yamaha 650 guys... i gotta question.

[SportsterMike]

ive been looking for a xs650 and i think i found one on the cheap. im new to jap bikes so the question is..

how can you tell a XJ650 from a XS650?

the bike is a 1973 ??650. i didn't get a chance to look at the VIN/title. 1/2 way home i remembered....

[workingman]

the motor is way different. If it doesn't look like this its not a xs650

[Hobbes]

XJ series are 4-cylinder, dohc, shaft-drive bikes. Made beginning in 1980 (I think.) Only thing they have in common with XS650 is the letter 'X'.

If your bike is a '73 yamaha with a 650cc twin motor (that looks like workingman's pic), it is a TX650. Yamaha changed the model designation to TX for 1973-1974, then changed it back to XS for 1975. Essentially the same bike, though.

HOWEVER, a 1973 bike will have the early 256-type motor (used 1970-1973), not the later 447-type motor (1974-1984). There is no obvious difference between the two, but there is some incompatability in the engine internals. 256 uses a 22mm piston pin, 447 uses 20mm. 256 uses a 34 tooth cam sprocket with 4-bolt cam chain tensioner, 447 uses 36 tooth with 6-bolt tensioner, and different chain pitch. Parts for 256 motors can be harder to find, since way more 447s were made by the end of the XS650 production run in '84. Most engine hop-up parts like big bore kits and hot cams are made for 447 motors and will not fit a 1973 motor.

That's probably way more about XS650s than you wanted to know. But if you want to tweak the motor, you might want to find a later power plant to work with. Send the '73 to me and I'll do a stock restoration, then sell it in 10 years and buy a house...

[philbey]

Damn, thats useful information Hobbes, I've been trying to find a nice clean concise explanation of the differences....

[SportsterMike]

cool, thanks for all the help everyone. it is nothing like the picture attached. guess ill keep hunting. im suppose to look at another about 2 hrs away this saturday.. no clue on the year of it.. so more to come...

[jamesgs4]

cool, thanks for all the help everyone. it is nothing like the picture attached. guess ill keep hunting. im suppose to look at another about 2 hrs away this saturday.. no clue on the year of it.. so more to come...

here is a 73 tx650

[SportsterMike]

weird it doesnt have any of those round plates at the top of the cyl. (sorry not being technical) the one i saw today... the 73...??650.

[ChoppyGee]

weird it doesnt have any of those round plates at the top of the cyl. (sorry not being technical) the one i saw today... the 73...??650.

those are just Valve covers mike.

[SportsterMike]

ya the one i saw today didnt have those.

[akawaterman]

ya the one i saw today didnt have those.

the shinny one in the middle is the pointes cover and the two in the front and back of the cylinder are the valve covers --- the one in the center could be diefferent --- on the bike your looking at --- are U sure its a twin?

[SportsterMike]

the shinny one in the middle is the pointes cover and the two in the front and back of the cylinder are the valve covers --- the one in the center could be diefferent --- on the bike your looking at --- are U sure its a twin?

yup

[beezerglide]

i just looked at a xs400 maybe they just didn't know what they had.

did it look like this?

[SportsterMike]

ya it looked alot more like that, but the dude swore up and down it was a 650.... all the badging was scraped off so i had to take his word..

[Robhall]

Don't all bikes have their displacement stamped into the lower side of the cylinder? Generally on the left side.

[Hobbes]

The XS650 motor in my basement right now has "653cc" stamped on the front of the motor, at the bottom of the left jug.

I don't think Yamaha started making the XS360/XS400 bikes until 1977. Another possibility is that you've got a TX/XS 500 - 1973 was the first year (assuming the guy has the right date for his bike.)

They're cool bikes, you might consider getting it if you want something a little different. Not a huge commercial succcess when they were made ('73-'79), but some say they're underappreciated and were ahead of their time. 499cc twin, 180 deg. crank with balance shaft, allowing the motor to peak at 8-9k rpm with almost no vibration problems. 8-valve head, 10:1 compression stock. Fast like shit through a goose on the street. Read this - http://www.realclassic.co.uk/yamaha04112500.html

Rarely customized, but can be done. Wrenchmonkees have an awesome cafe racer XS500:

http://www.wrenchmonkees.com/monkee04.html

http://www.youtube.com/watch?v=H43zgPjF2sc&feature=related