Engine revs flat out on a closed throttle!

Twangled your powervalve grommit in your woodruff key? ask someone how to fix it here
Post Reply
boggy
Heavy Smoker
Posts: 159
Joined: Tue Jun 07, 2011 5:29 pm
Location: United Kingdom

Engine revs flat out on a closed throttle!

Post by boggy »

As the title says,i tried starting my bike this week and the revs went through the roof!i hit the kill switch before any damage was done.This is what i have done to try and remedy the problem:checked fuel tap-it's not leaking,stripped carbs,checked float heights,tried several spark plugs,checked float valves weren't sticking,checked slides move freely and tick over screws set to minimium,throttle cable has plenty of slack.I tried a spare set of carbs and still had same problem,bike just revs like hell without touching the throttle.I thought it might be the choke,but again the cable has the correct amount of free play.Has anyone had this problem before?What should i check/try.Any thoughts/recommendations much appreciated.

Rich ](*,)
headcoats
Avgas Sniffer
Posts: 2120
Joined: Sat Jun 09, 2007 10:10 am
Location: Pig on the wall country

Post by headcoats »

Air leak
Flywheel side crank seal shagged :?
Can it yer old boiler
boggy
Heavy Smoker
Posts: 159
Joined: Tue Jun 07, 2011 5:29 pm
Location: United Kingdom

Post by boggy »

Thanks,you could be right as the engine is second hand.I thought i would try it out to see if any good,looks/sounds like i bought a dud. :-({|=
User avatar
ScottaKR
Premix Junkie
Posts: 1521
Joined: Fri Aug 10, 2007 2:52 pm
Location: Australia

Post by ScottaKR »

Check the carb manifold rubbers and reed block housing gaskets for leaks first.
KR250 Tandem Twin (Naked) :mrgreen:
KR1 Red/White
KR1S Track Bike (has been put on hold for now)
ZXR750 H1 (Winter project)
boggy
Heavy Smoker
Posts: 159
Joined: Tue Jun 07, 2011 5:29 pm
Location: United Kingdom

Post by boggy »

Thanks,I will take them off and inspect for cracks.
dave32
Heavy Smoker
Posts: 472
Joined: Sun Oct 24, 2010 10:15 pm

Post by dave32 »

You could also try spraying some fairy liquid/water mix around the intake rubbers/area,will bubble up when running if there's an air leak in that area.
User avatar
JanBros
Avgas Sniffer
Posts: 3306
Joined: Wed Jul 26, 2006 11:50 pm
Location: the land of Francorchamps

Post by JanBros »

I can't believe an intake-airleak could cause the engine to "rev' through the roof" (allthough I might be mistaken). it only draws extra air into the engine, where should the fuel come from to rev that high ?

If you have an electric drill that has enough power, I would drain the carbs, let the engine run on the electric drill and than spray brake cleaner on the intake rubbers : if any firing occurs, you have a leak
My ultimate goal is to die young as late as possible !
boggy
Heavy Smoker
Posts: 159
Joined: Tue Jun 07, 2011 5:29 pm
Location: United Kingdom

Post by boggy »

I think i may have found the problem,i've tried another set of intake rubbers,but problem still persisted.Had a good look at the carbs and noticed the slides were not fully closed even with loads of slack on the throttle cable.Tried a different cable,now slides are at the very bottom!Trouble is now i have fiddled with the idle adjuster screws i am unsure how to set them roughly before starting engine.I think i have read you can stick a drill bit(5mm)to set them?I did try starting the engine today,it fired up briefly and didn't rev like hell,ran out of time will try again tomorrow.Fingers crossed! 8-[
Post Reply