Anther Cold Start Issue

Now that things are starting to cool down in North Carolina, my new-old bike is starting to make things difficult for me. I've a sneaking suspicion that I'm going to need to get into the darn carbs again... But I'd like some ideas, or things I can try to rule out every other possibility before I wrestle with those darn boots again.

Here are the symptoms:

1) Hard to start when the bike is cold. Takes a long time cranking before engine catches. I've even drained the battery a few times.

2) When it does start, with full choke on, I have to keep full throttle (more or less) for 30 to 45 seconds, while the engine runs around the 1,000 rpm range until it finally roars to life.

3) After it roars to life, I still have to keep the throttle on a little bit to keep the RPMs up over 2,000 for about 2-3 minutes, or the bike will die.

4) After 2-3 minutes, I can release throttle and the bike idles at about 2,200 RPM. While idling at this RPM, there are usually a cseveral coughs in the exhaust, perhaps one or two per minute of high RPM idle. RPM is solid, though. There is also a fuel smell coming from the exhaust.

5) After about 5 or 6 minutes of high idle, I can cut off the choke, and the bike will idle at about 700 RPM, but it is a little weak and may die if I'm not paying attention. After riding for a few minutes, and the engine gets up to operating temp, the bike will idle at approx. 1,000 RPM and is usually very solid.

6) The bike will idle at full choke, or no choke (when warm). There is no in between. At about half-choke the bike will drop all the way down to normal idle (if engine isn't warm, the bike will die). From half-choke to full choke, the bike will idle at about 2,100 to 2,200 RPM. There is some slight variation between half and full-choke, but it is only about 100 - 200 RPM.

7) When warm, bike will restart quickly and idle well.

Here's what I know:

Fuel level in float bowls is right at the bottom of the fuel bowl seam as per the clear tube method of checking.

Choke slide is smooth.

Valves were synched about two months ago.

Carbs were cleaned, including the enrichment tube, about four months ago.

The airbox boots are old and stiff (like ROCKS). I suppose they may be leaking...

Bike runs well, though it will occasionally bog down when starting from a stop, like at a light, or something.

Petcock seems to be working the way it should, now that I'm leaving it on "ON" and not on "PRI" all the time (thanks to the forum for explaining to me how that darn thing is supposed to work). There doesn't appear to be any flooding.

Suggestions?

Thanks in advance!

 

Sounds to me like you're too rich on your idle screws and it needs the extra air of the throttle open in order to run. Get her warmed up and try Rick's tune by ear method if you haven't already.

 

I'll look it up the tune by ear method. Thanks for the suggestion. I've been thinking about doing a plug chop, but I'm a little anxious about killing the engine at speed and coasting to the side of the road to check the plugs...

 

I dont know how cold it is right now in north carolina, but here in Michigan its been cold for the past month or so. When the temp gets down below 50 at night, my bike is pretty much guaranteed not to start. These bikes just dont like to start when the blocks get cold.

It warmed up to mid 60's this past weekend, and it still took me and my dad a good hour to get my bike running on saturday with a healthy dose of starter fluid. Got it out on sunday afternoon and i still had to use some starter fluid even though i had ridden it for a while the day before.

The bottom line is that you could be having fuel mixture issues, but also take into consideration the temperature. We figured out that to start my bike when it was cold we first had to give it full choke and push the starert button for a couple of seconds. Then turn off the choke and spray some starter fluid into the airbox on either side of the engine and with the choke off hold the starter button down, and when it started firing we had to hold the throttle open until it started and ran for 20 seconds. Then we could use the choke and let it warm up.

I hope this helps with cold starts.

 

1) I'd try leaning out the pilot screws a bit for the winter. I gotta do that to my bike. I was gonna ride in the other day to work, but couldnt get her started and killed the bat. So i took the stupid car.
2) Change out your airbox boots! There are $1.75 1/4' rubber plumbing couplings at home depot that fit PERFECT. Cheap and effective.
3) I'll have to check out this tune by ear method.
-Chris

 

Thanks for the suggestions. I'll turn in the screws a bit. I'll also get some starter fluid. The temps here in Eastern NC are only getting down to the low 50's, right now. But, really, anything less than about 70, it seems, makes the bike hard to start.

I think I saw something about the replacement boots. I'll check into those, too. After spending two hours hooking up my four carbs to the existing boots, I REALLY don't want to mess with that stuff unless there is absolutely no other choice!

Does the choke issue sound like a fuel mix problem? Could that account for the fact that the choke acts like it only has two settings, on and off?

 

+1 on what SLKid said. It takes me about two min to start my bike in the morning but its 32 deg F. If I use stater fluid Its starts right up but I try to avoid that if I can.

 

It was upper 40's here in Maryland when I rode into work this morning. Full choke and bike started right up. Stumbled a bit but did not die that only lasted 30 seconds or so then the idle stabilized. Then in the time it took to zip tie the expass to the handlebars and put on my jacket , helmet and gloves she was ready to go. I did leave her in her garage to help warm up but the garage is not heated and very poorly insulated (rental) so I doubt it was much warmer inside than out.

 

So, I tried the starter fluid this am. No change. I sprayed it into my airbox "snorkel", and the bike still wouldn't start. I even sprayed it directly into the air filter, and there was no noticeable difference.

So, is that an indication of something? Why would the bike be so hard to start, even despite using starting fluid, but eventually start up? Could it be an airflow issue?

 

Sounds to me like the first thing you should do before you ruin the engine from starting fluid is bench sync the carbs. If the carbs are out of sync it will make the bike take a long time to warm up. Before you do anything else check the sync on those carbs and I bet you will find your answer. Just a heads-up for future use, NEVER USE STARTING FLUID UNLESS ABSOULUTLY NECCESSARY! The engine can become "addicted" to ether and may never start easily again, or it may never start without the use of ether(starting fluid) again. I learned this the hard way on my xj. The PO had used starting fluid to start the bike a few times, when I got the bike home I cleaned the carbs very well and did all the maintenance that the bike required, but sometimes it wouldnt start without starting fluid because the bike was addicted to it.

 

Hmm... Hello, I'm a Maxim, and I'm an addict...

LOL OK. Well, this is the first time I've tried it. You know what they all say, th ough... Just try it, once isn't going to hurt!

Anyway, I thought I'd give it a shot. I did bench sync the carbs four months ago, then about three months ago I had a friend help me sync them with the mercury sticks. Do they go out of sync on a regular basis? It was my understanding that they only need syncing when you mess with them.

Still, I know there is a problem here, and I think the key is the way the choke works (or doesn't work) and now the issue with the starting fluid. Could the filter be completely choked off? I mean, is it possible that the fluid wasn't even getting to the carbs? Could all this stuff be happening because of poor airflow?

 

Some Fuel Filters are so poorly made that upon becoming wet they cease to be porous.
Remove the Filter and blow through it. If it provides a great resistance, ... its NO GOOD!

The Enrichment System is wholly dependent upon the Passage, Syphon Tube and the Metering Jets to the Fuel Bowl Well being clear and passing Fuel.
Without the Enrichment System in good health ... It will be Very hard to Cold Start.

The Enrichment Lever:
Treat it as a Variable Adjustment. Not as just and ON-OFF device.
Leave it ON FULL while the Bike warms-up.
Get the Head and the Block warmed-up and start easing it off.

Even if your Bike is in Perfectly good condition and on the edge of Fine Tuning ... A cold XJ-Engine is a Stubborn Machine to Fire-up.

Keep the Battery charged or tended.
Rig it for introducing Starting Fluid.

Don't wear-out the Starter Clutch trying to start a Very Cold Bike.
If you do ... you may pay a price that leave you stranded.
The Bike will begin be difficult to Start in August!

 

OK. Thanks for the tips, Rick. As always, good advice succinctly given.

I did just purchase a new fuel filter today. But, I was wondering if the problem might be the air filter. Since no one has mentioned it, I take it that these symptoms don't lead anyone to suspect low or no airflow?

As for the enrichment lever, if that is the choke, then part of my problem is that it isn't a variable adjustment. It doesn't seem to result in anything other than full choke idle and no choke idle. The engine RPM pretty much stays at 2400 when idling with the choke lever open fully, and then at about half-way the idle drops to below 1000, and there it stays until the choke is all the way down. It really seems like the thing is either on or off.

How do you suggest rigging it for introducing starting fluid? I'm not sure I know what you mean by that.

Thanks again!

 

I just ran a length of Windshield Washer Hose into the Airbox and Duct Taped a loose end to the Seat Rail.
Strictly a Cold Weather Mod.
Once it warms-up I take it off.

Carb Cleaner or Starting Fluid.

 

Hey, neat trick! I'll give it a shot.

Any idea why the starting fluid in the air box didn't have an affect, though?

 

If you had it running and suddenly it quits running ... go right to the Ignition Fuse and see what that looks like.

If you have an old Fuse Box.
Replace it.

 

I'll be replacing my boots and cleaning out my enrichment circuit again on Friday. However, after talking with some buddies, they pointed out that the reason the bike is not firing up is because only once cylinder is firing. You can hear it go "pop-pop-pop..." as it cranks. Also, the #2 header pipe gets warm while trying to start. When it does start, its like another cylinder fires, and then I have to hold the throttle wide while the other two get going.

Still sound like a fuel issue? I replaced all the plugs, just in case, and they work fine. There is spark. I also leaned out the mix a bit because my plugs were sorta black.

I'm thinking I might need to check the compression, too. What do y'all think? Why would only one cylinder start? Could my carbs really be that fouled up after only four months of riding (since I disassembled and completely cleaned them the first time)?

 

Do a quick check.
Spray some Starting Fluid into the Airbox.
Try to start the Bike.
IF the Bike comes to life: >> It's FUEL Related
IF the Bike don't fire-up: >> It's IGNITION Related.

Worst case scenario: BOTH making troubleshooting difficult.
So, ... you go Back to Square One.

There was a time that we could say, ... "The likelihood of it being BOTH Coils being bad" was remote.
That's still pretty-much true. But, NOT as sure as it was before the Coils had their 25th Birthday.

You have to test them.
Bear in mind.
The Coils might be good, ... But the Spark Plug Wires bad.

After looking over what you've done and reading your report on what's been done, so-far, ... I'd "Take a hunch" (WTF).

Try running the Bike using a TEST IGNITER.
A Test Ignitor is simply: An Igniter known to be good.

See what shakes.
Take it from there, ... one step at a time.

 

Thanks, Rick. I tried the starter fluid, and it didn't start.

If one or both coils are bad, would I still get spark? I just checked today, and the spark seemed good. Blue/white color, more or less constant with one or two arcs all the time. Seemed good to me. Should I still try and test the coils?

By test igniter, do you mean an igniter coil that I know is good?

 

The Ignitor is the Black Box Brain.

If you got Spark.
Your's is OK.