XJ 550 running fine, to running bad.

Hello everyone, I'm new to the site and I want to say this place is awesome. I recently acquired an XJ550 that had been torn down entirely by someone else and got it running fairly easily with the help of the threads already posted here.

Unfortunately I've hit a wall with the bike. When I first put it together it ran great, but now I can only get it to start with starting fluid while holding the throttle open. Once it's started, I have to hold the RPM's up with the throttle to keep it running and it runs very very rough.


Bike sat for a week while I waited for a new stator and rotor to come in. During that time the only thing I fiddled with was the pickup coil so I was thinking that the timing of the spark might be off. After some searching, I read in a thread here that removing and reinstalling the pickup coil does not affect timing. Before that week it started easy and ran smooth as silk, so I'm baffled as to why it's having such a hard time running now.

I rebuilt the carbs, they're clean but I cleaned them again. They were full of fuel like they should have been.
Good spark on all four
Tank I cleaned out and re-coated
Brand new petcock
New plugs and plug wires

I'm at a loss here so I figured I'd make a post and see if anyone had a similar problem or any advice to give.

Thanks for reading!

 

Sorry to tell you this but here are things to check...
First of all check your valves, next clean the carbs again and check float levels (besure to clean all passages), sync the carbs then color tune.
This will probably fix your issue.

 

Forgot to mention, valves were checked and found to be in spec suring rebuild, carbs were synced during rebuild as well.

 

okay, did you check the float levels before you sync'ed? Did you color tune?
All these things need to be done and in the proper order!

 

Yes, they were both done. I had the bike running but only drove it about 10 miles so I would think theyre still in sync but perhaps I need to do it again.

 

Stop and back up.

Did YOU check the valve clearances; now, since you've tried to get it running? Or are we taking somebody's word for it? Have YOU checked the compression?

WHO set the floats and sync'ed the carbs? You? Or are we taking somebody's word again?

YOU need to double check the valve clearances, wet-set the float levels and properly sync the carbs.

Or it won't run right. Those are absolutely required steps.

Between me and the OBD, we've got three fully functional and fine running 550s. Take our advice; if you want it done right you'll have to do it yourself, thoroughly and properly and in order.

Don't just take somebody's word for it. That's gonna get you nowhere.

 

I did all of that myself, before I had it running good the first time. I suppose I'll go back and do it all again to be sure.

 

So I've rechecked the valve clearances and they are all still in spec. I rechecked the float levels and they are in spec as well. Also did another bench sync and the bike still has the same issue. Is there anything else I should check up on? Is there anything I could have messed up when I removed the pickup coil or stator/rotor? I had the bike running perfect before I messed with those electrical components.

 

You need to properly sync. Bench sync only gets you close you then need to color tune also.

 

I'm still not sure how they would have gone out of sync just sitting in the garage. I can't color sync because it won't idle.

 

If it won't idle then your floats are probably not set right. Once you make sure the floats are set then you need to correctly sync the carbs then color tune.

 

What exactly did you do in regard to the pickup coil(s?)

What did you do with/to the stator and rotor? (although those would more affect battery charging than how the bike runs.)

 

Pickup coils I took off and cleaned up, stator and rotor I replaced.

 

Battery....It's not on your "done" list.
Did you have it on a battery tender for that week?
How old is the battery?

It may sound silly, but I have had bikes run like complete crap because the batt was weak. Just one more easy thing to check that can make tuning a nightmare if not done.

A bench sync should get you close enough to idle/run half way decent to finish the tune. Once you get this issue sorted out don't forget to re-sync and colortune.

 

The done list is huge, had the bike down to a sand blasted frame so I didn't include for the sake of time. But yes it has a brand new battery which I've kept on a tender since it first ran.

 

Is it getting fuel? You re-did the tank correct? Pull the tank and remove the petcock. See if there's debris preventing fuel flow.

 

Tank interior stripped and recoated, brand new petcock installed as well as new inline filter. Fuel pours out when I open the valve, float bowls full of fuel as well.

 

Two questions from carefully reading your posts so far:

Float levels-- WET set? I see "checked and OK" but that isn't the same as accurately wet-setting them, especially with the Mikunis.

Back to the ignition pickups: "cleaned them up." How? Did they get doused with brake/contact cleaner?

 

I wet set them during the rebuild before it ran the first few times. I checked them last week wet and they have not changed. Pickup coil assembly I removed and cleaned with 3m electric contact cleaner.

 

Ouch. Saturating the ignition pickup(s) with contact cleaner may have killed or wounded one or the other (or both) of them. This is the reason we don't use spray cleaners/strong solvents to clean the alternator stator either. Present-day solvent-based cleaners can penetrate the thirty year old "potted" insulation and wreak havoc.

You didn't use the same stuff to clean the spark plugs with by any chance? Spark plugs can also be saturated and "drowned" (even by flooding the engine.)

Have you installed a brand new set of NGK D8EA's, properly gapped, since this issue started?

If not, start there. Then diagnose the ignition pickups; you'll need a meter (volt/ohm.)

 

I didn't clean the plugs, just replaced them. Once during the rebuild, and once again after it quit running and I did gap them properly. Guess I'll break out the volt meter this weekend

 

OK, just trying to cover all bases. Do you have a factory book?

You mentioned blasting the frame; are the frame-to-engine ground straps all back in place and making good connections?

When stuff like this happens, I apply the "it ran yesterday theory." That being, no matter how many other things might be out of whack or needing attention, it WAS running and now suddenly IT AIN'T. The fifty-three other things that need doing didn't fail all at once; TWO probably didn't. So. What one thing, no matter how seemingly inconsequential, changed? It was ONE thing. What? Follow that line of thinking and you'll find it.

But yeah, you might need your meter.

 

No factory book or manuals, I built the whole thing from diagrams I found online and threads on this web site. I was really surprised when it started up on the first try. I sat for hours pondering what could have happened, went through the whole wiring harness again looking for anything out of place and the grounds are good. My room mate admitted to bumping it with his car but not enough to knock it over. Just going to have to keep after it.

 

Schpritzing the pickups with contact cleaner could have been the "one thing" I was talking about.

If you plan to keep/ride this bike GET A SERVICE MANUAL. You can snag a factory book off eBay for $15 if you know what to look for.

PM me with your email address and I'll send you the ignition troubleshooting pages from the book. These bikes are extremely COUNTER-intuitive at times; if you don't get a book it's gonna kick your butt.

 

Will do, thanks for your input.

 

Hey I love a good 550. We gotta get yours running right.



OK, two...

 

Beautiful! Both yours?

 

Yep. Check my sig. The black bike has 11K miles on the resto; the white bike around 10K on its resurrection.

The white one took about 5 ~6 months and caused me to join XJBikes; the black bike took 11 months and was well worth it.

Like I said, we gotta get yours running right.

 

Wow, props! I've only had mine since early March. I worked on it like mad and had it running in 3 weeks but responsibilities have since taken priority. Here's mine next to it's younger brother.

 

Nice bike. Put your bike info in your sig. Converted Maxim, huh?

But dude. I'm old. I like padding in my seat.

Especially for occasions like this:




My other bike is older yet: