engine

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ant75
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Bike owned: yamaha r1 5vy,vfr400 nc30 91
Location: oswestry,shropshire
Re: engine

Post by ant75 »

hi,wel ive just done that revved it up turned off engine and unplugged it,when unplugged the idle is bobbleing around and lumpy when revved,but when plugged back in idles fine and revvs ok to 6k then after that vibrates it it feels if its holding back.
Neosophist
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Re: engine

Post by Neosophist »

ant75 wrote:hi,wel ive just done that revved it up turned off engine and unplugged it,when unplugged the idle is bobbleing around and lumpy when revved,but when plugged back in idles fine and revvs ok to 6k then after that vibrates it it feels if its holding back.
Ok cool.

The it sounds like the speedo is working when connected.

This means your problems lies elsewhere

I don't like the sound of 'vibration'.. is it a lumpy running causing the 'vibration' or does it sound like something more serious, i.e. Mechanical.

What did you do to the carbs? Are they setup properly?
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ant75
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Posts: 46
Joined: Sat Aug 20, 2011 9:56 pm
Bike owned: yamaha r1 5vy,vfr400 nc30 91
Location: oswestry,shropshire
Re: engine

Post by ant75 »

hi, kinda sounds as if some has put thier hands over the exhaust stopping it revving freely,not really done much 2 the carbs just checked jets and are ok floats ok,checked the slides and they were not worn,only i noticed some one had drilled a small hole in them think its summut 2 do with a flat spot, the mixture screw was 2 1/4 turns out so ive backed it in a 1/4 so its 2 turns now,she seems 2 rev a litle better but not 100%.
magg
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Bike owned: VFR400
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Re: engine

Post by magg »

Just to confirm you said: when speedo unplugged idle is poor and remains so when revved; with speedo plugged in idle is ok but engine runs rough above 5500rpm.

The result with speedo unplugged is strange, it is not what I have experienced. When the speedo is unplugged engine should idle ok and only run rough above 5500rpm just like a faulty speedo.

Your description of how the engine runs with the speedo plugged in sounds like how the engine should run with either an unplugged or faulty speedo.
marti
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Re: engine

Post by marti »

Is the bike fitted with a 33hp restriction kit?
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BillingCBR
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Bike owned: '88 NC23, NC30, '98 R1, NC35
Re: engine

Post by BillingCBR »

if you can put a new set of plugs in give it a try, mine was running a bit rough higher up, swapped a plug and it was fine (I was lucky and had a set from another engine which I knew for a fact were running ok)
'89 CBR400RRJ and '91 VFR400R NC30 project
Neosophist - The NC30 doesn't go very well when it's on fire
ant75
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Joined: Sat Aug 20, 2011 9:56 pm
Bike owned: yamaha r1 5vy,vfr400 nc30 91
Location: oswestry,shropshire
Re: engine

Post by ant75 »

hi,not sure if its got a restriction kit on how do you tell?? it has a full after market exhaust system on. its had new plugs in i think densos had them out and they was in very good condition.

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