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Outlaw Tractor Collector
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Discussion Starter #1
I am working on a 1986 Lawn Chief 18/42 GT made by Murray. It has a great running 18HP Briggs & Stratton Opposed Twin engine but the fuel pump on the front of the carb leaks pretty bad. I ordered a kit that includes 2 gaskets, the diapragm thingy, small spring, and large spring and some little metal ring thingy. Now my question is how the heck do I put this together to were it will work right? Which parts go first in the reassembly of this thing? I need some proffesional help!
 

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Outlaw Tractor Collector
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Discussion Starter #3
Maybe this will help http://outdoorpowerinfo.com/repairs/briggs_opposed_twin_carb.asp
as far as order of assembly, can you go to the parts drawings at Partstree or somewhere to see a drawing. I put a kit in a 16hp a few weeks ago but I think the 18 is a little different. Here's a guy doing a 16 (I think). http://www.youtube.com/watch?v=JF80OyeOG9g
Cannon
Thank you very much! Once the kit gets in (should be next week) i will try and install it and I will let yall know if it works or not.
 

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Senior MTF Poster
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13,173 Posts
I can send you a PDF copy of the Service Manual for your engine IF you like, Address below, put in proper format and include the model number and what you want.

Walt Conner
wconner5 at frontier dot com
 

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Outlaw Tractor Collector
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Discussion Starter #5
I can send you a PDF copy of the Service Manual for your engine IF you like, Address below, put in proper format and include the model number and what you want.

Walt Conner
wconner5 at frontier dot com
Thank you that should help me alot.
 

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I did one on a 16 hp 2 weeks ago and I tried to do it on the tractor, but I found it was easier to take the carb off and do it on the bench. The biggest problem was not losing the 2 little springs inside. It was a pain, but it worked ok after I rebuilt it.
 

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Outlaw Tractor Collector
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Discussion Starter #7
I did one on a 16 hp 2 weeks ago and I tried to do it on the tractor, but I found it was easier to take the carb off and do it on the bench. The biggest problem was not losing the 2 little springs inside. It was a pain, but it worked ok after I rebuilt it.
Thanks you for that tip! I will remove the carb so I can do this easier and not loose anything
 

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I did one on a 16 hp 2 weeks ago and I tried to do it on the tractor, but I found it was easier to take the carb off and do it on the bench. The biggest problem was not losing the 2 little springs inside. It was a pain, but it worked ok after I rebuilt it.
That's what I had trouble with, one of the little springs fell out when I was disassembling it. The kit I got on ebay had new springs. I figured out from the video where it came from. Mine would only run on full choke before but cranks and runs good now.
Cannon
 

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Outlaw Tractor Collector
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Discussion Starter #9
The gasket kit got in today (alot earlier than I thought) Got it installed and the engine runs and does not leak anymore. Thank you all for the help. I need to clean this carb because while it runs it dosent run great. At first it needed choke to run at all but after about 5 minutes it changed to where it wuld only run at 25% choke and only at full throttle the whole time. It surges quite a bit and I adjusted it some but it never helped. As soon as I get to or below half throttle it dies. It has a brand new air filter on it and is running on fresh gas but I have not gotten new plugs. The old plugs are RJ12C and I am not sure if they are origanal or not. Every other opposed twin I have messed with has RJ19LM plugs but this one does not. Is this motor suppose to have RJ12C plugs or RJ19LM plugs?
 

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I bought the carb kit because it has the carb and fuel pump parts in it. I overhauled the carb at the same time. Not that hard to do. THis tractor had been sitting a long time before I got it, so I wanted it to run right. THe worst part was the back bolt holding the carb to the manifold. I would do the carb.
 

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Just use some grease to hold the little springs in place and you will be successful in changing them on the engine. First run, gas washes the grease away.
 

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Make sure the carb gaskets are sealed good, Air leakage will cause surging and the need to run the choke. To a lesser extent the throttle shaft brass bushings will cause this too.
 
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