Carb adjustment headaches. Please Help!

I have an 82 Maxim 650

I had starter problems last year and after fixing that it would crank but not fire. Has good spark. The float bowl screws were all seized up making it difficult to tell the gas situation. I took the carbs off several times. it would fire on some cylinders and not others and I'd take it off again and adjust the floats and try again. Long story short....I messed it up and I need help!!

WHere it's at now. . .
It will fire up with choke but the idle is all screwed up. I can't run it long enough to actually get it warmed up because its running too rich within a minute or two clean plugs are thickly covered in black buildup and it won't run smooth.

The good:
All four plugs get blackened each time so at least all of them are firing.
It's dry black buildup not wet so rings are probably ok.
And it's not pouring gas out anywhere so the carbs aren't just overflowing.
I can now get my carbs off my bike in under 5 minutes and hooked back up in under ten.

The bad: I have no idea what to do now.
I've never broken the carbs from the rack and haven't messed with the setting screws because I don't have the tools or skills to sync them properly.(nor the money to pay someone to do it for me)
Last summer I thought I had it ready to go a couple times and each time it would go less than a mile and start racing then dying. Not sure what that was about. I've read that rubber gaskets between the carb bodies can rot out letting too much air in and causing the engine to race erratically. I took off the little 'E" clips on the outside carbs and the rubber looks great. So I didnt want to separate the carbs and risk messing it up more.

my method thus far is, clean the plugs, start it up and run a few minutes. It's responding to the choke, the throttle, and idle adjustment screw properly. But I can't get it to just idle. After maybe two minutes,choke off, idle screw up gradualy, it runs rougher and rougher til it dies. Then I pull the plugs again and they are all black after just a minute or two of running.

Please HELP.
Tell me what to do now. In non proffesional, girl terms would be especially helpful. I have the service manual and study it daily but i'm hoping there is something simple I'm missing Is there a trick to get the floats set right when they are off the bike and bowls removed?
Thanks Sarah

 

In the simplest terms..
You need to rebuild the 32 year old carbs completely and with extreme detail.
Make sure your valves clearances are in spec.
Proper bench sync.
Wet set the floats to spec
Running vacuum sync with YICS blocked.
Use a Colortune for final adjustment of the pilot screw.
Should be done with new spark plugs.

Without being able use the drain screws it is really difficult, but not impossible, to wet set the floats.

I found that olive oil and a torch will "cook" the corrosion and let you back out the drains. Also worked on the pilot screws. Be careful not to melt the carb bowl or body with to much heat.

Sorry if this isn't what you wanted to hear, but this is what it is going to take to get the bike running correctly..

Hope this helps

 

I agree that you will need to carefully clean the carbs and do all the things mentioned above. It looks a lot harder than it is and there are a lot of instructions and help on this forum to help you get through it all. You have to be patient and go slow and ask questions when needed.

Here is a sync set-up that I copied and it works great.
http://xjbikes.com/Forums/viewtopic/t=15650.html

carb cleaning:
http://xjbikes.com/Forums/viewtopic/t=2908.html

valves:
http://xjbikes.com/Forums/viewtopic/t=14827.html

setting floats:
http://www.xj4ever.com/setting%20fuel%20levels.pdf

bench sync:
http://xjbikes.com/Forums/viewtopic/t=6 ... bench.html

I have all these bookmarked for easy retrieval.

Rather than buy a special screwdriver to fit the jets, I simply took an old one I had and carefully ground it down to fit perfectly.

Unless you see issues with the rack, I wouldn't break the rack.

Good luck, the bikes are worth the time and effort.

 

Sarah, I would suggest strongly in breaking the rack and replacing the fuel rail seals and the throttle shaft seals when you rebuild and clean the carbs. The explanation for this is time and experience. I cleaned and rebuilt my carbs and three months later the fuel rail seals started to leak, after all, they are over 30 years old.

Most people expect to open one of these carbs and find a million little spring held parts that pop apart like a broken pocket watch. It is completely the opposite. Very few and usually very easy to deal with.

If you can't get the float bowl drains out, you might find a good mechanic, or a local machine shop to help out if you don't have the tools.

feel free to ask....answers are always free..

hope this helps

 

Hi Sarah, Ive got 2 complete xj 650's which I been working on for months . Short story stripped , cleaned , re jetted , 2 serts of carbs and bike still back firing and popping. From what Ive learnt carbs should suck at back when air filters are off. Got a friendly mechanic who knows what he is doing , and finally says I have to get the head off which we did . Valve settings were all over the place either too loose or too little , ( should be between 6 to 8 thou for both inlet and exhaust valves .. looks like valve was sticking as well so by week end will have head back( a bit poorer ) and start again. Luckily I got a new re bored barrell and pistons etc when I bought the 1 bike (stripped ) so been swopping parts around .
I'm also a retired do it your-selfer so made a lot of new friends searching. and spent many hrs learning.
Looks like you head needs to be skimmed and valves skimmed reset etc . good luck. Pity I live in S.Africa else I could help you.
Mervyn

 

my apologies Sarah not trying to hj your thread. mervyn, have your mech double check those valve shim spec numbers. he may be correct for s.Africa models but here in the states the intake and exhaust clearance are different.

 

The valve clearances specs for the XJ650 are .11 ~.15mm intake; and .16 ~.20mm exhaust. No matter where in the world.

The specs that show them the same for both intake and exhaust was a mistake Yamaha made at some point and it got picked up and carried by Haynes and others. There should be a sticker in your sidecover listing the correct clearances; which are what I posted above.

 

So guess what?? I figured it out and it was just a dumb oversight. I was reading other posts and found the problem. I pulled my carbs off and sure enough, I'd swtiched the pilot and main air jets in each carb. Proof you should not drink and tear apart your bike. I put it back together and it was running great on all cylinders, warmed up and idling just right. Grabbed my helmet and went on a test run. Made it a mile before I noticed something pouring out. Whipped around to head back to the house(I live in the woods and can't physcally push my bike back up the hill, learned that too many times) Got it home and it is pouring what seems to be a gas oil mixure from the airbox.
So....what did I miss??
The sad thing is I had this happen once before on a bike and can't for the life of me remember what was going on.

 

I just gotta say, I LOVE THIS SITE!
Anyways, looked at other posts and sounds like I have stuck float/s. I'm heading out to pull the carbs again. But I had a couple other questions.
The air filter is coated in the gas/oil mixture. Can I just blow it out and let it air dry or do I need to get a new one? And also I was planning to change the oil once it was running good anyways, so I have the yamaha oil already. But I'm curious if I should run some regular motor oil for now so that if I don't fix it the first time I don't wreck my fresh oil.. Like put clean crap oil in it and let it warm up to see if it's going to suck Gas back or not. And if it doesn't, THEN change to the good stuff. Money is an issue for me. I don't want to hurt my bike tho. I want to make sure I get all the gas out.

 

Did the gas make its way into the oil? Pop the top and take a whiff.

 

to rocs82650.
Hi re the xj650 1980/1981 h series valve clearances questions posed last few days
I checked the side covers .... no luck re checked the workshop manual which state as I advised to Sarah (ie)"should be between 6 to 8 thou for both inlet and exhaust valves" or equivalent in mm
I dont understand your technology (copied) ""Solid" 17.8k in 6/11, 33k now"
Please could u translate/
Also another post from bigfittz52 said "specs for the XJ650 are .11 ~.15mm intake; and .16 ~.20mm exhaust. No matter where in the world." Unquote.
I am now confussed . Already told the engineer to use the manual figures!! Am I in trouble???
Mervyn (South Africa)

 

The clearances that Fitz posted are correct. The clearances in the Manual are a misprint that has never been corrected; do not use the specs that are in the manual.

 

as Fitz stated the manual is wrong for the 650. the shim intake clearance is .11mm - .15mm; exhaust is .16mm -.20mm. It is NOT .16mm - .20mm for both.The info in my signature is for my bike. Her name is "Solid", she had 17k on her when I got her, she has 34k on her now.

Gary

 

Drained the oil and is was as much gas as oil I think. Very thin. I put fresh oil in it and turned it over a couple times to spread it around. I pull the carbs and the floats all looked fine. The diaghram assembly thing( the cylinder thing that is supposed to slide up and down) wasn't sliding smoothly on two carbs. I don't know if that could cause the gas in the oil and pouring out problem, but that's the only thing I could see that wasn't quite right. And suggestions what else I should do before I go put them back in?
There was a Ton of gas in the oil. could that much have made it in in under two miles? The petcock seems fine(when turned to "on" gas only comes out when it's running.)
I'm ready to get back out there but getting pretty tired of taking it apart each day. Anything else I should check before I try it again?

 

If you had gas in the oil and the petcock works properly, then one or more of your floats are sticking open or set way too high. You'll need to wet set the floats before you reinstall the carbs or you'll just end up polluting the new oil with gas. Wet setting will also reveal a sticking float if present.
http://www.xj4ever.com/setting%20fuel%20levels.pdf

The slides (diaphragm assemblies) should move up and down freely. Have a look at this:
http://xjbikes.com/Forums/viewtopic/t=1 ... art=0.html