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Progressive Suspension Upgrade for '78 KZ 650
- Jonny
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In my slow, student budget fasion, I am trying to upgrade a thing at a time on my KZ, and I thought that this summer I'd go over the suspension, and make it all shiny any new. I figured that since she came with the 4 into 1 and pods, and she got a DYNA last year, the next thing that will really effect rideablity would be suspension. (If this in itself is a false premise, then chime in, but as all else is in generally good running order, I can't think of what else might get more bang for the buck in terms of upgrades...)
In any case, progressive front springs are reasonable, and I can get a new set in easily enough, with new seals, oil and such of course. But, the rear shock/spring combos are costly indeed. Now, I've read a fair deal about people swapping out their stick KZ stuff for older Harley bits. I think this could be a pretty cost effective way of going about, it, but I cringe at the though of having anything harley related getting near my Kawi. Moreover, I found of set of Progressive coil/shocks on ebay not too far from where I am, for a (so far) reasonable price.
Here is the rub: they are exactly the same in dimension as the set which progressive recommends for my bike, so I know they will fit. However, the spring rate is slightly higher than suggested. The rate on the recommended part is 75/120 lbs/in, while the ones available are 105/150 lbs/in. (They are lightly used, off of a newish VMax.)
So... all that being said, I'm really just curious if anyone figures thats gonna be enough of a difference to really ruin my day of riding. I am a pretty slim guy ~150 lbs, but I do sometimes have a passenger, and do some light touring with the bike, ie. strap on a backpack and do some day/overnight trips. So, I will occasionally have a moderate load on. I just don't want to have too stiff of a setup which will shake my old girl to death.
My initial reaction is that this won't be a big enough difference to really mess anything up, and that new suspension all round is going to improve handling and ride quality a little by comparison to the stock stuff that is currently on there. BUT, as always I am hopine there is someone out there with more experience in this that might be able to chime in, and confirm, or deny that and save me spending money on this sorta thing.
As always, thanks in advance.
Jonny
'78 KZ 650C2 'Lila'
'71 Norton Commando 750 'Eadie'
St. Catharines, ON (Mostly, anyway...)
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- wireman
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posting from deep under a non-descript barn in an undisclosed location southwest of Omaha.
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- mjg15
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'80 Z750fx
'81 KZ550A
'81 GPz550's, Too many!
'82 KZ1000R
'82 GPz750
'90 ZR550
Project photo album: s163.photobucket.com/albums/t289/mg15_ph...GPz-ZR550%20project/
s163.photobucket.com/albums/t289/mg15_ph...current=DSC01286.jpg
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- steell
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I now have Progressive fork springs with 15w oil and koni rear shocks, rides like a dream.
KD9JUR
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- Jonny
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So it seems like using that high of a spring rate for my application wouldn't be worth it. Nice to find a bargain on ebay, but not when it ends up being false economy.
Given the price, the progressive springs for the forks are still a good option, but I suppose I will either have to spend the big money, or keep trolling ebay for a set of rears.
Glad to have the warning tho. I'd rather not have bought something that turned my bike into a hartail.
Jonny
'78 KZ 650C2 'Lila'
'71 Norton Commando 750 'Eadie'
St. Catharines, ON (Mostly, anyway...)
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- mjg15
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$10 springs.........
'80 Z750fx
'81 KZ550A
'81 GPz550's, Too many!
'82 KZ1000R
'82 GPz750
'90 ZR550
Project photo album: s163.photobucket.com/albums/t289/mg15_ph...GPz-ZR550%20project/
s163.photobucket.com/albums/t289/mg15_ph...current=DSC01286.jpg
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- Jonny
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We'll see how it all works out.
btw - that rear looks great. I know a guy with access to an aircraft grade aluminum CNC mill. Did you do the design on that swingarm yourself? Or did someone else have a pattern for you? That would be a great mod for waaay down the road (or really, a second bike). I've always liked the look of KZ's done up as streetfighters.
'78 KZ 650C2 'Lila'
'71 Norton Commando 750 'Eadie'
St. Catharines, ON (Mostly, anyway...)
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- wireman
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- gengomerpyle
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same one that i have on my bike but mine has the calfab stickerwireman wrote: thats a cal-fab swingarm
1982 GPZ750R1 ELR
1978 Honda CB750F SuperSport
1971 Honda CB750K
1970 Honda CL100 Scrambler
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- Jonny
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Having taking a quick look at some other option, (Ie, Ohlins, Marzocchi's etc...) I figure they are way out of my price range, and probably a whole lot more performance oriented that I need to a very mildly modded semi-stock KZ. Progressive it is...
I am curious however, if anyone has found that there is a serious performance difference between the gas charged shock and the oil immersion shocks as rears. I have used both in automotive applications, and having worked at a parts counter for some years know the main differences, but am not particularly familiar with how they may effect motorcycle ride performance.
I figure either is going to be a pretty big improvement over the (presumably) stock shocks and springs still on my bike, and again, as a fairly light rider (~155 lbs) who infrequently rides with passengers or panniers, probably the regular duty air shocks should do. I just wanted to ask if anyone has really rave reviews for the 14 series oil shocks, and if its worth the extra cash...
Jon
'78 KZ 650C2 'Lila'
'71 Norton Commando 750 'Eadie'
St. Catharines, ON (Mostly, anyway...)
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- Nebr_Rex
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I run 90/130 springs on some old KYB shocks,I'm 250 and bike is 600ish.
2002 ZRX1200R
81 GPz1100
79 KZ1000st daily ride
79 KZ1000mk2 prodject
78 KZ650sr
78 KZ650b
81 KZ750e
80 KZ750ltd
77 KZ400/440 cafe project
76 KZ400/440 Fuel Injected
www.dotheton.com/forum/index.php?topic=39120.0
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- Jonny
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I know this has been a bit of a string for such a small modification/replacement of parts, but as with many others here, but my budget for the bike is sadly much smaller than my imagination and desire. Every purchase has to be a smart one... Also, much of this is preparation for a pretty big road trip at the end of the summer, to go exploring the east coast of Canada. (Another thread on that already....)
Can't wait to get back home and have a pile of new parts in boxes waiting for me.
Cheers all
Jon
'78 KZ 650C2 'Lila'
'71 Norton Commando 750 'Eadie'
St. Catharines, ON (Mostly, anyway...)
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