wont rev above 8k
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ADG
- Settled in member
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- Joined: Mon Oct 28, 2013 10:14 pm
wont rev above 8k
Since I disturbed the air filter (checking its condition) the bike hasnt run properly for some reason. The bike starts but sounds like its not fuelling properly on all cylinders when idling. The pick up from tickover is sort of hesitant when you crack open the throttle - and it WILL NOT rev above 8000 
Ive emptied the tank (lots of rusty fuel) and started running it on fresh fuel from a plastic tank. Ive managed to get 2 of the spark plugs replaced so far - but its still not right...
Im pretty sure the fuel level sensor is knackered though - but I guess the petrol switch should just override it?
Has anyone got any ideas??? If the ECU still thinks that its running out of fuel does it make the engine run differently?
Any help would be appreciated!
Ive emptied the tank (lots of rusty fuel) and started running it on fresh fuel from a plastic tank. Ive managed to get 2 of the spark plugs replaced so far - but its still not right...
Im pretty sure the fuel level sensor is knackered though - but I guess the petrol switch should just override it?
Has anyone got any ideas??? If the ECU still thinks that its running out of fuel does it make the engine run differently?
Any help would be appreciated!
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Evilchicken0
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- Joined: Tue Apr 29, 2008 8:59 pm
- Bike owned: Bimota SB6 Yamaha FZR 3TJ x2
- Location: Lundin Taan
Re: wont rev above 8k
It should run on 4 even with the fuel sender disconected.
make sure the air box is sealed, both at the top where the snorkel attaches and where the carbs join.
You say you have lots of rust in the tank - check and replace the fuel filter. Clean the carbs.
8000rpm though sounds like the EXUP is stuck closed. take off the chrome cover on the side stand side of the exhaust, turn on the ignition and see if the pulley moves.
make sure the air box is sealed, both at the top where the snorkel attaches and where the carbs join.
You say you have lots of rust in the tank - check and replace the fuel filter. Clean the carbs.
8000rpm though sounds like the EXUP is stuck closed. take off the chrome cover on the side stand side of the exhaust, turn on the ignition and see if the pulley moves.
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ADG
- Settled in member
- Posts: 46
- Joined: Mon Oct 28, 2013 10:14 pm
Re: wont rev above 8k
Ive not touched the EXUP mechanism, and the servo seems to be making the usual noises. Ill check it anyway just to be sure.
Ill try it again with the airbox etc all back in place - but I cant believe that just taking the snorkel & filter out would prevent it revving and cause really poor running??
By lifting the tank off I might have disturbed some crap in the there which has made its way into the carbs. Ive already added a 2nd fuel filter but now Ive got the carbs off Im going to give them a clean. Fingers crossed its a simple (&cheap) problem like something stuck in the jets...
Where can you get replacement carb spares too? The needle looks a bit worn - so Im guessing the emulsion tube will probably be oval shaped now.
Ill try it again with the airbox etc all back in place - but I cant believe that just taking the snorkel & filter out would prevent it revving and cause really poor running??
By lifting the tank off I might have disturbed some crap in the there which has made its way into the carbs. Ive already added a 2nd fuel filter but now Ive got the carbs off Im going to give them a clean. Fingers crossed its a simple (&cheap) problem like something stuck in the jets...
Where can you get replacement carb spares too? The needle looks a bit worn - so Im guessing the emulsion tube will probably be oval shaped now.
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Evilchicken0
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- Joined: Tue Apr 29, 2008 8:59 pm
- Bike owned: Bimota SB6 Yamaha FZR 3TJ x2
- Location: Lundin Taan
Re: wont rev above 8k
You've got a fuel filter gauze on the fuel tap, then the usual inline filter and theres another where the fuel hose joins the carbs, the last one is small and sits inside the carb spigot.
The bike should rev cleanly on the stand with the airbox off, but I don't think I've revved it that high like that. If you rode it with the snorkel off then the mixture would be very weak.
needles and emulsion tubes would probably be a Yam part, unless there's a direct Mikuni supplier. looking at that kind of cost you might be better finding a second set of carbs.
I'd say it's probably a dirty filter though, take the second filter off. Clean the fuel tank - theres a thread on here about that - water can lay in it at the bottom so dry it out before you use it again
The bike should rev cleanly on the stand with the airbox off, but I don't think I've revved it that high like that. If you rode it with the snorkel off then the mixture would be very weak.
needles and emulsion tubes would probably be a Yam part, unless there's a direct Mikuni supplier. looking at that kind of cost you might be better finding a second set of carbs.
I'd say it's probably a dirty filter though, take the second filter off. Clean the fuel tank - theres a thread on here about that - water can lay in it at the bottom so dry it out before you use it again