Time to re-jet - advice

[Bartolucci]

Shattered the record high today (84 degrees - Rochester, NY). Have started working on my XS400 'rat' project. I've de-badged and lowered it. Also opened up the air intake and exhaust. It was running lean but now won't stay running at all. It will start up cold with choke, but will after-fire and spit and die at low rpm. Seems worse warm/hot.

I haven't taken a cycle carb apart in years. Where should I start with jets (has stock jets)? The bike is an 82 so I'm wondering if I should do a carb kit while I'm at it.

Any help in getting me pointed in the right direction is appreciated.

[rpgoerlich]

82 XS400 Midnight Special is it ?
I'd clean those carbs and check to make sure your float levels are correct before you go too far with the jetting.

I just picked up an 82 Seca XS400 today. Into the carbs at this time as well. Has sat since 1995. Carbs weren't too bad though. Gotta get a key for it tomorrow. Will post a pic then.

[Bartolucci]

Carbs are off the bike

Yanked the carbs off today. I guess there's no such thing as a carb-kit for these. Therefore, I guess the easiest route to go is adjust the floats and re-jet. I've not done this before so I'm going to search for a tutorial on the site.

[Bartolucci]

Update

UPDATE: I've not done this before and could use some advice. The bike is running very lean, so much so that it will hardly run at all. How many sizes larger should I go on the jets? I'm thinking two. Also, where is a good source to purchase them?

I also need to adjust the floats (gas runs out the carbs if the petcock is left open). What is the procedure for doing this?

Any and all help is greatly appreciated!

[rpgoerlich]

Po-boy Carb kits are available on Ebay most are only float bowl gasket and float valve. Carbkitcapital has them and they come with the float bowl gasket, float valve& seat

Most times the valve and seat can be polished up with a Q-tip and some brass cleaner so it seats.

They didn't have a float height measurement but 23-24mm off the gasket mounting surface(gasket removed) gets you in the ballpark. To verify the fuel level in the float bowl you need a clear tube inserted into the float bowl drain passage so it doesn't leak and open the drain screw. Hold the clear tube up along side the float bowl and the level is supposed to be 3mm below the bottom of the upper carb body +/-1mm. I checked mine on the bench in a vise hooked up to a fuel tank. Make sure they are level when you do whether its on the bike or off. Adjust the floats as needed to get the right fuel level in the bowl.

Did you pull the jets, emulsion tubes and clean all the ports?

[ManagerMike]

Don't re-jet yet. Get the carbs thoroughly cleaned first, new float valves, and floats set. Changing jets is for fine tuning an already running engine. If it won't run due to a lack of fuel, then the carbs are crapped up. Start from a baseline, then after it's running tweak the performance.

[Bartolucci]

No, I haven't taken the carbs apart yet. I'm confident that a re-jet is in order since 1) I made the mods of opening up the exhaust and air intake; 2) Since I did #1 the plugs are white, not tan. I'll see if I can get the bowls open on Monday.

Thanks for the help!

[Montreux_Blue]

Jetting Recommendations

http://www.xs11.com/forum/showthread.php?t=382