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Post by brakeline on Oct 26, 2013 16:13:56 GMT
Well I've heard it all Brakey giving sound advise Top Man, Top Man, can you please tell me why my Honda Blackbird stutters & misfires at 11,000rpm or 180 mph in top gear ? cause yer telly cant keep up with the frame rate of yer Playstation
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Post by durcott on Oct 27, 2013 12:50:02 GMT
Sooooo - have now replaced all of the plug caps with NGK, and new plugs as well.
For a brief minute or so, the motor was sounding really good off-load. By the time I threw my jacket and lid on, it was rough again.
I found plug #1 had fouled - replaced with an old one and we;re off again, but within 5 miles, the damned thing was barely running.
I noticed the spark looks quite weak. It also dances between the two electrodes - I reckon it ought to be good and bright.
I reckon the new plug caps, with their suppression resistor, have provoked a weakness in the spark, which has meant the plugs are getting fouled.
Is there any sense in that argument?
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Post by Burchy on Oct 27, 2013 14:38:11 GMT
Reckon you are more likely to have a leaking carburettor float needle that is causing an over-rich mixture. Try disconnecting the vacuum pipe on the tap and plugging it. Then run the bike around until it stutters from lack of fuel, then turn it on to prime to get the fuel going again. All this will allow the fuel level in the carb to drop right away and hopefully the float needle will re-seat when the fuel comes back on.
Got to be worth a try
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Post by durcott on Oct 27, 2013 22:07:46 GMT
Thanks for that Burchy - could be that. Did I say I get a flood on the floor pretty quickly if I leave the fuel tap on Prime? Newbie mistake - only I can't see how the carbs would flood if the floats were working - it's not as if the fuel gets to the carbs by a different route. My mate told me his Ducati would flood on prime, (and catch fire...) so I assumed this was 'normal'. So apart from dirty carbs, wrong plug caps - it's all going well I reckon I was given wrong info by the dealer on the plug caps - I reckon he should have sent up SD05FM - but they were free, so no harm done.
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Post by lightspeed on Oct 28, 2013 1:45:07 GMT
Rev limiter (or maybe its the rider's trembling hands!) ;D
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Post by durcott on Oct 28, 2013 8:29:18 GMT
Trembling hands and more.
If this is what the Rex can do when it's running rough, what the hell is it going to be like when it's sorted?
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Post by Burchy on Oct 28, 2013 16:33:00 GMT
Should be able to sit all day with the tap on Prime and not flood. Mine would
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Post by brakeline on Oct 29, 2013 7:15:29 GMT
Should be able to sit all day with the tap on Prime and not flood. Mine would Hmmm, never tried that
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Post by durcott on Nov 19, 2013 20:57:44 GMT
Hi Folks - thought I'd give an update on this saga. The carbs were filthy as it turned out, and there were other horrors like loose fuel bowls and broken vacuum pipes. I've done a complete strip, blow through and rebuild, and threw in a fuel filter as well for good luck. The good news is that she runs better. At least on no load on the side stand ... She runs on all four for a start. From tick over, I can grab full throttle, and the motor responds immediately. Throttle blipping at revs below 6 to 7000 seems clean enough. If I allow the revs to build to 8000 though, she suddenly goes very rich, refuses to rev above 9000, and on the overrun, I'll get a good blast of flame out of the can I suspect from this that the carbs must be roughly right, and I'm probably getting another ignition problem at high revs. Anyone care to comment? Jeff
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Road Toad
Stuck in the saddle
Work to live. Live to ride!
Posts: 208
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Post by Road Toad on Nov 19, 2013 22:26:43 GMT
Welcome in.I would go with plug covers too. Have u taken the plugs out to check fuel burn. New plugs and refit of plug covers sorted mine.
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Post by cartwrightzrx1100 on Nov 20, 2013 11:04:32 GMT
The problem could be the emulsion tubes, in the carbs? I had a ZX7R previously that had been fitted with a Dynojet kit at some point in its prior history. I had all sorts of problems with it from failing to start, running poorly, miss firing and not being able to rev through the rev range without coughing and spluttering. Until it eventually it just stopped working and died on me! I changed the plugs and leads but the problem still persisted!! After closer examination by GP Performance, they determined that the emulsion tubes had been enlarged by wear created solely by the Dynojet needles used. Regrettably on the ZX7R the emulsion tubes are not removeable, as they are cast in to the carb bodies. So after some hunting around, I managed to purchase a second hand set of carbs on eBay. These were fitted, jetted, balanced and the bike was given a Dyno test on their rolling road. The problem was completely resolved and the bike ran real sweet there after. Hope this helps?
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Post by durcott on Nov 22, 2013 9:34:50 GMT
Hi Folks, can anyone recommend a rolling road / Dyno test in the South West?
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