Uncontrollable idle

I have recently acquired a 1980 XJ650 Maxim, which was not running. I have cleaned all of the carburetors and got it to run (I currently do not have an air box installed (FYI)) but in that I now have a problem when it starts it pegs out the tack causing me to have to shut her down, Does any one have any suggestions (I was told I had to run the air box and that it synchronizes the crabs) I am lost please help.

 

The air box has nothing to do with the crabs! LOL
Anyway, the engine is just an air pump, the more air it gets the faster it goes so if you want it slower reduce the air input. You need to find and fix any leaks in the intake boots and make sure the throttle closes. The throttle cable is probably binding and not letting it close.

 

I second that, throttle has to be stuck. Check the linkage being stuck under the head, make sure the hose clamps on the engine side aren't preventing the returns from closing. The sync screws should appear completely vertical when you are looking at them, if not, they are stuck open. They have to be stuck on something.

 

What about not having them synced properly. What if the butterflies are open to much?

 

I can disconnect the throttle cable and it will not help and the boots all look great no cracks and I noticed the piston that is attached to the diaphragm in the crab flutters up and down and I thought that was controlled by vacuum hence air box so I tried changing crabs and that did not help that is why I got a rebuild kit and went through each of them, still no luck any ideas .

 

did you bench sync the carbs?

 

If you did not think I was dumb yet you will now the butterflies on the inside of the crabs are controlled by the choke correct? If not I have something hooked up wrong lol

 

I did not bench sync the carb ( I did not see any adjustment but idol and choke I have no adjustable jets or anything

 

Check out this link this guy has a good walkthrough to do it!

http://xjbikes.com/Forums/viewtopic/t=8588/

I would start there as I stated before your butterflies could be open to far thus getting to much air through there also try adjustin your idle setting.

 

Thanks for the ideas I will look some more .

 

Even with the carbs out of sync it couldn't rev to redline without getting A LOT of air. The butterflies have to be open...

 

I forgot to mention make sure you check your float levels also when you are in there. That's what got me!

 

I will take the carbs back off sync. Them and go from they’re Thanks again for all the help.

 

what are you talking about I am a person like you!!

 

I was just saying thanks

 

you have choke and throttle cabeles mixed up,throttle cable controles butterflies

 

good catch I didn't even see that!

 

Thanks I feel dumb now and I will change that first thing in morning and I will now go pull my head out of my a** (back side.) thanks thanks thanks

 

Thanks I feel dumb now and I will change that first thing in morning and I will now go pull my head out of my a** (back side.) thanks thanks thanks

 

Just saying thanks the cables were messed up; switched them around and sync the crabs and all I can say is wow. Does anyone know where I could find aftermarket seats that may fit a 1980 xj650 without to many moods Needing to be done. My seat is not bad I just would like a something a little different. Or what if any other models may fit thanks again. Can’t wait to get a day off so I can get her legal and go for a long ride.
As soon as I get my computer issues at home fixed I will up load some pics.