Engine revs low then extremely high

Hi all, i am new to these boards and hope someone may have a suggestion for my current problem. I have managed to get a XJ600 1989 started that wasn't firing at all however it is completely tempramental as to when it works or not. I have to sometimes hold in the start button for a few seconds before it starts and when it does can rev up to about 6 thousand revs sometimes higher. The carbs have been cleaned out three times now and i have made sure the pin holes etc are clean from dirt.

Other times the bikes starts no problem and will idle quite happily at about 1 thousand revs, but as soon as you turn the throttle it once again goes mental and hit up to 6 thousand revs. The bike admittedly was a non starter before i had it and it sounds ok when it is started. I can't trust taking it out due to the tempramental fashion the idle/engine revs at.

Any help would be greatly appreciated.

Cheers

 

Did you clean and polish the piston slides? They could be hanging up. Possibly the throttle cable or linkage could be hanging up

 

Hey bill, thanks for getting back to me. Yes i did clean all the sliders and all parts of the carbs with a toothbrush and carb cleaner. Its a nightmare getting the carbs out but will persevere once again this weekend, i'll overhaul the carbs again hopefully that'll solve it.

Cheers

 

Check for a post by Rickomatic called clunk test. Just cleaning the slides may not do it. He recommends wet/dry sandpaper from 800 to 1500 in stages using wd40 as a lube. It gives the slides a mirror finish...

I just did mine this weekend - it's a pain but worth it. Rick also has step by step instructions on cleaning posted and there is a pictorial breakdown of the carbs posted by schmuckaholic that help a lot.