fe400 running issue carb???

[Bad92Silverado]

Copo. It is the 400 carb what screw it the mixture screw? After setting governor it runs better but still studering.

[Copo427ss]

Low speed mixture screw is on left side of the carb side closest to the engine. It might be slightly hidden under the vent hose. If this was screwed in or out to far it will cause the engine to run poorly. Also you could have a partially plugged pilot jet.

[lockman1]

Bad 92... when you say "everything is new" does that mean brand new? or just new to you?
If it's brand new... I doubt the pilot jet is plugged! (no disrespect Copo!)
I don't know FE400 carbs, but if it's similar to my FE350, there only two adjustments,
One for the throttle stop, (at the top of the carb. under the shield at the throttle cable) and one for the mixture,
now... my FE350 mixture screw has a stop on it, and it only turns 180 degrees. (from 12:00 to 6:00)

If yours is similar, and it's been running like this since you've had it in,
I'm thinking there's something else that may be causing the "stumbling"!
(fuel delivery, internal carb debris, settings or adjustments from the factory)
I'd start by pulling the carb and give it a good cleaning... even IF it's brand new!

[Copo427ss]

Originally Posted by lockman1

Bad 92... when you say "everything is new" does that mean brand new? or just new to you?
If it's brand new... I doubt the pilot jet is plugged! (no disrespect Copo!)
I don't know FE400 carbs, but if it's similar to my FE350, there only two adjustments,
One for the throttle stop, (at the top of the carb. under the shield at the throttle cable) and one for the mixture,
now... my FE350 mixture screw has a stop on it, and it only turns 180 degrees. (from 12:00 to 6:00)

If yours is similar, and it's been running like this since you've had it in,
I'm thinking there's something else that may be causing the "stumbling"!
(fuel delivery, internal carb debris, settings or adjustments from the factory)
I'd start by pulling the carb and give it a good cleaning... even IF it's brand new!

That's why I said it could be a partially plugged pilot. He said that once he's going down the road at speed it's fine. But low speed is the problem. I cut my tab off of my mixture screw so I can remove it for and cleaning and to also have better control over my adjustment. A little compressed air through the carb ports with some carb cleaner will get it clean

[lockman1]

Hmmmm... cutting the tab off... you didn't say that before... not a bad idea!

[Bad92Silverado]

thanks guys! and yes. i mean factory brand new... i thought that was the screw you were mentioning and yes.. that is only a 180 degree turn and it doesn't change a thing in any position it is in... now there is a brass screw bellow that one on the carb (looking from the front) i started to back that one out and it made a world of difference.. it starts up right away and idles nice and revs nice. im not sure what that screw technically is... however by the time i was done messing with it last night it was fully warm. when i get home tonight im going to see how it starts up from a true cold start... hopefully like it did last night!

[Copo427ss]

That brass one is your pilot jet. Take the carb off and clean it. There is something in the passage way or in the pilot jet, also blow through the air jet passages on the from of the carb. When you started unscrewing the jet you let fuel around it.

Lockman, I am a motorsports technician by trade. I'm full of good ideas lol. Check out my cylinder head mods thread I started. My Cart rips now.

[Bad92Silverado]

thanks Copo. i appreciate the help! and where do you work? and do you know polaris stuff?

[Copo427ss]

Originally Posted by Bad92Silverado

thanks Copo. i appreciate the help! and where do you work? and do you know polaris stuff?

Yes unfortunately I know Polaris. And pretty much the rest

[Bad92Silverado]

That doesnt sound good... lol. well here is a question you may also know the answer to. i have this baja car i built. all custom...



and it the polaris 500 the engine is out of the prototype predator or outlaw... i forget. its a dry sump setup and for some reason the oil leaks out of the vent hose... so i welded up a tiny secondary catch can and put a filter on the top. it stopped most of the leaking but it still does leak some. how can i correct this?

here is a pic of the setup now.



i know its only tie wrapped in this pic. its now mounted to the frame with tabs. its annoying how it leaks oil all over the back engine area and get on the header and smokes. any insight?