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bike struggling over 7k rpm

Posted: Sat Aug 23, 2008 7:54 pm
by meno
hi, at last bike is on road and motd :D

just wondering has anyone experienced any probs with the 400sf or cb1 being reluctant to rev past 7k while riding (its fine in neutral). tried it on a long straight yesterday and i can get it to 10k but itse spluttering liek hell by then..
pretty sure its not got 33bhp restrictors on it but not totally 100% sure.
any ideas? thanks in advance

Re: bike struggling over 7k rpm

Posted: Sat Aug 23, 2008 8:58 pm
by veefer400
Should rev all the way up even if restricted??
Recently picked up a NC23 that would rev past 6k - this turned out to have a dry(as in empty...) battery and a duff reg/rectifier, hence the fried battery.... the lack of electric wouldnt let the bike's ECU run beyond 6k-ish?? Back home with a new battery an reg/rectifier it was fine!

Re: bike struggling over 7k rpm

Posted: Tue Aug 26, 2008 1:32 pm
by meno
beginning to think its fuel starvation of a sort.. reg/rec is fine ty for ssuggestion. now found itll rev to 12k no probs when first opened up.. then after say a coupla gears of full trhottle tehn it starts doing it... back off for a while then its fine again. gotta be fueling of a sort surely?

Re: bike struggling over 7k rpm

Posted: Tue Aug 26, 2008 1:53 pm
by zimm
sounds more like its running REALLY rich and loading up ..

is your air filter manked ?

Re: bike struggling over 7k rpm

Posted: Tue Aug 26, 2008 11:06 pm
by meno
air filters brand new, garage was meant to have cleaned carbs.. does seem rich at times ye m8. think i may remove carbs and see if they did what i paid for.(bike was stood for a year b4 i bought it)

Re: bike struggling over 7k rpm

Posted: Sat Aug 30, 2008 10:05 pm
by meno
zimm i reckon yerr spoton, my m8 got a facefull of unburnt fuel today on his er6 following me, and in end had to overtake cus the smell was sooo strong.

Re: bike struggling over 7k rpm

Posted: Sat Aug 30, 2008 11:22 pm
by zimm
w00h00 ! had to be right one day !

im not familiar with the setup on a superfour/CB-1, so cant really help in any detail, just generic advice..


clean the air filter out with some petrol, leave it to dry, and re-fit it.. maybe they just over oiled it ?

check the choke isnt sticking on too.

failing that, and assuming they have actually stripped and rebuilt the carbs, and havent needlessly changed the jets, make sure the float heights are set right..

if you think its at all likely that you'd get your money back, i'd try that too.

Re: bike struggling over 7k rpm

Posted: Tue Jan 06, 2009 9:26 pm
by meno
after months of farting about, new filter, cdi, plugs, coils, leads, and 3 carb cleans i noticed soemthing... one needle was rly worn... a pinprick hole in a diagphram i hadnt spotted before, and also much to my confusion a float that randomly got stuck that i couldnt seem to get to stop doing it. so in all.. i got new carbs from wemoto (dear job but at last bike works) all is now well at last... was fun test riding it at -5 outside... did 74 miles all was well :D :D

thanks to all that suggested things to help.

Re: bike struggling over 7k rpm

Posted: Tue Jan 06, 2009 9:34 pm
by wullvfr
good find mate and job well done.....cost you plenty for the carbs but saved a packet by doing it youself



william