1981 XJ650 Build

I scored an 81' XJ650 from Craigslist for $100

 

hows it look got any pics

 

I see how this works now. I figure this is a good place to share my build. Last week I got my first street bike, an 81 XJ650. The guy I got it from was going to have his kid build it, but it never happened. He had it for 3 months, before that it sat for around 5 years, probably in a garage. My plan is to build a bobber eventually out of it. I got it as a project I could work on while I recovery from knee surgery.

Today was the first day I worked on it. I pulled the carbs and spent about 5 hours cleaning them. Tooks 3 cans of carb cleaner and 2 metal brushes, but they are much cleaner now. The gaskets and some other parts need to be replaced but otherwise they are in great shape.

After cleaning I installed the new battery I got as well as plugs (didn't have any when I go it.) It turns over and sounds good. After a few start attempts I checked the spark and found that cylinder 2 and 3 don't have any. I called it a night after that. I'm thinking either coil or maybe the battery was to low to power everything. Going to let it charge and try again tomorrow.

 

did you pull all the jets and clean them too and yes a good charge on the battery will make a big difference. waht did the fuel look like in the tank it will probably need a good cleaning.

 

Yeah, all the jets were blocked, gas in the tank smelled something feirce. I wish I could take a picture of smell.... The tank will have to be cleaned with some sort of solvent and some aggregate.

 

buddy of mine used a pressure washer in tank set in the sun to dry...... I advised him dump some alcohol in it to dry out moisture...... you mgiht be able to use clean river pebbles and then rinse with alcohol ..

 

I did some electrical work on the bike today, looks like both coils are good. I get spark on cylinder 1 & 4 and when I reverse the coils I get spark. I found a wireing diagram. I checked the connection point for the positive in the wiring harnase. It was a bit nasty so I cut it out and re-sodered it. Farther down the electrical line I'm pretty sure theres a short. If the ignition is on and I wigle the harnese next to the fuse box the netural light goes out. Havn't found that short yet. Back to the spark issue, I'm thinking it may have something to do with the ground to the coil. It uses a green/yellow wire which is not shared with the other coil. Traceing it back through the ignitor uint it goes to the pick-up coil, might be loose in there. I think i'm going to have to break down tomorrow and find my multi-meter or replace it. Has anyone seen issues with the pick up coil or power not getting to one of the coils?

 

Anyone have any advice to trouble-shoot the electrical system on the coils?

 

After cleaning I installed the new battery I got as well as plugs (didn't have any when I go it.) It turns over and sounds good. After a few start attempts I checked the spark and found that cylinder 2 and 3 don't have any. I called it a night after that. I'm thinking either coil or maybe the battery was to low to power everything. Going to let it charge and try again tomorrow.[/quote]

2&3 use the same coil ...check the ground wire for the coil Mine had a broken ring terminal under the tank only it was a black wire.


OOPS! didn't read far enough. Your already on to it. OBTW those carb bowls were pretty gummy. Not sure if you know but one of those bowl drillings has a jet in the bottom that's small like .3mm and is part of the idle ckt. They are almost always plugged with goo. most install an inline filter.

 

I'll keep an inline filter in mind. I was thinking about running one for the first few tanks of gas then replaceing it incase there was some more goop somewhere else.

I think the CDI box is the issue with the coils. Have a look, leeky cap's are never a good thing to see.

 

How about a pic or two of the whole bike? Nice job cleaning those carbs.

 

Finally got some solder wick and was able to pull the CDI box apart. Heres a close up, I'm not sure thoes caps are leaking. Looks kind of like glue or a sealent or something. Either way, I'm gonna solder it back togeather again and try it out after messing with it. I got my tools back from a friend so this week i'm going to dig into the bottom part of the wireing, I'm still hopefull its a loose wire down in the deepths of the bike....

 

Well after putting the CDI back togeather again I'm getting no spark in any cyilnder. New one from e-bay is on its way.

 

Yeah our CDI boxes can be finicky - even frustratingly annoying when it gets damp out. Good luck with the "new" one!

 

Got the "new" CDI box today. Still no spark in cylinders 2&3....

 

I would put a large amount of money on you're TCI (CDI) being the culprit. You switched your ignition coils both work, pickup coils are pretty indesructable, and finding a shorted wire would make everything too easy. I spent over a month working out this problem when I first started with my XJ. After replacing my suspected kaput TCI with a working one off ebay, I found after that month of troubleshooting everything else that both off my TCI's were Kaput... A third one resolved the issue.

 

Really, you went though 3 CDI boxes till you got a good one? I tried the new one yesterday and it didn't solve the problem. Still no spark in 2&3. I tested the whole system again (as best I could) and still have the same symtons. I even cut the wireing harnase apart and all the wires looks good, no rot or broken wires. The next thing I'm thinking of is the Ignition Pick Up could be off. Although I kind of doubt it because its just a magnit right? The rotor passes the one on the bottom and cylinder's 1&4 spark then the top one and nothing, even though I'm getting 12v from the red/white that connects to the coil. There seems to be something that is causing a short/break/gremlen on the other wire(gray wire?) from the coil, which leads to the top of the rotor in the ignition pick up.

So do you think I should try another CDI/TCI box or try a new pick up first?

Thanks,
Perry

 

I think I have solved my spark issue. I dissasembled the plugs which connect to the CDI box. When I reverse the Orange and Gray wire I get spark in 2&3 but not in 1&4. I can reverse the Black and Brown wires in any combination and nothing changes with the spark. I'm quite confident that the pickup was the issue all along. A "new" one is on the way.

Perry

 

Progress!! I got a new pickup coil from E-bay off of a 81 Seca. Hooked it up and I'm getting spark in all cylinders now. I'm working on starting it now, it's made a few noises and some back fires. I'm thinking the batt is to flat now to do any good and may have a fuel delivery issue. Bike is charging now going to try again in a little bit.

 

So I played with it for a bit, the longest it would run for was about 2 seconds. It backfired a few times, spudders and made some a few other noises. I think the carbs are still durty, going to open them up again tomorrow.