New auto decomp. - do i have the right part??

Husaberg

Help Support Husaberg:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
sixdays

sixdays

Joined
Nov 8, 2005
Messages
61
Location
Denmark, Europe
I just got a new autodecomp, and i wonder if it´s the right part. It looks exactly like the old part, and the only difference i can measure is on the end on where it lifts the valves. The new one is about 0.2 mm thicker than the old one...? So i wonder - how can i check if i have the "new" model - the right one..??
 
Sorry, don´t know how to upload. I have 3 different Autodecomp. 2 looks very similar, like described above, and symmetrical. The third looks excatly like the one on your photo, but is to short - 2 mm shorter than the 2 others (that fits).
 
Owners Docs describe that you may have to tak 2 mm off the shoulder on some cams to get it right.... I had the same done to my cam, to accomodate new style decomp.

Anders, DK
 
I have studied the picture now, i really don´t know what is ment by the "shoulder". Maybe you misunderstand me.? The axle is simply to short by appr. 2 mm.
 
http://www.husaberg.org/index.php?name= ... t+shoulder
http://www.husaberg.org/index.php?name= ... t+shoulder

I just did a search.. "camshaft AND shoulder"

Read the 2 threads above and have a look at attached photo... If you take some off that shoulder it will allow the weight to get closer to the sprocket, and thereby the auto deco will sit correct in the cam lobe.

And I have NO idea why the shoulder on some cams are longer than others.. !! But I beleive that the new style deco only comes in one length... Somone else in here might know !

Hope this helps.

Anders, DK
 

Attachments

  • cam_shoulder_close.jpg
    cam_shoulder_close.jpg
    17.1 KB
the "shoulder" on the cam matches the older style aluminum cam gear. the newer steel cam gear is thinner at the point where it bolts to the cam. the dutch clog style decomp is shorter that the older style, thus requiring one to remove the material from the cam, as well as shorter bolts. so, to be able to do the upgrade, you should change:

cam sprocket
decomp
decomp spring
cam sprocket bolts
removal of shoulder (machining required)
 
See.. someone knows
But as he has a 2003 model, sure he allready has the steel sprocket ??? But his camshaft stil has the long shoulder with old style decomp.

Anders, DK
 
But then i will end up with a gap between the deco and the ball bearing!!?? Or am i misunderstanding something?
 
Yep, I was also very sceptic about it, and u end up with the coiled spring actually beeing the only thing that prevents the autodecomp to move axially....., and slide out towards the bearing..... But none the less, it seems to work.
 
The Docs describe that the steel sprocket was introduced in 02/03 and the new style Decomp introduced in 04. And so there is bikes with steelsprockets, old decomp and "long" shoulder !!

On the bikes originally equipped with steel sprocket+ "short" shoulder+new style decomp, what is actually preventing the decomp to move axially ??? Is the bearing positioned closer to sprocket, or is the spring holding it in as it does when upgrading your self ??

Anders, DK
 
the spring has a trench/cutaway in the shaft that the spring's tail runs back across the middle falls into preventing the decomp moving out. it's at the cam lobe end on the '04 decomps.

whereas the 97-03 decomps had a groove all the way around the shaft that the coiled part of the spring sat in and this is at the sprocket end.

regards

Taffy
 
sixdays

you have a shorter modern auto decomp and that is what you should fit. by taking the shoulder down 2mm it will all fit correctly. i do 3 or 4 a month. sometimes the auto decomp spring gets 'coil bound', so simply unwind one 360d circle of wire and that should be good.

it really is easy. BTW, you don't need shorter bolts if you always had a steel sprocket with the fat shoulder (seen in the photo above) simply machine the cam shoulder and note that the two screws have massive washers under them making it all good.

regards

Taffy
 
Thanks! I got it mashined today, 2mm off the shoulder. Could you explain what you mean about "coil bound".
The spring didn´t fit, so i have cut of one circle - 360 degrees, but i´m not sure how strong it has to be - how do i know how much i have to "tighten" the spring so the decomp does excactly the job at the right rpm?
 
chances are, if the spring didn't fit, you have the old style spring. getting the spring on and in position is a pain. the ones i have installed worked great without modification (once you get it on)
 

Attachments

  • berg 04 cam (2).JPG
    berg 04 cam (2).JPG
    128.4 KB
I had the same worries... I took off one coil and shaped a new "D". It was still a "strange" fit, this design really sucks in my opinion. But it works when you get it right. The power of my spring would retract/lift the weight, holding it upside down, and that should be enough ! It snaps the weight in at all other positions with a CLANCK.

If i set my idle speed really low, I can hear the weight start moving in the cam, and at normal idle speed it's just fine. So if the weight retracts fine at any cam position your'e good to go. But too tight will result in a hammering noise and engine cutout and speeds below "normal" idle.

Taffy did my cam for me, and he removed the little stopper bolt, so now the weight stops at the bolt that holds the sprocket onto the cam. The reason for this is that the little stopper bolt has broken off in some cases resulting in damage. Probably happening if idle set too low ! My weight now comes REALLY closte to the chain, but never touches and the clog is still "inside" the cam profile in running position. Up to you if you want to do the same.

I sounds like you did the same as me, so keep on!
 
as husaden says, if it can't ping up while dangling underneath you must make the spring stronger.

if the tail is one end and the other the 'cross-section' you need the tail to be opened clockwise by 45 degrees. IF and i say IF you opened it 90 degrees then it would point in the same direction as the 'cross section'. i always do thjis now and i've had to take one back a bit and add a bit to another so it's the average of too much and too little.

regards

Taffy
 
I did the spring, and it seemed to work perfect. Then i put the parts back together, cleaned and greased all the cables and tried the starterbotton (no gas). It rotaded fast, just like my KTM!! But then it started "slipping"...! AArrgghhh, is it the freewheel?
I will try to fire it up and go for a spin, maybe it can start when it´s hot?
I will keep you posted!
 

Similar threads

o6550
2006 fe550e - New valve spring kit without removing the head?
Replies
6
Views
676
o6550
o6550
T
570 engine rebuild help!
Replies
5
Views
526
TurboYoda
T
G
2003 fe501 cylinder head repair/replacement questions
Replies
8
Views
588
Taffy
Taffy
D
FX vs FE rear fender comparison
Replies
4
Views
770
DTeuscher
D
F
FE570 low idle issue, outside of the usual suspects! (I think)
Replies
2
Views
425
AussieBlue
A

Register CTA

Register on Husaberg Forum! This sidebar will go away, and you will see fewer ads.

Recent Discussions

Recent Discussions

Back
Top