VTR1000 with strange "miss" at 5000rpm
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VTR1000 with strange "miss" at 5000rpm
I have a 1999 VTR, that starts, and runs perfectly from idle to 5000 rpm - then it goes into fits and wont rev properly - the symptoms are just like it has hit the rev limiter, but at 5k rpm
What I have tried to date - (naturally it seemed like a carb problem) - so have had them off and on 4 times now, firstly cleaning everything and ensuring all galleries are clear. pilots have been tested at 45 and 50 , now on 50's.
Needles are Factory kit ones, tried 2-4 clip position, now on 2, but no appreciable change. Filter is K + N, pipes are stock with carbon end cans - a brand ex japan, with all titanium interconnect pipes ( very nice ).
I have tiried from high 180 mains down to 170 imains - no change, mind you it wont get much past 5000 revs to check top end jetting.
Pulling the choke on while riding does not make any differnce to the 5k miss.
Have tied new plugs - that is not the probllem. We have substituted both CDI boxes - no change ....having tweaked the jetting it is now running perfectly up to 5k, but then it just plays up.
We even tried disconnecting the TPS to see what happened - still did it.
Could this be a coil or a CDI pickup issue ? ( we have yet to try alternative coils, as coils tend to work or not work, rather than have a miss at a specific rev range.
( Is there a secret tricky electrical box on the VTR that we have overlooked ? Has anyone had a similar problem and have any ideas.
Thanks
Grant
What I have tried to date - (naturally it seemed like a carb problem) - so have had them off and on 4 times now, firstly cleaning everything and ensuring all galleries are clear. pilots have been tested at 45 and 50 , now on 50's.
Needles are Factory kit ones, tried 2-4 clip position, now on 2, but no appreciable change. Filter is K + N, pipes are stock with carbon end cans - a brand ex japan, with all titanium interconnect pipes ( very nice ).
I have tiried from high 180 mains down to 170 imains - no change, mind you it wont get much past 5000 revs to check top end jetting.
Pulling the choke on while riding does not make any differnce to the 5k miss.
Have tied new plugs - that is not the probllem. We have substituted both CDI boxes - no change ....having tweaked the jetting it is now running perfectly up to 5k, but then it just plays up.
We even tried disconnecting the TPS to see what happened - still did it.
Could this be a coil or a CDI pickup issue ? ( we have yet to try alternative coils, as coils tend to work or not work, rather than have a miss at a specific rev range.
( Is there a secret tricky electrical box on the VTR that we have overlooked ? Has anyone had a similar problem and have any ideas.
Thanks
Grant
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Joined: Jan 2005
Posts: 127
From: Northeast Ohio
Re: VTR1000 with strange "miss" at 5000rpm
Pull carbs again. Remove tops and pull slides.check for SMALL holes or tears in diaphrams. I have had the same symptoms before and that is what I found. It wasn't on the Hawk but a vertical twin. It would take throttle to a certain RPM and if you tried to give it any more it would start missing and just plain not go any faster. under that RPM it ran perfectly. What would happen is that the diaphram would pull the slide so far the loose vacum and the slide would just flutter up and down. Diphrams came attached to the slides(pricey). After I replaced it,bike ran as new again. One more thing to check are the spark plug caps. Not sure if the Hawk has them or not but some bikes spark plug caps have an adjustable resistor built into the cap. Sometimes they fail. But being that it happens at the same RPM I'm leaning toward the carbs.Good luck and let us know what you find.
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Re: VTR1000 with strange "miss" at 5000rpm
Had very carefully checked checked diaphrams for damage - they are in perfect condition, but the 'flutter " you tallk of does happen at 5k ..I have tried revving it with the airbox top off to see what happened....the slides refuse to rise afte 5k...I have triple checked everything in the carbs and no luck. The plug caps I have had apart as well, they are pretty simple , no resisitors in there, just a meatl tube that clips over the plug top...no obvious problme there.
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SuperSport
Joined: Mar 2005
Posts: 758
From: Laurel, MD
It is likely an ignition problem and quite likely a bad coil. As revs increase the coil has less time to charge between firings giving the symptom you describe.
It may also be further back in the ignition system. However it could be as simple as a loose primary connection, bad ground, or loose sparkplug wire.
It may also be further back in the ignition system. However it could be as simple as a loose primary connection, bad ground, or loose sparkplug wire.
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Re: VTR1000 with strange "miss" at 5000rpm
Solved it - it was a bad front coil ....thanks.....
I have never ever had that problem before - have only ever had a couple of dud coils, and they were just no go - not a miss at 5000rpm
We live and learn...
I have never ever had that problem before - have only ever had a couple of dud coils, and they were just no go - not a miss at 5000rpm
We live and learn...
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