87 marathon 2pg wont run

LSPowered65 · 04-22-2018, 07:38 PM

Hi Guys,

I need some help. I was able to fully rebuild the engine on a 1987 Marathon 2pg with guidance from this thread. Have run about 3/4 of the first tank of fuel through it and after a back fire will no longer run. New piston, connecting rod, jug, crank, crank seals, carb, fuel pump, GM HEI upgrade, spark plug (iridium gaped at .40), starter/generator rebuilt, one new micro switch, other switches cleaned and rebuilt, reed valve cleaned and resealed with new gaskets. I have premix in the tank at 40:1 and eliminated the auto oiler and blocked off all ports associated with it. Cart was running awesome until the backfire. Spark is great, compression is great, i can not feel the carb sucking air in. Thoughts?? Thanks in advance. Engine sounds normal during cranking and spark is great, no difference in forward or reverse.

cart around · 04-22-2018, 07:43 PM

"After backfire will no longer run".

You popped a crankshaft seal. Simple as that.

Pull the engine, use green Loctite, and stake them in three places.

LSPowered65 · 04-22-2018, 07:47 PM

That’s a bummer, i thought i used rtv when i put them in but i did not punch them. Any way to prevent this in the future?

cart around · 04-22-2018, 07:49 PM

RTV? Seriously? There is no strength there.

Green Loctite, staked in three places will hold them in.

Get a spring on the end of the throttle cable to prevent the backfiring.

Look at my pictures here. http://www.buggiesgonewild.com/gas-e...djustment.html

LSPowered65 · 04-22-2018, 07:52 PM

I have the spring and have not encountered a single backfire, my brother and his 10yo son took it out and this happen. I like RTV normally works well for me. “Normally” HA. Thx for alll your help.

rib33024 · 04-22-2018, 08:18 PM

You could of sheared the key way in the fly wheel.

LSPowered65 · 04-22-2018, 08:40 PM

I’m pretty certain that cart around is correct, i have zero air pull on the carb inlet. Of course its two of the hardest to reach seals.

rib33024 · 04-22-2018, 08:46 PM

Quote:

Originally Posted by LSPowered65

I’m pretty certain that cart around is correct, i have zero air pull on the carb inlet. Of course its two of the hardest to reach seals.

Yes they are hard to get to

Spicyunicorn · 04-22-2018, 09:52 PM

[QUOTE=LSPowered65;1494748]I’m pretty certain that cart around is correct, i have zero air pull on the carb inlet. Of course its two of the hardest to reach seals.

Maybe want to do a compression check before you pull it to do the seals

LSPowered65 · 05-03-2018, 11:24 AM

Pulled the motor on Tuesday, clutch side crank seal is no longer where its supposed to be. Thanks guys. i am gonna install new seals with loctite and use a punch to dimple the metal around the seal , as suggested, to help stop this.

04-22-2018, 07:38 PM	#1
LSPowered65 Not Yet Wild Join Date: Oct 2017 Posts: 10	87 marathon 2pg wont run Hi Guys, I need some help. I was able to fully rebuild the engine on a 1987 Marathon 2pg with guidance from this thread. Have run about 3/4 of the first tank of fuel through it and after a back fire will no longer run. New piston, connecting rod, jug, crank, crank seals, carb, fuel pump, GM HEI upgrade, spark plug (iridium gaped at .40), starter/generator rebuilt, one new micro switch, other switches cleaned and rebuilt, reed valve cleaned and resealed with new gaskets. I have premix in the tank at 40:1 and eliminated the auto oiler and blocked off all ports associated with it. Cart was running awesome until the backfire. Spark is great, compression is great, i can not feel the carb sucking air in. Thoughts?? Thanks in advance. Engine sounds normal during cranking and spark is great, no difference in forward or reverse.
LSPowered65 Not Yet Wild Join Date: Oct 2017 Posts: 10

04-22-2018, 07:43 PM	#2
cart around Test before replacing Join Date: Aug 2013 Location: Ohio side of the Pennsylvania border. Posts: 3,496	Re: 87 marathon 2pg wont run "After backfire will no longer run". You popped a crankshaft seal. Simple as that. Pull the engine, use green Loctite, and stake them in three places.

04-22-2018, 07:47 PM	#3
LSPowered65 Not Yet Wild Join Date: Oct 2017 Posts: 10	Re: 87 marathon 2pg wont run That’s a bummer, i thought i used rtv when i put them in but i did not punch them. Any way to prevent this in the future?
LSPowered65 Not Yet Wild Join Date: Oct 2017 Posts: 10

04-22-2018, 07:49 PM	#4
cart around Test before replacing Join Date: Aug 2013 Location: Ohio side of the Pennsylvania border. Posts: 3,496	Re: 87 marathon 2pg wont run RTV? Seriously? There is no strength there. Green Loctite, staked in three places will hold them in. Get a spring on the end of the throttle cable to prevent the backfiring. Look at my pictures here. http://www.buggiesgonewild.com/gas-e...djustment.html

04-22-2018, 07:52 PM	#5
LSPowered65 Not Yet Wild Join Date: Oct 2017 Posts: 10	Re: 87 marathon 2pg wont run I have the spring and have not encountered a single backfire, my brother and his 10yo son took it out and this happen. I like RTV normally works well for me. “Normally” HA. Thx for alll your help.
LSPowered65 Not Yet Wild Join Date: Oct 2017 Posts: 10

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04-22-2018, 08:18 PM	#6
rib33024 ...................... Join Date: Apr 2009 Location: FT Lauderdale FL. Posts: 16,416	Re: 87 marathon 2pg wont run You could of sheared the key way in the fly wheel.

04-22-2018, 08:40 PM	#7
LSPowered65 Not Yet Wild Join Date: Oct 2017 Posts: 10	Re: 87 marathon 2pg wont run I’m pretty certain that cart around is correct, i have zero air pull on the carb inlet. Of course its two of the hardest to reach seals.
LSPowered65 Not Yet Wild Join Date: Oct 2017 Posts: 10

04-22-2018, 09:52 PM	#9
Spicyunicorn Gone Wild Join Date: Jun 2015 Location: NW Iowa Posts: 1,669	Re: 87 marathon 2pg wont run [QUOTE=LSPowered65;1494748]I’m pretty certain that cart around is correct, i have zero air pull on the carb inlet. Of course its two of the hardest to reach seals. Maybe want to do a compression check before you pull it to do the seals

05-03-2018, 11:24 AM	#10
LSPowered65 Not Yet Wild Join Date: Oct 2017 Posts: 10	Re: 87 marathon 2pg wont run Pulled the motor on Tuesday, clutch side crank seal is no longer where its supposed to be. Thanks guys. i am gonna install new seals with loctite and use a punch to dimple the metal around the seal , as suggested, to help stop this.
LSPowered65 Not Yet Wild Join Date: Oct 2017 Posts: 10

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