Starting Issues & Backfiring

[xsilerating]

OK, before anyone jumps down on me to tell me to check the tech tips & search engine, I've done all of that.

I've checked, re-checked and, checked again. I've examined, cleaned and put dielectric grease on all electrical connectors (dealing with the starting/running sequence) .

Now, so far, the bike has started each time it has been tried since the above was carried out. However, I haven't been able to mimic the conditions that led to the 'No Start/Backfire' problems - and won't be able to until later today and tomorrow morning - with the exception of the initial cold (first one of the day) start, in which the first, 2nd, 3rd, 4th... attempts resulted in "Failure to Launch" .

I won't go into the circumstances right now of when, where or how the engine turns over (starter OK) & the 'backfiring' that occurred (WOW, the loudest KAAABOOOOM !!! I've ever heard in my (ancient) life ears are still ringing from Wednesday morning
!) It's obvious that what I've been experiencing over the past week or so is not uncommon, as I discovered in the tech tips and various threads (other references to XStremely loud backfires. Which, I suppose, is good... makes it that much easier to diagnose the problem & find a solution.

What I don't understand is, even with the failure to start using typical starting procedures, on two occasions (last night & Thursday night), when all else failed, we got the bike started by.......

PUSH STARTING IT . HUH ? ? ?

How could it start by 'push start' when a) I wasn't getting a spark in (probably) #1 & #4 CYLINDERS, b) the engine would turn over without any problems using typical start procedure, c) when battery was run down, would turn over with a boost, again, without problems... all of which resulted in a failure to start the bike.

Anyone ?

Please, help turn -----> into ------>

Thanks

[blue giant]

Ron,

Two things come to mind right away.

1. What is the voltage reading at the battery while cranking the engine? Does it drop below the 10.5 volts require to energize the ignition system?

If it does then I suggest you load test the battery if it fails then you know what to do.

2. if it passes I would suspect the stater is drawing excessive current and lowering the available voltage at the battery for ignition.

I have a spare starter if you want to try another.

Let me know!

Paul!

[Ken Talbot]

That is exactly the kind of thing that happens when you've got broken pick-up coil wires. One broken wire will give you two dead cylinders. The other broken wire will kill the other two cylinders. With the break hidden inside the soft insulation, you can't see it. When you get mucking with it, such as push starting, things jiggle enough to restore the connection, all of a sudden you've got spark again with an overcharge of fuel, and things come to life with a bang. Then, you'll be going along and the problem will appear to be solved for quite a while. Finally, things wiggle enough again to break the connection at the bad spot, and there goes two cylinders or more.

Sometimes you can check and check this, and not find the problem. Then, when you loosen the crimp at the bottom of the housing, you find the break(s) is(are) right there. Trust me, if all of the other connections are as good as you say they are, this is the only thing that will cause your symptoms.\

BTDT, (more than once)

[Ivan]

I'd bet the back fire came from cranking on it for a while, while not firing. This pumps fuel air mix into the exhaust, and when the bike finally fires, the whole thing goes off like a bomb.

My dad used to do this with his propane powered pick up truck. He would turn off the ignition and coast for a while, and then turn the ignition back on. It would backfire loud enough to rattle your teeth. Once, he blew the sides out of his mufflers, and you'd think he got a boy scout merit badge for it.

I also agree with the cranking drawing the system volts down to below 10.5V

[xsilerating]

So Far, So ???

Paul, no, battery is strong and generally maintains a voltage output (while cranking) of between 11 and 12.3 until, the battery starts to wear down and, even then, it will stay between 10 and 10.9. I've been quite happy with the cranking abilities of both the battery and the starter.
(p.s. How was your ride today)

Ken, while I greatly respect you knowledge, experience and abilities as they relate to these bikes, I don't think that it's the pick-up coils. Strangely enough, that was one of the first things that I checked, even though I didn't know what it was . (I was following wires to ensure everything was attached i.e. grounds and, I ended up there.) I'm pretty sure that these wires were changed not all that long ago by the PO. And, as I stated initially, as this was one area that was routinely mentioned in the 'threads', it was one that I checked early on.

Bear in mind that, I don't entirely 'disagree' with you for as you said, you can check and check and not find anything until....
That being said, I don't see how push starting the bike would be sufficient to reconnect the wires, though it's something that I'll keep in the back of my mind as I monitor the ongoing shenanigans of this machine.

Ivan... Yup, bang on (pun intended) . One other strange encounter was, as pointed out with the build-up of gases in the exhaust, when I shut the ignition off after a failed attempt to start the bike, it triggered a backfire, of varying degrees, inside the exhaust. This also occurred when, with the ignition in the 'on' position, the 'run'/'kill' switch was turned to the 'off' position.

Something to note, while I was checking the wiring, connectors, fuse panel, etc. there was one thing, for whatever unknown reason, that I had paid particular attention to and, that is the Ignition Unit. While researching this problem one tech tip in particular re-inforced my concerns. That was This One which details ignition problems and provides a good overview of just how things work. Because of its location and ease of access and, because of my concerns with the unit, I made sure that I pulled apart the connectors, paid extra attention to cleaning all of the contacts, adding the dielectric grease, ensuring a tight reconnect and, good inspection of the wiring harness and connectors immediately at hand.

Since all of the steps previously outlined were completed, bearing in mind that I have not as yet been able to mimic the other conditions that led to this problem, I have been out and about quite a few times since my original post... with NO ADVERSE EFFECTS . It has started each and every time, with no hesitation or backfiring.

Fingers are crossed

[Bud Manley]

Replace the kill switch or jumper it out.

[scalded dog]

If you are getting a build up of gas in your cylinders, leaking floats, gas in air box etc, it could be flooding, make sure to constantly check for gas in oil. Later 'Dog

[Ken Talbot]

Re: So Far, So ???

Originally posted by xsilerating
I don't think that it's the pick-up coils. Strangely enough, that was one of the first things that I checked, even though I didn't know what it was . (I was following wires to ensure everything was attached i.e. grounds and, I ended up there.) I'm pretty sure that these wires were changed not all that long ago by the PO. And, as I stated initially, as this was one area that was routinely mentioned in the 'threads', it was one that I checked early on.

I hear what you're saying, but the reason I keep harping on about the same thing is what I don't hear you saying. What I don't hear is that you personally loosened up that crimp (which is prone to cut into the wires) and personally pulled virorously on all four of the crimped wires so you are absolutely sure none have been weakened.

Sorry to keep on like this. I've had my say, so I'll leave it alone now.

[egsols]

Originally posted by Ken Talbot

I keep harping

Same reason people clean their carbs three times

As for it push starting, the only time my signals cut on me is when my kid is riding on the back. Sounds like a connection issue somewhere. My 2 cents.

[Ivan]

I am wondering now, if your solenoid isn't the culprit.

If I am correct, the solenoid on these bikes provides voltage to the coils during cranking, which in effect, bypasses the ballast resistor. Bigger spark during starting, then when the starter button is released, the resistor cuts voltage.

I could be off on this, because i have an 81 with no resistor, so I have no first hand experience.

I would put a volt meter on the positive lead of the coil and make sure it gets voltage during cranking.

[dwain61]

Have you taken a good look at your fuse box?? If it's original then toss it and replace. My old fuse box caused similar problems for me. If you have replaced it; what did you replace it with? How did you connect it? If you just used little plastic connectors then you should probably take those off and solder the wires instead. Just my $.02.

[xsilerating]

Sunday morning... bike started, no problem
Time for errands... shopping milk run. Gotta make up for all that down time.
Handful of stops... each re-start successful
Let bike cool down 'til dusk and the onset of the evening dampness. Out I go to see if 'The Mistress' will fire up. Three, two, one... Success !

OK... put it through its paces and mimicked the conditions that resulted in a "failure to start" and, IT STARTED each and every time... no issues, no problems.


Problem solved ? Stay tuned

Ivan: Ballast resistor is (semi-)permanently by-passed due to the Accel coils that were installed.

Dwain61: Fuse box was replaced by the PO, though I'm not sure of how long ago this took place. All connections in and around the panel have been checked and, all connections on the panel are soldered. Everything looks good there.

[egsols]

That's the beauty of these bikes.....they were built with a mind of their own just to screw yours up.

I've been chasing carb problems, mainly overflowing carbs for a while....changed valves, seats, adjusted floats, ensured none were sticking....road for weeks, no problems. Figured it was time for a new air filter now, should be safe, haven't had any gas overflow for a month a half. (Only wasted 3 filters so far)

Go for a run, stop at a corner store, gas dripping from airbox.....aaaaaaargh.....quick bang on the side of the carb and away I go.

In your case, I hope you inadvertantly solved the problem and it doesn't re-appear.

[Stralya]

This is a pretty old thread but maybe someone remembers it.

Exactly the same thing happened to me today. Riding along happily then cough, splutter, goodnight.

Fully charged and load tested battery turns the engine nicely but no start. Two or three more attempts then an almighty BANG!

I've run the battery down twice in my attempts to start it.

I've checked all the usual suspects except the ignition module. I have a spare that I'll try tomorrow.

My poor bike is sitting on the side of the road waiting for me to help it.

Being on the side of the road, it's difficult to run full diagnostic tests but I can assure all that these tests have been done within the last few days as I have had other issues.

These other issues are unrelated.

Please don't make me tell the whole story, suffice to say that everything has been checked.

The reason I'm replying to this post is to try to find out if there's anything I can do if, when I return to the bike tomorrow with a fully charged battery (load tested today) and swap out the ignition unit (which I know is fully functional), is there anything else I can do on the side of the road that will allow me to at least start the bike and limp it home?

Dan.

[madmax-im]

Sorry to hear of your troubles Dan...I would bring someone with a truck and/or trailer and bring it home to a more friendly locale...