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1993 900ss Superlight

Discussion in 'Supersport (1974-2007)' started by DesmoDog, Jun 26, 2022.

  1. I ordered a new fuel pump from Desmotimes on Saturday afternoon, July 2nd. Yesterday was the 4th so no mail, but it showed up today on the 5th. Can't complain about that!

    Replacing the pump wasn't a horrible experience but let's say I'm not a huge fan of having everything stuffed inside a tank I can barely fit my hand into. And I'm getting good at replacing the PITA rubber grommet. I did it twice this afternoon thanks to forgetting to hook up a drain line to the cap. The good news is I realized it while finishing up the cap install, before dumping any gas back in.

    Hit the button, heard the pump, good to go, let's try this again.



    I've never had a bike with FCRs before but I'm guessing that chirp isn't normal?

    I HAVE had 900ss's before, and that didn't sound right. It sounded more like a 450SS, hence grabbing the pipe. Yep, only running on one cylinder. I could see a ton of gas getting blown around in the carb/airbox (holy reversion Batman!) so I know they were both getting that. I can look down the bores of the intake manifolds so I know they're both getting air. So I pulled the plugs and nope, no spark on the front cylinder.

    I haven't even begun to start checking out why, I was done for the day.

    Getting closer, maybe the third time will be the charm!
     
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  2. you probably know you can swap coil and igniter/exciter over to rule them out (apart from just a wiring fault) - I hope it's the latter rather than an ignition pick-up within the bowels of the engine, sometimes it's only the oil-soaked wires to this going open-circuit, or even shorting out, but when they stand, the pick-ups are also even more likely to break down with oil ingress these days (with tell-tale cracks in pick-up outer body casing). I'm sure you know all this already but added it anyway.
     
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  3. And after some poking around I've been able to make every component in the system work... except the pickup coil or ignition sensor or whatever you choose to call it. And my handy meter shows that as an open circuit.

    Dag nabbit. Buying new ones doesn't seem trivial either. The dealers here want around $300 for a set. If I go international it's closer to $200. Electrex has them available seperately for a lot less but I'm not sure about getting a new wire fed into the old harness.

    I also have a couple here on (the remains of) a spare engine that measure ok, but the wiring is trash so I'd have to splice the replacement into the original harness. I'm not sure how realistic that is, I'll have to take a closer look tomorrow.

    So I know what the problem is now anyway. That's a start.
     
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  4. One of these fellas? As said, might be the wiring if you’re lucky, I’ve used the Electrex unit many times and they’ve been reliable and worked as well as the originals.


    upload_2022-7-7_9-21-35.jpeg
     
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  5. I have an engine with the sidecover pulled off that still has the pickup coils. The resistance checked out on them, so I took a closer look to see how hard it would be to switch one out.

    I didn't see any way I'd be able to pull the wiring for the stock part let alone feed wiring from a new one back in. It was all or nothing if I wanted to replace anything outside of the cases. That means $200-$300 and who knows how long of a wait.

    But looking at the used one, I thought if the right side was the bad one I'd have room to splice it inside the case and not have to disturb the wiring running through the case seal. If it was the other one, things would get more crowded. But, as luck would have it, the bad one was the easier pickup to change out. Woo Hoo! I was about due for a win.

    No reason not to give it a shot, it's not like the stock part would be any more non-working if I screwed it up even more.

    So I pulled off the sidecover. I hate going backwards this late in the game but I had no choice.

    [​IMG]

    Notice the brown gasket on the sidecover. I'm not sure how it was attached to the cover but if the goal was to weld paper to aluminum, they did it. What a PITA to clean off. But anyway, that's how it looked before I started pulling the pickup out.

    And here's how it looked after the splicing in the "new" one.

    [​IMG]

    No different? That was the goal, I was happy with how it worked out. I checked to see if there was spark on that cylinder now. Vertical cylinder - spark. Horizontal cylinder - No spark. Son of a bitch. I thought I should check the resistance at the ignitor connector and remembered I never plugged it back in. Oops. Resistance was 99.5 ohms. Perfect. Plugged it in, turned the crank, Tah dah! Spark on horizontal cylinder.

    Time to put it all back together and try again. Sidenote - I really need to get a bike lift. I'm getting too old to be working on these things at ground level.

    Anyway, everything back on, oil back in, back outside.



    That sounds MUCH better. I had to crank it more than shown to get it to fire but I deleted that part. Also, I never did get it to idle. If the throttle is held open even just a little but it will idle, but even with the idle speed screw all the way in it'll die if I let go of the grip. Another issue for another day.
     
    #25 DesmoDog, Jul 8, 2022
    Last edited: Jul 8, 2022
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  6. Good news that you are now on two cylinders, just for my notes, it was a failed unit and not the wiring? And did the failed unit have cracks in the plastic casing whereas the one that’s still working have none?
     
  7. The wiring on the bike was fine, I'm still using it except for right up near the pickup. The failed unit didn't have cracks but did look like the flywheel had hit it??? There are wear marks on the face. I'll post a pic later.

    I'm not sure how that could have happened though. Maybe it's a manufacturing mark. But the other pickups I looked at didn't look like that.
     
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  8. I looked at the old pickup again. It has to be a manufacturing mark, the flywheel couldn't make a mark like that even if it did contact the pickup.

    This was probably one of the last Superlights in the US to still have the foam on the fairings, but it's too far gone and had to go. So what are guys using to clean off the crap left over when the foam is pulled off?
    [​IMG]

    There comes a time when you just have to ride the dang thing and see what works and what doesn't. I think I'm there but it's raining now so maybe tomorrow.
    [​IMG]
     
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  9. On Saturday I moved this from my walkout basement to my garage. I had it running, in gear at low rpm and slipping the clutch to help get it up the hill, no issues. Ran fine.

    Time for the first ride. I put my gear on, fired it back up, took off, and it wouldn't pull past about 3000 rpm. Then died. Wait, I know what this is. Been there, done that. Once again I had forgotten to turn on the gas. Turned that on, fired it back up. Took off again... and it still wouldn't pull cleanly past about 3000-3500 rpm. Returned home. Put .5 miles on it, never got out of 1st gear.

    I thought there was a very slight chance that it just didn't have enough gas in the tank. So today I put a couple gallons in and tried again.

    TURNED ON THE GAS this time. I'm slow but I get there eventually.

    Opened the throttle 4 times to get some gas in the intake. Hit the button, the bike started instantly. Not quickly, instantly. Like WTF? Seriously fast. Wow, that was a surprise.

    Then another surprise. It sat there idling at 1000rpm. No hand on the throttle, steady 1000rpm. Or as steady as these things get at idle anyway. That was weird, but, ok, I'll take it.

    Hit the street. Low rpm, fine. Open the throttle much at all and it struggled to gain revs. Buzzed around at low rpm a little to see if warming it up would help.

    Nope. I could get it to rev to about 6000rpm but not cleanly and I don't think I ever had it over half throttle.

    Rode about one mile, no change in throttle response. Got back to the driveway, and now it idles at 900rpm. Checked the idle speed screw and it's turned all the way in/fastest idle, yet still chugging along at 900rpm.

    I slowly opened the throttle sitting there in neutral and it struggled to rev then too. Wasn't running cleanly. I thought maybe it was running on one cylinder again but both downpipes were hot.

    I let go of the throttle and it died. Fired it back up, and it would idle at 900rpm but rev it at all and release the throttle and it would die.

    It's not the first time I've rebuilt carbs or changed jetting. Sure, the jetting isn't spot on but it should be closer than how this is running.

    Right now it's set up like this:
    [​IMG]

    This is different than what it was when I got it. I pulled the plugs back then and they were both black/rich, so I changed things... but not by THAT much. I got these initial settings from something Brad Black has on his site BTW, so it wasn't just a wild guess... but can I blame him for everything since it didn't run perfectly right off the bat? Yeah, that's it.. it's all Brad's fault! :D

    It's been a while since I've messed with carbs, but looking at another handy internet find it would seem the needles are the likely suspect here? But this is the most common size used in this application. Again I find it hard to believe they're that far off.
    [​IMG]

    Which all points to me screwing something up when I rebuilt the carbs I suppose.

    I'm not sure what my next step is. Pull the plugs and see if they're already fouled? Years ago I had a Honda Hawk I was screwing with and I managed to get the jetting VERY wrong to start with. It quickly fouled the plugs, but it still ran worlds better than this is. While it ran.

    I should probably also check the timing just to be sure that isn't jacked somehow... I can't help but think there's something I'm still missing and it's not that I'm way off on the carb settings.
     
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  10. whole can o' worms.. Keihins need to be in tip-top condition/wear free to avoid idle and mid-range fueling problems. The number of people i know who've ended up waving the white flag and going back to Mikunis after endless flooding problems, sometimes into the sump. Best you can do with a standard tune engine is strip and inspect/replace and fit all Brad Black's recommended set-up. If you think there's a problem outside the carbs then i would fit Mikunis if you still have them, just to rule this out.
     
  11. The engine flooding with fuel from FCRS float needle not closing due to grit, is something I've experienced, easily sorted with a fuel tap.
     
  12. I've already added a second fuel tap to avoid flooding the engine. The bike has something like 7000 miles on it, I doubt anything on the carbs is worn out already. It'd be much more likely I screwed something up when I rebuilt them.

    The more I think about this, the more I suspect I still have ignition issues. Well, ok, I'm thinking about that because comments made on another forum made sense with what I've seen. I was a little surprised at the (lack of) strength of the spark when I was checking for it but wrote it off because gosh, the coils and battery are brand new. And it was bright out. And my eyesight sucks. And I'm sick of working on this. So I told myself it was fine. But they don't audibly SNAP like the plugs on my bevel did when I was checking the timing. I remember that because I would watch the timing wheel while turning the crank and listening for the snap.

    Someone mentioned having similar issues when the coils weren't seeing 12 volts. That could easily be the case so it's on the list of things to check. When I start working on this again. I've taken a few days off and am working on a different project. Meanwhile I'm letting the Super Light sit in the garage next to me Street Fighter. Maybe it will think about what it wants out of life now that it's been jolted awake again, and be inspired to start cooperating with the attention being given because so far it's been a little needy.

    Come to think about it... my first problem was probably naming it "Sophia". In 30+ years of riding I have NEVER named a bike before, but for some reason I named this one after my favorite golden retriever. It was only after messing with it that I remembered Sophia (the dog) and I had a shakey start... I have what are these days affectionately referred to as "Sophie Scars" on both my arms. We had a few disagreements back in the day but she came around in the end. I expect the same out of the Super Light. With less bleeding I hope. Puppy teeth are sharp!
     
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  13. Due to previous comitments I had to take some time off of this. Strangely enough, it did not fix itself while I was gone even though I told it to think about what it wanted out of life.

    There has been some work done on it. I'm (mostly) convinced it's in the ignition and have been working with that. Then someone on another forum mentioned the timing being fully advanced. A picture I posted of splicing in the new lead reveals it's secrets... When I replaced the ignition lead, I checked the clearance but not the timing. Because you know, I assumed it ran fine when parked, and I didn't change the setting, so it should still be good, right? And I couldn't find the bolt that holds the turning tool/degree wheel to the crank. And I was sick of kneeling on a concrete floor working on it. So I buttoned it up and put the oil back in.

    Sigh...

    Basically I've known for a while that the timing is probably wrong, I just didn't get around to checking it until today when I finally got off my lazy butt and dug up my timing light. I haven't used that thing in years but it was right in the same toolbox I left it in last time. So I had that going for me.

    Put the bike on a rearstand. Fired it up - it didn't start instantly today but it wasn't far off. The thing it DID do is settle down into an idle right away. Which it never did before. Whatever.

    Pulled the trigger on the light at idle (roughly 1000rpm) and had to adjust the advance on the light to get the dots to line up. The TDC mark was about 5 degrees off. The firing mark at idle was about 10 degrees off... which tells me the timing is advanced 10 degrees past stock settings? Is there that much adjustment in the mount? I guess I'll find out.

    I screwed around a little more but point of the story is it seems to confirm the timing needs to be dialed back. Guess who's kicking himself now that he trusted previous work when he had it apart and could have easily checked/reset it?

    So I have a plan. Back into the shop and drain the oil (again) and pull the sidecover (again) and screw with the timing (again, sort of).

    Since I'll have the cover off, and I bought a new bolt for my engine turing/degree wheel tool, I may as well dial the timing in as best I can. Just like I should have done when I had the cover off last time!
     
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  14. Timing set to stock position.

    Bike starts easily as before.

    And runs the same as before. No power above about 4000rpm.

    I was pretty sure it was the ignition, now I'm pretty sure it's not the ignition. It's not the air. Must be the fuel?

    I think the next step is to pull the FCRs off the trackbike and see if/how it runs with those. The problem there is, I rebuilt those too so if I screwed up the SL carbs there's a good chance I did the same thing to the track bike carbs. They are jetted differently though, including different needles, so who knows.

    For now it goes back into the corner. There's an event next month I'd like to have it running for so at least I have a deadline. But if I miss the deadline I can just turn the key on my Street Fighter and ride that instead...
     
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  15. Sounds like your having fun o_O but you are getting there :upyeah:
     
  16. fine, except that Keihin flooding isn't always exclusive to when the bike isn't being used..
    and far more likely on the "downdraught" (sic) version.
     
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  17. Today was the day. No procrastinating by playing around with other projects, it was time to switch the carbs on the problem child.

    No big story there. The stuff I thought would be a pain was a pain, the stuff I thought would go ok went ok... except for the damn throttle cables.

    With the original carbs the throttle would snap shut with nice loud crack. "New" carbs - not so much. The carb itself snaps back, the cables seem to be alright but when I hook the cables up everything gets less than snappy. It goes back, but not with the authority it had on the last set of carbs. I messed with it more than I wanted and think it's the throttle itself? Maybe. Whatever, it works well enough to test the carbs.

    I finished hooking everything up. Stared at it a while. Found a wire that had come loose from a coil in all the jostling around. Turned on both gas petcocks. Let the fuel pump run a while. Worked the throttle four or five times. Pressed the start button... turns over but doesn't even think about firing. Turn off key. Stare at stuff. Wiggle this and that.

    Turn key back on, work the throttle a few times, hit the start button.

    Turns over, not a hint of firing.

    Repeat steps.

    No firing.

    Grab a gas can, dump raw fuel into the carb mouths. Turn the key, hit the button...

    And it's running. Not only that but it stays running. That's a good sign.

    It sounds different? Softer maybe? Maybe it's just me. I'll have to find the carb setings for both bikes to see what changed. I know they have different needles and main jets, not sure about the other settings.

    There's a lot more response to the idle speed adjuster. Now I can get something like 1000 to 3000rpm out of it. But it's not consistent. I'm not so sure that doesn't have something to do with the pokey throttle? I'm not going to worry about it for now.

    Time to ride it. No seat, no farings, no riding gear, no problem. Down the driveway, seems to be running well enough. Get it onto the street... roll on the throttle....

    I suppose I could have put all the bodywork on it but the last time I did that nothing worked and I had to pull it all off again and put it back on and then pulled it back off and so on, You get it. I'm tired of dealing with the fairings and tail section so I'm cutting some corners.

    So anyway, I roll on the throttle and... well before I get into that I know some of you are going to get on my about not wearing any riding gear and you're right. But it's like the fairings - I spend all the time getting suited up and then things don't work and I'm standing there in a helmet and gloves trying to mess with crap and sweating and getting generally annoyed and I know that's no excuse but that's life.

    I headed down the drive, onto the street and got a feel for everything while I tried to think of ways I might shock myself by sitting on the frame rails. So just like before the low end was fine and I rolled on the throttle...

    And it pulls to about 5000rpm before I let off.

    Try it again. Pulls pretty smoothly to about 5000rpm again. No riding gear... that's fast enough for now. Time to button up the bodywork, put on some gear, and go see just how far off the carbs set up for a 944 are when put on an 904 engine.

    I took a little break and then got the throttle worked out. It seems the tank hits the cables and moves them where they don't want to be, so with a little calibrated tweaking of various things it's working now. Still not the SLAP it had before but it snaps when it closes so good enough.

    Rode it a little over 20 miles. It was idling around 3000rpm but I stopped and dialed that back. Ran it up to about 8000rpm with no issues. It's deceptively fast - I kept thinking it wasn't pulling all that hard and then being surprised when I looked down at the speedo.

    Along with all the typical 90s Ducati noises the carbs chirp now too. Not always, it seemed like every so often when I'd roll into it they'd start chirping. I'd love to find some era correct FBF slip ons for it but that's not a high priority. Shoulda kept the fake Termis off my 851.

    So yeah, it works. Knowing me I'll just put gas in it at this point, ride it and see what breaks. If it's anything like my 851 was this is just the beginning of the process. Over the winter I'll try to figure out what's wrong with the first set of carbs. And shorten the other throttle cables, put the stock throttle back on, etc. The jury is still out on what will happen with the donor bike.

    The Corbin seat seems to be a good investment too. I was only on the stock seat for a few minutes but it wasn't impressive.
     
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  18. Great write up
    Good to hear the first start up even if it was a bit shaky, did make me smile :)

    Sophia is coming along nicely
     
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  19. well done that man! great news!
     
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  20. I never updated this with the new riding season...

    When I took the bike out of storage last spring, the cold starting was horrible. Took FOREVER to get it running without lifting the tank and dumping fuel down it's gullet. This would not do. In researching things further I found out the pilot jets I had put in were on the small side, which some said could be why it wouldn't start. I still had the original jets which were larger so I thought I'd put them back in.

    Before pulling the carbs I took a closer look and decided I could replace the jets with the carbs in place. Woo hoo! No airbox removal! So I pulled them out, and discovered one of them was plugged. Brand freaking new (last season) Keihin jet with 75 miles on it and it was 100% blocked.

    I put the larger jets in and the bike could now be started without all the drama. Success. So this season I put maybe 300 miles on the bike. I was thinking of selling it at the beginning of the season but changed my mind once it was rideable. The carbs still need work but the bike is useable now.

    I also pulled apart the original carbs to find out what was wrong with them. The ony thing I found was the, um, I've forgotten what they're called. The needle valve thing that the float controls seals against this... jet? I'm blanking on the term! (EDIT: It's actually called the float valve, not needle valve, and the thingie is called the valve seat) Anyway, the thing the needle valve seals on had a huge hole compared to the original part. I don't see how having more flow there would make the bike stumble at high rpm but it's the only thing I found "wrong". It will be next season before I can try out the "fix", but I'm hoping that's the issue.

    And the obligatory picture. A buddy has an 888 that get's ridden even less often than my SL, but I convinced him to take it out late this season. This is from a break we took mid ride. He thinks the SL is much more comfortable than his 888. I think it's a better streetbike than my 851 was, so I'm feeling ok about selling the 851 to get it.

    [​IMG]
     
    #40 DesmoDog, Nov 6, 2023
    Last edited: Nov 6, 2023
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