xj550 Seca 82 idle problems

Starts fine with full choke. Will not idle unless choke fully on. If I start moving in first gear with choke fully on revs increase under load fine but do not go down when closing throttle between gears. Bike runs fine with choke off when at speeds above 3k. When I reduce rpm below that with choke off it stalls. Can only keep engine running by opening and closing the choke and that kind of sucks haha.

I have all the tools to do a complete carb job and sync just looking for a few suggestions on what to check first before going to all that trouble. Ran fine last year.

Help

 

Idle circuits.

Go to Church.

 

Have you checked valve clearances?

 

Not yet will do thanks

 

Thanks for the reference will try and determine what one or two carbs are having the problem(s) and focus on idle circuit as you suggested. Can compressed air clear the port or seat without carb disassembly

 

By all means go to church, tear carbs down completely and replace all seals (IE butterfly seals= xj4 ever ) get a gallon of Carb cleaner ( Berryman from Autozone etc) sub merge in cleaner 1 to 2 hrs blow out with compressed air clean everything them re assemble.. bench sync butterflys , and wet set float level . By doing this you are saving yourself from the frustration of just having to play with it and not having it run right. You will still need to do fine tuning , but will be much easier.

 

I knew the solution would probably mean a complete removal and full cleaning and setup again. It has been 3 or 4 years so I should have expected it and done so during the winter, just being lazy looking for a quick fix. Carbs are a sensitive matter. I'll take everyone's advice and refer to the previous posts , bite the bullet so to speak. I suspect putting the carbs right in the cleaner does a number on any seals still on them. Well off to get my hands dirty haha I'll post how it concludes moving forward. Rather a formal response Yamamann lol. Thanks to all.

 

why just 2 carbs?
some have cleaned carbs with lemon juice soak and heat, as long as you do not over heat no seal issues.
no you can clean pilot jet not with out dissambly, but you do not have to break the rack if you are just doing the pilot jet= Idle circuit. you have to remove carb hats and diaphrans to get at the pilot air jet then the mixture screws and finaly the pilot jet in the bowl.
with diaphram and slides out and bowls off you should do the main jets and asperator tube ,
put it back togrther and do a wet set of the fuel level
I have a carb pdf file on rebuilding mikuni carbs if you want it start a conversation with me and leave me your email

this would be the time to replace all the "rubber" parts a little preventive maintance seeing you are going to be in there any way

 

Do all four. They are all the same age, and will all need the same attention (unless you like removing carbs more than once).

 

Done all four. Unable to remove pilot air jets in bowels beside needle jets. Used plenty of carb cleaner and blew all ports out with compressed air ( 90 to 100 psi ). If I blow air in the pilot air jet where does it go. Would like to be sure the pilots are clear before putting back together.

 

Decided to put carbs on and test prior to replacing all other parts just in case I need to remove and work on them more. Do a driveway engine test. Since you have been so helpful I'll share a little trick I use to prolong the life of the rubber boots that connect the carbs to the cylinders. I paint them with black brush on electrical tape. It fills any minor cracks and has stood up to the heat. You can brush it on without removing the carbs.

 

this link will show you cut away of carbs and where things flow
Something New, Something Naked

Pilot jet if you spray into the pilot jet cleaner should come out the air jet which is under the carb cover under the diaphram. it will also come out the mixture screw hole in the carb throat and into the mix screw well with screw removed there are also holes in the top of carb throat that spray will come out of.

 

here the many suggested methods are, clean the boots with carb spray then coat with black rtv, also some have put heat shrink over the boots . or rtv and wrap with a section of innertube, or rtv and wrap with a section of heat shrink.


I have a carb pdf file on rebuilding mikuni carbs if you want it start a conversation with me and leave me your email

 

Success, another hour or so reinstalling the air box, gas tank, electrical fuse box and seat and that's it all done. Do you think adding an in line gas filter to compliment the one in tank would cause a problem ? It is not very restrictive gas flows easily. I want to thank you XJ550H and others that took the time to give me some valuable advice.

 

I'll take some time later to delete my old emails. Would appreciate the pdf let you know. 40,292 miles on my Seca XJ550RJ. A USA bike originally from Mass. I'm planning to show her off to the Yamaha factory reps at a dealership tomorrow. Feels good ....

 

Naked ya baby ya. Haha

 

The screen in the tank is not much of a filter. A sintered-bronze inline filter is a must-do in my opinion.

 

That's the type I have thanks