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misfiring

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by thecptn, Feb 6, 2006.

  1. My bike has developed a strange habit last few weeks, where under normal throttle from 60-70 clicks it will splutter for a few seconds than go back to normal as if it was runing low on fuel. So this morning I took the plugs out one seemed normal tan colour with a tinge of black on the side, and the other had these small black deposits on one side which smelled like fuel, any idea of what wrong with it?


     
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  2. It knows it's about to be replaced and it's chucking a sooky nah nah???
     
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  3. both?
     
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  4. perhaps! :cry: I have notice how ever, this first started when I switched to reserve on a full tankmany weeks ago, it just almost died down, dont know if it swallowed some crap in the tank.
     
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  5. Yes, sounds like it might have pulled some junk through from the tank. Does the bike have in-line filter(s) between the tank and the carbies? If so, pull it out and either clean or better still, replace.
     
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  6. hmmmm, it most likely has, I might give it a check. :grin:
     
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  7. I also have a '94 Virago and recently it started doing a similar thing. Would cut out when dropping back from high speed to round town. Nothing nicer than coming into a roundabout or intersection and NOTHING!
    I put some carby cleaner in with the next lot of fuel and switched back to premium fuel. Since then it has purred :grin:

    I also tried the 'Boost98' fuel and that was crap. Premium is the best.
     
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  8. hmmm, ive been using bp ultimate, perhaps regular premium will do the trick, about the carb cleaner, what sort is this? the spray type or liquid type? I tried using some carb cleaner with the motor running to clear any thing in there (always worked on my old fords) didnt seem to help, ill give it a try though.
     
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  9. Cptn, I used the liquid, and damned if I can find the bottle now to give u the brand. Just off the shelf at auto store. Added it to a couple of tanks of fuel and no problems since. When I tried the Boost98 or similar I lost around 40km from a tank of fuel. I usually just fill at Woolworths fuel.
     
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  10. Well I got some nulon injector/carb fuel cleaner stuff, put a whole bottle in with some reg unleaded, lets see how it goes, I noticed when I came to a stop, that some times it would sputter and cough about, when given some throttle during this state its very slow to reacte.
     
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  11. Well i found out what it was, it wasnt fuel carb as I orignally thought, but misfiring on one of the cylinders! great, where do I go from here?
     
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  12. If you have any black soot on insulator of spark plugs. replace them.
     
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  13. It was only mild soot, and no where near the gap of the plug, plus there quite new as well, still worth replacing them?
     
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  14. CHECK RESISTANCE IN PLUG CAPS ALSO GET COILS CHECKED
     
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  15. Plugs are ceap.

    They can have fine cracks or broken resistance in them. Might not be able to see it.

    Chuck the pair and put in two newies. If that don't fix it, mech job, check the coils. Shouldn't be fuel because it would affect both cyls. Does it have two carbs? If so open fuel bowls, (if not injected engine.) If it has two bowls there may be water or gunk in one of them.

    Still go plugs if it was me. If bike burns a bit of oil, get slightly hotter plugs.
     
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  16. Put a new set in today, went for a ride and it began again, looks like some thing is borked for sure, coil? leads?
     
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  17. How does that work? (not trying to be argumentative, but i don't know enough to understand how that would be the case)

    Phil
     
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  18. Hotter plugs burn off the oil better (I think that's how it works)
     
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  19. have you tried pulling all plugs out (leave leads on), resting them against engine block and turn engine over, see if you actually getting spark?
    If no spark, check lead, maybe swap lead with the one that works...
    if still no spark then probably coil.
     
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  20. Hi cptn
    Try draining fuel from carbs. If you have a screw at the bottom of bowl, undo a couple of turns and fuel will drain out. Most bowls have a hose connected, if you can save the draining fuel into something to see if there is water or sediment.
    A good thing to do once and awhile anyway.
    Good luck
     
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