Idle issues

I have a 82 xj550 maxim that I got next to nothing. I rode it home last year from where I got it from. But the choke had to stay on. Over the winter I rebuilt the carbs . I did replace 1 pilot jet and all the valve needles( I believe that what there called. New fuel and fuel lines and vacuum line to the cock pit. Cleaned the it . New plugs ,adjusted the float height. The slides work the same so no issues with that.

Started it up have the idel set to just under 1500rpms. After it warms up (About 10 mins).

So here is my little problem . With the choke open at 1st start up its at 5000. Is this common? If not how do I take care of it ? After it warmed up the choke is off idling just under 1500rpms. I give it some gas as the ideal comes back down it wants to hang out at 2500rpms for a minute or so. I have check all cables nothing is binding . Oh I did also sync the up with vacuum gages.

Ps I know my grammar suck lol

Thank for the help.

 

First thing I'd do is check for vacuum leaks - you can use an unlit propane torch on low and waft it around the intake boots, airbox boots, and throttle shaft - these are the most common places to leak - and if the revs go up, you know you have a vac leak. Or you can use carb cleaner or starter fluid and spray around the same places. Just wipe it off any surfaces when you're done testing to prevent any discoloration of the rubber.

Also make sure that your vacuum line coming off carb #3 (or one of the others) is plugged into your fuel petcock, or at least plugged if you have issues with the petcock, and the others are plugged with a rubber cap. 1500RPM is a bit high, should be closer to 1000RPM.

 

Thanks will do a leak test. Will keep posted

 

Did you break the rack?
Did you replace the throttle shaft seals?

 

Did you fully disassemble the carbs when you rebuilt them? If not your probably gonna have to do it again and replace all of the rubber orings and seals.

You set the floats but did you do a wet set?
Here's a link on that if you didn't.
http://www.xj4ever.com/setting fuel levels.pdf

Also, did you sync the carbs after the rebuild?
If not, that will cause an idle issue.

I'd visit the church... Helped me a lot.
https://xjbikes.com/forums/threads/in-the-church-of-clean.14692/

And if you really want to read something here ya go!
https://xjbikes.com/forums/threads/the-information-overload-hour.27544/

Hope this helps!

 

with choke on the rpms will climb to 5000rpm. the "choke" is an enrichment circuit. it dumps fuel into the carbs. try setting to 1/2 choke or none at all when starting.
I only need to use choke in cold weather.
set your idle to 1200 rpm the spec is 1050rpm but 1200 eliminates the chain slap sound.
make sure the enrichment plungers are closing when you shut the choke off ,push down on them.
are you using stock paper air filter?

 

No I did split the carbs. I did set float to 21.5mm. Just a a paper filter. Got it running with the idle down to about 1200rpm rides it for about a half hour no issues. . Yep drop here in northern Michigan. Now it will not fire up getting spark and fuel and it does have a new battery .
Thinking maybe weak spark??

 

setting floats is just the beginning of setting fuel levels you need to check the wet level and set properly

Setting the fuel levels

what happens after a half hour?

keep battery charged if it drops below 10 volts when cranking bike will not start. even new battery can be bad.

 

Battery is fine . It turns over very well. The only thing that happen after I rides it last is that it rained hard for a day. Going to check the spark if cap. Making sure it's getting good connection.

 

Well I did some inspecting of the coils.and found this. . Could I epoxy it for a short until I can get a new one? And I will be getting a new one here shortly. And should I just do both at the same time

 

You can epoxy it forever. We used to do that when there were no alternatives.

 

Ok have new plugs again and new coils plus caps. Fires up again . But still a hanging idle. Going to propane test this weekend. Check for leaks. Never wet tested float height as I understand that it needs to be 3mm below the top of the fuel bowl. Now will that cause a hanging idle??.
Will a air leak from where ever show on plugs. As rich or lean? Plus should I polish the slides ? They do seem to move alright and about the same.

I am all ears.

 

Sounds like a vacuum leak to me. Vacuum synch? Colortune?

 

Well just did a wet test after about 10min riding it. And yes I did let it warm up I was ravening up to drop the idle down and then stall out and I just can't get it adjusted happy medium to get it to run did Chuck what test it supposed to be 3 mm from the top of the lower fuel bowl I'm about Lovin would that have anything to do with it

 

Well just did a wet test after about 10min riding it. And yes I did let it warm up I was ravening up to drop the idle down and then stall out and I just can't get it adjusted happy medium to get it to run did Chuck what test it supposed to be 3 mm from the top of the lower fuel bowl I'm about Lovin would that have anything to do with it

 

The fuel height affects the ability of the jeets to pick fuel up from the bowl. Too low will cause a lean condition.
The float bowl levels are supposed to be checked with the carbs on the bench, and fully level.
setting fuel levels.pdf

 

Ok did a wet test for float height. I am 11mm from the top of the bowl. I know it needs to be 3mm .
Could that be apart of my issue . Goi my to rest set it later to day . But before that I want to leak test it with propane.
Since I will be taking carbs out again. I should polish up where the slide goes.
Anything else I should do ?

 

Heck yes that's the problem. No wonder she's lean.


Under no circumstances should the slides be polished. There is a coating that has to stay on them, and it's very thin. Pull the top hats. Lift the slides until they don't quite clear the top of the bore, then let go. If they go 'clunk' then everything is fine. If they stick, or slide down slowly, then you can take some 800 grit wet-and-dry and clean up the bore (not the slide).

 

Time to rip apart again lol. But I want this bike to run right.

 

All you need to do is adjust the float heights at this point. Don't make any other changes until you've ran her with the fuel levels set correctly.
There might still be something else that needs tended to, but you'll jsut be grasping in the dark unless you tackle one thing at a time and confirm what effect it has.

 

That sounds right should j still do a propane test since I pulling carbs again?
Or wait unt ok that problem is solved first. And what is a easyer way to pull these carbs. I have it down the way I have been doing it but is there a better way?
I am very mechanically incline.
The guy I got it from did check valves there all good . Just did not want to mess with the carbs. And i will check slides again and bore with pix.

 

Ok readjusted my float and now I have and strieght idle now can get it down 1200 and stay running. So I do have a slow hanging idle. Some times it stays but most times it will go down.
Going to build a syncing. And never heard of colortune. What is it?

 

color tune is a clear spark plug used to see the flame inside the cylinder . it is used to adjust the pilot jet fuel/air mixture

 

p209_Gunson_Colortune_See_Through_Spark_Plug_Kit.html

 

I'm on my second brand new colortune and cannot seem to nail down the art of the process. Previous Maxim I rebuilt ran well, but as soon as I'd put the colortune on the thing would act like it was missing and you'd see a brief glimpse of the combustion color, otherwise you'd just see arcing either above or below the clear window.

Anyone run into this problem? On my previous colortune I tried throwing some electrical tape just above the clear window, but the thing would still spark and arc out and the bike would barely run. On my Seca Turbo it's the exact issue. As soon as I take the plug out and reinstall the spark plug the bike fires right up and idles as it should, but for whatever reason I cannot and have never been able to use a colortune.

Almost feel like tuning based on the spark plug coloring is more accurate in my case.

 

Are you using the extension lead that comes with the plug?
They did have problems with them arcing, and were replacing faulty ones free of charge the last time I checked.

Alternatively you can make sure the crimps are tight, and wrap it with tape that's rated for high voltage (above 35 kilovolts). The black vinyl stuff that most stores stock is only rated to insulate up to 660 volts

 

Yeah, using the extension and black plastic tubes.

 

I did move tubes closer. Can get it close. Read some where people using nig welding tops to restrict it a bit. I think that will help bounce around a lot. When tuning. Did use it and can I say it sounds way better. . .
Do need new clamps for the carb boots. The original are all the way and still loose a bit but no air leaks

 

Don't think I need colortune. All is still factory and I have the stock air box.

 

If the carbs were cleaned properly, then the idle mixture screws came out of the carbs. You need to reset the mixture. Plug chops work, but the colortune saves time.

 

I have never took them out.
Did fire it for about a half hour. As I would come to a stop i would have a hanging idle and other time I don't.
Going to redo a propane test .
And is there a stranded way on synching. Like syncing crab 2 with 3 them 1 or 4 ?? Is there a more accurate sequence?

 

syncing crab is a little hard.

syncing carbs you want to sync carb 1 and 2 then sync carb 3 and 4 to finish you sync carb 2 and 3

 

Did you break the rack when you cleaned the carbs?
I'm thinking that the throttle shaft seals my be no longer sealing.

 

No I did not break the carbs. Just re did a propane test no leaks that I have found.

 

Leaky throttle shaft seals aren't always obvious when doing a propane test.
I have no reservations in telling you that the throttle shaft seals are probably hardened, and not sealing properly.

 

Ok . Today it ran great . No issues .
Until......
I started it back up. It was idling about 1300rpm . Let idle for a bit then put of know where the idle shot up 5000. I didn't touch anything it did it all on own.

Any clues . I did a propane test right after that to . No leaks. Spent a good 2min per carb on that test.

 

Got ya but it ran great for a bit today then it was idling for like 5min and the the idle shot up to 5000

 

If I redone my carbs again I will set by set go through it in a new thread. Along with checking valve clearance. Those where done to but I'll redo it and share

 

How do I sync all 4 carbs when there is only 3 adjustment screws

 

the carbs are all synced to #3 the idle knob sets 3 to your starting point. you syn 4 to 3 with the #4 carb sync screw.
1 and 2 are synced then when you sync 2 to 3, you are bringing 1 along for the ride with 2.

my 650 manual has you syncing 1&2 then 3&4 then 2&3. the 3 carb is the baseline for the other 3 carbs

 

Oh that makes sense

 

Ok did some more reading on the throttle shaft seals. So if there wore out. And card still cool it fine after warm up and riding and while riding it ldles up.
So with all that movement it will re seal then leak. Or the vibration might make a leak or seal.
Am I understand that correctly??

 

the different metals heating and expanding at different rates cause the seals to leak when hot.the worn seal makes bike run lean and hot and faster rpm bliping throttle floods in fuel , running bike to a rich state then idle drops
and /or shaft moving around reseals the seal idle returns

 

If your screws still have the brass plugs over them , and you soaked carbs , there is a small rubber O ring on the tip . The seal is probably shot , from the factory mixture is set lean . You really need to remove screws and replace the O ring .

 

That makes a lot sense. Well time to order some thing. Oh 1 question. On top of the carbs is a plug with a hole what is the and what under it

 

Is that on top of the carb ? The plug with a small hole?

 

Yes.

IN THE CHURCH OF CLEAN

Replacing your Hitachi throttle shaft seals

Setting the fuel levels

Inside your Carbs

 

Thank you it all make sense now .

 

To get brass plug out take a small drill bit hit trigger a couple of times ,but be very careful you dont want to hit the mixture screw , wiggle the but a little till plug comes out .

 

Great cant find the plugs and o ring that came with my kit.
Where can I order these and throttle seals.
I also read some where I can replace all carb screws with Allen heads.