Starter Fluid Question?

[dllewis5]

Hey guys about a month ago i posted on here about my bike (1980 Cb750c) not starting after discovering rust in the previous gas tank that I had. Well a new gas tank and rebuilt carburetor later, ol girl still hasn't started.
I tried spraying some starter fluid and i get NOTHING, not type of hesitation of wanting to start. The engine just keeps turning over. If the bike isn't even kicking over with some starter fluid, what does that mean?

-Ive checked to see if I'm getting spark, I am.
-Gas is definitely going into the carbs from the tank
-The new tank is rust free
-Back in July the bike was running when I had another carburetor on it(that one just leaked bad)
-Maybe the insulators connecting the engine and carbs are not sealed up enough??

Would greatly appreciate some insight.

Thanks

[Re-run]

Starting fluid is so explosive that even if the boots were leaking air, it would still at least cough.

You may be getting spark but it may not be strong enough, timing might be off.

With starting fluid, you almost don't even need compression. You just need the fluid to get into the cylinder and have spark.

I would check all aspects of spark first.

[TOOLS1]

Are the butterfly's in the carbs going all the way closed? I have had bikes hard to start because the idle was set too high, or something was preventing the slides/butterfly's from closing.
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[dllewis5]

When you ay butterfly's, your  not referring to the ones on the side of the airbag/filters attach. Your talking about the ones on the side that goes into the engine right?.If your referring to the ones shown in the photo, then , then theres my problem. They are open just as you see them in this photo(this photo is old)

[TOOLS1]

The ones you can see are the choke butterflies, and the ones towards the engine are the throttle butterflies. Both need to be closed for the engine to suck enough gas through the pilot jet to start the engine. That is why you will never get one of these bikes started with the throttle open. I get a kick out of watching guys that twist the throttle as they are kicking away at the bike, and it never stops. And if you tell them not to twist the throttle, they get p$%^& off at you, so I just watch, and quietly chuckle.
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[dllewis5]

Feel like an idiot right now!!! ..wow.. Well i know for sure that the throttle butterflies are closed. I guess when I'm trying to start the bike have the choke pulled all the way out,so that those butterflies are closed? Or is there another way of closing these up, without having the choke pulled all the way out?

Thanks for the reply BTW.

[TOOLS1]

The choke knob is the only way to operate the choke.
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[dllewis5]

Gotcha, so i need to have the choke knob pulled all the way out while trying to start it.  I know what ill be doing this weekend. haha. Today since it was decent out I figured I try to get it going. I put brand new plugs in her, checked for spark, cleaned the carbs about a week ago, and put it in some fresh gas. With he end resulting being a dead battery from attempting to start it so much. Ill give it a try as soon as I'm able to and give an update.

Thanks

[shinyribs]

These DOHC bikes hate to start cold if the accelerator pumps aren't working. Crank the throttle and see if all four are spraying fuel out of the little nozzle behind the choke plates.

But, starting fluid will easily fire a bike. Accel pump or no.

Since you have fuel ( fluid) and spark it should run.  A few things come to mind then.

1: spark is timed wrong. Either out of adjustment or the coils are firing the wrong cylinders. I'd check this next.

2: weak spark. Make sure your battery is strong. A weak battery gets even weaker during cranking. Weak spark is as useless as no spark.


3: cam ain't turning. Not very likely, but possible.

[dllewis5]

Hey guys finally had a chance to test out the bike to get her started. Still no luck, even having the choke pulled out. One of the cylinders just backfired a bit. I made a video to help give a better perspective of what I'm dealing with. Near the end of the video you can hear it backfire.

http://youtu.be/AHx4L0PyjRA

Thanks,

[TOOLS1]

There are a few things that could be going on here.
1. Your coil wires are crossed, but have had it running?
2. The timing is way off.
3. You are not getting gas into the cylinders.
4. Your ignition is not firing.
5. Your idle is set too high, or you are opening the throttle while trying to start the engine (these bikes will only start with the throttle closed.)
 However It seems like your pilot jets might be plugged #3.
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[dllewis5]

The wires should be correct but i'll take a look at it again. It was running back in June, but I changed the carburetors and hasn't started since. Currently the bike has the carburetor that was on it when it was running.



I think my problem is being caused by the ignition or the carbs. Since it backfired twice on me(in the video).
And i don't think starter fluid can get "old" and since the bike itself won't even start when spraying starter fluid.
Im thinking that where the ignition issue comes into play.


Ill take a stab at it when i get some time. This issue is starting to become irritating.

Thanks for the advice.