DO IT NOW...COMPRESSION TEST AND SYNC CARBS!

I was prompted by one of our members to post this forum. In June last year I bought my 650. I did'nt know much about bikes but have liked them since highschool. I bought the Haynes manual and Owner's manual. Came on line found and joined this website in August. I am a Sheet Metal Journeyman so I am used to using tools and equipment. I started tinckering with my bike in my garage (with some verbal support from my wife) and got it to start. Took a Rider's course and started riding. Got "bit by the ride" and before long the 17.5k miles on the speedo now reads 19.5k. I decided to open it up one day and it started sputtering and dumped a large amount of fuel/oil from the airbox. I posted a thread and was told to do a compression test. I did and I am now in the process of a top-end overhaul. For all xjers new to these bikes it is essential that you do a compression test, check your valves clearance and clean and sync your carbs. And the proper spark plugs will help also. I can't wait to get this put back together and post the before and after pics. Thanks for listening and happy riding!



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rocs82650j 1st bike, 17.5k when I bought it, 19.5k now

Removed and cleaned front forks + seals
Replaced bent '82 handlebars with '81 handlebars
Rebuilt both control switches including re-soldering starter button
New s.s. mirrors
Replaced 2-3 coil
New seat cover and cushion
Rebuilt all flasher lights including making front flashers "runners".
New tires and brake pads (had local shop mount tires).
Rebuilt mc to caliper + new seals (the seals were leaking)
New clutch cable, replaced worn choke cable
New battery and solenoid
New oil filter, air filter and plugs
New intake boot clamps
New front foot pegs
Added new in-line fuel filter
Re-wired fuse box + new fuses
Cleaned carbs + carb kits, set floats, bench sync'ed + pilot screws 2.75 turns out from bottom.
Replaced missing forward bolts in grab bar + adjusted shocks
New ignition switch
Replaced modified 550 pipes with stock 650 pipes.

In process:
Top-End Overhaul
Replace flasher unit, checked wiring with mulitmeter...it's bad.
NTB right side cover...it was missing
Replace petcock filter and gasket
Replace clutch friction discs

 

19.5 ? HA ! try 38,700 and still running strong !

 

Tell us what you FOUND when you pulled the head... the reason for the overhaul.

 

What I found? Do we really want to know...of course we do. A nickel sized hole in the cap of the piston. NOT GOOD! From the school of HARDKNOCKS...You've been warned. Check those clearances. Take those carbs to "Church". If not...get ready...hold on, you might be in for what I did...A whole lot of reading and highlighting, re-reading, pacing the floor, explaining the top-end overhaul process to my wife who did'nt have a clue as to what I was talking about, smoking too many cigarettes and praying I would'nt mess anything up while removing the head and jugs including not letting broken rings or dirt from the studs fall into the crankcase or dropping the chain. It's something I'd say most of us will eventually end up doing at some point if you continue to own one of these bikes or we would'nt be able to oversize 4 times. This, however, is NOT, I repeat...NOT the reason you want to have to do a top-end overhaul.

Oh, and fakeplay...39k, cool and encouraging. I'm hoping this one, and everyone else that owns one get 100k. I did'nt know what I had when I bought it and I know our members are biased to them but it seems that everyone I talk to including the "Big Harley" riders I work with say it's a strong bike. The more I work on it and learn about it, the more I like it. I thought when I got it I'd ride it for a couple years, then sell it for a 1100. Not anymore. As long as I can get the parts for it and keep it running strong...it stays.

 

sounds like you're hooked... like a lot of us. just can't get away from these bikes and check craigslist for barn finds everyday lol

thanks for your story!

 

Appreciate that. When I get it running right and able to ride again I KNOW I will be. When I first told my wife I was going to buy it she said i didn't need a motorcycle that I am too old. So if I don't get this put back together and running it might turn into one of those "She told me so". I'm just a regular old dude...43, married, 19 yrs, actually 17, but I'm also counting the 2 yrs we dated before we got married (Smiles). Two teenagers, 16 and 14. Starting to do their own thing. My son has his permit. My babygirl can't wait to get hers. Wanted something to do when I finish a work week and house chores and don't want to become a complete couch potatoe. (We enjoy a good flick, ball games, and the likes.) Seems like yesterday I was 18 standing on those yellow footprints at MCRD San Diego and yet I'll be half a century in 6 years. Not a bad thing, age is wisdom. While I'm embracing my age I'm in no hurry to be 50. Thing is...most of us, including those who live long lives, don't live long enough to explore 1/3 of all the wonderful things this world has to offer. Hence the adage...Life is Short". I'm trying to embrace "living" with the hope that on my day I can pass without regrets. I hope to be able to say on that day, "It was what it was, it is what it is...SO MOTE IT BE.

 

It's not just the valve clearances that need to be check. I put a hole in my 1100 because #3 was running way lean. I had just completed a valve adjustment a couple of week before the mishap. I ended up swapping in a donor engine.

I had purchased my XJ750 with the intent of keeping it forever...I ended up trading it for 2 XS1100 (but my wife still has her XJ750 that I can ride anytime) and I have only 2 weeks to my 50th so I understand what you are saying. I got my first rode bike when I was 45. The extended family called it a midlife crisis but it's going to last me the rest of my life.

If you have them show pictures of the damage. I might drive home the point. (and we're kind of morbid we like pictures, even broken bikes)

 

I was just about to do a thread titled the exact same thing, rocs! Do a compression test! Everybody!

I let my bike sit for 11 years due to gas/oil mix coming out the air filter. Well, I just went through the carbs meticulously, had to replace #2 carb body due to a seized pilot jet. Replaced all pilot jets, float needles & other parts. Bench synced, wet set and valves put in spec. After 11 years it fired right up. Even sounded & responded well. BUT... would not run without full choke (pilot mixtures 2.5 turns out) & smoked when I gave it throttle. Decided to do a compression test with results of 75 65 78 88. Now, I'm in the planning & tool gathering stage of a top end rebuild. Kinda pumped about the procedure but not about the cost.

A compression test should be done when any odd or out of the ordinary symptom arises (assuming valve clearances are in spec first). These are 30 year old bikes with many owners (in some cases). No telling when a valve/valve guide/piston/ring/gasket is gonna give up the ghost.

Do you have a build thread going? I'm interested in seeing that hole.

Good luck with the rebuild. Follow the manual, use the right tools and recruit some help getting those jugs off and on. That's what I'm gonna do.

 

The factory recommends a compression test after every valve clearance check/adjust. I do it once a season before I put the bike up for the winter, just for the logbook. It helps you stay on top of the motor, and gives you a warm fuzzy feeling when you have good numbers.

CJmax, I think you're going to find rusty/stuck rings at the worst; I'll be surprised at any serious damage. Lap the valves and replace the valve stem seals while it's apart.

Things like a compression test are just a part of a good regimen in the proper servicing of your old bike. Doing all the inspections recommended by the manual isn't always necessary at quite the tight intervals they specify (other than valves) but you do need to do them to keep your motor healthy and your bike safe. The better job you do preventively the fewer rude surprises you'll be dealt; and a compression test is just a good habit to get into.

 

Glad to see you've been studying,reading, learning, and experiencing. Funny, you're preaching to the choir. Well, sort of.........many of us already know those things and are constantly telling people those things. Many listen, many try to fight it and ignore it. So, it's nice to see a newbie saying basically, "Guess what I learned that MUST BE done!".

Glad you're hooked, and please know that if you take care of your XJ you'll be riding it a long LONG time. 42,000 on the one I sold this past summer and a valve check was part of the deal--had to move two around, swap out one that was all. Of course, I don't ride hard......But-- these bikes will go 100,000 easy.

Dave Fox

 

CJ and any others with this problem. Hopefully it's just your rings. My head and jugs are off my bike. My thought was I'd take them to a local shop and have them lap the valves and hone the jugs since I didn't have the equipment to do it. I have the necessary equipment to do the valve and carbs maintenance every 5k miles. Turns out, one shop referred me to another shop who referred me to another shop annnnnnnnd......now my head is in my garage with the combustion chambers full of seafoam getting decarbonized and I finished cleaning my jugs this weekend. I've been taking a lot of pics since I decided to do the work myself including pics of that #3 piston with the hole in it. I still have yet to perform the newbie "Hat Trick"...putting it all back together...everything inclusive, rechecking the valve clearances, syncing the carbs and having it idle at 1k rpm. I've read and viewed quite a few threads from various forums including the one about using Elmer's glue and a carb straw in the channel on the valve cover to help the gasket spread and flush with the head. Take your time, follow your book and do forum searches and post questions....keep us informed. I will try to get some pics posted real soon.


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rocs82650, 1st bike

 

Elmer's glue and a carb straw in the channel ? please explain ? Thanks

 

There is a channel in the valve cover. The cover gasket has a rib on top running completely around it. The rib is glued in the channel. There is mention of a member using a high heat adhesive to glue the gasket to the cover. The thread also said that this particular member uses Elmer's glue to fasten his gasket to his head. Search>Forums>cover gasket replacement. You can read the thread. Hope this helps.


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rocs82650, 1st bike

 

Or you can just use spray gasket sealer sprayed into a cup and applied with a small brush.

The whole point being to "glue" the gasket to the cover, then lightly lube the other side so it will seal tightly and still come back off easily.

 

Note - If you painted your valve cover or head, the Elmers Glue would provide for a water based clean-up of what might squish out, rather than risking wiping around with solvents over fresh paint (of questionable quality).