want to confirm next steps after smelling gas from oil filler opening

Looks okay, little bit on the low side though:

Cylinder Compression Gauge:

Yamaha recommends that you perform a compression test every 5,000 miles or so, and that you should record the readings, per cylinder, for future comparison and evaluation. The acceptable readings (specified at sea level) are as follows:

To do a compression test properly, you should first make sure all of your engine valves are properly adjusted to their recommended clearances, as valves that are too "tight" (not enough clearance) will allow the intake or exhaust valve to be open more than is necessary, or at the wrong time within the compression stroke cycle, thus bleeding off compression that would otherwise be developed.

http://www.xjbikes.com/forums/threads/compression-test-xj650.113151

Do not use thread adapters or the like on your pressure gauge, as the added volume of air space within the adapter will reduce the indicated pressure readings.

a) make sure the engine is cool/cold, 60F is the ideal temperature to take measurements at,

b) remove all spark plugs, and then stick the plugs back into their caps and make sure the plugs are grounded to the cylinder head (or even better, disconnect your TCI unit).

c) remove the airbox filter lid and the air filter.

d) make sure the battery is FULLY charged, and remains so throughout the course of these tests! It is actually recommended that for purposes of compression testing that the TCI be un-plugged and jumper cables to a large capacity battery (i.e. car battery) be used to make sure that the cranking speed remains pretty constant between each reading. Slow or sluggish cranking speeds will reduce the indicated compression pressure.

e) open the throttle FULLY and keep it open during testing.

f) crank the engine over until the needle stops advancing.

g) Let the starter cool down for a minute or so, then do the next cylinder, etc.).

h) If the readings are below spec, then shoot about a teaspoon amount of motor oil into each cylinder, crank the engine over a few revolutions with the starter (to spread the oil around), and then re-test each cylinder using the above procedure.

i) compare the two results and analyze.

j) keep all of your figures, and note the date and mileage from your odometer, so you can compare the next time you take readings (every 5,000 miles or so).


The specified compression pressures should be:

XJ650 and XJ750 air-cooled engines:
Minimum: 128 psi
Standard: 156 psi
Maximum: 171 psi
Max. variance between lowest and highest: 14 psi

 

As Chacal pointed out, the numbers are a bit low. Follow step h in his instructions (adding oil to the cylinders). If the numbers go up, it could be that the rings dried out and weren't sealing properly. Another reason for the low numbers could be as simple as your tester. It might be reading low. If you repeat the test with a second meter, you can eliminate this.

 

Compression numbers are low, but not so low as to keep the engine from running properly.
Since the problem is with 1 and 2 (each running off of different ignition coils), and swapping plugs and wires hasn't changed that, the problem will be found in the carbs.

 

Remembering this time to hold the throttle open all the way and comparing 2 different testers, I have revised compression numbers:
Cylinder 1: 144
Cylinder 2: 140
Cylinder 3: 144
Cylinder 4: 151

So, it's not compression and it's not a coil or plugs. Echoing K-Moe (and the voice of dread in my head), it's got to be the carbs. So, I'll use my just-received Deluxe Complete Rebuild kit from XJ4Ever to rebuild the carbs from the "new" Seca and will swap them out when done. With everything else I need to complete before winter, it'll take a while, bit I'm hoping to ride it at least once more in 2017.

 

Reviving this thread, now that spring is here in Minnesota.

I did not take my spare carbs to church. Instead, working with the carbs from this bike. I re-cleaned the carbs. First, I disassembled them and soaked in Berryman's and used all my little wires and brushes. Then, I put the carb bodies in an ultrasonic cleaner, heated distilled water. I sprayed carb cleaner through all the passages, to make sure things were flowing through everywhere and reassembled them.

I remounted the carbs, used the enrichment circuit and fired it up. Sounded good, but when I felt the pipes, 1&2 were cold while 3&4 singed my fingertips. This leaves me exactly where I ended last season.

If it has to be the carbs, I'm at a loss for next steps.

Also, would a moderator kindly change the title to "Kosel's 82 650 Seca"? Thanks.

 

In my limited experience, I've learned that if you cleaned everything but did not change the float needles and seats to new matched pairs (Metal), you are seeing one of the faults you had to begin with. If those two cold cylinders have rubber needle valves they are sticking closed. I went round and round with my carbs through multiple openings and settings until I sent them out for full replacements.

Or, those two floats are way out of adjustment and not opening. I'm assuming you you dry set and then wet set the floats?

Even then, after the bowl fills the first time and the needles get stuck in the seats, it doesn't matter that the wet test looked correct. The valve just never opens again to admit more fuel...

 

New needles and seats last fall. Wet set the floats about an hour before starting it up. I'll check for the needles stuck closed, but considering these are the same symptoms I had at the end of last season, I'm not expecting to be that lucky.

 

could be the butterflies on 1 and 2 are closed to much from bench sync.
bad spark plugs or arcing spark plug wires, bad spark plug caps, corroded spark plug wire ends
are you sure of placement of wires 1 and 2?
be careful of tunnel vision maybe its not the carbs

 

When mine were sticking, it was with brand new needles too... that's when I learned they had to be a matched set. When I went to the metal ones I never had another issue with that.

I did however bite the bullet and had someone here do a soup to nuts rebuild of the whole carbs... $400 later for that but reliable ever since.

The other folks here have also repeatedly said that if you give the bowls in question a few good whacks with a screwdriver handle, that might free them up for the moment and you will at least know the carbs are flowing. When I did that successfully before full rebuild it would let me go for a ride... but then they would get stuck again when the bike sat a little...

 

To verify it is easy enough put petcock to PRI for a minute or two . Put back to ON , open the float bowl screw if you get a good amount of fuel then that is good if only a couple of ounces this will tell you float is either not opening or just barely . Agree with XJ550H this could be a coil issue or plug wire / plug cap or a bad spark plug .

 

it is possible and something I will check when I re-pull the carbs. I remember seeing a uniform sliver of light through each of the 4 when I was done.

last fall I moved the plugs but 1&2 remained cold. I also swapped wires 1 for 4 and 2 for 3 - still 1&2 remained cold. I also trimmed all plug wires.

I'm not 100% sure what you mean by this. The plug wires are labeled and the #2 wire is too short to reach the #1 cylinder.

 

I'm adding this to the list of things to check. FYI - I'm using an auxiliary tank

Yeah. I have a set from a second 650 Seca as well as a spare set in rough shape. I'm strongly thinking about outsourcing the re-do of one of those.

 

Had time to check the floats today. They are working as they should. Before I pull the carbs again, I will explore valve clearances, check timing, and check coils, plugs & wires.

 

The fantastic news is that my cold cylinders were cured by @hogfiddles taking my carbs to church for me. The bike fired up and I have 4 warm exhaust headers!!!!!

I completed the running sync and got that dialed in. I then puled the Colortune out of the drawer. For whatever reason, it never seems to work well for me. I adjust the mixture, blip the throttle and don't really see a difference.

Rather than screw things up, I'll leave them as set by hogfiddles and get the mixture dialed in by doing plug chops.

So, in the past 14 months, I've:

• taken the carbs to church (and was left at the altar)
• taken the carbs to church again (and again left at the altar)
• outsourced my carbs to @hogfiddles (Success!)
• replaced brake lines with stainless steel brake lines
• rebuilt the master cylinder
• rebuilt both brake calipers
• new brake rotors
• replaced brake pads
• replaced rear brake light switch
• new tach gear seals
• new exhaust header gaskets
  
• rebuilt the gas cap
• rebuilt the petcock
• replaced the fusebox
• wired up the neutral light
• new speedo cable
• new tach cable

...and I'm sure there are some other things I've forgotten about.

It's been a long (too long), frustrating, and incredible experience. I've never worked on any motorized anything prior to taking this on and I have to say thanks to everyone that hung in there to help me along the way. Also, a shoutout to @chacal for his incredible service and knowledge.

 

Actually, given your lack of prior experience and the inherent problems associated with trying to bring back a 30+ year old bike with spotty (or little) previous maintenance, you've done quite well and should be proud of yourself!

 

Absolutely he should be. Most would have given up long ago. He stuck with it and now... Congrats!

 

I agree, you've probably learnt a HECK of a lot....theres NO shame in asking Hogfiddles for help, I would have too, by this time, and HIS 'Church of Clean' is probably way better than most of our attempts anyway.....and carbs CAN be a nightmare, on the XJ's, unless maintained/set up correctly, but once they are set, they are usually good for quite a mileage!!!

 

Saturday I rode the bike on a 5-mile round trip to show a friend. After I stopped to show him, it didn't fire up right away, but did start. No issues either way.

Sunday I fired it up to warm up the oil for an oil change. It started right up without choke, but sputtered a bit, so I gave it about 1/3 choke and it was fine.

Monday (this morning) I rode it to work. Unfortunately, traffic was terrible; a lot of accidents meant a lot of stop/go. By the time I got to work, it didn't have much umph starting out in 1st until I got to around 3k rpms. Once moving, it was fine.

So, I'm asking if this is what others call "bogging down". Also, have I correctly read that it implies a rich mixture?

Thanks.

 

Pods or airbox?
I don't remember--did you check shims?
New plugs?
Seafoam?

 

I have the factory airbox. I did have some difficulty getting the number 3 airbox-to-carb boot to seat. When I would tighten the clamp, it would un-seat the boot. It looked fine before I put it all back together, but I will check with an inspection mirror when I get home.

Shims are all in spec. Double-checked while I had the carbs off.

The plugs were put in last year and only used in the garage during all this work, but not on the road. I cleaned them up with a brass brush before I did the 5-mile road test.

one possibility is that I put oil in the cylinders and tank for the long winter. I know the oil in the cylinders burned out when I was warming it up to do the running sync. And, I rinsed the tank with a bit of gas (and poured it out) before re-mounting it. I then put about 3 gallon of non-oxy in the tank.

I should put the Seafoam in the gas, I assume?