Have you got hard starting problems.

Go and buy a YUASA YUMICRON battery. I have put one in my 85 XJ600 (FJ600)and what a difference.I thought my conventional battery was ok and my cold starting problems may have been something else but the battery.
How wrong i was.These batteries have extra plates for more capacity, and are supposed to be better if the bike is not used regulary.
If you are using a Yuasa 12N12A-4A-1, the Yumicron type is a YB12A and fits straight in,or check out here by veihcle type.-
http://www.yuasabatteries.com/

 

And of course it also helps to upgrade the original weak coils to Dyna or Accel high performance models. Even stock Harley coils are a lot better than the ones Yamaha used.

 

Just about every single bike I have ever seen that didn't like to start right-up -- cold, had some issue with the Enrichment Circuit.

Either the Fuel Bowl Metering Jets that allow Gas to fill the Siphon Tube Well were Clogged ... and / or

The Siphon Tube was Clogged or the Starting Circuit Passage was blocked ... and / or

The Activating Rod was rusted and not allowing the Enrichment Valves to fully open.

These XJ-Bikes don't like to Start ... Dead Cold.
They NEED the Enrichment.

It is nice to have a Battery with High Cranking capacity.
There's NO Doubt Hight-Performance Coils make a difference.

But, you should be able to Start the Bike by Pushing the Starter Button and a Stock Battery and Coils should make it GO ... IF, the Cold Start Circuit is all cleaned and the supply of Enrichment Fuel can get into the Combustion Chambers!

 

Does anyone find that it helps to set the petcock to prime for a few seconds before starting?

 

Setting it to prime will help if your fuel is leaking out of the carbs since they have to be full to start but otherwise it won't make any difference.

 

Where do you get aftermarket coils?

 

Parts stores.

You need to get the ones you like. They all don't fit quite as nice as Stock Coils. You might have some fabricating to do ... depending on your selection.

 

Also make sure the coils you buy have the same ohms as or close to, the coils you are replaceing (stock). Go to far either way and you can burn out the TCI drive transistors.

 

If your carbs are sync'ed and floats & mixture set right and are clean, your battery is in good condition and charging circuits OK, your coils are within spec and not breaking down (when hot or when wet) and starter motor is good, then the standard parts are fine.

By all means upgrade to "better" parts if you have problems, but a new battery or coil is not going to fix a bad starting enrichment circuit, new coils are not going to fix a weak charging circuit, etc., you get my drift?

Trouble shoot the bike and find the problem!

Standard coils are OK.

 

Clean the Carbs.
"It's the Carbs, Rick. It's always the Carbs"
___ 35+ Year Yamaha Lead Tech

Measure the Alternator Brushes.
11mm Minimum.

 

Rick,

Yeah 8 out of 10 times the carbs need a tweak/clean/air leak fixed, eh?

The other 2 times seems electrical and a new set of sparklers never hurts!

Carbs? What carbs? It's NEVER my carbs . EFI RULES!

These bikes go for years (25+) on stock parts but now they are getting old and need some TLC every now and then.

 

Carburetor talk scare's the heck out of me.(I have three carbs to many), but i like the bit on starter brush length.I'm an electrician and that makes sense to me.What the is an enrichment circuit?. Cannot find mention of it in my wk/sp manual.

 

The "choke" is the enrichment circuit. The XJ does not choke like a car with a plate covering the inlet, it has a circuit that lets more fuel in when "choke" is on.

The carbs are not too bad, getting the sync even is easy enough using a manometer (bit of tube and 2 stroke oil) see my $5 sync tool in suggested FAQ section. A YICS tool is also easy enough to make if your XJ has YICS passage.

Where are you in NZ if you are down South I could help?

It's the Alternator brushes Rick refers to. A good idea is to go over all the electrical switches, connectors and wires making sure all are good and replace the fuse box with a Blade type one.

There is another XJ owner locally who is also a sparky, I am (was) a telecom Lineman. BTW I'm in Waimate, other guy is in Timaru.

 

ahh!! so thats why i dont need the choke to cold start my bike. It only floods if i do. But as stated at start of thread, one of these new batterys was all i needed to over come my yes/no cold starting (and save some hair).
It is so good to now be able to start up in the mornings, without having to leave the bike in the sun, and i thought the old battery turned the motor over Ok. but obviously the sun was warming the temperature of the battery to give it more oomph. Not from the south, but from the north.

 

Not needing the Enrichment to start a Dead Cold Bike is a hint that you might have the Pilot Mixture a shade too Rich ... unless ...

It's already above 68-Degrees F. when you go to start her up!

 

on my one xj650, yes, on some others, no

 

No. I just leave it in the ON Position for Fuel and never touch it unless I get low on gas and that's something I haven't done recently. I keep the tank above 1/2 Full. Or try too.