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andy b Show Star !
Joined: 11 May 2007 Posts: 1 Location: manchester
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Posted: Sun Oct 23, 2011 4:17 pm Post subject: ns400r flat spot |
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[img]http://s1116.photobucket.com/albums/k566/andybirts/?action=view¤t=atlast16.jpg[/img]
Hi. Can anybody please help with my ns problem.
I have just finished restoring it but other than service the bike (fluids/brakes lines pads/gear oil etc i have not stripped the engine or carbs.. It has a terrible flat spot....The bike revs fine up to 5000 rpm then hits a point where the engine note sounds bogged down (almost like its trying to run on 2 cylinders until it gets past 6000 rpm when 7000 is reached it zings along as it should. First thought was possibly an electrical breakdown but above 6500 it doesn't miss a beat...
When i try to lightly throttle through it on the move it still does it but not as bad as when i try to put it under load at these revs..Changed plugs and got rid of a exhaust leak from the atac cover but still the same. If i raise the revs slowly whilst in neutral it still hits the dull tone at 5000 rpm.
A pal of mine is a mechanic but with no experience of these and does not seem to think it will be the carbs as it is fine below 5000 and the main jets must be clear for the response above 6500.
I really would appreciate any advice on this.. I have heard some do have a flat spot but this feels like it is being dragged back and in all honesty i have had 2 of these before and never had it...
It has standard pipes on and to my knowledge has neveer had race pipes or been jetted..I really dont fancy taking the carbs off especially if this symptom does not require it.
I really would appreciate advice as there are not many good weather days left before the crap weather sets in and cant bear to see it sat sparkling in my garage having not had any fun on the bloody thing and spent the last 18 months contemplating then getting round to doing it !!!...
Thank You.
Andy.[img][/img] _________________ you can lead a horse to water but a pencil must be led. |
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Alastair
Joined: 13 Jan 2007 Posts: 62
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Posted: Sun Oct 23, 2011 8:15 pm Post subject: |
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All 2 strokes have a midrange flatspot where they are off the pipes. You are welcome to bring it to sunny Glossop and I'll soon tell you if it is running right. _________________ Alastair
CBR1000RR6 (0 - Court in 2.5 seconds)
NS400RF
MTX80RFD |
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Bitacticus
Joined: 13 Apr 2009 Posts: 276 Location: Netherlands
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Posted: Mon Oct 24, 2011 4:10 am Post subject: |
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Sorry maybe its a bit silly but you never know.
I had the same problem with one of the RG 250's
Turned out that the powervalves were not working correctly.
broken AEC control unit and the PV cables connected the wrong way round.
Hope this helps
Regards Erik |
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colp
Joined: 22 Feb 2009 Posts: 41 Location: middlesex
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Posted: Mon Oct 24, 2011 4:47 pm Post subject: |
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i know it may sound bleeding obvious but have you cleaned or replaced the air filter? i know when my kr-1 filter needs a clean because the power drops off at about 5000rpm _________________ just do it |
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