Reviving my 81 xj 550 maxim

I introduced myself a while back in general chat but didn't have my bike at my house at the time. I purchased my maxim 14 years ago, rode it for 3 or 4 years, then stored it when I got a newer bike due to it running like crap (of course it wasn't my fault). I was young & didn't maintain it the way an older bike should be. I sold my Intruder years ago & recently got the bug to ride again since many of my friends now finally have bikes (they were a little late to the game ). So, time to get this bike going again.

This thread will be heavy with pics mainly for my own reference and for anyone else that may catch something I miss or to chime in if they want to call shenanigans. I've got mechanical knowledge and fab skills but not much experience with the YICS bikes. With research and a little help from the great minds on this site, I strongly feel I can turn this bike into what I'm lookin for. And I do mean great minds on this site. I've been reading thread after thread on this site for about 3 months now and the vast information on such a specific group of cycles, the XJ's, blows my mind.

I'm not planning on riding this bike for a while. This first phase will be to get the bike to fire and at the very least run very poorly. I want to make sure it is worth putting the money into. I'll then check valve shims & resync the carbs with the YICS tool, replace front brake line and check rear drum for delamination. The front tire also needs replaced.

So here is the bike. After being stored in a farm shed for 6 years and various other places for years before, it's not in bad shape. We loaded it up on the trailer to be brought 3.5 hrs out to my house next time dad came out here.





My dad makes a great workhorse :lol:




The tank looks a bit goofy. I used it as a test piece when I repainted a truck years ago. A friend of mine tried getting the maxim going years ago, and in his efforts, sanded down the tank.


Yesterday it arrived at my house and today I started tearing into it.
First, I washed it to remove dust & grime so i don't get filthy every time I touch it.












The seat doesn't look too bad. I thought for sure the the field mice would get to it or the skunks that laid claim to it under the tarp. It really stank when I uncovered it.




Then I removed the seat, tank & battery. I filled the battery back up & set it on the charger just for the hell of it. I also removed the gas cap and petcock from the tank.







I then disassembled the petcock and left several parts to soak in some Lysol overnight along with the rubber boots from the carbs. Which means I pulled the carbs next.






It looks like my friend had the rack apart since he numbered the carbs.




He also unfortunately used silicone cauk on several things when he reassemled so who knows what he did in there.










I also noticed the choke pulls (?) are not set equally either so I would gather a bench set wasn't done. I guess he thought he'd just slap them back together and...viola!

The clutch arm spring has a tab broken off so I will need to get one.





I'm gonna have to clean out the inside of the tank since it has quite a bit of rust. I'll research that. Tomorrow, I'm gonna pull apart those carbs & start investigating.


A different friend gave me his old Honda CB 400T Hawk. When we graduated college, he had no where to put it so he gave it to me since I had the means to store it. I'm gonna have to do some major work to it though. It either has a blown piston or rod. The last ride we went on it limped back to the house sounding like someone rattling a wrench in a coffee can. Otherwise, a very clean platform to build from. It's gonna have to wait though.

 

The Maxim's actually in remarkably good shape.

The little bits and pieces that you'll need are easy, get ahold of chacal. Stick to your game plan and you'll have a nice rideable bike in no time.

 

Actually with as long as it has been parked BOTH tires need to be replaced.

Looks like you have a good list going, and Fitz is right, the bike looks to be in VERY good shape. Shouldn't take long at all to get her back on the road.

And that 400 project looks like a fun one too, keep us posted on that one also!

 

I started disassembling the carbs today.

The guy that tried to get this bike going a few years ago didn't go easy on the silicone. It's everywhere; the fuel channels between the carbs, the caps on top of the carbs and slide diaphram, the fuel bowl. The inside bottom of the fuel bowl is a mixture of varnish and dissolved silicone.

I've fully disassembled carb 4 EXCEPT for the throttle shafts. I can not get the screws for the buttlerfly to come loose. I'm using a screw driver that fits perfectly but will not budge. I don't want to strip the screws. Does anyone know a good solvent I can use to soak the carb body (with throttle shafts & gasket in) to break up the vanish but not the throttle shaft gaskets?

 

Oh, and I was wanting to compression test the cylinders. BUT I was going to put some mystery oil in the cylinders to keep from scoring the walls when I turn it over. That will skew my compression #'s. What do you all think?

 

Mikuni butterfly screws are peened over on the backside to keep them from unscrewing. You need to open the butterflies and hold them there (a half-moon lengthwise slice from an appropriate diameter dowel works well) and VERY CAREFULLY file the back end off the screws before trying to remove them. If you got the others out already it's a miracle.

You'll need to use new screws and Loctite on reassembly.

It's not a good idea to soak the carbs in anything if the throttle shaft seals are still in them.

Put some MMO in, roll the motor over a few, then wait before doing the compression test. Might want to get the valves in spec before worrying too much about the compression numbers; a couple of too-tight valves can give you wonky readings.

 

I started on carb 4 (don't know why). The right screw on the butterfly broke free (I did not remove it to keep it tight while trying to loosen the other) but the left screw would not even budge. I stopped there before stripped it. I think I will just skip the throttle shaft seals & hope they're not hashed. I know my friend wasn't in there since those screws were not stripped like everything else.

Good point on the compression test. That will come after valve clearances.

 

This is what happens when silicone cauk is used for carb assembly. It turns into a jelly and then gets everywhere.









Carb 4 went well. Disassembled, cleaned all parts and reassembled greasing the float bowl gasket and other things. PB blaster wet sanded the slide bore with 800 then 1000 grit and polished the slide and jet needle. Clunk test perfect. I will need a float bowl drain screw (will wait to from chacal until I disassemble all 4).


Carb 3 did not go as planned. Popped the fuel bowl to find this...



A broken float pin tower. At least the tower that is broken is not the one for the press fit of the float pin. The pin actually holds the float just as tight so i'm not too sore about it.

The PO almost had the pilot jet stripped. Knowing its brass, I dug in a bit with a sharper screw driver & was able to remove. Will need a new one but no big deal.



I FUBAR'd the drain screw on carb 3 though...
It was already fully stripped, so I drilled a small hole down, switched to a few bigger bits, and tried to chizal it loose. The head twisted off down to the O ring. Looks like I'll just set the float to match one of the others and JB weld the drain closed. I do not have extraction bits that small

 

Just swap float bowls (with one with a good drain screw) to set the float height on the one with the buggered drain screw.

You might want to pick up a "parts rack" of carbs off eBay. I got mine for under $20; all it takes is a float bowl or carb body replacement to make it worth your investment.

I would fix the broken float pin tower so you can be sure that one float won't always have "issues."

 

I also had a broken float tower when I pulled the crabs on my latest Xj, had to use carbs of the parts bike. Its not fixable the float pin might hold it but once the carbs are on the float will not work properly.
The bike looks great and keeps up the good work.
Al

 

Well, the pilot jet on carb 2 is stripped. So, I guess a different set of carbs is in order. (considering micro extractor bits)

Are the 550's the only ones that came with these Mikunis?

 

The 650 and 750 have Hitachi’s im not sure about the 700 and 750 x, I think the 900 have Mikunis to but would not fit a 550 because there to big, so there are no other carbs that will fit(with out modifications).
Keep up the great work.
Al

 

My last post was just frustration and desperation. :? I was still hoping this was just gonna be a take apart/clean/reassemble job. I was only fooling myself. I'm serious about getting these carbs perfectly clean!

So, I did find a very small Easy Out here at work that I will try tonight. Gonna also apply some Olive Oil and heat to help penetrate the threads.

I was also having issues removing the float valve seat & was able to remove one. I scuffed up the outside of the exposed portion with some needle nose pliers but I don't believe it will effect anything. I'll file smooth the shards as not to allow any deposits to take hold.

Emulsion tube was a lot easier to remove than I first thought. The hardest part was removing the main jet washer. Then, I used a large punch that matched the diameter perfectly to get it started (small light taps) then used a pencil to get it the rest of the way down (the pencil cleared the locating pin). After it was out, I swabbed the bore with a copper brush from my gun cleaning kit wetting it with carb cleaner to get the deposits off. Worked like a charm.
Still have to polish the emulsion tubes.

The screws on the butterflies are another story. I can only break free one of the screws on each butterfly. I'm seriously considering just drilling a hole in each of the other ones to hopefully relieve some of the pressure. Those throttle shafts need to come out.

I ran across a thread someone post a while back with a pdf writeup on replacing the throttle shaft seals. I can't seem to find it with search. Anyone have a link to that?
thanks

 

The plot thickens with a broken easy off stuck in there.... ugh....I'll never be able to drill it out. Back to cussing in the garage...

 

I filed down one of the screws for the butterfly.





I used some small metal files that I had. It took a while but I was careful not to damage the butterfly or the main bore.

Unfortunately, the screw will still not budge. Applied heat with no help. I don't think that screw can take much more. Any Ideas?


The offending pilot jet with broken Easy Out lodged in...

 

So, I've been creating some polished carb parts porn the last couple of days. Each carb has all of it's parts polished to this degree.










If you ever run across this stuff, Noxon, purchase it. It will polish pretty much every metal you put it on. Just pouring it on brass starts the polishing. Takes rust off very well also. Don't remember where I got it 14 years ago to polish some aluminum parts on this bike.




I'm also compiling a list of parts to order through xj4ever. Then I can get these carbs buttoned up.

I was able to get the throttle shaft out on carb #2 without damaging the butterfly screws. It's my test carb so I don't think I'll do that to the other carbs. It also didn't move as freely as the other carbs, something was binding it up. The plastic washer was missing on the spring side which was causing the aluminum spacer to dig into the carb body a bit. Polished all the parts.



CLEAN YOU ENRICHMENT TUBE PORT on the float bowl. This port gets easily clogged (being that it is down in the float bowl). From what I understand, having this port nice and clean greatly helps starting ability.

I purchased these little dental brushes at walmart for about 3 bucks for a pack of 30.




Spray some carb cleaner in both the holes (wear safety glasses, these little clogged ports will easily back spray you in the face) and work at it with the dental brush. Don't push hard (they easily bend) just keep spinning it and adding carb cleaner. Let the brush do the work. Work at it from both holes.






when you make it through, check with a little pen light to see the hole.



After I get the old varnished cleaned out, I polish the port with some Noxon and the little brushes and Q-tips for the larger portion of the port. Just make sure to get all the polish out. Follow up with swabbing out with carb cleaner to get all polish out.

 

Also, I used that Noxon as a wet sanding agent on the slide port. With 1200 grit it came out almost as a mirror finish. I'm so excited about the throttle response I will gain from the polished slide ports. They never went clunk before.

 

I was able to save a float bowl! Finally got the drain screw with the ripped off head to come out with an easy out. I'm 1 for 1 with easy outs on this carb.

 

While waiting on a line on some carbs to pan out, I Inspected my exhaust & noticed some holes that needed to be patched on my mufflers. I tried to take off the mufflers with the exhaust on the bike but it wasn't working so I pull the whole exhaust off.




The collector is actually in pretty good shape




Some of the muffler holes to patch. They are bigger than they look.









And all patched up. Definitely gonna have to paint them now so it's not noticable. Not gonna win any contests but should help keep the pressure right. Still have to weld a pipe in each tip. It easily burned through in a few spots due to weak rusted mufflers so I had to patch the burn throughs also.






Anyone have a rack of 550 carbs they wanna sell? Or even the #2 carb?