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Honda Spada Carburetor Woes :(

Discussion in 'Technical and Troubleshooting Torque' started by jaguarfanster, Nov 6, 2011.

  1. Hey All

    My recently aquired spada seemed to smell rather petrolly of late. I happened to notice this particularly after I turned on the choke and didn't seem to return well. The bike would start and need substantial throttle to keep it running. These effects would normalise after a while

    Anyway today I removed the tank, and opened up the vacuum compartments of the twin carbs to see if the cable was effective. Well the cable didnt seem to properly open and close the choke valve, in the vacuum compartment. I just disconnected the cable and forced the valve to remain in choke off position.

    Now the problem is from 4k-9k revs the bike seems to not have any power. Speed stays constant, and gearing up really makes the engine struggle at these values. Only when I completely open the throttle, does it take off like a rocket. So basically the throttle has become "all or nothing" in regards to acceleration. Worst of all it still smells petrolly...

    Also I disconnected the choke cable from the handle, and when I pull on it I don't notice any change in revs, up or down...which is odd.

    Would greatly appreciate it if anyone could give me any insight. Also if anyone could explain the principle/theory behind the honda dual carb, it would help immensely. The wikipedia carb schematic does not look anything like my carburetor...

    Thanks All!
  2. relevant to my interest i also just got a spada would like to know if its a common thing / solution for reference just in case mine goes down lol
  3. Haha, well just reading around I found this on the interwebs http://www.motorcyclecarbs.com/carbs101.pdf

    That helps a lot with theory..

    I'm feeling no throttle reponse at around 50 percent throttle...like I mean nothing happens speed does not change, until i go all out on the throttle, which almost rips the bike from under me....yeah dont wanna die.

    Anyway the theory stipulates that for 50 percent throttle the needle jet/jet needle is the primary supplier for fuel/air mix....I remember screwing around with a needle (taking apart/putting back to learn haha) from a carb i partially dismantled...

    that's probably my issue, when i put it back together I must have done it incorrectly so fuel that jet is inhibited, hence no powaa at 50 percent...

    I'll get back to it in 3 days after uni exams are done! and keep posting on developments.....fuel economy as opposed to performance is really what I'm striving for here
  4. How does the performance change between when its hot or cold?
    Usually problems that arise when cold and go away when its hot mean its a lean issue. And conversely, problems that make themselves know when the engine is hot are usually because its running rich.

    You might also want to double check that you put everything back the way its supposed to be, the number of problems Ive created by putting things back the wrong way is massive!
  5. ahh the problems arose when I opened up the vacuum chamber on the rear carburetor and then put it back together again....half throttle=absolutely no response, full throttle=takes off like a rocket....the symptoms present themselves immediately. So probably yeah just a stuff up in rebuilding, or I somehow put the needle back on incorrectly...

    anyway I'll be checking tomorrow to make sure I the vacuum piston thingys havent lost their vacuum seal, and move back and forth....if thats all good ill work on the needle....lucky for me I have one untouched carb to compare with, so grateful for dual carbs on spadas haha
  6. well you seem like you know what to do, where as i dunno shit haha thanks for the link and love the spada so i want to keep it as long as i can.
  7. Well finally got around to checking it out today and turns out I forgot to put back the spring when reassembling the throttle slide valve....so the throttle slide never retreated back to home as there was no spring force....meant a whole lot of air was entering the carb for the same amount of fuel, hence it ran super lean? well anyway im an idiot...

    But the bike still smells slightly petrolly and revs far higher than spec....so I mucked around with the pilot jet screws, taking it all the way in and bringing it back to spec (2.75 turns from bottoming out)...idles great at 1300, exactly what it should be in the spada manual haha....when i got it was "idling" at 2500 rpm LOL....

    Still has a faint smell of petrol (doesnt smell as clean as my mate's cbr250rr) so I think I'll have to redo valve timings....although the timing chain is rattling a bit so probably tension that before I do the valves.....

    @thecatsmeow: hahaha no worries mate, also grab yourself the spada manual if you havent already....the one people often link to is in pieces but I made an ordered 168 page pdf with acrobat pro....ill upload it tomorrow morning and link it.....spada's a really fun bike and I'm loving my transition from 4 wheels to 2 :)
    • Like Like x 1
  8. bloody hell, it lost throttle response today again

    although it happened when I was running with little to no fuel in the tank. Anyway removed the carb from the bike disconnected the throttle cable, and will dissemble and clean it up with some wd-40 tonight...

    I suspect its running lean due to some gunk clogging a jet or so...worth a dissemble for curiosity sake anyway
  9. It's fine again, carbs were a bit dirty....note its a bit challenging reattaching the throttle cables, as odd positioning tends to make the throttle loose its snap recoil. Apart from that its still consuming fuel a bit too quick for my liking and smells of petrol. Possibly loose cam chain hence bad valve timings? not really sure asking around for help on that