lifted club cars - lifted ezgo
Home FAQDonate Who's Online
Go Back   Buggies Gone Wild Golf Cart Forum > Golf Cart Repair and Troubleshooting > Gas EZGO
Gas EZGO Gas EZGO Marathon, Medalist, TXT and RXV.



Post New Thread  Reply
 
Thread Tools Display Modes
Old 09-30-2021, 12:13 PM   #1
Justinh722
Not Yet Wild
 
Join Date: Sep 2021
Posts: 6
Default 1986 Marathon. No power unless muffler removed

Iím fairly good with small engines in general but Iím new to carts. Iíve been working on a 1986 marathon with the robin 244cc engine for an older woman who paid $2700 and was only able to drive it a week before it died on her.

Iíve tuned it up and checked all the basics. There were signs of leaking at both crankshaft seals so those have been replaced. I did replace the carburetor with an aftermarket but it runs the same. Reason for replacement is the Mikuni has loose throttle linkage and looks like someone tried fixing it and ruined it. Cart is getting fuel. Previous owner had bypassed oil injection so I emptied the tank and put some non-ethanol in and mixed it 128-1.

Iíve had this here for about a month now researching to my wits end. Belt drags a little at idle but nothing major. Does make the cart hard to push. Verified the pulsar coil has the correct resistance as well as the primary and secondary windings in the ignition coil. Pulsar is adjusted right at the middle. I marked the slots when removing during seal replacement. It runs okay and builds RPMs in both forward and reverse but only with the muffler removed. But when running in forward it makes a clattering noise. Muffler was barbecued in a hot fire for 3-4 hours. Seems to have more air flow when blowing through it from the tail pipe to the flange. Iíve yet to check the exhaust port on the engine for any kind of carbon blockage. Iím currently testing the cart with the rear up in the air and the drive belt removed while making sure I donít over-rev it.

I thought I would give this a shot to get some other suggestions while Iím out checking on that. Engine has 125 psi of compression. Air filter is completely plugged so I have one on order and Iím currently just running it without for testing purposes. Spraying carb cleaner in the intake kills the engine so the issue is definitely air flow. Does she need to spend the money on a new muffler or has anyone else not had luck with the barbecue method for the muffler? Iíve yet to run into a small engine repair that has stumped me like this aside from completely disassembling the engine and checking everything. The noise in forward has me concerned a bit. Any guruís out there familiar with this issue?
Justinh722 is offline   Reply With Quote
Alt Today
BGW

Golf car forum Sponsored Links

__________________
This advertising will not be shown in this way to registered members.
Register your free account today and become a member on Buggies Gone Wild Golf Cart Forum
   
Old 10-12-2021, 10:11 AM   #2
Justinh722
Not Yet Wild
 
Join Date: Sep 2021
Posts: 6
Default Re: 1986 Marathon. No power unless muffler removed

Iíll post an update for anyone curious. The muffler had an internal breakage that caused the baffling to get hung up not allowing the exhaust gasses to exit like it should. So requiring a new muffler and with all the reliance mufflers being on backorder, it looks like I may have to just buy a muffler and fabricate my own. The factory muffler is 12 1/2Ē long by 6Ē in diameter. I found a farmall tractor muffler 13 inches long and similar diameter that I can just close off one end and weld in a flange to the side and figure out the tailpipe routing.

Unless anyone knows of a better option as the powerband of the engine comes from the header design I believe it should work.
Justinh722 is offline   Reply With Quote
Old 10-12-2021, 10:54 AM   #3
crash12888
Gone Crazy
 
Join Date: Jan 2007
Location: Chesterfield, Va
Posts: 5,870
Default Re: 1986 Marathon. No power unless muffler removed

Keep us posted on the outcome and noise level, Everyone is always looking for options with the older carts.
crash12888 is offline   Reply With Quote
Old 10-12-2021, 12:19 PM   #4
trig123
Gone Wild
 
trig123's Avatar
E-Z-GO
 
Join Date: Sep 2009
Location: Out there somewhere
Posts: 2,209
Default Re: 1986 Marathon. No power unless muffler removed

Quote:
Originally Posted by Justinh722 View Post
Iíll post an update for anyone curious. The muffler had an internal breakage that caused the baffling to get hung up not allowing the exhaust gasses to exit like it should. So requiring a new muffler and with all the reliance mufflers being on backorder, it looks like I may have to just buy a muffler and fabricate my own. The factory muffler is 12 1/2Ē long by 6Ē in diameter. I found a farmall tractor muffler 13 inches long and similar diameter that I can just close off one end and weld in a flange to the side and figure out the tailpipe routing.

Unless anyone knows of a better option as the powerband of the engine comes from the header design I believe it should work.
I have a used muffler from a 1987 with the 2pg engine I would sell
trig123 is offline   Reply With Quote
Old 10-16-2021, 01:34 PM   #5
Justinh722
Not Yet Wild
 
Join Date: Sep 2021
Posts: 6
Default Re: 1986 Marathon. No power unless muffler removed

I just built the muffler last night and welded the 1 1/4Ē pipe with the old flange through the hole I made in the muffler outer core and the inner baffle. I then tack welded a 3/4Ē tailpipe about the same length as the old muffler. It has more flow than the broken one and sounds decent aside from the leak around the tacked on tail pipe. I chose to tack it in case I wanted to remove it and go with a 1 inch pipe. But if the stock muffler is 1 1/4Ē through the core and 3/4 coming out and itís supposed to run normally, then I have a different issue as it still doesnít have any acceleration even with a new muffler. Just strange how it runs great and can build rpm quickly and fast without the muffler. It still has the noise when running it in forward. Iím completely stumped.

I have way too much time in this owners cart. New crank seals and new carb and new fuel pump and linesÖcompression is good. New air filter and fuel filter. Pulsar and ignition coil all test fine. My only other option is to remove the engine again and tear it down and check everything. She doesnít like to spend money so it becomes an issue when I have to try and repair it at little cost the way it is.
Justinh722 is offline   Reply With Quote
Old 10-16-2021, 03:18 PM   #6
CP241
Eats dirt.
 
CP241's Avatar
Club Car
 
Join Date: Apr 2018
Location: Michigan
Posts: 6,230
Default Re: 1986 Marathon. No power unless muffler removed

You have to keep in mind, it is a 2 stroke. It needs that back pressure in the muffler to run right. You canít just go put on any ol muffler and expect it to run like it should. You may be able to adjust the carb and make it workÖ but with an opened muffler and stock carb jetting itís gonna run crazy lean and not last long
CP241 is offline   Reply With Quote
Old 10-16-2021, 04:44 PM   #7
Justinh722
Not Yet Wild
 
Join Date: Sep 2021
Posts: 6
Default Re: 1986 Marathon. No power unless muffler removed

Itís not so much an opened muffler as itís still restricted by the inlet and outlet. I mentioned itís more free flowing than the bad one simply because the other one had broken off inside and plugged it up. The issue is that it should be running with the muffler regardless. I can tune an engine if it turns out to be too lean but the pipe thatís more restrictive to the tune of the engine is the header pipe before the muffler. The warning should have been if I were to just drive the cart without a muffler at all and risk a melted piston. Iím wondering why itís still not running correctly with the same back-pressure the stock muffler would be giving it. Itís being starved for air somewhere. You would have made a valid point had I said that the new muffler was causing the engine to over rev or run hot. When opening a muffler you are introducing more air. More air would mean it needs more fuel. It will only run well with the muffler removed. The carb is sucking plenty of air, but not enough for it to run correctly.
Justinh722 is offline   Reply With Quote
Old 10-16-2021, 04:58 PM   #8
CP241
Eats dirt.
 
CP241's Avatar
Club Car
 
Join Date: Apr 2018
Location: Michigan
Posts: 6,230
Default Re: 1986 Marathon. No power unless muffler removed

You are correct, and technically you ďcanĒ even run a 2 stroke with a straight pipe.

These small engines are not your typical small engines, however. They are tuned very specifically and even the smallest little air leak, airbox missing, or even a Chinese carb that looks just like a real carb can make or break it. Iím not saying you wonít be able to make it work with a different muffler, but itís going to take a lot of tweaking given the finicky nature of these little motors. The stock muffler is designed for these to work with the stock carb and stock airbox and etc. even the slightest change in any of the makeup results in huge tuning problems, and again Iím not saying you canít or wonít be able to make it work. But itís gonna take some tweaking. Iíd start by putting a fresh plug in it, run it, and then pull and read the plug. Then adjust accordingly.
CP241 is offline   Reply With Quote
Old 10-18-2021, 05:27 PM   #9
Justinh722
Not Yet Wild
 
Join Date: Sep 2021
Posts: 6
Default Re: 1986 Marathon. No power unless muffler removed

Thanks for the help. Iím just at my wits end and about to tear it all down and see whatís going on with it. The piston is installed correctly. Compression is good. No noise in reverse. Noise in forward not sure if it could be a main bearing issue.
The subframe that the engine sits onÖis it supposed to move completely up and down? Iím able to grab the engine and lift it up and down a good few inches or so.

The carb I ended up getting was a Chinese pos and I compared the main jets and the jet in the aftermarket carb was slightly bigger. So moving back to the stock carb and using couple pieces off the Chinese one I was able to get it to run decent. It will top out and gain speed after it gets going. In forward I can get it to move from a stop a little easier than reverse. But in reverse the engine just wonít rev at a stop like itís a low speed jet issue. If I hold wide open it will build up and finally take off. I noticed both the oem carb and the aftermarket had the float adjusted under 1mm when it should be between 1-3. I have it at about 1.5mm now. Wondering if I should lean it out a bit to 2. Even with the rear wheels in the air, it wonít pick up speed down low right away.

The Drive belt is dragging causing the secondary clutch to move but that shouldnít be the issue as the primary should still hit harder with throttle. Even with belt removed it just picks up slow then goes to wide open throttle just fine. Iím convinced the issue is tuning or timing but the noise in forward has me concerned. Adjusting timing on these would require removal of the flywheel to adjust the pulsar and then assemble and check again and repeatÖcorrect?

The drive belt is worn but still a tad over an inch wide. Measured at 45 1/2Ē long using string around the outside diameter. I would have gotten stock carb but the woman paid 2700 for the 1986 cart and literally no maintenance was done to this thing. She said she canít afford to put too much into it. I hate using any Chinese parts. Starter belt is at its tightest adjustment point. So it seems she needs to get a new mikuni carb, new belts, and ultimately a rebuild. Fuel is mixed 128-1 non ethanol. Itís clearly running too rich at low speed but opening the air jet doesnít help much.
Justinh722 is offline   Reply With Quote
Old 10-18-2021, 07:06 PM   #10
Justinh722
Not Yet Wild
 
Join Date: Sep 2021
Posts: 6
Default Re: 1986 Marathon. No power unless muffler removed

I just checked the timing using an inductive light and forward timing is lining up on the mark just a little to the right but the reverse timing is so far off itís maybe 4 inches to the left of the mark. What would cause this? This would indicate the timing being retarded which would explain the very slow acceleration and higher top end power.

EDIT: pulsar coil is reading 156 ohms. Secondary coil orange to green reads 4.5 ohms and secondary orange wire to plug boot is 11k ohms. All within range. How can the ignition timing in reverse be far off when setting one direction correctly automatically puts the other in range.
Justinh722 is offline   Reply With Quote
Reply

Tags
reduced power, slow acceleration
Go Back   Buggies Gone Wild Golf Cart Forum > Golf Cart Repair and Troubleshooting > Gas EZGO


Thread Tools
Display Modes


Similar Threads
Thread Forum
Club car ds 48 volt still has power with key off and removed Electric Club Car
1986 G3A No power anywhere Gas Yamaha
1986 marathon muffler pics Gas EZGO
1986 Gas blowing out of muffler Gas EZGO
ideas for muffler 1986 ez go gas golf cart? (dont have 1... very loud) Gas EZGO


All times are GMT -5. The time now is 12:46 PM.


Club Car Electric | EZGO Electric | Lifted Golf Carts | Gas EZGO | Used Golf Carts and Parts

Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
This Website and forum is the property of Buggiesgonewild.com. No material may be taken or duplicated in part or full without prior written consent of the owners of buggiesgonewild.com. © 2006-2017 Buggiesgonewild.com. All rights reserved.