Shock angle

fredintoon

Fred Hill, S'toon.
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A few days back I was part of a discussion about the difference between a Standard and a Special XS650.
Yes the frame got sturdier over the years and there are minor differences between passenger footpeg mount styles
but those can be easily removed with a Sawzall & angle-grinder as part of a custom build and then how can you easily tell what the dreaded PO started with?
The only thing that can't be swapped from either and put on t'other is the rear shock angle.
Using Skull's posted frame dimensions and a measured 430mm swingarm pivot to lower shock bolt
dimension of 430mm me and my 40+ year old H-P 11C ( remember reverse Polish notation?) calculate
the Standard's rear shock angle is 15º and the Special's is 24º.
 
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Yes Fred, I think its that 24 degree angle that gives the Specials superior handling properties. That along with the fat rear tire, turns the XS650 almost into the sport bike handling area. Did I mention, I love my 1978 Special:laugh2: . Then again I know didly squat about bike handling!
 
Dang it rtgman, you're always one step ahead of me. ;) So its the 24° angle that makes those Specials so nimble ? I just bolted those chrome shocks on my Standard .. Oh well... Bling is good ! -RT
 
Fred, the frame got sturdier exactly once, in 1974, then stayed that way till end of production. There was no progressive evolution. The way you can tell what the PO started with is to look at the VIN stamped into the steering head. If it ain't there, don't let the CO (Current Owner) become a PO--walk away!

Jeez, RG, the children are likely to take your leg pulling seriously in spite of that smiley face. Well, that's their problem; go ahead and dangle the bait, I'm not biting!
 
I've owned them both and, like children, loved them equally for what they are. To me the 77'D handles the twisty's a bit better but for some reason I do not understand, the 78'SE is a bit more fun. Maybe I take myself too seriously on the 77'D.

roy
 
From what I have recently learned the standards also have a loop around the passenger foot peg. I mean I guess you could chop this off if you want, but I feel like it would be pretty noticeable....I guess specials have a like a stick instead of loops. So I think unless someone chopped of the passenger pegs, you should see the loops.:bike:
 
Fred, the frame got sturdier exactly once, in 1974, then stayed that way till end of production. There was no progressive evolution. The way you can tell what the PO started with is to look at the VIN stamped into the steering head. If it ain't there, don't let the CO (Current Owner) become a PO--walk away!
Jeez, RG, the children are likely to take your leg pulling seriously in spite of that smiley face. Well, that's their problem; go ahead and dangle the bait, I'm not biting!

Hi grizld1,
all I know about the XS650's frame development is that the first time I tried picking one up I reckoned I knew why an XS650 was 80lbs heavier than my BSA Gold Flash, it was because they'd left the hollow middles out of the frame tubing.
Then I tried lifting the motor. Then I bought a shop crane.
Not wanting to be politely asked to Eff off when peering at a stranger's XS650 steering head takes something you can see from across the street
to determine what that modified bike started as.
The rear shock angle is the only unchangeable feature to determine that.
And I'm sure that RG is fully aware that the Special's somewhat less lively handling ain't caused by it's 24º shock angle.
It's the Special's big fat (by 1970's standards) rear tire what's doing it.
Swapped my Special's artillery wheels for wire wheels off a Standard for vanity's sake.
That 110/90-18 rear tire nimbled my Special right up, 24º shock angle and all.
Swapped back to the artillery wheels to keep peace in the house.
(Whatcha want for your birthday? Bike needs new tires Dear. So she looked 'em up and got the right sizes for a Heritage Special.)
The nice new 130/90-16 dulled the bike's handling right down again.
 
Oh yeah, Fred, the Japanese sure knew how to make their motorcycles heavy! With a lot of slimming where it doesn't show much, I've managed to get my old D-model down to around 50 lbs. heavier than the '68 Bonneville I rode back in the day. Lots of variables affect handling--tire width, rear end height, overall weight, unsprung weight. My first XS650 was an F-model Special, and its cast wheels hurt handling on every one of those points.

It takes a truly generous man to bite the bullet and sacrifice the performance of his motorcycle to spare his wife's feelings. Well done, Sir!
 
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It takes a truly generous man to bite the bullet and sacrifice the performance of his motorcycle to spare his wife's feelings. Well done, Sir!

That's why I love you guys!

Dick, do you remember my (smart ass) reply the last time you were giving me crap about my Special?
 
Wish I could, Marty; my memory must be slowing down to match my riding. "Golden years" my ass!
 
Oh yeah, back in the distant past when I could keep up. Camden used to say "It's better to ride a slow bike fast than it is to ride a fast bike slow." I'd tell him it was still better to ride a fast bike fast. Now I'm old and slow no matter what.
 
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