Hard to cold start

Hi everyone I have an 81xj750 Seca. Recently it's been a real pain to cold start the bike. This is after taking the carbs apart and cleaning them. As I was trying to get the bike running and it died one day on me. (thanks to the forum I got it running great! ) I'm assuming it has to do with the enrichment circuit. I am looking for any knowledge or ideas or things I may have missed. Thanks!

 

Good chance your enrichment circuit is gummed up ...usually the float bowl jets ...You could try to give it a "HOT SHOT" pull the fuel line off of the petcock , drain the float bowls , Take a large syringe ( Meat injector type) fill with Either Seafoam or Berrymans B12 Carb Cleaner fill up as much as you can , let sit for several hours . Drain float bowls, reconnect fuel line put it on PRI fill bowls ,and see if it starts with enrichment engaged ..

 

You should check your battery if you haven't already.

 

Agree on checking battery. It may crank, but if the voltage drop is too much because of a weak battery, it won't fire the plugs.

Cold batteries produce less current, and cold engines are harder to turn over, requiring more amps.

Put a voltmeter on the battery while cranking, and if it reads below 10v, then battery may be the issue. If you don't have a voltmeter, you can buy one for $5 at Harborfreight. Otherwise, you can jumper to car battery and try to start (without the car running...).

 

Battery is brand new should have mentioned that. It also sits on a tender when not in use

 

If you search this site, you will find even brand new batteries have been known to be bad.

Try the jumper cables to car battery if you don't have a voltmeter. At least you can check one possible source of the problem off the list.

 

valves in spec?
carbs synced?

how cold you talking about

 

Valves done and carbs synced when ever the bike sits doesn't matter the temp. It's starts fine once warm

 

try turning the petcock to prime for 3 seconds see if that solves the issue

 

Did you ever figure out what was causing this issue? I've always had serious trouble starting my cold xj650. I just found that my starter solenoid was bad -- only would start when jumping the two connectors on the solenoid. It's finicky and will start sometimes but I've got a new one that I plan to install shortly. I'm going to test my battery and re-tear down my carbs and see if the issue persists.

Let me know if you found the culprit.

Ian

 

I think your problem is with the carbs as you first thought. I had the same problem until I spend a lot of time on the pilot system and enrichment circuit. After getting them squeaky clean, I made sure I got a good wet set on the floats, and properly synced the carbs. Then I worked on the proper settings for the pilot screws which I think is extremely critical for easy starting and fuel economy. If you have a colortune plug use it and close the pilot screw(s) until you get a white flame (lean setting). Then open until the white disappears. Repeat for each cylinder. Then install new plugs and ride 15-20 miles and take a look at the plugs. You are looking for a very light tan or gray color. If still white open the pilot screw about the width of a dime. Ride and read the plugs and continue until you get a nice light tan or gray plug. Unless it is cold I do not need enrichment and my mpg went up about 5 mpg. If you do not have a colortune plug start with the pilot screws at 1 1/2 and make your adjustments.

 

Shouldn't that be 2 1/2 to start?

 

Not if you want to start with new plugs so they can be easily read. Using the colortune the white flame disappeared a little before 1 1/2 open. None of my pilot screws are out much more than 2 and most under 2. If I had started at 2 1/2 I probably would have gotten black plugs and it would have taken longer and probably be more difficult to read the plugs. This is a tuning process and I didn’t take long trips or ride hard until I got the pilots set correctly. Every bike—every carb—is different, so where you end up depends on your bike.

 

You may also want to consider doing a carb synch each time you make adjustments to mixture.