77 D motor into 80G frame

I was wondering if the motor from a 1977 400D would swap into a 1980 400G frame. Or, will the heads from the 80 swap onto the 77 lower engine. I would like to get a kickstart back onto the 80 and since I have choices here.... I also assume that the forks,swing arm and wheels will swap along with disc brake components.

Look at the mounts......I swapped a motor into a frame on the first build and had to open up one mounting hole so the bolt would go through. Otherwise it was pretty easy. Not even sure what the years were 78 to 81 maybe.....I do know I hate the late model mounts that extend forward on the bottom front mounts......the later 70s mounted to tabs coming off the frame inwards the later models had tabs going forward and they hit the aftermarket exhaust...…

Also I did have to weld new mounts to the frame as the earlier models used a rear mount that wasn't found on later models...….my 81 I have now has the hole on the motor but no mount on the frame to make it work...…

To be honest I think the motors all stayed the same over the years from what I have seen as I have 4 or so in the garage.

My experience I was the same. I used the rear mount bolt to make a bushing rather than drilling the engine. Different method, same outcome. I had to buy front lower mounts because as Spectra said, they project forward rather than to the rear and rub on my Mac 2 into 1 pipes. Actually they clear by about the thickness of a business card. I also had to remove the rear master cylinder mount from the old frame and weld it to my 80 frame. The triple tree and swing arm fit with no problem however in my case the plastic inner fender on the rear had to be modified to clear the battery box. In my case the 77 frame as well as the entire front fork was severely damaged in a colision with a Jeep Wrangler. In short it can be done with a little work and ingenuity.

Old Mose said:

My experience I was the same. I used the rear mount bolt to make a bushing rather than drilling the engine. Different method, same outcome. I had to buy front lower mounts because as Spectra said, they project forward rather than to the rear and rub on my Mac 2 into 1 pipes. Actually they clear by about the thickness of a business card. I also had to remove the rear master cylinder mount from the old frame and weld it to my 80 frame. The triple tree and swing arm fit with no problem however in my case the plastic inner fender on the rear had to be modified to clear the battery box. In my case the 77 frame as well as the entire front fork was severely damaged in a colision with a Jeep Wrangler. In short it can be done with a little work and ingenuity.

Click to expand...

Mine clears my MAC exhaust just barely and I had to do a little grinding on the inside mount that holds the studs to make it work. Will see if it rubs once I get it on the road.

Now that you mention it, I remember I removed the plates and ground the rounded ends off to get the business card clearance. Didn't think of that before!

I am running dual exhaust, stock pipes so I should have clearance