Are XS2 engines 256 or 447 engines?

[scott s]

We pulled and engine out of a '74 frame last year. Only recently did we take a look at the serial # and it appears that it's a '71-72 engine.

I found a chart to verify this and the "code" is 306. I know the XS1's were 256 engines, but what about the XS2?

 

[gggGary]

I believe a 306 is a 256 with electric start. IE 72, 73, the 71 did not have electric start.

 

[jamesgs4]

generally speaking,they are the same as the 256 engines.

 

[cra-z1]

The XS2 is a 256 engine. Keep in mind you can use 447 internals with the 256 engine. Look things over good if you tear into it. You never know what someone has done.

 

[xstra]

There are quite a few differences between the 256 and 306 engines (let alone those between the XS1 and XS1B/F versions of the 256). These are from memory. Purist restorers will be able to give more differences I'm sure.

Some of the differences:

Electric Start
Decompression assembly and the square cover
Larger battery box and different brackets
Crankcase breather is different, straight instead of inclining down
Crankcase bolting
Gudgeon pin has a roller bearing for XS1s
Left crankcase cover
Cam chain stoppers and front guides changed
Oil pump lost the pressure release valve
Kick start gear has 25T (-1)
Gearbox main shaft 1st gear has 13T (-1)
1st gear 32T (+1)
Shift cam assembly is different. Cam and shift wheel both.

Also: air filters and boxes, carbs, guards, front brake and wheel, forks and electrics

 

[scott s]

Well, the engine was pulled from a '74 XS650. I assumed it was a '74 engine (similar outward appearance, non-linked carbs, etc) until we checked the numbers.

The bike was definitely a '74 and the engine is definitely a '72.....I think. It has no decompression lever on the square cover, for example.

 

[Carolina]

???? were the motor mount locations on any of the 650 engines ever changed?

 

[gggGary]

72 up engines will fit any set of frame mounts. The engine mounting plates, brackets and frame locations DID change. 73 to 74 I think but again as long as you use the mounts designed for your frame any 72 up XS650 engine will bolt in.
As corrected by others below the front mount on the 70 engine is a bit further forward than the later engines. I don't know if that is true on the 71 but the hole has moved back by 72 The casting is actually different, the early motors have a more pronounced step just below the oil tube. Lets call the early motor bulge and drilled hole 1/2" further forward?

 

[Punkskalar]

???? were the motor mount locations on any of the 650 engines ever changed?

YES! The very early XS1 engine does have a different front motor mount location, I can verify that one as a fact, as it does not fit into my engine stands the way any of the later model engines do.

 

[OakBehringer]

Well, the engine was pulled from a '74 XS650. I assumed it was a '74 engine (similar outward appearance, non-linked carbs, etc) until we checked the numbers.

The bike was definitely a '74 and the engine is definitely a '72.....I think. It has no decompression lever on the square cover, for example.

If it has a square cover, it might have had a decompression lever at some point. They went to the square cover when they introduced the decomp lever and never changed it back when they stopped producing engines with a decomp lever.

 

[Patches]

YES! The very early XS1 engine does have a different front motor mount location, I can verify that one as a fact, as it does not fit into my engine stands the way any of the later model engines do.

Yes, this is correct. I have had this same experience. I have a couple XS1 motors and they use different hole placement on my motor stand then my other later year motors.

People have argues with me in the past about this matter and I'm glad Hugh is here to back me up. I onl know this for a fact becaus I probably have 17 or so motors laying around. But people still seem to question this fact. Not sure why....

The XS1 motor is a special little guy. The head is totally different in flow design too. It will out perform the later model heads any day. Not to mention the many other subtle changes...

 

[OakBehringer]

I onl know this for a fact becaus I probably have 17 or so motors laying around.

I think it's time you work on expanding your collection. Only 17? Geez. Talk about amateur hour

 

[Patches]

I think it's time you work on expanding your collection. Only 17? Geez. Talk about amateur hour

Just you wait buddy..... I'm getting ready to do a liquidation and I will have more cool XS650 shit for sale then you can shake a stick at. i.e. XS1 front wheels, XS1 motors, rollers, carbs, complete bikes, frames, wheel sets, etc....

 

[gggGary]

Youse guys are right as always. I corrected my first post, now someone has to see if the 71 engine has the same hole as the 70 or as the 72? I am going to guess it matches the 70 not the 72 since it's actually a different casting and the change was probably made when they changed the cases to add the starter???

Corrected first post:
72 up engines will fit any set of frame mounts. The engine mounting plates, brackets and frame locations DID change. 73 to 74 I think but again as long as you use the mounts designed for your frame any 72 up XS650 engine will bolt in.
As corrected by others below the front mount on the 70 engine is a bit further forward than the later engines. I don't know if that is true on the 71 but the hole has moved back by 72 The casting is actually different, the early motors have a more pronounced step just below the oil tube. Lets call the early motor bulge and drilled hole 1/2" further forward?

 

[hmusket]

A couple pictures of the front mount hole of my XS1B engine. If I remember correctly when I had it in the '79 frame it was misaligned by about 1/4 in. for the front mount, using the '79 front mount bracket.

 

[gggGary]

That appears to be consistent with the 70 motor mount hole. IE further forward than the 72 up mount.