82 yamaha having idle problems, plz help

[Hero_X]

I also posted in the "performance and handling" section but I think this bike section is more appropriate.


Anyway, I bought a 82 yamaha xj750 and am having issues wit it. It starts up after bit of pushing the throttle ( I think the start up is having issues cuz of battery) but the problem is that the bike will stay on for a bit and the rpm will start dropping and it turns off.

so unless i keep giving it throttle, it turns off. I"m really not sure what the problem is.

Please help me out. As well if you know any mechanic I can take the bike to, can also help. Thanks again

[Graham_A_M]

I assume your idle set screw is set too low. I'd recommend finding it (its probably a singular screw that controls the idle rate on ALL your inter-linked carbs) and screw it in probably a turn or so.. but do it when the bike is running. Ideally the bike should idle at about 900-1000rpm. Watch the tach and use that as a gauge. It doesn't hurt to go a bit higher then that too, as in 1000-1200. If the bike still has trouble idling at 1200 rpm, then you have other problems at hand. Perhaps a very worn engine or the carbs are not sync'ed... it can be a bunch of things. Try that out and let us know if that helps.

BTW. Welcome to the Beyond.ca, but please DO NOT double post questions. Place them in the appropriate section (as in this one, and this one alone) and we'll try to help the best we can.

[Hero_X]

sorry about posting twice.

Umm would you by any chance know where I can find the idle screw?? I'm totally new to this.

Also do you know any mechanic I can take this bike to? Let me know thanks for your help

[bjstare]

Idle screw is usually a gold/bronze colored screw, something to set it apart from the rest. It will be on the engine, usually under the gas tank. I don't mean literally underneath so you pull the tank off, just around the bottom of the tank. If you get on your knees you should be able to see it clearly. It will also have a spring on it (like wrapped around the threads) to keep it from moving unless your turning it by hand.

Edit: Sometimes the screw has a large head (almost dime sized) for easier hand adjustments, but not EVERY idle screw has a big head.

[3g4u]

Here is a pic of the screw you are looking for. (off an 03 R6)


I suggest investing on a Shop manual, it will save you alot of headaches.

[Hero_X]

Okay I tried but I can't seem to find it at all.

Here are the pictures of the engine, please tell me if you see it.

thanks

[Graham_A_M]

Yeah I think you have the singular idle speed attachment. If you can offer a few pics of the top of the carbs, that would help. Just as I thought your carbs are interconnected. It shouldn't be hard to find.

[turbotrip]

take some pictures from a little further away

[ZedMan]

Try looking around where the throttle cable attaches (1st pic)

Turning the idle up, however, may just be a "band-aid" solution.

Has the bike had fuel sitting in it for a long period of time? If so the carbs could be all gunked up. Take a look at this.

[3g4u]

I found a breakdown of all parts on that bike for free on a pdf if you are interested.

http://www.eserviceinfo.com/download.php?fileid=24724

[Forkster]

http://www.xjbikes.com is a forum specifically for XJ bikes (like yours).