Bike died and now won't start

The bike: 82 XJ550 Seca. The background: this past Sunday, I put my carbs back together after having replaced a leaking T fuel connector. Because I had to break the rack, I bench synched them but didn't go beyond that. I stuck the rack back on and the bike started right up and all was good. As it warmed up though, the RPMs reved up, and I thought this was because my idle knob was now set at the wrong place. So I dialed it down and it was better. I took a short ride and it seemed to run well, although the idle was too high when I returned.

So yesterday, before I took it on a longer ride, I reached up and turned the idle knob counter clockwise to lower the idle somewhat, as I had been idling too high the day before as mentioned. I started the bike up and all was fine. I drove about 10 miles when the bike gradually started losing power and didn't seem to respond to the throttle. I got off at an exit, and the bike died when I let the throttle down as I approached the stop sign, and it hasn't started since. Even after I allowed it to cool so I could squeeze my hand in and rotate the idle knob clockwise, thinking that I had lowered the idle to the point where it would die. I had to get it towed home a few hours later.

So, am I right that the idle setting is the issue? I thought it was, but the fact that it wouldn't start again after it cooled makes me think I'm barking up the wrong tree here...

 

You don't have to answer this.
Did you turn the gas back on?

 

I don't find any question insulting, Polock. Yep - gas is turned on.

 

Sorry to say but you might want to start by doing a compression test; my thinking being if you inadvertently caused a vacuum leak (which could cause a high idle/racing) and then rode on it you might have cooked something. Let's hope not...

Did you re-check the float levels after replacing the fuel feed coupling?

You didn't simply run out of gas did you? Have you put it on "PRI" and checked for fuel flow?

 

Thanks for the input, Fitz. If I had a vacuum leak, I just figured it would of manifested itself in some running problems earlier in the game. I last did a compression test about 1000 miles ago and had great numbers. And nope, I didn't check my float levels after fixing my T-connector because since they were fine last fall, I didn't expect them to change come spring.

The tank is full and I'm running on the "winter gas". I did just change both my fuel line and filter and my vacuum tube as well.

 

Your idle issue sounds like the carbs are out of sync... I was having the same issue last week until I did a vacuum sync, been purring like a kitten since.

As to why it died, I'm thinking like the others - float levels. It won't even start if you crack the throttle a little?

 

When you replaced the vacuum line, did you use REAL vacuum line, or just tubing of the appropriate ID?

I ask because if it's not actual vacuum line, it can cave in on itself when it gets warm and restrict airflow, thus causing the bike to "run out of gas" because the petcock isn't operating properly.

 

It was real vacuum line from a motorcycle place.

OK, so when I get home today, I'll carefully check over my carbs and fuel/vacuum lines for any possible issues/leaks. If not, I'll try to start it again for a bit.

If the motor doesn't catch, I'm hesitant to pull the dang carbs again and open 'em up because all 4 floats don't go at the same time. At least a few of them should work. So yeah... I'm guessing there's a vacuum/petcock issue. I'll share what I find.

Thanks guys - without your advice, this would all be a LOT more frustrating.

 

I don't recall you mentioning your valve clearances in spec, unless I missed it.
I think vacuum syncing should've been done before actually riding it...while you had the tank off anyway. Bench sync will only get you close.
Oh and how's your battery/charging system... just to rule it out.

Sorry for your misfortune, man. Hope you get it figured out soon!

 

Open the oil filler and stick your nose down there to smell the crankcase oil. If it smells gassy, drain the oil, replace the oil filter. Then set your carb floats and synch the carbs.

 

Carb sync is probably your idle problem. I wanted to put a few miles on my little suzuki get the 5 years of sitting out of it. After about 3 miles the idle kept going up was idling about 3500 rpm when i got home. How do the plugs look wet or dry check spark then compression. If you do have a vac leak see if it runs on prime. You could of got a little piece of oring or trash in some of the seats from pulling the t out

 

Are you sure that it is gas, and not condensated water build up?
Also check the cap vent for plugging. Just to cover everthing.

Ghost

 

I wasn't able to complete my troubleshooting last night, but it appears to me it was a simple fuel issue. Remember how I mentioned I had changed my fuel line? Here's what it looked like:



You can see how's it's kinked somewhat. After straightening the line with my fingers and putting the petcock on prime, I saw the fuel running, and the bike did start, so I think I correctly diagnosed the problem. I didn't think it was that much of a problem (since I was able to ride off for 10 miles) but now I'm thinking it was. I admit to not liking these new types of see-through fuel lines; I liked the old school rubber ones. Here's the original one:



At least with those types, you didn't have to worry about them getting pinched in the same way.

Apparently, my fuel line runs better if it all slants down towards the carb for gravity's sake. I just thought the volume in the tank would create the pressure, but I seem to be wrong.

I've bought a longer piece of that same yellow fuel line (I seriously can't find the right diameter rubber stuff locally!), and will find a new route from the tank to the carbs tonight and see if that takes care of the problem.

One last piece of advice please: is there a starting setting anyone can recommend for the idle knob? I'm guessing all the way counter clockwise until it stops, and then 1/4 turn back or something?

Thanks!

 

Hi Wirehairs - Midwest Cycle Supply in south Mpls has black rubber fuel line. I might have some spare too, I'll look....

Mk

 

The idle knob has a pretty wide range of adjustment and it really depends on the vacuum sync for the entire set of carbs. Basically you want to set the idle to 1250rpm. If the RPM gauge doesn't work, you kinda just have to play it by ear. It should be just at the point where you can pretty much hear each cylinder firing individually. If you have doubts, Rev a 4-cyl car to 1200 and listen to what that sounds like.

The clear line won't work because it gets too hot on top of the motor and overheats. Any excess pressure from routing will cause it to kink.

Any 1/4" fuel line will work better than the clear stuff.

 

XJ4Ever carries the original style molded-in-a-curve rubber line, as well as "restoration proper" actual motorcycle fuel line as originally used. Neither are expensive. Space is kind of tight under a 550 tank, I'd recommend the molded rubber piece and the smaller-OD motorcycle fuel line.

It's what I used.