Help,Bike not starting.

[dllewis5]

Hey everyone,

Ive been working on this project for about a year now, and I have hit a wall. I need some help in trying to figure out why my bike won't start. Last year I around this time I had it running after cleaning the carbs,after getting it going ended up removing the carbs due a leakage of gas between each individual carb(o-ring was bad).
AFTER doing so, my bike has not started since.

Just to give you guys an idea of what I have done to try getting it started:
1.new spark plugs
2.checked the coils and wires(good to go)
3.Checked the fuses
4.new battery
5.cleaned the carbs and jets
6.new tank, and making sure gas is getting to carbs itself(it does)
7. as far as compression, i haven't used a gauge to test the compression.but i can tell it has a lot .
8.made sure that the butterflies(on the intake side of the carbs are closed(thanks TOOLS)), and having the choke pulled out, when attempting to start.

Below is a video i made to give you guys an idea of whats going on....the weather is starting to break and this becoming very frustrating. ANY HELP AND ADVICE PLSS & THANK YOU.


https://youtu.be/soei5KonqGw

[TOOLS1]

It sounds like the timing is off. Did you somehow get your wires to your coils crossed? Also, If it will not fire in 15-20 seconds of cranking, 5 minutes of cranking is not going to change anything, other then burn up the starter.
TOOLS

[dllewis5]

The wires should be fine, I followed the diagram(see pic below) from the Clymer manual of how it should be.

In regards to the timing, what else should I check for?

[TOOLS1]

The yellow, and blue wires could be switched in other places, as they have a few connections.
TOOLS

[motogrady]

After cranking for a bit, the plugs should be wet when you pull them.
When they are out, in the wire and grounded to the fins, in a dark garage or at night,you should see spark.
A blueish spark.

You have both of the above, and compression, wires mixed up or timing way off.

[Re-run]

Have you verified your fuel level in the bowls? Use 4 pieces of clear tubing and connect them to the over flow drains and then turn them up. Make sure they are not kinked and then open the drain screws. The fuel will go into the tubing to the same height that it is in the bowls. It could be your level is not high enough for fuel to be getting up the jets into the engine.

Without knowing your year, I can't say what your height should be, but the manual will have it. When you measure it. hold the carbs at about a 45 degree angle. The floats need to be closed but not pushing the little pins on the needles, in. Then measure from the gasket seat, at the middle of the float.

[TOOLS1]

After it cranks for awhile, you can hear it kick back against the starter just like it is 180* out of time.
TOOLS

[dllewis5]

I spent a little bit of time checking those connections. Everything is wired the same way as it was when it was running.

[dllewis5]

Ive never messed with the timing before, but based other people I've asked seems to think its something with the timing as well.

As for the gas getting to the bowls, when having the fuel on. I cracked open the drain screw and had gas coming out of them.

[TOOLS1]

Just because gas is in the float bowls does not mean it is getting into the combustion chambers. The gas still must go through the jets, and if they are plugged it will not go into the combustion chambers. However it sure sounds like timing the way it eventually kicks back. However just for reference, have you pulled any of the plugs, and checked for spark? It must be consistent, and not erratic.
TOOLS

[Maz]

Hi all, my '79 dohc did exactly the same after a 1 year rest. Fuel was getting to the carbs but no further (the plugs were dry). The strange thing is that I sprayed some 'Easy Start' (or Ether or whatever you guys in the US use) into the carb intakes and it fired right up and then just kept on running like nothing had happened. I didn't pull the carbs and clear the jets. It's been running fine ever since!

Maz

[LukeM]

You may have had fuel to the carbs, but the 79s and later had a fuel vacuum manifold thingie (sometimes called the Spawn of Satan or SoS).  As long as your motor has good vacuum, the SoS stays open and supplies fuel to the carbs.  If the engine is off, fuel doesn't get where it needs to be.

If the bike has sat for a week or so, you can expect to crank the starter quite a bit to get fuel to the carb bowls.

Luke M

[dllewis5]

I sure as hell hope the carbs are not plugged up, guess its worth taking off and checking again though.
This past Sunday when I made my video i checked the outside cylinder plugs(1 & 4) and they were dry, didn't even smell like gas(btw they are brand new).

What exactly would I check to see if the timing is off and or correct it?

Also the bike is a 1980 cb750c

[TOOLS1]

You could always try spraying some starting fluid into the carbs. It will either fire, or really kick back. As for the timing, a timing light is the best method.
TOOLS

[Re-run]

Spray just a little starting fluid, that shit is potent stuff and a little goes a long ways.

[dllewis5]

Ive actually tried using some starter fluid on it. I sprayed around the carbs(where my pods are at), I got nothing, not even a hesitation to start. Just the constant turnover of my engine.

Any ideas as to why it wouldn't start off of that??

BTW thanks for the input everyone.

[TOOLS1]

Ideas? Dead ignition, Have you checked for spark? Or maybe out of time.
TOOLS

[Re-run]

Take the pods off and spritz directly into the carb. If you still have nothing, you are looking at your spark then. I don't remember if you tested the coils or not, but the manual shows how to do it.

If those check out, check spark by being in a dark garage and test each plug by itself. Make sure fuel is off, but make sure kill switch is on. You have made sure the kill switch is on, right? It's ok if you missed that. It is sort of a rite of passage in a funny way as all riders do it sooner or later. Speaking of which, the switch could have gone bad. So you may want to pull the housing off and check that, taking care not to lose anything inside. I have seen switches look find but the contacts have corroded.

Just make sure you have spark at each plug.

If you still don't start, then we need to look at timing.

[dllewis5]

Sorry for the late reply.

So i took some starter fluid and sprayed it right down the carbs and attempted to start it. Still no luck!!

As for the coils and spark, I have tested each plug for spark and they all get fire and I even pulled each one out and smelled a small hint of gas on them. As for the ignition coils, I've never tested to see if they are good. Since I'm getting spark, they should be good right?

After doing all of this I decided to pull my carbs off and see what each bowl is looking like. When I pulled the carbs off, i noticed the boots had gas residue in them( see photos)





At this point I'm going to check to check each carb bowl and see what the jets look like.

As for the housing, I've only opened it once, when I changed handle bars. The bike has started since I have done that.

For some reason I'm thinking my coils may be the issue.

[Re-run]

Well, honestly, you should have gotten something with the starting fluid.

So at this point we should tackle the ignition issue.

Just to recap, I am going to run down a list. Some of which you may have already done.
How old are plugs? If there were in before you got the bike, get new ones.
Clip 1/2 inch off the end of each plug wire.
Test the cap for resistance, should be 5K ohms.
Make sure cap is screwed on tight.
Do NOT put in plugs yet.


Most likely, since you got nothing from starting fluid, your timing is way way off.

I just go through this list as weak spark is just plain bad.