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Uncontrolled revving 5K RPM at idle

Posted: Thu Dec 18, 2008 10:26 pm
by Sligeach
hey guys,
finally got the carbs back on the V4 and got it fired up. it was without the airbox and with a direct continuous petrol supply(funnel and pipe).

when i started the bike the bike revvs up to approx. 5K rpm and holds the revs there.

i checked the butterflies and they are all closed, the slides going in an out no probs, choke isnt sticking, and there are no air leaks around the carb rubbers.

priory the taking the carbs apart the bike was running superb, i only had to do so due to a leak in the plastic y-piece.
because it was running well i didnt bother to adjust the idle just yet.

any ideas from you wise guys and gals?

Re: Uncontrolled revving 5K RPM at idle

Posted: Thu Dec 18, 2008 11:06 pm
by royster81
declangaelic wrote:i checked the butterflies and they are all closed, the slides going in an out no probs, choke isnt sticking, and there are no air leaks around the carb rubbers.
if the idle is adjusted properly and the above checked ,you've got me ... :| :|

Re: Uncontrolled revving 5K RPM at idle

Posted: Thu Dec 18, 2008 11:21 pm
by Sligeach
well i am not sure if it is.
it was adjusted to 1,5K RPM, prior to me taking the carbs apart, but i have put them back together and cleaned them spick and span, so i too am stumped, i can usually figure it out by i am stumped by this one

Re: Uncontrolled revving 5K RPM at idle

Posted: Thu Dec 18, 2008 11:45 pm
by Cammo
Did you adjust/move the 2 nuts on the throttle cable (carb side)?

This problem can't be too hard to figure, its either getting too much fuel (through throttle, fuel delivery method) or too much air (no airbox, leaking carb rubber/s).

Shouldn't take too long to find the culprit.

Re: Uncontrolled revving 5K RPM at idle

Posted: Fri Dec 19, 2008 2:01 am
by Sligeach
Stickshift wrote:Did you adjust/move the 2 nuts on the throttle cable (carb side)?
yes i did but the throttle returns to rest on the idle screw and the cable has slack in it

Re: Uncontrolled revving 5K RPM at idle

Posted: Fri Dec 19, 2008 2:29 am
by Cammo
declangaelic wrote:hey guys,
finally got the carbs back on the V4 and got it fired up. it was without the airbox and with a direct continuous petrol supply(funnel and pipe).
Any chance you're just fuelling the cr@p out of it?

Without an airbox it will have access to enough air to rev up if you provide the fuel!

Best to try it with the airbox and the tank supplying the fuel and see what happens.

Re: Uncontrolled revving 5K RPM at idle

Posted: Fri Dec 19, 2008 12:17 pm
by Sligeach
Stickshift wrote: Any chance you're just fuelling the cr@p out of it?

Without an airbox it will have access to enough air to rev up if you provide the fuel!
i did actually wonder that myself as just it ran at about 1,5K RPM for a min or so, at which point i got very excited and filler the funnel up with fuel and it took off again. i had wondered if it was just a coincidence tho!

Re: Uncontrolled revving 5K RPM at idle

Posted: Fri Dec 19, 2008 12:23 pm
by royster81
check to see if you can roll the throttle closed ,what i mean is instead on you twisting the throttle anti clock wise to rev the bike up ,twist it clockwise to close the throttle,,i have done this a few times when i have accidentally fitted the cables wrong or balanced the carbs wrong and it would idle fast until i sorted it

Re: Uncontrolled revving 5K RPM at idle

Posted: Fri Dec 19, 2008 5:00 pm
by MexicanGringo
i had the same problem a while ago after taking carbs off and cleaning, problem was after cleaning linkages the butterflys didnt close to previous positions. Try visually adjusting the butterflys by turning the balancing screws so that theyr all closed, shine a light from behind to be sure, while ur at it you may as well put a tiny drill bit between the butterflys and adjust them all the same, but with bit out they should all close completely

Re: Uncontrolled revving 5K RPM at idle

Posted: Sat Dec 20, 2008 2:24 am
by Sligeach
first of all tried Rhory;s advice on the cables and all was well there.

then tried stickshift's idea for putting on the whole air filter assembly and tank, result was same problem, started up and held revs at 5K RPM

then tired mexican's suggestion of closing all the butterfly valves. i adjusted them turning the carbs upside down and filling the engine intake side of the carbs with fuel and then gently opening them until the fuel seeped out.
replaced the carbs, same problem