Crank no start

[jmcclish]

Hello everyone I am a new member. I just picked up a 81 xs4 about 2 weeks ago.

I was told it has not ran since last year.

-Electric and kick start.
-Straight pipes and pod filters

-I have replaced the fuel lines and filter
-Cleaned fuel tank with vinegar and baking soda
-cleaned petcock

-checked plugs, gets spark and I cleaned them
- the bike has pressure from the exhaust and inlet holes for the spark plugs

It spins over fine but never fires. So I removed the carbs a few times and cleaned out the jets. 142.5 jets and I did a full turn plus half on the mix screws.

Every whole in the carb is free of degree, I soaked them in brake cleaner and gave them a thorough wiping. There is a lot of green residue over the bowls and floats.

 

[avemachina]

Have you checked your engine compression? Even if it does have some pressure, it might not be enough. If you've got fuel, spark, and air, that seems to be the questionable ingredient.

Check your battery voltage, and try 2.5 turns out on the mix screws, too.

 

[jmcclish]

Have you checked your engine compression? Even if it does have some pressure, it might not be enough. If you've got fuel, spark, and air, that seems to be the questionable ingredient.

Check your battery voltage, and try 2.5 turns out on the mix screws, too.

I'll check the pressure thoroughly tonight. And will correct the mix screws. I keep the bike on a 500ma maintainer

 

[CaptChrome]

Welcome to the forum and congrats on the new bike!

Sounds like a fuel issue if you have spark and compression. I second @avemachina's thought of opening up the idle mixture screws on each carb. I would go at least to 3 turns open especially with the pods and straight pipe exhaust - it might need even more with your stock pilot jets.

Also you probably will want to check the fuel level in the float bowls with a piece of clear tubing to make sure you have the level set correctly.

The float bowl level has a surprisingly large effect on fuel delivery. It should be 3 +/- 1mm down from the upper flange casting (I have a small black dot at that location in the photo.

 

[jmcclish]

So I did I turned the mix screw to 2.5-3 turns.
After kicking the bike of a few times it actually ran for about 2 seconds then died.
The choke was fully extended.

I checked the bowl levels to the best of my ability and one bowl is spot on and the other may be a little bit lower that where it should be.

I turned the mix screw a little more, removed my starter button and found that my cable had been frayed apart and a lot of rust. I cleaned the contacts and I have a cable on the way.

The bike would try to crank, but wouldn't. Maybe I turned the mix screw a little much? Or idl screw?

Any tips from here are greatly appreciated.

 

[avemachina]

So I did I turned the mix screw to 2.5-3 turns.
After kicking the bike of a few times it actually ran for about 2 seconds then died.
The choke was fully extended.

I checked the bowl levels to the best of my ability and one bowl is spot on and the other may be a little bit lower that where it should be.

I turned the mix screw a little more, removed my starter button and found that my cable had been frayed apart and a lot of rust. I cleaned the contacts and I have a cable on the way.

The bike would try to crank, but wouldn't. Maybe I turned the mix screw a little much? Or idl screw?

Any tips from here are greatly appreciated.

Hey, that's promising!

If it ran at that idle mix screw position, keep it there for now and you can adjust those later. The choke (technically it's a fuel enricher) being extended might mean you need to clean the carbs and adjust the other stuff (balance and float level)--if there's something blocking fuel flow, or the float level isn't providing the right amount of fuel, it'll die off.

 

[tstidham]

When I first got my 78 running, I had cleaned the carbs three times, but in the last time I used a single strand of multistrand 10 or 12 ga copper wire to ream out all the jets and ports while using brake cleaner. The pilot jet had the most crud the pushed out of them with the wire, even though they eyeballed clear. But you really need to remove every jet in the bowl area and clear them as well as the main jet tube. Also inspect each idle jet mixture screw tip and make sure no one overtightened them in the past and snapped a tip off.