Any issue's putting a 75 motor in a 72 bike

[CalsXS2]

I have a a 72 XS2 that needs a new motor. Rebuild is too pricey for me at this time. So I got lucky,,,hopefully,,,, and found a 75 motor. I got the motor, drag pipe's, new chain, new pod's, new cable's,,,and well, let's just say I get a heck of a pile of part's for $150. I just hope the motor's good. For $150 I had to gamble. I'm sure I could sell of the part's and get my money back.

So anyway. Will I have any issue's putting in the 75 motor. Will I be able to hook up my compression release/starter from the 72. Is the drive chain sprocket the same. Thanks.

 

[5twins]

The motor will swap right in. The compression release will not work unless you swap heads. The rocker arm has a tab on it for the compression release lever to work against. That would be missing on the '75 rocker arm. You could install the compression release cover on the new motor and the handlebar lever will then trigger the starter when pulled, you just won't be doing any decompressing.

 

[CalsXS2]

Help me understand about the chain and sprocket. This is copied from Mikes. Am I reading this right. But does this basically say the chain and sprocket is the same on my 72 as the 75,,,right??

SPROCKET FACTS

North American model XS/TX650's (1974-84) Use 17T/34T 530 pitch Sprockets (Original Stock Size) XS1/XS1b/XS2/TX650's (1970-73) Use 17T/34T 530 pitch Sprockets (Original Stock Size)

 

[jayel]

front motor mount is a little different too, chain and sprocket(s) the same

 

[CalsXS2]

I do have the motor in. All though they are different, I was able to use the 72 mount. Now I just have to hook up the rest of the stuff.

 

[OakBehringer]

Motor is a direct swap, as you have learned, as long as you use the original mounts. The drag pipes will not be, without fabrication you're going to have to use your originals. If you're worried about the sprocket, and they're different tooth counts, just use the one off your original motor. Buy a new chain.

 

[CalsXS2]

Motor is a direct swap, as you have learned, as long as you use the original mounts. The drag pipes will not be, without fabrication you're going to have to use your originals. If you're worried about the sprocket, and they're different tooth counts, just use the one off your original motor. Buy a new chain.

Ya I found out about the drag pipes. But you know I gotta fire it up just once with those on there.

I think the sprocket's are the same. I got a new chain with the pile of part's so I really want to be able to use it.

 

[XSLeo]

On the compression release they stopped using it in 73 but they stll used the same rocker arms for many years after. My 75 had the rockers with the nub for the compression release.
I'm not sure what year they stopped useing them. My 81 and 82 engines don't have them.
On the Drag pipes, use the stock exhaust, it will run better and be easier to tune the carbs. Drag pipes will only work well under full throttle accelleration, as in Drag Racing, thus the name Drag pipes.
On the chain and sprockets they are the same. If you have any doubts about the chains being to worn, get new sprockets and chain. The 17/34 is not a bad around town combo. A 17/30 works well as a highway set up. A 17/32 is a good all around set up.
Leo

 

[CalsXS2]

On the compression release they stopped using it in 73 but they stll used the same rocker arms for many years after. My 75 had the rockers with the nub for the compression release.

I think I got lucky. Is this the nub you speak of. I'm sure it is. I can get the compression release on, and I can feel the resistance of the valve, as I can't feel it with the release in my hand.

Also, I got thing's mixed up. I think this big gasket was on the compression release. And the other cover just had a o-ring around it. Should I use both, or just the big gasket. Thanks.

 

[XSLeo]

Yes, thats it.
On the covers if you look under the o-ring you will find a groove. It needs the groove to properly use the o-ring. On the one with the gasket you won't find the groove.
You can use a gasket on a cover with the groove but you can't use an o-ring on a cover without the groove.
Leo