Hello Everyone.

I recently purchased an 1984 FXRT with a pulled cylinder stud. In addition I purchases a 1990 EVO motor to replace the 1984 motor. I swapped out the motors and was running the oil lines and started to discover some issues I can't seem to find a good answer on.

Please see below diagram of oil line routing on the early model 1984 FXRT.



There are two oil lines that go into the primary. One is a "T'ed" off line from the oil pump going up the the oil vent tube. The other is routed to the engine case separate from the engine case breather vent. . The issue I am running into is the 1990 EVO motor does not have that oil line attachment on the engine case as the original motor cases had.

I have done some reading about isolating the primary. I believe I could do this rather easy but reviews on the longevity of the fix are mixed. If I did do this and needed the vent the primary how would you do this. In addition since I have a dry clutch in there if I fill the oil just to the bottom of the clutch basket will it be okay or will my clutch go bad.

The other question I had was if I wanted to keep the oil system that is in place. Instead of running the line back to the engine cases could I run the line and "T" it off to an existing oil line? Perhaps the feed line from the oil pump into the oil filter?

Thanks in advance for you assistance.

 

Well, my shop manual says that hole is plugged for late 84 and 85, and implies that it isn't there at all for 86. That is the return line from the primary back to the motor.

I think that if I was in your position, I would convert to a wet primary. That is, seal up the primary, throw a quart and a half of ATF in it and call it good. You already have the correct seal on the 90 motor for a wet primary. That's the tricky part in my experience. The clutch plates will probably be just fine. They use to just sell plates as "wet or dry" anyway. For a vent, if you want one, you could route a hose from say the feed line fitting up high somewhere, like behind the oil tank and put a small filter on it.

Another choice would be to drill and tap the missing hole in the block and put a fitting on it.

Of course, I have screwed up enough here lately that I'm glad no lives depend on it. So, take that for what it's worth.

 

The book also says: "On the early 1984 models, during the piston upstroke, a timed opening in the breather valve draws oil from the primary chain housing..."

Don't know if the breather valve is the same on early 84 to later models. If it is, you could probably drill the hole OK, if it isn't then not.

 

Wasn't that one of the differences between the lower end of the shovel and the evo ? Because I'm thinking you pulled out the shovel motor and installed an evo ?

 

Hello,

Bringing this thread back because I've decided to isolate my 1984 Evo primary and install a wet clutch. I've removed and plugged the two oil lines that go into the primary and plan on adding ATF fluid to it. I saw the post Dr. Hess mentioned that the engine draws oil from the primary on the piston upstroke and want to make sure I'm not f***ing anything up while doing this. Has anyone else done this? Am I missing something?

As far as a vent goes: Could I just drill a whole at the top of the inner primary, add a fitting and run a hose from it? Is there even a need for a vent? Any feedback would be much appreciated.
Thanks!

 

I did that once on a shovel. It did not go well. The crank seal between the primary and the motor is different on the isolated primary bikes like mine. I think there are more lips, or they are pointed in the other direction or something. So, you would need to change that out as well if you want to do this successfully.

 

I can run the clutch both dry / wet. I should be alright if I add ATF in there just up to the bottom of the starter ring - a.k.a not fill up the entire primary with fluid, but just enough to keep the chain lubed. Thoughts?

 

The problem is that the oil will blow out the crankcase into the primary. Do what you want, I made my suggestion.

 

Thanks. I see what you mean - what type of seal would you suggest in that case?

 

I suggest the seal that the MoCo put in the later style bikes, like, I suppose late 84 up when they changed to an isolated primary. Certainly 86 up. As I said, the seal is different in how the lips keep the 2 chambers separated. On the dry primary, it doesn't matter as any oil that gets past the seal will be sucked back in by the scavenger.