Running bike sat for a bit, now doesn't want to start

Long time, no see to everyone here. Hadn't had much trouble out of the bike, and with limited knowledge just not much reason to hang out. Coming back, I kind of miss it. Here's my problem before I go off on a tangent.

A few weeks ago, I finally took my 82 XJ550 out of winter storage. (It's been a cooler than average spring in Michigan, as MiCarl can verify) When I did that, I noticed my battery cells were just above the low mark, so I topped them off with distilled water, and put it on the charger. Popped it in the bike, and after a couple tries, it fired right up, and ran all day without any problems.

Fast forward to yesterday... I had another chance to get her out of the garage, but this time, she would crank strong, but not start. I added a little starter fluid, and got a muffler backfire. The bike would crank strong, and I would get a couple rumbles from the exhaust; which suggests I have fuel, spark, and *some* compression, but it would never catch. Just a few rumbles and then die out.

When I last rode a few weeks ago, I did not top off the tank. My initial thought is that some water got into the fuel and has not quite worked its way out yet. Picked up some Dry Gas last night, but had to stop messing with the bike to get to work (was planning to two-wheel in.)

So, question is... am I on the right track, or is there something else I should be looking for? It just looks like something is giving it a bit of a hard time, but I don't want to make any assumptions. Worked on enough old steel (mainly my dad's Model T, my Olds, and a few assorted 20's vintage Chevy's) to know you never quite know what "issues" you inherited from PO's.

Thank you in advance for your help. Semper fi.

 

You have to start from the basics - can only be one of three things air, fuel or spark. If you had water in the gas it would drop to the bottom of the float bowls and probably not go far from there. You can do some basic checks by pulling a plug out and checking for spark, Air is a visual check of the filter - but fuel is the hardest to identify. These Mikuni carbs are not easy to clean, lots of little passages and holes. I have learned one important fact, the pilot jet hole is really important to clean out, if you can get the jet out of the carb (i have 4 sets of carbs and only 2 jets have ever come out with screwdriver - the rest are fused in there forever) then push a wire from a wire brush through the hole... its a really tiny hole but it plays a huge part in the idle and starting the bike. It supplies the pilot screw with fuel - so if its blocked - which it often is, then it means that you can do all the turns of those screws you want and buggerall will change. I would start there. You can drain the float bowls into a clear container at the same time and prove your "water in the fuel" theory.

 

I thought you'd got a Harley or something :lol:

Put the fuel valve on PRI for a minute or so before starting. The fuel will evaporate out of the bowls in a few days.

Did you put fuel stabilizer in for storage? Was the tank full? If the answer to either is false you're probably in for a carburetor dive in.

And we had some great weather in April. You have no excuse for letting your poor XJ sit so long. It's probably punishing you.

 

When it was in winter storage, I put Sta-Bil in the tank, and then topped it off. The last few weeks, it still has gas with Sta-Bil in it, but only about half a tank. Maybe I'm not letting it prime long enough. It ran great when it got out of winter storage.

As for not getting it out... I moved a few months ago when I got married, and my building doesn't allow motorcycles, so it's at my folks' house. I just wish it wouldn't punish me... gotta get my knees in the breeze. :roll:

 

If you let it sit without draining the Fuel Bowls, the gas in the Fuel Bowls likely evaporated leaving behind residue on the surfaces from which it evaporated.

That residue likely became loose and clogged your Jets once you tried to start it.
The Pilot Jets are too small for foreign matter to pass and become clogged quite easily.

My best guess is that you are going to have to pull the Carbs and do at least a lower-end cleaning to get your performance and starting back.

 

Thank goodness, no. Let it prime for a LONG time, and she fired right up. Thanks again, time to get on the road!