Those are the KYB piggyback shocks, yes? I have not personally tried them, have been real tempted to though. Other guys have done this and said they were very pleased with the outcome. I think they are about a half inch longer than the stockers. Honestly, I don't see how they couldn't be better than the originals. Give her a go! I'd like to hear what you think about them!

I just bought a set of these off the ZRXOA forum. Im hoping these will ride a little better than the stock KZ shocks. Is this the case ? If you have this conversion I'd like to hear from you

I fitted a custom 650 swingarm into a 550 twinshock, from memory there was several mm difference which was fixed by machining down the bearing caps. IIRC also about an inch longer.

Going any bigger than 130 on that rim won't work, really you want a complete swingarm, wheel, caliper assembly, zrx1100 would be a popular choice.

I just measured my bare 550 81 d1 frame, getting 225mm for the swingarm pivot. You don't want to go too long on the length, the 550 twinshocks have a short wheelbase which makes them agile.

another consideration is your sprocket offset, there are various ways of fixing this...

I did a couple bolt-on mods to mine. As much as I want to brace the frame and put better brakes on, it aint happenin. My mods are pretty much ZRX shocks, wind screen, short stems for the mirrors, bars and pipe. I preserved, not restored, the rest of the bike. Replating/refinishing original parts when possible. I have a set of reproduction shocks I slap on for bike shows and what not. EVERY PART on your bike is worth some money, so don't throw anything out!

Dave, I will confer with the factory, although my main guy is travelling today, he is great about getting back with me,

Looks like that is 14.25" in standard free length for the ZRX - can you confirm that's what you're running? Looks like you're all the way rearward on your swingarm bracket - 1/2" shorter would put you in the middle so you'd have adjustment in either direction. Would that be useful?

For me fade is not an issue running 1/8th mile the shocks don't build much heat.
I had been running strut's and lowered and couldn't stop the wheelie's so I took the one's off my ZRX project
and used them to go back to shocks and get a base line of spring rate and valving.

At the track with the ZRX shocks I can launch it harder then I ever have and it's not wanting to wheelie
so I'm thinking some thing close

zukdave wrote: So could you set up a set for drag racing ?
I need to do something for my KZ650 right now it got an 8 inch over swingarm and a set of factory ZRX shock's.
Me and the bike are right at 600 lbs total.

Hey Dave,

When you lay that shock at that angle you more or less halved your effective spring rate, so I'm going to guess the bike squats like mad and that affects your launch. Short answer is "Sure!", I can make any length you want and dial the spring and damping up, too, I'd say we are probably best off using the gas charged shocks with the threaded preload so it can be fine tuned.

HOWEVER...

These are all emulsion shocks. Fine for street use and casual off road, but like all emulsion shocks they are prone to fade in extreme conditions. I don't frankly know if that's a factor for drag racing, but I'm interested in learning more and I'll work with you if you like.

So could you set up a set for drag racing ?
I need to do something for my KZ650 right now it got an 8 inch over swingarm and a set of factory ZRX shock's.
Me and the bike are right at 600 lbs total.

Hi all...just an update. 550 is waiting for the frame to be blasted still; all other parts done. I am debating on a big bore kit and a megacycle cam with a road race grind. It would wake it up nicely. The 1100 is mostly done, rear end is mounted with a modified stock swingarm and the 87 gxsr 18" rear wheel. I purchased a 87 gixxer rear brake and rebuilt and mounted it. Had to weld a bracket on the bottom of the swing arm for the torque arm. Mounted up the zephyr shocks, no prob. Front wheel FINALLY fitted with the 86 gsxr 18" wheel, had to mill the mounting points for the rotors almost 10"mm. Fabricated adapters for the brakes and milled spacers and shims for the 15 mm to 17 mm bearing and axle. And it all works....18" gsxr wheels on a GPZ1100. Really makes it look like S1 with those wheels. I bought a zrx 1100 swing arm, but..it does not bolt up, slightly to wide between pivot holes. Also the lower bar of the arm does not clear the Kerker pipe. So I guessing this needs to be modified (the kerker?) The tank still needs to be sorted, I really want a late model J tank, I have two GPZ1100 tanks I could trade for one? I was also thinking about dropping in a megecycle .385" cam to beef it up a bit.

Oh and picked up a set of ZRX shocks for $150 usd

And new rear sets

This is everything mocked up before the new springs.

You can just barely make out the where the bike was sitting before the new springs. Gained over an inch and the stance is much nicer. Not to mention more ground clearance