Husaberg Jetting Problem

[CraigW]

I have just purchased a 2001 FE400E. Its really a great enduro bike with awsome handling and suspension.

The only problem I have so far is one of jetting. If the bike is idling and one very slowly twists the throttle, the motor rpm will drop slightly before increasing. If one twists the throttle very quicky, the response is fine with the motor reving very quickly, no lag being detected. The problem manifests itself on tricky downhills where the motor stalls regularly. During normal riding, from 1/8 throttle up bike response and performance seems normal

I have tried to increase the idle speed to no avail. I have tried different adjustments on the air screw, also without success. Currently it is adjusted to only a 1/4 turn out. This doesnt seem right as the manual says 1 1/2 to 2 1/2 turns is the normal setting. In fact the motor idles at its highest when the screw is fully in ???

I typically ride at altitudes from sea level to 800m. The problem seems worse at higher altitudes.

Questions:
Does the mixture screw lean out as you screw it in, or visa versa?
Could my floatbowl level be too high?
Do I have the wrong jetting ie too rich/lean at low rpm?
:think

 

[Scott in KC]

Craig,

turn it in...lean

If you're able to crank it all the way in and the bike still runs (and in your case runs better) then your pilot jet is too rich. That and the fact that it's getting worse as you gain elevation.

Do you have access to jets? Get a couple of them leaner in 3-5 steps. Like if you're running a 40 pilot, get a 35 & 33, try the 35 first. You should be at least 1 turn out, but 1 1/2 is more like it. You might also get a couple of Main jets & needles while you're at it, parts for these carbs are nice to have on hand. Not sure what you carb is like exactly but mine wears needles like crazy. Cranked in it should start to run slower and/or try to die.

www.herdan.com is where I get my Dellorto parts.

 

[drehwurm]

Servus Craig,

In your post you refer to an 'air screw' and a 'mixture screw'. As far as I know the Husaberg carb (Dell Orto) uses only an 'air screw' thus turning it in makes the mixture RICH. Using only a 1/4 turn out would indicate that your pilot jet is too small, but there is a also the possibility that your pilot jet is clogged. Try running the bike with the choke on and see if it changes anything with your problem.

BTW, I've owned a 1998 Husaberg 400FEE and never liked the performance of the stock carb. Switched to a Keihin PWM38 carb kit modified for the Husaberg and was very happy. I have this carb still lying around in my garage and if you pay for the shipping from Europe to SA and back I would happily send it to you to try out. Maybe we can make some business here :p

Michael

 

[Scott in KC]

If your Husaberg ONLY has an air screw then you have the only two-stroke Husaberg in existance. :eek:

To my knowledge the adjustment screw is for fuel, tighten it in...cuts the fuel & loosen it up..increases the fuel.

If your carb has a fuel and air screw I will withdraw my remark, but I don't recall seeing a 4 stroke carb with an air screw?

One thing we CAN agree on is that the Dellorto is not a great carb, especially if you're changing elevations. :think

 

[drehwurm]

Servus Scott,

If your Husaberg ONLY has an air screw then you have the only two-stroke Husaberg in existance

The 1998 Husaberg 400 used a VHSB carb which [surprise on] is a carb mainly used on 2-strokes. I do not say that all Husabergs use Dell Ortos with an air screw only, but I'm of the oppinion that many of them do!

It is easy to tell, isn't it. If the adjustment screw is located before the slide it is an air screw, if it is behind it is a fuel screw. Would you take a look please Craig?

Michael

 

[CraigW]

Thanks for all the input guys.

Just to give you some more feedback on the problem:

The mixture screw is located between the carb slide and the engine.
There are only 2 adjustment screws, the other being the idle or slide adjustment screw.

The fact that my problem gets worse with increased altitude tends to point to there being too much fuel and not enough air.

I will strip the carb tonight and look for obvious problems ie. loose idle jet , incorrect float level. otherwise I will try leaning out the idle and/or pilot jetting.

Keep the suggestions coming.
regards
CraigW
:think

 

[drehwurm]

Servus Craig,

I was wrong then and your problem seems to be a too rich pilot circuit. I heard from some Husaberg owners that they had problems with the choke not fully closing due to some dirt. As I recall it is quite easy to clean the choke. Sorry I couldn't be of more help :(

Michael

 

[SFO]

Slide cut-away

I had to increase the size of my slide cutaway to get my 95 501 to run smooth in the region you are wondering about.