rev high idle, sticks 1982 xs400

[1982xs400]

recently picked up a 1982 xs400.......
help ....carb issues ???

1. starting bike has high rev- idle up to 4000 rpm ,and stays steady there.. twist throttle goes higher.

2.some times it kicks down to 1200 rpm.

and ideas, thanks.

 

[16VGTIDave]

Search function. There is one here, please put it to good use. This has been discussed numerous times.

 

[bcware]

It sounds like you're running lean. The solution is usually just cleaning the carbs like 6 times. Barring dirty carbs make sure there are no leaks in the air intake and that the carburetor "boots" are not cracked. Make sure the fuel is good, etc.

As Dave said, search for more detailed information. It's all here.

 

[1982xs400]

ty very much...

 

[1982xs400]

thanks, any good way to check boots for leaks? could float,"s" be stuck?

 

[bcware]

If the boots are cracked on the exterior I'd replace them. You might have to remove the carbs and clamps on them to get a good look.

Floats do get stuck occasionally. In my experience they tend to get jammed open which results in flooding. If they are stuck in a closed position the respective carburetor will run dry and the bike will run on one cylinder or shut off altogether.

The carburetors on this particular motorcycle are finicky and need to be very clean. Unless you are seasoned with regard to experience you will very likely not clean them adequately the first time.

If you're looking for the basics and an introduction to the carbs (on my 1978) I made a few videos a long time ago. Your carbs will likely be a bit different on an '82.

 

[arfstrom]

Thanks for dusting those off, I remember them, when I first started going down the road of cleaning my carbs!

 

[Lou Ranger]

thanks, any good way to check boots for leaks? could float,"s" be stuck?

There's at least one Thread on here describing how to use propane or carb cleaner to test for leaks. You spray it around the boots and tubes while the engine is running and if any gets sucked in through a leak it will change the way it's running. Don't remember how it changes... - though, I think if there is NO change then it's good news.

 

[1982xs400]

I did spray carb cleaner around all areas. the only areas that the Idle increased while spraying was across the cap "covers" on top the carbs. would that mean a leak in the seal of the caps ???

 

[16VGTIDave]

That would suggest to me that either the pilot screws are leaking or that the diaphragms are shot. You really should remove the carbs, clean and rebuild them.

 

[1982xs400]

ty, will have to get a better look this weekend.

 

[1982xs400]

UPDATE !!!!! Ok. after looking at the carbs, housing and filter... I removed the old dirty filter, which looked like it had not sealed well. I started the bike without the filter and the Hi-rev is not there. just have to get new filter or pods.

 

[16VGTIDave]

Get a new filter. Pods require jetting changes.

But don't be surprised if you still have to clean your carbs...

 

[1982xs400]

will try filter. recently bought the bike for a few hundred. should pass inspection. blow out the cobwebs. and TLC.

 

[1982xs400]

ok looked at the carbs some more. "looks like starter plunger is missing" on left side carb . and on the right side carb looks like a "screw" is missing also.

 

[1982xs400]

what is the screw that is missing on the right carb. cannot seem to get info what it is !!

 

[16VGTIDave]

Relax! These carbs are used on many different bikes. Not everything is used on a particular application.

 

[1982xs400]

so on the xs 400 these holes are not used....safe to say.

 

[16VGTIDave]

Not on my XS400 DOHC... The "hole" on the right carb goes nowhere. It would join to the fuel feed passage but was never drilled through at the factory. And the screw hole on the left carb doesn't even exist on mine.

 

[XSLeo]

The starter plunger is on just one carb and the extra fuel flows through crossover hose between the carbs.
Leo