Won't start in cold weather, enrichment or ICU?

Hey, I have an xj550. I rebuilt and cleaned the carbs, bench synced and got a new battery. When the temperature drops below about 55 farenheit the bike won't start. It will crank a few times then die and won't crank again no matter how long I run the starter. When it is warm it will crank up pretty well on choke, after the second or third set of short cranks. Once it runs on choke it will idle fine. I'm trying to figure out if the low temperature is dropping the battery output enough for the ICU to not shoot hot sparks or if its just a carb problem. Any ideas on what to test? Thanks in advance.

 

Have you tried hooking a battery charger up to it while cranking the bike over? You'll want to set it to its boost setting to ensure you're getting lots of juice. If it starts that way, I'd say it's a weak battery, but from what you're describing, my money's on a clog in your enrichment circuit.

 

At cooler temps the fuel doesn't atomize well. So this means a good spark is necessary to ignite the "wet" fuel. I do two things to get my bike to start in the morning. I put a clamping lamp on the engine which helps keep the fuel bowls and therefore the fuel in them warm and I put the battery on a charger about an hour before I crank it. On really cold mornings I use a ceramic heater on the back or intake tract of the engine. The battery charger is the main thing. I can't get mine to crank without it. These bikes have weak coils and in the cold they make themselves known. I have been toying with the idea of using iridium plugs to see if they would help boost the spark.

 

Iridium plugs won't boost your spark.

 

What about some huge value 12v capacitor discharge to boost the power when its cold?

 

I'm running them in mine and they seem to work fine. My XJ550 starts right up but I keep it in a garage that's heated to about 40-50F. If you go with iridium plugs you might want to replace the resistors in the spark plug connector with copper wire. There isn't a direct replacement for the XJ550 plugs and the ones I found were resistor plugs with about 5k ohms impedance.

sanoke

 

Mine hasn't ever liked to start cold. I rebuilt the carbs and it still doesn't. I installed these today, but it was about 70 degrees so I don't know if they made much difference. They are pretty much exactly what you're talking about. A capacitor that sits on top of the spark plug for some extra oomph.

 

CHeck your battery voltage WHILE CRANKING, if it's less than about 9.5V, then you've got a battery problem.

Otheriwise, assuming the plugs, coils, and engine compressions is okay, then it's probably your enrichment circuit is clogged, meaning the tiny starter jets down in the fuel bowls.

If your battery is good, and your engine is good, and your coils/coil wires/plugs are good, then your bike should start almost instantly even in cold weather.

 

Not to hijack this thread, but yeah, I put in a new battery when I did all the other stuff, and the last time I checked compression it was good. (Ranging from 45-47) My bike runs great once it starts, and the whole reason I started rebuilding the carbs anyway was because it had suddenly decided not to start when cold. I know for sure I've got a good battery, good starter circuit, good spark, and compression. I might just check the alternator brushes. I've never done it. The bike only has 11k on it, and I figured they must be ok. However, I should probably listen to Rick and check them anyway simply because of age. That's the only thing it could be on my bike other than the enrichment circuit being clogged. Does anybody happen to have a pic of this tiny jets that I should clean? I'm planning on doing it tomorrow.

 

Look here:

http://www.xjbikes.com/Forums/viewtopic/t=4050.html

 

I agree with Pacocase. I used to have this similar problem, but after I cleaned the starter circuit in the carbs and float bowl, it starts up much easier now. I followed Rick's advice with the Oxy-Acetalene tip cleaner tool and it worked great. Now I can start it in cold weather with no problem.


Paco, if you look at the float bowl, where the that long thin tube from the carb insterts, thats where the lil jet is. Keep in mind that the jet is angled up about 45*. Sorry i dont have a picture, but I'm sure if you poke around you will find it.

 

Check your choke cable adjustment!

This caught me out when I bought my 550. The next day I spent about 10 minutes cranking the engine over with nowt but the odd "wet fart" out of the exhaust. After a bit of fiddling around, draining the carbs to check for water (none), checking the plugs for flooding (none) and sparks (lots), I noticed that the choke cable was only opening the actual choke mech on the carbs by about 3/4 or so.

Readjusted the cable, and Bang! Fired up first spin of the motor.


Since then, it's fired up on the button without fail every time. Example, not used it for the last few days, it's parked outside, it's been bucketing down with rain, it's currently 2C outside and it's just fired up happily first time after 1 second on the starter button.