77 vs 81

[rockjock729]

I am bringing an 81 xs400 (4300 miles) back to life. The engine fires up and sounds good, but the front forks are bent(the triple tree looks good). I have access to a 77 with several features that make it attractive (good front, disc rear). My questions are:
Will the front from the 77 transfer easily over to the 81?
Can the rear disc be transferred over to replace my rear drum?
How much different is the frame regarding swapping parts? ie. swing arm, Engine
Are the carbs the same?

I am not married to either regarding registration so I can go with the 77 frame using the 81 engine or stick with the 81 frame. I have all summer into the fall to put this together.

 

[HoughMade]

...I can go with the 77 frame using the 81 engine...

IMO, this is the simplest way to utilize the '77 parts you want to use.

 

[xschris]

I would put the 81 motor in the 77 as all the brake swapping will be a pain in the ass. Or just pull the fork fork tubes out of the 77 and put them in the 81's lowers/ trees. That will be the quickest route.

 

[rockjock729]

I am picking the 77 up tomorrow and will be able to see just how clean the frame is. I like the idea of moving the engine since I rather have disc then drums. I will post some pictures tomorrow/Saturday.

 

[HoughMade]

...Or just pull the fork fork tubes out of the 77 and put them in the 81's lowers/ trees. That will be the quickest route.

But that won't get you rear disk. That would require a swing arm swap....and welding on the mounts for the rear master cylinder.

 

[rockjock729]

The 77 frame is no good(a supporting weld with steel on the siding).

This morning will involve stripping the 77 down and salvaging parts. Fork,swing arm, front/rear caliper, etc..

I stripped the 81 frame yesterday and will start with the swing arm/fork from the 77.

I have an arc welder and am not very proficient with it but can do small stuff. I will have questions when I see the specifics on what has to be welded.

 

[rockjock729]

I have a rolling piece of junk to be rid of. The 77 frame is set up with bent forks and other junk left over. The only things on it worth anything are the wheels, triple tree, tachometer, fenders (okay condition), and a motor missing the points cover and a spark plug broken off on the left. Miscellaneous electrical stuff(no ignition box was found) attached by the harness.
I do not know the mileage but was told the compression on the right side was 110-120. I will put this in the classifieds with pictures. The frame is NOT usable, it just holds the engine. I figure I can get $50 from the scrap guy, so if someone wants this, $50 and it's yours.

I now have a 81 frame with a 77 swing arm and will start cleaning everything up.