1981 Maxim XJ 650 restore project

Hello everyone. I am brand new to this forum, and hoping there is some help for me, because I am not a mechanic, but I would like to get this old beauty back up and running after more than 20 years. First things first, I did everything wrong when I stopped riding the bike. I didn't empty the gas, change the oil, ect.... My first child was being born, and any and all money and care went to him.
Now that he's an adult,( ya right) I am going to try to restore the bike. I have taken the carbs off the bike and cleaned them, but I broke one of the posts off down towards the base of the carb. Does anyone have any ideas as to how to fix this delema? I'm sure it will be the first of many.
Thanks for any and all help in advance.

Glen

 

Pics of the carb damage? Nice first name, btw. I'm Glen as well.

 

I will send some pics when I'm done work, and thanks for the fast reply!

 

there are a few ways to fix broken float posts. threads are posted someplace including someone who welds them or just get another carb body.
carb body 1 is unique carb 4 is unique 2 and 3 are interchangeable but the throttle shafts must be correct for position.


thread to read
The Information Overload Hour

and how to clean those carbs
IN THE CHURCH OF CLEAN

 

Here is a pic. I tried some Marine weld, but it didn't work. Hard to rough up the area.

 

jb weld and such things do not last.

 

Since the break is so low it could be TIG welded. Epoxy, alone, won't be a permanent fix.

 

What if I was to drill a small hole in the post and the bowl, and insert a pin to keep it in place?

 

you can do that with pressure fit.

 

You would have to bisect the break with a diagonal pin, with it secured together in original position. Still it could shift and affect the carb. Personally I would tack it back with my TIG welder. The body needs to be stripped to do that. You will always have to use a post support to reinstall/remove the float pin if you repair it by any means.

 

https://www.xjbikes.com/forums/search/6630812/?q=float+post+repair&o=date

 

Could I drill a hole on both sides of the post diagonally and screw the post to the base with a self taping screw? Just wondering? I can't reinstall yet anyways because I need new gaskets, and the drain screw is really stuck. I don't want to strip the head so I have it soaking in carb cleaner.

 

you will need to apply some heat to drain screws and bowl help free it up

post repair 1
http://www.yamaha-triples.org/workshop/Mikuni_MKII_Post_Repair.pdf

 

post repair 3
jim-french-precision-welding-broken-float-post.117989


best way is to buy a carb body.

 

If you have a mill you can drill for a center core pin. Anything else is going to be a hack repair unless it is TIG welded. Try what you feel comfortable doing but be ready to buy a used body. Brazing will require too much general heat on the carb body to be doable.

 

https://www.ebay.com/itm/USED-CARBU...915014?hash=item26099b1286:g:KaYAAOSwUu5b6cKa

 

Do you have any idea where I can get a used one from? I don't trust ebay too much. Never know what you are going to get, and when you are going to get it.

 

post in the wanted section many members here have carb bodies

 

Thanks for the info. I have posted, and had a reply! This site is awesome!!!

 

Can't do much until I get a new carb, so I started doing some cleaning. Just used some tinfoil and water. What a difference after 20+ years of sitting.

 

I was thinking of taking the starter off this weekend, and cleaning it up, or is there something else I should do first since the bike has sat for so long?

 

Well, I found my old regestration from 1992. That was the last year I rode the bike. Turns out, the bike is an 82, not an 81. I don't think that should change anything with the rebuild.

 

After days of adding lube to the spark plug holes, and putting the bike in gear and manually turning the back wheel to free everything up, I had an old battery that I hooked up to the bike and tried short bursts to see if there was any compression in the cylinders. Low and behold the was!!! The engine isn't seized!

 

So I did a cold compression test, and the readings were
130
130
95
125
Is there anything I should be concerned about?

 

the 95 is a concern could be the rings are still stuck a second treatment of atf/acetone may help for that cylinder.
have you checked the valve clearences? that could be your issue too.

the 125 to 130 cylinders are in spec

 

I haven't tried that yet. What is the mixture for atf/acetone?

 

50/50 works table spoon and let it soak into the rings it will lube and dissolve the crud

to free up the rings if they are stuck

 

just courious what order did you test in? 1 2 4 3 ? battery could have just got weak on you

 

That's a good question. Lol. I think I went 1234, but I might have gone 1243. Brand new battery. I haven't started the bike yet because of a broken float post, and the carbs aren't on the bike. I'll test again tomorrow.

 

from info overload https://www.xjbikes.com/forums/threads/the-information-overload-hour.27544/
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. Yamaha specifies their compression pressures at 300 rpms (which is why the battery needs to be in good shape).


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

 

How long does it need to soak for?

 

a few days

 

As far as a new carb body, hit up @chacal

Mine is still repaired with JB weld, but I know it won’t last forever so I bought a spare so I can do a replacement this winter-or whenever it goes TU.

For my 700N it was $130.

 

I picked one up in the wanted section for $55 after postage.

 

While I wait for the new carb to be delivered, and while the cylinder is soaking in ATF/acetone, I was thinking of replacing the throttle shaft seals. Does the carb have to be completely disassembled to do this?

 

Yes and in my experience the butterfly screws will be your main problem. I had at least 1 screw on both sets I have snap off or have head strip out. The screws are very soft metal. The factory peens the tip of the screw on the back side so you have to deal with that to remove the screws. Sometimes they will back right out sometimes they won't.

 

Would heating them up first be ok to loosen them up? I don't think an impact driver would be a good tool there.

 

Heat will help but if you can use a dremel and smooth off the peened end of the screw it should come out a lot easier. I didn't do that.

 

He has Hitachi carbs on his 650 which aren't peened like the mikuni's on your 550. They can still be a bit of a pain but the proper sized JIS screwdriver, the right amount of torque in the right place and they usually come out without too much issue. Penetrating oil or heating may help just dont try to use both or you may end up with a fire. Use some locktite on the screws when you put them back together making sure the throttle blade is aligned properly in the bore

 

I use PB Blaster with a torch all the time. Smells great and gets rid of the gnats in the garage.

 

Any ideas as to where I can pick up throttle shaft seals?

 

@chacal for all your XJ needs

 

Go for a full out deluxe rebuild kit if you can swing it. Very nice to have everything right there to replace.

 

Put the carbs back on the bike, but I haven't cleaned the gunk out of the tank yet. Is there a way I can get gas to the carbs without the tank hooked up? Just want to test things.

 

You can either buy or make a remote fuel tank. You can also just fill the carbs using a 2-stroke mixing syringe and squirt fuel into the fuel line on the carbs.
I make my tanks from old steel lawnmower fuel tanks, but most anything that can safely hold fuel will do.

This thread has plenty of ideas. Pay attention to my post on page 2 (well...pay attention to all of the posts, but tht one in particular, because safety).
homemade-aux-fuel-tank.41309

 

Hooked up a makeshift gas tank made of a coffee can and brass fittings. The bike started, but reved like crazy. Shut it off right away. What would make it rev like that?

 

first thing to check is the choke and throttle cables reversed on carbs.
did you shut off choke when bike starts running away that's what the choke does as bike warms up or if bike is warm enough.

check throttle cable adjustment and that cable is sitting fully in cup and linkage is not binding.

turn down idle knob rear of carbs


this link shows carbs throttle linkage middle of carb outter bracket clamp style is choke
https://www.xjbikes.com/forums/threads/owww-my-eyes.112790/

 

I feel so dumb. Forgot to put the air cleaner and cover back on. I'll try and start the bike again tomorrow.

 

Shouldn't rev high with the filter removed if everything else is OK.
That will lean the fuel mixture out, but not enough to keep it from holding an idle.

 

I took the cover off the front brake reservoir, to find everything crystallized. Is there any way to clean that before I replace the brake lines and brakes?