Help rebuilding twin carbs

[EJ8TrapKing]

I'm very new to motorcycles, but have mechanical experience with hondas so my question is how hard is it to rebuild carbs on my 81 xs400sh? I never messed with two carbs before. I just need warnings and caution before I actually mess it up.

 

[Scorpio1963]

We have a nice little function here on this site,Its called a search featureIll answer the question vaguely,These carbs are very simple to work and easy to work on.

 

[ECP89]

Buy a manual, read the carb section over a couple times. It's best to rebuild them one at a time (always leaving one carb complete). Also, do it in a space where nobody will move anything around. Some of the parts are tiny and next to impossible to find if you lose them. Take your time, the worst thing to do is try and rush it... you'll only end up doing it over.

 

[Scorpio1963]

He can find the manual right here

 

[jmd_forest]

There is a very detailed carb cleaning/rebuilding thread on xjbikes.com for the carbs on the XJ series bikes that I used the first time I cleaned the carbs on my XJ700. They are similar enough to the XS400 carbs that I used it again when cleaning the XS400 carbs for the first time. I know there a few decent cleaning/rebuilding threads on this site but the xsbikes.com guide has great detail for a first timer.

 

[frwinks]

prolly the most in depth carb cleaning manual floating around


http://www.mtsac.edu/~cliff/storage/gs/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf

 

[EJ8TrapKing]

I know it was a noob question, but thanks for the help and support. i'll start the process and keep you guys updated. thanks again

 

[EJ8TrapKing]

i took apart the carbs and looked inside. the guy who had the bike before me said he rebuilt one carb but not the other. It looks like he put the left side floater on backwards. so I flipped it around and cleaned it a lil n put it all back together. heres a picture. my question is does it make a difference? I havent ran it yet cuz its night time but will in the morning.

 

[Scorpio1963]

I cant beleive the Po painted over the carbsOther than that why would somebody just rebuild one carb?They look pretty rough and definately need a good cleaning.Make sure you replace the rubber covers over the pilots.

 

[EJ8TrapKing]

I'm thinking of ordering 2 carb rebuild kits but they don't come with the plugs for the rubber piece for the pilot

 

[Scorpio1963]

You can order jets,plugs and carb kit from MikesXs.Since your going to be inside your carbs you might as well rejet also.Get a couple of different size mains and a couple of sizes up for the pilots also.You might only use one size jet but you will have extras so you can tweak the carbs just right.It also makes the shipping more worth while.The air jets inside the venturi dont do anything but make sure they are not plugged up.Oh most of the time you can salvage the gaskets on the fuel bowls just depends on how bad off they are.

 

[EJ8TrapKing]

Here is what I found out. I know rust when I see it and this is definitely rust. so my question is if there's rust in one of the carbs then how would the bike run? sluggish or just shut off motor. I absolutely need a carb rebuild kit now. lol

 

[Scorpio1963]

Rust will clogged almost every passage way and jet through out the carbs.Your bike will run like crap if it runs at all.It will stall out not idle correctly.

 

[EJ8TrapKing]

I think I will try to clean my tank also. Any comments on how to do that??

 

[EJ8TrapKing]

Thanks for the reply. Any more details that I should know about?

 

[Scorpio1963]

Take petcock apart and thuroughly clean it also.Gently clean the screen thats attached to it.Cleaning the tank would very important its probaly your source of rust.Check underneith your gas cap for dirt,corrosion and rust.Run a small fine wire through all the passage ways and jets of your carbs.Use a good carb cleaner like chemdip or something equivelent.Check and measure your floats when you assemble the carbs.Also make sure you sync them after reinstallation on the bike.Theres threads that explain how to do this.

 

[EJ8TrapKing]

thanks for the advice i'll keep you all update

 

[Scorpio1963]

Theres a thread about how to clean rust from the gas tank.Use somthing like atf and whole bunch of bbs or nuts and bolts,swish then all around your tank for several minutes then flush the tank.If rust still persist repeat this step and the pentrating oil or atf do its job.

 

[jmd_forest]

Make sure you add an inline fuel filter into the fuel line between the petcock abd the carbs. It will be a big help keeping those rebuilt carbs clean.

 

[EJ8TrapKing]

New Thread question.

http://www.xs400.com/forum/showthread.php?p=99352#post99352