Hello, new here. 79 xs400 won't run

[pinchflat]

Hello,
My name is Jeremy. I live near St.Louis mo. In a small town in IL. I am the service manager in a bicycle shop.
I recently picked up a "barn find" '78 XS400. It is pretty rough. The chrome parts are pretty much shot and the tires are weather checked pretty bad.
After alot of cleaning to the fuel tank and carbs I was able to get it to fire. The problem is it only runs on the prim. I can not seem to get it to run for more than a few seconds. I guess it a carb issue. Will it not run without the air cleaners?

 

[Orgoth225]

Hello there, welcome to the forum, for your question it is possible to run without filters but HIGHLY not recommended. Have you adjusted the adjustment screws on your carbs?

 

[pinchflat]

I have not made any adjustments to the carbs. Where do I start?

 

[eric123]

If it only runs on prime it is a petcock issue. Is the vacuum hose attached between the petcock and the carb boot? Is the hose in good shape? Is the petcock and petcock screen clean? The bike needs to have the filters on it, running without, the bike will run lean and will suck crap into the motor.

 

[pinchflat]

It is getting fuel. I have a clear filter on the line so I know it has fuel. Also when I pulled the carbs off there was fuel in both of them.
I don't plan on running around with no filters. I was just wondering if not having them on would lean out the mixture too much for the engine to even run. It is easier to have no filters on it for the initial firing up of the bike.

 

[drewpy]

welcome Jeremy, your not Jeremy the annoying horse are you?

best to do a search on carbs as this has been talked about manu many times before.

 

[pinchflat]

I got it running! It took many attempts at cleaning the carbs and all new jets. I also found that the stock mufflers had collapsed on the inside and were clogged. It has been setting since 1984.