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Autodecompression Device Spring

husabutt

husabutt

Joined Feb 2003
3K Posts | 384+
Escondido, Ca. USA
Upon removing the head cover on my 01 470 Fx today and inspecting the autodecompression device I found it to be nonfunctional. So maybe thats why this particular 01 model would never e-start. The spring loaded device is supposed to remain in this position (I think), which is on or open
Decom2.JPG

and then once centrifugal force takes over it should move to this position
Decom3.JPG

Apparently the spring is not doing its job at all and slips when I move the device back and forth. Here is a shot of the return spring.
Decom%201.JPG

Can anyone tell by looking at the spring if it was installed incorrectly or if it looks defective? Interesting to note that the cam chain came with a master link in it from the factory and it was not riveted. Also has anyone compared a 05 autodecompressor spring to the 01-03 ones?

Thanks,

Eric
 
eric

there others more qualified than me to say-after all you wi;; only ever see the OEM set up the first time you pull the rocker cover!

but that flat part of the spring should go across the "flat" (slightly curved) face of the decomp lobe. the other end then gets twisted round and you build the tension into the spring.

regards

Taffy
 
My camchain was and still is on a spring clip, never riveted. My 470 engine will this week look similar to yours, as a different cam is going in, bye bye #55 and welcome to a much softer cam. Should make it a nicer ride imho :D
 
Wow, this is the first I have seen the auto-decompressor mechanism. That looks pretty clever. Without seeing or playing first hand with it, I would tend to agree that if that spring was not pre-loaded that you would have issues with the mechanism not working.

So, the spring holds the mechanism "in" (towards the cam "axle"), and when you are running, the thing swings out to hide the nipple in the cam lobe? Correct? If so, pretty clever. Do you guys have a manual decompressor too? Is this only for the e-start?

Is this what everyone is talking about when they describe welding on the bubble onto the decompressor????? They meant the autodecompressor?

-Parsko
 
JoeUSA said:
Eric,

Yours does not look like it was installed correctly, take a look at Husadawg's exellcent pictures. The spring needs to be wound enough for the spring tang to fit over the flat on the decompressor.

http://www.husaberg.org/modules.php?set ... _photo.php

Joe
Click to expand...

Thanks Joe,

Quite a difference in the way they were installed. I wonder if cutting a few coils off would add a little more spring tension to help open the exhaust valve. I have never heard of anyone doing this one. It would sure be a lot of effort to undo if it didn't work.
 
Two similar yet different springs are available. Insure your spring and weight are from the same year lest you have a spring which slips position. (like yours)

Sincerely,
Dale
 
Thanks Dale, Taffy and everybody:

In the parts manual when it lists the autodecompression device it says:

"Note, should be calibrated with camshaft"

The question is then:

How do you calibrate it? Is there an adjustment?
 
husabutt said:
Thanks Dale, Taffy and everybody:

In the parts manual when it lists the autodecompression device it says:

"Note, should be calibrated with camshaft"

The question is then:

How do you calibrate it? Is there an adjustment?
Click to expand...

Hi Husabutt,

What Husaberg indicates is one should use matching year and model components. Example: 04 650 camshaft should have an 04 de-comp unit and spring.

Kind Regards,
Dale
 
husabutt said:
Decom%201.JPG
Click to expand...

Hello everybody,

isn´t it even possible to preload the spring a bit, to hold the autodecomp weight for a longer period on the inner position.
So the e-start is able to reach higher rpm´s and the engine fires easier.
The SEM ignition needs 800 rpm´s to fire.

Another point is the bubble where someone mentioned to weld on.....
I got a hint from a guy here in germany, that a lot of camshafts has a worn whole for the autodecomp shaft. A result of this condition
is that the decomp mechanism isn´t able to push the rockerarm as far as the outtake valve should open.
The rockerarm needs a bit more lifting.
I´ve seen several camshafts with this worn whole, so I can confirm this theory.

Eric,
have a look to your decomp device and press with your finger on the "bubble". If the decomp device goes down, the bubble won´t
push the rockerarm, if it doesn´t stick out a bit over the cam. So your e-start couldn´t work correctly.
A clever solution of this problem would be a bushing. No prob for a skilful craftsman, is it?
I haven´t tested it yet, cos I haven´t got an e-start.
I can look after your bike when I come around. But can you wait 4 weeks? :wink: :)

greetings

hribman
 
hribman said:
husabutt said:
Decom%201.JPG
Click to expand...

Hello everybody,

isn´t it even possible to preload the spring a bit, to hold the autodecomp weight for a longer period on the inner position.
So the e-start is able to reach higher rpm´s and the engine fires easier.
The SEM ignition needs 800 rpm´s to fire.

Another point is the bubble where someone mentioned to weld on.....
I got a hint from a guy here in germany, that a lot of camshafts has a worn whole for the autodecomp shaft. A result of this condition
is that the decomp mechanism isn´t able to push the rockerarm as far as the outtake valve should open.
The rockerarm needs a bit more lifting.
I´ve seen several camshafts with this worn whole, so I can confirm this theory.

Eric,
have a look to your decomp device and press with your finger on the "bubble". If the decomp device goes down, the bubble won´t
push the rockerarm, if it doesn´t stick out a bit over the cam. So your e-start couldn´t work correctly.
A clever solution of this problem would be a bushing. No prob for a skilful craftsman, is it?
I haven´t tested it yet, cos I haven´t got an e-start.
I can look after your bike when I come around. But can you wait 4 weeks? :wink: :)

greetings

hribman
Click to expand...

Good advice Michael. I'll check mine this evening. That may be an overlooked issue regarding the lack of necessary exhaust valve lift. I can't wait 4 weeks because this is the bike you will be riding. E-start or no e-start :lol:
 
No problem Eric,
we can fix it on sunday evening, besides bbq and some beer,
and then we´re going to ride it on monday. :wink:
The main thing is that the gasket is dry before we start the engine! :lol:
 
LINEAWEAVER said:
What Husaberg indicates is one should use matching year and model components. Example: 04 650 camshaft should have an 04 de-comp unit and spring.

Kind Regards,
Dale
Click to expand...

I have a knot in my stomach reading this. My 02 501 recently had some upgrades done and one of them was the installation of an 03 650 decomp mech. The bike never had an e-start problem before this but now it struggles and seldom e-starts when warm. It also has a new YTZ7s battery.

Log
 

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