philbrad73 Posted March 11, 2009 Share Posted March 11, 2009 HI I'VE GOT A 98 THUNDERCAT IT'S STARTED MISFIRING AT 6000RPM AT IDLE AND 9000RPM UNDER LOAD (ALL GEARS) AT BOTH TIMES THE REV COUNTER NEEDLE DROPS TO ZERO FOR A COUPLE OF SECS THEN BACK UP? IT'S A CONSTANT MISFIRE AND WON'T ALLOW THE REVS ANY HIGHER SOME SORT OF INBUILT PROTECTION/FAULT CODE? I'VE FOUND A THREAD ON ANOTHER FORUM OF SOME ONE WITH THE SAME PROBLEM BUT NO ANSWERS? ANY HELP REGARDS PHIL Link to comment Share on other sites More sharing options...
ally tonks Posted March 11, 2009 Share Posted March 11, 2009 HI I'VE GOT A 98 THUNDERCAT IT'S STARTED MISFIRING AT 6000RPM AT IDLE AND 9000RPM UNDER LOAD (ALL GEARS) AT BOTH TIMES THE REV COUNTER NEEDLE DROPS TO ZERO FOR A COUPLE OF SECS THEN BACK UP? IT'S A CONSTANT MISFIRE AND WON'T ALLOW THE REVS ANY HIGHER SOME SORT OF INBUILT PROTECTION/FAULT CODE? I'VE FOUND A THREAD ON ANOTHER FORUM OF SOME ONE WITH THE SAME PROBLEM BUT NO ANSWERS? ANY HELP REGARDS PHIL was gonna say moisture in the plugs as old problem I had on an exup, but wouldn't account for the speedo, the only other problem I had (3 bikes) was the kill switch going u/s, bypass and see if it cures...(same for kick stand switch) Link to comment Share on other sites More sharing options...
steve m Posted March 12, 2009 Share Posted March 12, 2009 HI I'VE GOT A 98 THUNDERCAT IT'S STARTED MISFIRING AT 6000RPM AT IDLE AND 9000RPM UNDER LOAD (ALL GEARS) AT BOTH TIMES THE REV COUNTER NEEDLE DROPS TO ZERO FOR A COUPLE OF SECS THEN BACK UP? IT'S A CONSTANT MISFIRE AND WON'T ALLOW THE REVS ANY HIGHER SOME SORT OF INBUILT PROTECTION/FAULT CODE? I'VE FOUND A THREAD ON ANOTHER FORUM OF SOME ONE WITH THE SAME PROBLEM BUT NO ANSWERS? ANY HELP REGARDS PHIL If the rev counter goes to 7000 rpm then drops back to zero several times then this is the fault code for the EXUP valve, sounds like the EXUP needs a strip, adjust and service, or may be the EXUP motor is U/S. Link to comment Share on other sites More sharing options...
chrisw Posted March 12, 2009 Share Posted March 12, 2009 Thundercats don't have an Ex-up valve so it can't be that and I'm sure they only have 2 error code 1 at 3000rpm and the other at 8000rpm, the 8000 rpm fault as this is quite common. If it is the 8000rpm fault then this is just a fuel sender fault, and is usually because a wire has broken away from it's soldered joint. You need to use up your fuel so you can lift the tank and remove the fuel sender unit, once you have it withdrawn from the tank you'll be able to clearly see the wire that has broken from it's joint (if it is connected then that not the problems and could be a failure of the unit. However this code wouldn't cause a miss-fire, so you might have a plug / coil on it's way out. Link to comment Share on other sites More sharing options...
Paul Mc Posted March 12, 2009 Share Posted March 12, 2009 Knowing nothing about that model, I'd guess it's a problem with the rev limiter (assuming it has one). There's a fault with the XZ550 where the rev limiter can kick in (and cut the spark to one of the cylinders) lower down the rev range than it should - 'fixed' by disconnecting a wire at the TCi (but this has removed the rev limiter function completely). Dunno if you can/need to do the same for your machine. But check other items as per above first? Paul Link to comment Share on other sites More sharing options...
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