Idling problem -- erratic

Hi all, I've got an erratic idle on my 85 XJ700 (it's all stock). When I start the engine the idle sits at aroung 1100 or 1200 RPM. When it is real warmed up (after approx 50km) the idle sits at around 1400 or 1500 RPM. A little high I know but that's not my problem yet. Sometimes when I come to a stop the idle will sit at 1700 for let say 10 secs than go up to 2200 for 15 secs than come down to 1900 and then back up to 2200. So it is high (real high for idle) and erratic. I have a few ideas for idle problems but no idea at all about an erratic idle like that that keeps going up and down.

Any ideas from the crowd of XJ riders out there?

Thanks in advance

Martin Leblanc
Gatineau, Quebec
Canada

 

That used to happen a lot on my 81 XJ650H Maxim. What solved it was a careful carb synching and then using a colortune plug to set the idle jets.
It would be very helpful for you to get the XJCD set offered on this website and the Haynes manual is excellent as well. But before you synch the carbs, make sure the valve shims are within spec. For that you'll need a valve shim tool, about 20 bucks. Unfortunately, the carb synch kit and colortune plug are more.
By the way, where are you located in Canada? I'm in the west end of Toronto.

 

have the carbs been torndown & cleaned? have you checked the intake boots for cracks? just a couple of suggextions for you xj. you are in the right place to get your problem solved.

 

I just got the bike very late in the riding season last year so I did not do anything on it (other than a new oil filter and new oil). So nothing done to the carbs by myself. However some work must have been done very recently because the intake boots appear almost brand new.

Baz666, FYI I live in Gatineau.

 

the po may have cleaned the boots to make it look better or he was having the same problem. you need to pull those carbs & clean the them like you want to eat out of them. for extra help got to the forums area & select xj4ever supporting vendor & read "in the church of clean", it is all about carb cleaning, also there are plenty of threads in the forums about getting you carbs right & we are all here to help if you need us.