Oil Change on 1991 Fat Boy
#1
Oil Change on 1991 Fat Boy
Hi Forum,
I would like to do an oil change. According to the service manual I just drain the oil from the oil tank and not the motor. I looked all over the motor bottom and canīt even find an oil drain plug at the motor. Is this normal? I have an all my former bikes had the oil drain plug located at the motor.
Looking forward to your replies.
I would like to do an oil change. According to the service manual I just drain the oil from the oil tank and not the motor. I looked all over the motor bottom and canīt even find an oil drain plug at the motor. Is this normal? I have an all my former bikes had the oil drain plug located at the motor.
Looking forward to your replies.
Last edited by mike_snoo; 12-30-2020 at 07:53 PM.
#2
#5
#7
Great, Delboyīs Garage is awesome. I just watched all videos. Seems like I have to do much more than just an engine oil change.
Question:
- What dimension has the Gearbox oil drain plug O-Ring?
- What dimension has the primary oil drain plug O-Ring?
In the video he is talking about blue hylomar. https://hylomar.com/en/universal-blue/
That stuff is not available for pick up. Would this stuff work too? https://www.autozone.com/sealants-gl...E&gclsrc=aw.ds
Here is the link to the videos for all other ones with the same question https://www.youtube.com/playlist?lis...6J95AUvBNMSXYv
Question:
- What dimension has the Gearbox oil drain plug O-Ring?
- What dimension has the primary oil drain plug O-Ring?
In the video he is talking about blue hylomar. https://hylomar.com/en/universal-blue/
That stuff is not available for pick up. Would this stuff work too? https://www.autozone.com/sealants-gl...E&gclsrc=aw.ds
Here is the link to the videos for all other ones with the same question https://www.youtube.com/playlist?lis...6J95AUvBNMSXYv
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#9
I don't have the manuals, or experience, with a 1991 Fat Boy...
I used to own and/or maintain my 1989 EVO Heritage, and a friend's 1997 EVO Springer... both softail models... and I kept the Service manuals and parts manuals...
PRIMARY
For both the '89 EVO softail and '97 EVO softail... it shows an HD primary plug part number 739 (or 739A). It is below the clutch inspection cover on the bottom of the outer primary case. It is a 1/8" NPT plug that takes a T-40 Torx. It is NOT a shouldered bolt with an o-ring, nor does it tighten up against the case... it's a pipe plug. There is no torque spec. The spec tells how far to tighten it so it protrudes below the surface of the cover... 0.16" - 0.18".... Since it's a pipe plug, you don't want to over tighten it, or you could damage (crack) the case...
TRANSMISSION
Both '89 and '97 EVOs again show the same drain plug for the trans as used in the primary, an HD plug part number 739 (or 739A). It is on the side of the trans, just below the clutch release cover, facing out to the side, not down... It should be tightened just like the primary plug.
Just FYI... the EVO FLTs and FXRs show a shouldered bolt trans drain plug, with nylon washer, (HD # 722) in the middle of the bottom of the transmission case... but the softails show the #739 (or 739A) pipe plug on the side of the trans case...
Hope that info helps....
PS- Those #739A pipe plugs are used on primary drains of my 2001 and 2003 Twin Cam bikes... When I change the primary oil, after removing the plugs, I clean the threads and the plug with a thread chaser... I put some Loctite 545 on the pipe plug for reassembly, and let it all set for about an hour (probably unnecessary) before adding the primary fluid. I've yet to have one leak after I service them...
Last edited by hattitude; 12-31-2020 at 09:31 PM.
#10
No hylomar needed on a drain plug, just use teflon tape.
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