Primary and engine oil confusion
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2nd Gear
Joined: Jan 2009
Posts: 6
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Primary and engine oil confusion
Hey guys, I know this is sorta a repeat question but I am rebuilding a 1973 Ironhead from top to bottom and finally getting the motor back together. I talked to the guys in the maintenance shop at Harley and they told me to put "Sport Trans" fluid in my primary for the clutch and tranny. I read two different things in the maintenance manual one said that the fluid is the same and another said they are different and should be changed at different times. Whats going on here? I understand that the breather valve will allow them to mix, are some guys plugging them? I am also worried that the motor oil will be too thick the sport trans fluid is almost like water. Any help you could give me would be great.
Thanks
Thanks
Last edited by JZscoot; May 17, 2009 at 10:35 PM.
Road Master
Joined: Aug 2006
Posts: 751
Likes: 6
From: 500 miles south from Artic Circle
Yep it's good to put Sportster Transmission Fluid, but it mix with small a mount of motor oil coming from breather valve, as you knowed. That breather valve can be blocked, valve is located inside primary, under that primary chain tensioner. If you block that valve you need to do breather into transmission. Motor oil that has been meant to motorcycle use (= has additives for clutch) can be used (not recom) in primary/transmission only sportster with generator. You notice from clutch when there is too much motor oil mixed in transmission fluid, it starts to drag and its hard to put gear on neutral. Then it's time to change primary oil.
It is common practice to block the transfer valve; then install an external breather. This can be done by drilling a small hole lengthwise thru a mounting bolt [must choode a right one].
I use the modern version of SportTrans, whatever it is called, i always forget.
I use the modern version of SportTrans, whatever it is called, i always forget.
Road Master
Joined: Aug 2006
Posts: 751
Likes: 6
From: 500 miles south from Artic Circle
Bet solution is remove that plug and weld it and put it back. -77 and up there is hollow bolt in engine rear bracket where you can put a vent tube. I don't have that oem#...
34744-77 FITTING, crankcase vent
used on 79 and 80 according to the 79 to 85 parts book. Probably, as already said, on 77 and 78 also.
Road Master
Joined: Aug 2006
Posts: 751
Likes: 6
From: 500 miles south from Artic Circle
Actually part has come to same time when newer crankcase arrived -77 -> case modified for "lefthand" shifter, new primary chain tensioner, adjustment from "outside", no more transfer valve. (maybe someting more?)
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Stage II
Joined: May 2009
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If I recall correctly, the manual states 60wt in the engine and the primary (which is also connected to the trans). Sport Trans fluid succeeds the OEM recommendation; Sport Trans meanwhile is also now out of date as of last year. Though personally, I have continued to run 60wt as recommended by the original manual with no problems. 
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Road Master
Joined: Aug 2006
Posts: 751
Likes: 6
From: 500 miles south from Artic Circle
If I recall correctly, the manual states 60wt in the engine and the primary (which is also connected to the trans). Sport Trans fluid succeeds the OEM recommendation; Sport Trans meanwhile is also now out of date as of last year. Though personally, I have continued to run 60wt as recommended by the original manual with no problems.
I have my "personal stock" so when that runs out I need to switch that. With 60W it might work but oil that you put in primary should contain additives for clutch and factory oil recommendation is 80W. -71 and newer sportsters...
