usually a direct jumper from the positive battery terminal is used to prevent blowing the fuse.  

3 hours ago, Bnrober2 said:

but that doesn't seem to be working

 I'm guessing you mean the S/G isn't charging the battery.  To test where the problem might be, you can follow Al's advice:

"You can check the SG unit by hooking a voltmeter to the A terminal and grounding the F terminal. the voltage chould come up to 13 to 14 volts with the engine wide open. If it goes to 15.5 or more the regulator is not connecting it to the battery as these units don't have the capability of going that high into a battery unless it is sulfatated and doesn,t take a charge. If the SG puts out OK you probably have a regulator problem."

The above is from Al's first response from this post:

https://simpletractors.com/forums/topic/570-startergenerator-gen-light-on/?tab=comments#comment-161986

He also has a second response in the above post you might want to read.   

 

  • Like 1

Share this post


Link to post
Share on other sites
jdwilson

Had 2"x3" hole in my 8hp block. Had a machinist weld a patch in. Then had it bored .030 over. Well worth the money, as they are so rare, and didn't want to make any changes to the grill. You used to be able to buy a shortblock from Small Engine Warehouse.

 

On 2/9/2021 at 7:23 PM, Bnrober2 said:

Im not exactly sure what blew on the old motor, but there is a hole in the side of the crankcase.  I found a "new" 9 HP briggs from a 1999 craftsman rear motor mower.  Fits like a champ, plus a gain a single HP!  Just got to get some electrical figured out.  Mine has a belt driven starter generator this one has a normal starter/magneto set up. 

9615588A-AFB7-46C3-992D-3414511136FD.jpeg

 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Who's Online (See full list)

    There are no registered users currently online

  • Today's Birthdays

    1. davidmoll
      davidmoll
      (61 years old)
    2. Mikethemasher
      Mikethemasher
      (50 years old)
  • Recent Status Updates

    • SonOfCreepfeed

      SonOfCreepfeed

      Thinkin' about this old girl.

      · 1 reply
    • Dean McFadden

      Dean McFadden

      Good morning peeps! I’m always searching for helpful information with my AC collection. Hope to find out new information and pass on my own experience in restoration. Here are some pics of my babies. I’m still looking for front rims for the 410 so yesterday I put the 310 wheels on took it for a drive. Working pretty good but still needs some carb work. Gotta get the 310 running next. Have a great day!😁
       

      · 1 reply
  • Adverts

×