grahamfirestorm
New Member
Been riding since 1967,raced in the 70s and early 80s,dont like all the surveillance on our roads .
Posts: 3
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Post by grahamfirestorm on Jun 25, 2019 18:39:48 GMT
Hi everyone,ive just bought a lovely restored 1991 fz750 genesis,which has the standard 4 into 1 exhaust and air filter,valve clearances done,38800mls.Im puzzled though as I expected this bike to be rocket ship after 7000rpm,but it isn't.It will rev round ok to 10000rpm,but with no real urgency,and the idle speed is a bit erratic.Carbs have been cleaned,[not ultrasonically],new pilot jets,floats and needles,2 new diaphragms,but I don't know what size the main jets are as I haven't had the floatbowls off yet.All this was done by the previous owner who has done 1500mls on it since the restoration.Any help would be most welcome,cheers Graham.
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Post by Graham on Jun 27, 2019 13:00:27 GMT
I’d be looking at bigger main jets for a bit of extra top end grunt.
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grahamfirestorm
New Member
Been riding since 1967,raced in the 70s and early 80s,dont like all the surveillance on our roads .
Posts: 3
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Post by grahamfirestorm on Jul 2, 2019 18:20:25 GMT
Thanks Graham,i don't know if my last reply went through,but my carbs have 105 main jets in 1 and 4,and 102.5 in 2 and 3 carbs.Ive noticed the coolant level drops in the rad,and starts expanding out of the expansion tank,suggesting to me that the rad pressure cap is not working correctly which could mean the engine isn't reaching the correct operating temp,so im waiting to fit a rad cap that works.But each time I go out on the bike,its definitely trying to get better power wise,cheers,will keep you posted.
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Post by Graham on Jul 2, 2019 23:28:24 GMT
Those are standard jet sizes..
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Post by fzjamie on Jul 5, 2019 12:19:17 GMT
Hmm mine really takes off after 7k, pretty tame under that - in fact \i was loking to find a ower curve graph recently. It could be what you're used to of of course but for me the FZ is PDQ!
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grahamfirestorm
New Member
Been riding since 1967,raced in the 70s and early 80s,dont like all the surveillance on our roads .
Posts: 3
|
Post by grahamfirestorm on Jul 25, 2019 20:53:22 GMT
Well,ive got the bike running better now.I discovered the fuel filter next to the pump was on the wrong way round,so ive fitted a new one and she revs a lot better past 7000rpm than before,still a bit fluffy about 95% there now,maybe the carbs need ultrasonic cleaning,but its odd its only doing it on main jets,from 0 to 8000rpm it pulls really well,then it starts pulling hard,hesitates slightly,then pulls again round to redline,any ideas anyone.
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Post by Graham on Jul 30, 2019 13:47:40 GMT
Still sounds like fuel starvation to me. I'd be looking at the condition of your fuel tap gauze/filter & the general state of your fuel tank internally. Dirty/rusty fuel will clog up one or both of the filters enough to deprive the engine of much needed fuel at high revs.
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