-
Enjoy XS650.com? Consider making a donation to help support the site.
XS650.com receives a small share of sales from some links on this page, but direct donations have a much greater impact on keeping this site going.
For Sale - 1972 Yamaha GS650 (XS650 w/factory 750cc engine)
- Thread starter Virginia404
- Start date
Interesting, ill have to investigate this further and my 72 which was bought by my mother for my father on my 1st birthday from the Yamaha dealer in Royal Oak Michigan. The handlebars and seat also were purchased at the same time from the dealer and installed by the dealer.
Attachments
Last edited:
If it's a GS, the motor will have a VIN that starts with GS650...
Faster? Yes. Much faster? Probably not. Why would it have better braking? 100cc is a jump but not nearly enough to justify having to changes brake elements for a limited model (unless im wrong and that was an additional selling point to this model) especially with 70s tech. Even if it brakes better its still only adequate at best by today's standards. Unless the original documentation says you have a GS650, or the stamp tells you it's a GS650, having the original paperwork of just a regular 72 xs650 is cool but going to mean a lot more to you than it is to somebody else.
Remember the 1972 TX-750 factory bike was only 444.0 ccm (45.40 cubic inches)
And the 1972 750ccm motor looks completely different.
Ive built a few motors and this is about the best you can do.
Does a 1972 xs-650 bored over 3 times equal a 750 ?
Bored 3 times, the pistons 3x over and rings 3x over 0.75 are oem available.
And the 1972 750ccm motor looks completely different.
Ive built a few motors and this is about the best you can do.
Does a 1972 xs-650 bored over 3 times equal a 750 ?
Bored 3 times, the pistons 3x over and rings 3x over 0.75 are oem available.
Its difficult enough to convert a 1970-73 256 motor to a accept the 446 motor oem parts from 1974-1981
and now somebody pops up with a 750 that looks like a 650.
It could only be 3 over bored 256 cylinder and 0.75 over pistons and rings.
If you put a 1974 top end on a 256 lower end, she'll maybe give you 500 miles and be hard as hell to keep the tune.
Otherwise how do you make a motor that looks like a 650 into a 750 in 1972 ?
Yamaha may of bored some of their cylinders that didnt pass inspection 3 times over and put 3x over pistons and rings to salvage those motor parts.
The 1972 TX-750 bike makes 186 mph, - why need better brakes in 1972?
So the GX650 story doesnt really make sense to me.
and now somebody pops up with a 750 that looks like a 650.
It could only be 3 over bored 256 cylinder and 0.75 over pistons and rings.
If you put a 1974 top end on a 256 lower end, she'll maybe give you 500 miles and be hard as hell to keep the tune.
Otherwise how do you make a motor that looks like a 650 into a 750 in 1972 ?
Yamaha may of bored some of their cylinders that didnt pass inspection 3 times over and put 3x over pistons and rings to salvage those motor parts.
The 1972 TX-750 bike makes 186 mph, - why need better brakes in 1972?
So the GX650 story doesnt really make sense to me.
1972 TX-750 exists, look a lot like a mandarin or gold 1973 TX-650 except its clearly a different motor.
Im not sure how much ccm you get from a 0.75 bored cylinder package like the ones sold a long time ago on mikesx.com for the 256 and 446 650ccm motors.
Im not sure how much ccm you get from a 0.75 bored cylinder package like the ones sold a long time ago on mikesx.com for the 256 and 446 650ccm motors.
The 1972 TX-750 bike already existed and the 750ccm motor looks very different,
even thou the TX-750 bike itself, except the motor looked like a mandarin or gold 1973 TX-650.
Mikesxs use to sell cylinder upgrade sets (cylinders pistons rings, pins, clips) for the 256 and 466 650ccm motors that were just bored over .25, .50 , .75 many years ago. Does a 0.75 bored over 650 cylinder give you 444ccm like the 1972 TX-750 factory bike produced?
Thats the only way the motor shown in your bike could be considered a 750.
More accurately Id say the motor pictured in your bike could be a XS650 bored over .075
There are no factory 750 cylinders that install onto a 256 early year motor, i suppose Yamaha could of done the machining.
Very possible the 3 over bored cylinders were oem available as an upgrade because the rings and pistons are.
But who really knows?
This is what the 1972 Yamaha TX-750 looked like with a factory 750 motor that looks very different from a 650 motor.
even thou the TX-750 bike itself, except the motor looked like a mandarin or gold 1973 TX-650.
Mikesxs use to sell cylinder upgrade sets (cylinders pistons rings, pins, clips) for the 256 and 466 650ccm motors that were just bored over .25, .50 , .75 many years ago. Does a 0.75 bored over 650 cylinder give you 444ccm like the 1972 TX-750 factory bike produced?
Thats the only way the motor shown in your bike could be considered a 750.
More accurately Id say the motor pictured in your bike could be a XS650 bored over .075
There are no factory 750 cylinders that install onto a 256 early year motor, i suppose Yamaha could of done the machining.
Very possible the 3 over bored cylinders were oem available as an upgrade because the rings and pistons are.
But who really knows?
This is what the 1972 Yamaha TX-750 looked like with a factory 750 motor that looks very different from a 650 motor.
You bore out the cylinders and use different sleeves. That was already mentioned earlier in this thread. You can always call Yamaha and verify yourself to get a legitimate answer one way or another. As far as the tx750, it made what, 65ish horsepower? There is absolutely no way that bike went 186mph unless God did the engine tuning on it. 186 KPH, all day. MPH not a chance
Good lord riding the 1972 xs650 at 150mph, i dunno, those skinny front wheels with the cloth embedded thread in the rubber tires at 10 and 2 oclock to prevent slippage. A normal early year 650 can get you up to about 110 maybe a bit more depending on your how much guts you have.
The 72 TX-750 has a much wider front wheel for a reason and listed at 186mph top speed. Why need better brakes somebody asked.
Why need to make a special XS-750 when the TX-750 existed and then forget to badge it an "GX"
The GX may of been the Police bikes they made but werent they white and green? "GX" meaning government ??? Ive heard of those but they dont look like a brilliant red xs2.
If that is real theyre probably worth 15,000 because it comes with a great story.
The 72 TX-750 has a much wider front wheel for a reason and listed at 186mph top speed. Why need better brakes somebody asked.
Why need to make a special XS-750 when the TX-750 existed and then forget to badge it an "GX"
The GX may of been the Police bikes they made but werent they white and green? "GX" meaning government ??? Ive heard of those but they dont look like a brilliant red xs2.
If that is real theyre probably worth 15,000 because it comes with a great story.
Doesn't have to. The history of the GS650(750) is well documented. Yamaha did a limited production run... 200 iirc to meet the racing rules of the day. It was indeed a factory built XS2 with a 750 engine. You could buy 'em from the dealer.
Hey Scob,
I think you crossed up something you read.
The TX750 engine looks different because it is different. Only about a 3 year run because of ongoing issues with the motor.
Motor made less than 65hp.
No more of a performer than a 650 with 750 kit in it. Similar weights and power.
Top speed 95 mph
I think you crossed up something you read.
The TX750 engine looks different because it is different. Only about a 3 year run because of ongoing issues with the motor.
Motor made less than 65hp.
No more of a performer than a 650 with 750 kit in it. Similar weights and power.
Top speed 95 mph
Attachments
The TX750 didn't "MAKE" 744ccm. 744 cubic centimeters is the volume of the engine. In this case it is actually 743cc which is close enough they tag it as a 750cc.
Where you came across the fantasy land number of 186 mph is beyond me. That doesn't even convert to khp as Jesse was thinking. My original thought as well, but that converts to about 112 mph which is a dozen more than it was designed for. Anyways I enjoyed learning about the bike
You made me look.
Very basically...
And I believe this has already been covered in this thread in greater detail as well as mentioned by Jesse above; you remove the cylinder sleeves from the cylinders and then bore the cylinders to accommodate an 80mm sleeve. Install the sleeves with the matching 80mm pistons and ring set.
Thats what Im saying, mikesxs sold 750 kits,
So the bike is a 1972 Badged as XS650 xs2 with 653cc cylinders bored to 744cc but called a GX-750 ???
A 427 chevy vette motor bored a few times isnt a 454, its a 427 bored over a few times. that may produce the same horse power as a 454.
I cant advertise my 1969 427 vette as a 454 when its just a 427 bored over a few times. Is that right?
If making a special bike and changing the XS to GS why was it not badged correctly, if its a special bike?
I bet those gas tanks on the 72 TX-750 leaked too like the first 1973 TX650 tanks did leading to the recall on the emblem tanks replaced with the decal tanks.
******Im not arguing, Im saying this xs2 bike looks just like mine except the handlebars and seat. And the badges.
with the story its worth 10k more than mine. Mine has 5248 original miles. the skinny front wheel is the biggest that fits, unsafe for the horsepower of a 744cc motor.
The king/queen seat on my bike does have a Yamaha Germany sticker on the wooden bottom of the seat.
So the bike is a 1972 Badged as XS650 xs2 with 653cc cylinders bored to 744cc but called a GX-750 ???
A 427 chevy vette motor bored a few times isnt a 454, its a 427 bored over a few times. that may produce the same horse power as a 454.
I cant advertise my 1969 427 vette as a 454 when its just a 427 bored over a few times. Is that right?
If making a special bike and changing the XS to GS why was it not badged correctly, if its a special bike?
I bet those gas tanks on the 72 TX-750 leaked too like the first 1973 TX650 tanks did leading to the recall on the emblem tanks replaced with the decal tanks.
******Im not arguing, Im saying this xs2 bike looks just like mine except the handlebars and seat. And the badges.
with the story its worth 10k more than mine. Mine has 5248 original miles. the skinny front wheel is the biggest that fits, unsafe for the horsepower of a 744cc motor.
The king/queen seat on my bike does have a Yamaha Germany sticker on the wooden bottom of the seat.
