1981 XJ 550 Won’t turn over

Hey,
So the last couple of weeks been working on my 1981 XJ550. The bike ran (not perfectly) but was able to turn over about a month ago. here’s what I did in to the bike
1. Cleaned carbs( Did not separate into 4 singular carbs )
In the carbs I replaced
The top diaphragm, new main jet, new float needle float bowl gasket.
2. New petcock
3. New boots
4. Painted engine ( without taking apart)

some back ground
battery is fine have it on the charger when trying to start.
the spark plugs work
I can see fuel going down the fuel line
Has had starting problems in past but turns over after a few tries.

When I hit the starter button the starter rotates and I can heart the pistons going up and down. Just no firing

only other problem noticed after put back together is when the bike is in gear and the clutch is pulled in the bike doesn’t want to move freely but once moved back and forth for a bit becomes easier but becomes hard again once stop moving.
In neutral bike moves normally. Haven’t done an oil change in a few months but did not ride very far in that time maybe 10 rides less than 100km since last oil change. Put in a new clutch plates before last oil change.

What I think it might be
1. Idle screw not in right position
2. Fuel not entering engine.
3. Clutch causing starting problems
4. Bike is broken

 

So be more specific:

Turning over: means the engine turns, pistons and valves are not seized. Engine can turn over with either the starter, or by hand (wrench, rotate wheel, etc.....)

fires: engine turns over and tries to run

doesn’t turn over: doesn’t rotate due to something seized or a dead battery, etc.....

sounds like yours turns over but doesn’t fire.

rolling resistance sounds normal

 

Hog...you beat me to it.....

Hi and welcome to the board.

Just wanted to clear something up here. The bike is "turning over" as you can hear the pistons going up and down, but it is not "starting"

Not too sure how long you have had the bike and I see that you have done some work on the carbs. Those carbs will need a lot of TLC if they are nasty and will be one of the projects that will take you the longest to do on your bike. The next would be doing the valve checks as you have to take off the valve covers and inspect each valve. Have you done the valves yet?

Spark, yes those older plugs wires normally need to have a very small portion of the ends taken off them to get the "green" part of the wire removed. Look at the spark plug boot pip as it screws into the plug wire. Clean that up good and make sure none of the green nasty stuff is on there either. Adding some dialectic grease is a good idea to help with electrical bonding of the wire to the plug.

How are the fuses looking? Have you taken all of them out, checked them to make sure they are good? Check the connections they fit into for corrosion and refit them. This can be done to all the connectors on the bike if you have not done so in the past. These bikes are older and some of seen bad weather, water, snow or what ever over the yrs. This will cause issues inside some of the connectors. If you have not gone though them you should to clean them up. Make sure you remover the "-" negative battery lead first as you would hate to short something out.

Good luck with the trouble shooting and keep us posted.

 

We've had similar problems years ago with a 550 and it turned out to be a faulty pickup element of the ignition.

 

this is a normal thing untill the oil warms up.

unless you put the clutch in wrong.



do not try to start bike with charger hooked to it it can damage tci.

 

I’ve never had any problem starting anything with a charger on it. Heck, I’ve never disconnected a charger until after whatever I’m charging has started.

 

Some updates...
I have owned the bike for about 6months, I bought it off of a close friend who is fairly mechanical and took decent care of the motorcycle and just let it sit for a few months while he was working on his second bike. When I bought it had starting issues ( most likely firing ) but would run after multiple tries. About 4 months ago I had a family friend who is a heavy duty mechanic but works and rides motorcycles on the side( hobby) to help me because gas was leaking out of the oil air filter, the problem was loose main jet. He also checked other parts of the bike including spark plugs.

When I took the carbs off to clean this past week they were fairly clean because they were cleaned about 4 months ago by a semi pro. I mainly just took them off to replace some of the parts in hopes of the bike running better.

So after work yesterday I did some more investigating( still did not fire). Firstly, I loosened the screw on the bottom of the float bowl and gas came out so the bowls fill up. Secondly, I checked the fuses. they all were fine( not broken) but I did noticed that one of the fuses wasn't connected properly so I connected it properly. Thirdly, the spark plugs and boots all spark and are cleaned but just to see if it was the spark plugs I replaced two of them to see if that would make a difference. Finally, In the past I would leave the battery on the charger while trying to start the bike. The battery would go from 14.8volts to 10-11volts when trying to start it. Also according to the charger the battery capacity would go from 90%-less than 50%. when I hold the starter the I hold it for maybe 1o-20 seconds max ( even that seems long). So I got a new 12 volt battery, just been preparing it. just have to put it in now hopefully that solves the firng problem.

thank you for all your help, pls let me know if there is anything I am missing.

cheers

 

I do this as well. Maybe I am wrong, but I theorize the charger, even a 1 or 4 amp version, will help keep the voltage from sagging on a weak battery below the threshold where the ignition won't fire the plugs.

Is my theory correct?

 

Voltage dropping that low doesn’t usually give enough voltage to fire up. It’s just enough to spin the engine. Sound like your battery is toast.

if the battery is tested to be a good hot battery, then you have another serious drain somewhere. But, I’d start at the battery now that we got this update

 

Sort of.
The real issue is with damaging the charger since the starter draws a whole lot more than 4 amps. The charger will die from that sort of abuse.
You really want a 50 amp boost/charger, or ona of those wonderfully inexpensive and compact LiOn boosters.

 

Try starting it off a car battery providing the car engine is not running.

 

Doesn’t matter if it’s running either

 

Jump start didn’t work on the new battery. But left the bike for an hr or so on charge and it made one back fire but that was it and cannot re create it.

 

1. The backfire was probably from loaded up fuel.

2.what exactly do you mean by “gas is leaking out of the oil air filter”? Are you running pods? Is your crankcase full of gas?

3. How old is your “New Battery”?

4. carbs- now I’m concerned
A. Cleaned 4 months ago—they should be spotless
B. By a semi-pro - what EXACTLY did he do
C. Replace SOME parts - what EXACTLY did U do
D. what initial settings did you use?
Bench-sync them befor re-installing?
E. Check valve clearances?

still gotta trouble-shoot the battery issue, though.....

 

Final updates,

The bike finally runs!!!

Heres what I did. Firstly, I covered the air filter end of the carbs with some cloths to reduce the amount of air flow into the carbs and the engine started to make firing noises ( back firing) not too sure on the terminology. but still would not fully fire up. Then we made sure it wasn't the spark plugs so I replaced all 4 and made sure they sparked. Then I sprayed some carb cleaner directly into the carbs and it fired up quickly at a really high rpm. we might have sprayed too much in so I let the carb cleaner evaporate by wiping the carbs down and taking the spark plugs off and letting the bike air out. Then when we tried to start the bike up again it did the same started at a high rpm but I could control the rpm by restricting the air into the carbs. After a little bit of time searching the internet my buddy ( the one that sold me the bike) came by and noticed that the throttle bar that opens the butterfly valve he could push it down more even with slack in the throttle line. So we took the carbs off they seemed fine once off butterfly valves closed. So we put it back on this time making sure it was not catching on the boots. tried to start her up again and she ran perfectly started up no problem. I believe that why it was not starting before had something to do with fuel, air mixture.

thank you guys for all your help

cheers

 

2. I have pods and their was gas in the crankcase before like in October but we drained the oil and fixed that problem then( did not ride it during this time) the problem was the O-ring on the piece were the gas goes into the float bowls was very compressed and did not create a tight seal allowing gas to just continuously enter the float bowls even if the floats were up.

3. The new battery is 100% new bought it from the store put the acid in my self.
4. B he is a heavy duty mechanic, who has worked on bikes as a hobby.
C. New diaphragms, New gas intake, New gasket, New float stopper needle.
D. have not synced carbs