One pipe isn't as hot...

... I know this because when I spit on all four headers #2, #3 and #4 burn off quickly. The spit doesn't burn off header #1 for a long time. Bike has reduced power.

This is a Canadian built 1983 XJ550 Seca with 15,000 km. Some unscrupulous jerk left her sitting outside in a Canadian winter for 3 or more years but I saved her from certain doom for $150.

So it's either fuel or spark, right? Could it be air?

Fuel:
- Did a recent carb job and double checked to make sure the air plunger on carb #1 is moving freely with no obstruction. Admittedly, it probably wasn't my finest carb job, I didn't split them and it was my first Mikuni. (I hate that company, incidentally.)
- Opened up drain on cylinder #1. Gas drains. Carb is getting fuel.
- Put gauges on intake manifolds #1 and #2. Both rise and fall at similar intervals when I throttle on and off.
- Transparent fuel filter is installed. Gas looks clean and flows.

Spark:
(In a nutshell, I think it has good spark.)
- When I hold plug #1 against engine block and hit the starter it seems to have loads of spark.
- Has new spark plugs. Old plugs look like they should at 15,000 km. All four look the same with a nice light brown hue and no moisture.
- Cleaned all electrical connections from battery to spark plug.
- Solonoid (or starter relay?) needs a tap every once in awhile to kick over.
- The bike does run with some power. I removed the spark plug cap off cylinder #1 while I was driving at about 50 km/h. Noticed no effect on power.
- I'm starting the bike off of a 12 v truck battery with jumper cables. Battery is outside of truck and charged nightly.

Air:
- Could the first header be clogged? I was going to check that but I got frustrated and gave up for the evening.
- Intake manifolds look a little sketchy and cracked. A thorough check during the carb job revealed no cracks through the rubber.

Other and also of note:
- I did compression test on all cylinders. All OK, including #1.
- Bike will only idle with the choke on.
- Bike is hard to cold start. Requires carb cleaner sprayed into the air box.

Thank you all in advance. I know that by this time tomorrow I'll have ten answers to the question above. May your starter chain guide last 200,000 kilometres and may your second gear never grind or crunch.

Best,

Aaron.

 

I thought you aren't supposed to let a coil fire without a circuit being completed on the high tension lines for fear of it damaging the TCI (i.e. when doing a compression test). I believe the 550's have the same wasted spark system as my 750 seca, so if you take the plug wire off of #1, #4 will not get spark either, because current flows from one wire to the spark plug, across the gap in the plug, through the engine head (this does not act as a ground) then across the gap of the other plug and back to the coil.

Not that this helps you with you're problem, I just wanted to warn against potentially damaging anything (I unknowingly didn't "ground" the spark plug when compression testing, but my TCI box still works).

 

Is that so? How do you do a compression test then?

 

Noted and thank you. Found it here:

http://www.xjbikes.com/Forums/viewtopic ... +test.html

 

Check the pilot jet on the offending cylinder. I don't have alot of spit so I use brake cleaner. When ever I have this situation I go right for the pilots.

 

Now that you’ve confirmed compression, spark and fuel you need to check for air leaks.

Get the 550 running then spray your starter fluid at the connection between the intake manifold and the motor at cylinder 1 (don’t forget to check the plug where you attached the gauge).
If no change then move to the connection between the manifold and the carb.

You might have an air leak between the carb and air box but it wouldn’t cause a no run lean condition.

Then check the throttle shaft, both sides of the carb, then the top of the carb, by this time you can just spray the whole carb and if NO change then it’s time to take em off.

Check the float level if the needle isn’t opening you wont get any fuel.

Good luck
albran

 

Set float levels using fluid, bench sync, check valve clearances-- then report back.

 

Thanks fellas. I'm going to try those suggestions right now and I'll get back to the post this afternoon.

 

Thank you albran,
- Sprayed all connections along cylinder 1 with cleaner - no effect.
- Sprayed carb #1 with cleaner - no effect
- Sprayed all four carbs with cleaner - no effect

Thank you Bigfitz,
- Forgot to mention I already bench synced.
- Forgot to mention the bike had a professional valve adjustment 3,000 km ago, though that was in 2004.
- Just checked float heights. Carb 1 exactly at lock washer on the float bowl. Checked others as well. All OK.

Also,
- Checked header 1 for obstruction - none.
- Just for fun, dumped a little oil down cylinder 1 - noticed no effect. Pipe did not heat.

Stumped again.

 

I really don't want to take the carb off but I guess that's next, eh? Is there anything else I should try first?

 

OK, so I reminded the first cylinder it was there by removing the filter cover and spraying starter fluid into that carb alone. It seemed to work because the cylinder started firing and the pipe heated up.

Now I don't trust my bench sync. I twisted the adjustment screw counter-clockwise 1.5 turns and it livened up cylinder #1. Now Cylinder #2 isn't as hot.

Looks like I'm taking off the carb and bench syncing. My YICS tool is with a friend out of town... dang it.

 

Bench Sync with Strips of 3X5 Card ... 1/4 Inch Wide.
Do 3 first.
Then, ... 4
1 & 2 ... ALL snuggly holding a strip of 3X5 Card with drag.

Preset the Pilot Mixture Screws:
Use a Golf Tee
Cut the Pointed Tip-end off ... Flat and Square
Coat the Golf Tee Shaft with Red Nail Polish
Use Machinists Ruler and MARK Golf Tee with Razor Blade Line

13/100ths -- (Thirteen - One Hundredths ... of One Inch)

Use Razor.
Scrape Polish and Paint off Tee LEAVING everything above the
13/100ths Line alone.

13/100ths is the Preset Depth for the Pilot Screws.
Turn the Pilot Screws IN until the TOP of the SCREW is down-in 13/100ths of an Inch.
Line the Golf Tee Painted Mark to the Top Of the Pilot Screw Holel.

Run it there and see how it goes.
Use the T for a Baseline if you get lost Tweaking.

 

Hey Rick, does that depth go for the 650RJ as well?

 

OK. Got the bench sync done. Pilot mixture tomorrow.

 

Even if it does, you only need a burr on a screw head & you're a turn out.

 

Update

Fuel:
Took off the carb, cleaned a bit more and bench synced. Reinstalled. Bike runs again but still not perfect. Cylinders 1 and 3 less hot. Moisture I spray (read: spit) lingers upon them. Moisture bounces right off headers 2 and 4, which are piping hot.

Spark:
- Cylinders 1 and 3 are sparking but maybe weak spark. When I remove plug cap one with the bike running it has no effect on engine. Conversely, when I remove plug cap 2 with bike running it stalls out almost immediately. - Checked power to both coils - have power.

Also of note, I experienced a temporary electrical failure when I shorted out the + jumper cable on the pipe by accident. Power stayed on bike but it would not start. Replaced fuse and no change. It ended up being the TCI connection. That unit sparked on the lime green wire when I disconnected. Reconnected and removed a few times before the starter worked. That connection had been recently cleaned with contact cleaner and sand paper.

Any suggestions? Replace coil perhaps? TCI? I saw a parts bike at my local wrecker.

Thanks all,

Aaron.

 

That's the DEPTH of the Top of the Pilot Mixture Screw on my 750 Maxim after ColorTuning and two Plug Chops.

It is NOT a FINAL Adjustment.
Just a suggestion for those who:

Do NOT Have a ColorTune and need a Preset Value to get them somewhere close to where they can have a KNOWN Preset Value and make adjustments ... accordingly.

 

OK. It's electrical. My local bike wrecker agreed to let me troubleshoot in their yard.