Stock jetting

I have an XJ650RJ without yics. I have set the floats, cleaned the carbs, checked for airleaks,checked fuel flow, balanced and have the idle jets set at 3.5 turns out, any more does nothing. It has 110 mains and 40 idle jets. I still have all the cylinders running lean,ie white plugs and a slight lean lean hesitation coming off of idle but it does run very well. I just think it is running to hot due to running lean, ie bluing the pipes slightly and the engine feels excessivly hot even when its cool outside(hotter that my GS500E I had last and although its been 6 years I dont remember my old 650 maxim running this hot. Anyway, what are people running for stock jets? Second, being use to carbs with clip type needles, I would say I need to raise the needle slightly but these hatachi's dont have clips? Put a washer under them?

 

110 mains and 40 pilots are stock for a 650. I have seen some with 112 mains but the 110's are what is listed for a XJ650RJ. Yes some have used washers to raise the jet needles and it works fine. Before going through all that I would do a plug chop. Ride the bike and open the throttle. With the throttle wide open hit the kill switch and coast to the side of the road. Pull the sparkplugs and see if any are white. Which ever ones are white are running lean. That should tell you if the engine is running hot.

 

I have done that and they are all white. Maybe I will step up to the 112's

 

You'll be wasting your time because changing the main jets won't make any difference except at full throttle. To get the mixture correct you have to adjust the pilot jets if it's lean at slow speeds (just off idle), adjust the tapered needles for mid range and the main jets for WOT. It's normal for the pipes to blue and the engine normally runs at 300-350 F so it's impossible to tell if it's overheating without a head temp. gauge or IR gauge but if the plugs are white that means it's too lean but you didn't say what speed that was at and it may or may not be overheating but that has nothing to do with anything. I'd adjust the mixture at all three ranges, just off idle, midrange, and WOT then see what you get.

 

Alright, let me clarify. The plugs look good at idle. Last night I tried WOT and coasted to a stop(how far do you have to run wot? I did maybe 1/4 to 1/3 mile, didnt want to go any faster) and checked the plugs. They are neither white nor brown, some where right between, probably ok. The idle is alright as well. The white is when I am running at 55/4000-4500 rpms cruising. I only have the throttle cracked slightly. This is why I thought the needles should be raised, or should I look some where else?

 

It sounds like you're on the right track, firebrick.

I'd suggest you add one washer under the needles to richen it up in the midrange. I'd leave the idle and main jets as they are.

I believe you'll need M3 or M4 washers, which I have found at Radio Shack.

Good luck.

 

Is your exhaust stock? Have you changed to a K&N filter or pods?

 

Just for info, I'm running 118 main jets and 40 idle jets in my XJ650RJ and the needles (I have adjustable ones) set in the mid setting. Just colour tuned it and it runs a dream now, idles at 1000rpm without cutting out, no spluttering at any rev range and the engine is running cool (I've also fitted an oil cooler)

(My air filters are K&N style pods)

Lea