random high reving??

[dave1]

hi guys started my bike up let it warm up was ticking over about 1.3 or 2 quiet reasonably rode to the mot station passed mot no advisories thought great! ;D turned it on to drive home started reving high upto about 2.2 then i thought maybe it just needs a little thrash pulled up was ticking over about 2.7 just wandering if its the tick over adjustment underneath maybe? enyone else had anything similiar? what can be done trouble shoot wise were should i start ?
dave.

[bobh]

Unlikely to be the tickover adjustment suddenly going that far out. I'd be looking for trapped or damaged throttle cables or the throttle spindle not returning fully. That could be due to a broken spring, lack of lubrication, or something that's got in there and is stopping it coming back to the stop.

I'm assuming you are fairly new to bike maintenance, but if not forgive me if the following comes over as patronising.

You'll probably need to take the tank off to go over this lot - not difficult, but remember you need to take the petrol tap knob off (cross-point screwdriver required) before you can lift it off. Make sure the tap is in the "On" or Reserve" position (NOT "Prime") first - it's vacuum operated so won't let any fuel through unless the engine is turning over.

Obviously you also have to pull off several hoses, after squeezing the clips with pliers and sliding them along the hose away from the joint. If the hoses haven't been taken off for a while they can be sticky. In the worst case you may have to cut them as close as possible to the joint - they should be long enough to do this at least once!

While you're under there it's good to give everything, including the cables, a good clean and lube. Also check and clean or replace the air filter element and check the fuel filter, if there's one fitted.

Finally clean any gunge (usually "mayonnaise") out of the breather hoses that run into the air filter housing.

Good luck - Bob

[CD]

It could be the cloke mechanism sticking at the carb end. The mechanism may need some red grease on nylon parts. WD40 will make it stick even more and normal grease isnt good for nylon,

While its off the bike, also spray the tank underside with something like Waxoyl to slow down the inevitable rust.

[dave1]

hey guys just to let you know my experience with bike's is atchley quiet alot i own my own garage out of my house rebuilding engines doin carbs servicing electrics the lot! ;D but my experience is sorta between 70's to 80's proberly highest 1990 bikes not new or older an useally i join forums such as this to get to find out the bikes common problems an easy fixes an what goes wrong with them so i know what to look out for and keep on top of instead of trying to learn the whole lot by myself id have to have the bike for years to find out the problems so its a good thing these forums are about ;D

when it high revs persay if i really try an push the throttle forward it does go down when i let off it jumps back up so it is leading me to think that either the retern cable is craped up or is sticking within its cable surrounding so i think i might change both cables to be sure then see what else i can do but will grease it up but will spray the carburretor springs on the return with wd40 see if that helps the bike was standing a little while and it was preety crudy underneath there was cleaned a little bit breifly with break cleaner also when i looked underneath the tank the cable mounting nuts an bolts look either rusty not an orange rust but sorta white dark grey corrosion so by looking i can definatley see that they havent been changed it atleast 3 years for sure as ive fitted many a cables to many abike and to get that bad it would take a while but other than the look of them the action is ver nice theres no notchyness or sticky ness previouse owner "apparently oiled them up" and i can say that he has done a good job

choke seems to be fine moves in an out with ease an theres an obviouse diffrence when it is out then in as you could imagine but will go over the carbs a little with some red grease as you mentioned earlier and will try an see if i can trouble shoot this problem i useally find with carbs its 70% cables 20% needs cleaning and 10% internals ie jets springs ect but will break it down an sort it but anymore information is much abliged as im always open to suggestions thanks.dave

[CD]

The choke lever can move fine with the mechanism sticking at the carbs end. It wont be enough to lift the choke plungers but it does raise the tickover. The only sure way to know is with the tank and air box off.