'75 CB550K1 Gulf - Round...3, the fun stuff

Re: '75 CB550K Gulf - dual disc

Stock front end, just bolted on a second disc and caliper, and modified the speedo drive plate a little. Easy peasy. I'll need to play around with the MC...possibly go bigger.
 
Re: '75 CB550K Gulf - dual disc

Used the same left side fork too, just flipped it around?
 
Re: '75 CB550K Gulf - dual disc

Nope, both fork lowers have mounting points. The right side isn't finish-machined at the factory, so you'll have to do a little filing, and maybe add a washer or two.
 
Re: '75 CB550K Gulf - dual disc

i am jealous lol i want mine to be done already too hahaha
looks great though!
 
Re: '75 CB550K Gulf - dual disc

did you resurface the rotor? they look like theyve been roughed up a tad, or is it the pic? cuz i was thinking of doing it to mine
 
Re: '75 CB550K Gulf - dual disc

I didn't. The guy who copied the hole pattern onto the second rotor deglazed the hell out of both of them. A little more than I would have...
 
Re: '75 CB550K Gulf - dual disc

If you can find a way to flip the forks around with the calipers trail mounted instead of in front, it will be more modern looking. Just a suggestion. I did it on a cb400f way back with a cb550 front end. The only thing that might be affected is the fender mounting. The only parts that will flip left to right is the forks and accompanying calipers & mounts. The speedo drive and wheel will stay the same direction and side.
 
Re: '75 CB550K Gulf - dual disc

That's the plan eventually. I have to bleed the calipers and drain the forks before I do that. With the switch, the fork draining can be messy, and the bleeder isn't the highest point in the caliper.

Situating the calipers behind the forks is also said to help the steering not be so twitchy. The weight in front makes the wheel want to fall to either side; in back, the weight acts as a stabilizing anchor. Plus it's much easier to wipe bugs off the forks instead of the calipers!
 
Re: '75 CB550K Gulf - dual disc

Ok, good deal! Sorry, I was late to the electronics posting. Did you work out the controller circuit for the damper? A quick glance looks like it just needs a pulse width modulation (PWM) signal. But then, the pot used for the damper should have varied the damper - if it was specified for it. How did you come about to order that pot for the damper? Was it required by the damper or did you read that would just work based on another forum/thread (GSXR?)? I'm not sure but it sounds like you may have figured it out. Usually a solenoid is on-off (coil and magnetic plunger) and a servo is variable (stepper motor and hi resolution controller).
 
Re: '75 CB550K Gulf - dual disc

No prob, yeah we got it basically figured out. I got my original info from a suzuki forum (gixxer nation I think? ::)) The damper works on it's own just with power, but I'm interested in being able to vary how much it dampens. So yeah, it's solenoid operated, not servo. The potentiometer was just a whimsical purchase, to try and make it work. Luckily it was cheap!
 
Re: '75 CB550K Gulf - emulators: one oxidized

Hello again, I just wanted to share tonight's findings. During the process of the dual disc conversion, I tore apart the front end. This gave me an opportunity to pull the emulators and tune/modify them. When I pulled them, I was dismayed to see that one had oxidized. I'm going to assume that the tube with the oxidized emulator had water-contaminated oil, unless anyone has other thoughts. I'm not sure if I'm disappointed or not. There's no sign of leakage anywhere; the fork seals and cap o-rings were new last spring. Plus the bike isn't ridden in the rain. I'm thinking I'll just have to chalk it up to 37 year old forks.

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In other news, I'm going to drill another low-speed damping hole in the top plate, back the springs off a half tune, and see how it does from there.
 
Re: '75 CB550K Gulf - emulators: one oxidized

Scratch that; I'm just going to back the springs out a half turn for now.
 
Re: '75 CB550K Gulf - emulators: one oxidized

Are those proper Race Tech emulators or the MikesXS ones? I'm running the MikesXS ($50) and am thinking I might have a look at mine too :)
 
Re: '75 CB550K Gulf - emulators: one oxidized

They're the MikesXS knock-offs. After all the diagnosing I've done on them, and cross-referencing with the sohc4 guys and their troubles, if I can't get them reasonably dialed, I might have to spring for the Race Techs... Here's to hoping they work (better) !
 
Re: '75 CB550K Gulf - emulators: one oxidized

Hey Tim, out of curiosity, do you remember how you set yours up? I recall the instructions listing number of turns on the springs for "street" and "race" and I went half way between the two. High speed is great, low speed...not so much.

Or maybe if you still have the instructions, could you post the turn amounts?
 
Re: '75 CB550K Gulf - emulators: one oxidized

I did mine a long time ago - would have stuck with the original directions - probably 1/2 way between like you did.

Honestly I don't know how to judge how well they work. Doug rode the bike in 2010 at Kiley's and he said it handled well, so I haven't touched it since!
 
Re: '75 CB550K Gulf - emulators: one oxidized

Okay, thanks! So, hmmmmm. Since we're set up about the same, that throws a little wrench into things. Differences between 550 and xs650 forks aside, my vibration at 45mph may be stemming from somewhere else. I'm hesitant to make too many suspension changes at once because I want to pinpoint the source. Right now I've got the emulators backed off 1/2 turn, and extra unsprung weight from the second rotor. I'll test that combo out as-is and reevaluate. Fun fun.
 
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