over revving on startup

Hi i am new here i have just cleaned my carbs following the manual but now when i start the bike it immediately revs to 5500 and stays there could this be a pilot screw adjustment or is it possibly vacuum any help would be much appreciated

 

Hello alan61, have you tried th idle adjustment nob at th rear bottom middle of th carbs', in = higher revs, out= lower revs. Thats th first thing to do, if that aint it ask away, there are more things it could be.

A bit of background information is always better too, that will make it easier for all. Where are ya, whats th bike, history, whats been done so far etc.....good luck with it.

 

You may want to check the throtle cable and adjuster as well, Sometimes turning wheel left or right on full lock can effect idle and cause over reving

but as bushy says there are lots of things it could be!

 

Hi again tried all of those the bike is one i found in a scrap yard it had been in a shed for 20 yrs and the tank was full of rust which i have cleaned and sealed the brakes were all seized so i sourced second hand ones from the internet and of course the carbs were all gummed up so i have cleaned them out the rest of the bike is in full working order i think my real problem is the pilot jet adjustment i took a guess at it when re-assembling the carbs but think i have got it wrong does anyone have the settings in simple screwdriver turns if poss

 

The Pilot screws are set 2 1/2 to 2 3/4 turns from lightly seated, as a start, but that does not explain a racing engine, and CONGRATS !! for getting THAT far !!

If you screwed around with the sync screws at all, you could have one butterfly jacking the other 3 open.

You could have your cables routed incorrectly, or swapped.

You could have trapped your linkage.

Less likely - a bad air leak from the boots, caps, clamps

And don't actually ride this thing IN TRAFFIC until you do a better job on your brakes (please, thank-you).

 

I did have one of the sync screw holders bent when i took it off so i straightened it as best i could is it possible to reset these?? the brakes have been bled but i plan to take it to a mechanic before i ride it to check my work if i can find one locally that is

 

Did you bench sync the carbs? How?

As time said you've got one blade open to get that many RPM.

Where is local? Maybe someone on these boards close by to help out.

 

Your sync is all off !

You need to either take the carbs back off, bench sync, re-install, then running sync,

OR,

Make the BB sync tool, which does not require a bench sync as long as the bike runs.

http://xjbikes.com/Forums/viewtopic/t=2 ... vious.html

(so easy, Schooter could do it ! )

 

I have the carbs back off and i know i am going to sound a little stupid but i am learning this as i go how do i do a bench sync please.
And to answer the other question i am in holland

 

Not close to me. Though I'd gladly help for airfare!

Bench sync is done with a strip of index card you adjust the synch screws (between the throttle shafts outside the carbs) to just be able to get the card strip out from under the throttle blade.

Search here there are many more methods and probably even some pictures.

 

Thanks all i will let you know how it goes

 

Definately worth a search,

When I benched my carbs I used the paper clip method and was sure that I had loads of photos to look at.