650 Compression Ratio

Corsa · Aug 10, 2004

I have a 2001 FS650e which destroyed the roller bearing on the exhaust rocker arm so I'm currently having head work done while it's apart. Has anyone milled the head to increase compression and if so, by what amount, and any negative side effects.
Thanks in advance.

FC501EAST · Aug 10, 2004

Hi, Corsa...
Contact UHE member Dale Lineaweaver. He has close ties to Husabergengineering, has done extensive Husaberg engine work. Top notch!!
Gary, in Maine

Simon · Aug 11, 2004

Corsa said:
I have a 2001 FS650e which destroyed the roller bearing on the exhaust rocker arm so I'm currently having head work done while it's apart. Has anyone milled the head to increase compression and if so, by what amount, and any negative side effects.
Thanks in advance.

Well, I'd think you'd be better off just getting the 2003 1mm longer con rod and a high compression piston (e.g. using that of the 470).

While you're at it, bung in the 03 updated rollers too :wink:

Regards,
Simon

Supermoto_Husaberg · Aug 11, 2004

What effects on the power output would fitting an Omega piston into a 2002 650 have ?

Lloyd

ICE-BERG · Aug 11, 2004

Simon, are you saying that the 2003 rod fits in the 2001?

PowerFiend · Aug 11, 2004

PowerFiend · Aug 11, 2004

ICE-BERG said:
Simon, are you saying that the 2003 rod fits in the 2001?

The 2003 rod fitted to the 01/02 crank should make the piston flush with the top of the cylinder, instead of slightly recessed. This will improve the squish band clearance and raise compression. This also works for the 01/02 550, if you fit the 2003 550 rod.

ICE-BERG · Aug 11, 2004

If I have a 470cc piston in my 650 2001 does the 2003 fits or too much compression or not enough space?

PowerFiend · Aug 11, 2004

Simon said:
Corsa said:

I have a 2001 FS650e which destroyed the roller bearing on the exhaust rocker arm so I'm currently having head work done while it's apart. Has anyone milled the head to increase compression and if so, by what amount, and any negative side effects.
Thanks in advance.

Click to expand...

Well, I'd think you'd be better off just getting the 2003 1mm longer con rod and a high compression piston (e.g. using that of the 470).

While you're at it, bung in the 03 updated rollers too :wink:

Regards,
Simon

Simon,
Is the 650 rod truly 1mm longer??? I believe the 550 rod is only 0.5mm longer, which is approximately how much the 01/02 stock set-up is below being at zero deck height.

Simon · Aug 12, 2004

PowerFiend said:
Simon,
Is the 650 rod truly 1mm longer??? I believe the 550 rod is only 0.5mm longer, which is approximately how much the 01/02 stock set-up is below being at zero deck height.

Powerfiend,

<caveat>
Almost all my notes on the 'berg engine that I've done are still in a box somewhere since we moved house :roll:
</caveat>

However, IIRC the 650 con rod was extended by 1mm in 2003. The 01 650 engine definitely has this room for manoeuver.

If I'm wrong, I hope Dale will be along to correct me shortly :wink:

Cheers,
Simon

Simon · Aug 12, 2004

ICE-BERG said:
If I have a 470cc piston in my 650 2001 does the 2003 fits or too much compression or not enough space?

Ice-berg,

Please see my caveat above regarding reference notes

I haven't run the 03 conrod with the 470 myself but with the tolerances of the 650 engine, the room should be there. It was a popular mod with the Euro boys in 01 and 02 to fit at that time a 1mm longer aftermarket conrod with the high comp. piston - that being either the 470 or one by Omega or other manufacturers.

It is interesting however to look at the changes Husaberg have made to the 04 piston with a concave machining of the piston. They retain the squish band though.

Cheers,
Simon

Supermoto_Husaberg · Aug 12, 2004

What happens to power output (eg more where?) when u increase the compression ratio ?

Do u gain or lose top end power ?

Mid range ?

Lloyd

Simon · Aug 17, 2004

Supermoto_Husaberg said:
What effects on the power output would fitting an Omega piston into a 2002 650 have ?

Lloyd

Lloyd,

Because you already have a different cam and head, it would be very difficult to say.

Sorry,
Simon

Simon · Aug 17, 2004

Supermoto_Husaberg said:
What happens to power output (eg more where?) when u increase the compression ratio ?

Do u gain or lose top end power ?

Mid range ?

Lloyd

Well, there are quite a number of variables but you would normally find an increase in torque but possibly also a reduced peak rpm.

However, as a comparison, the 03 has higher compression than the 01 engine yet gives us more power at higher peak rpm - e.g. over 8k rpm v. 7300rpm.

Cheers,
Simon

ICE-BERG · Aug 20, 2004

I have to change the rod in my 2001 fx650. I have a 470cc piston and oversize valves. will the 2003 rod still fit with those mod?

PowerFiend · Aug 20, 2004

ICE-BERG said:
I have to change the rod in my 2001 fx650. I have a 470cc piston and oversize valves. will the 2003 rod still fit with those mod?

How big did you go on the valves? Also, did you check to see if the valve cutaways in the 470 piston are big enough for the larger valves?

ICE-BERG · Aug 20, 2004

I bought the valves from Dale( I think they are 1mm or 2mm larger), I don't think they had to mod. the piston. I will have to check.

Splat · Aug 21, 2004

Corsa said:
I have a 2001 FS650e which destroyed the roller bearing on the exhaust rocker arm so I'm currently having head work done while it's apart. Has anyone milled the head to increase compression and if so, by what amount, and any negative side effects.
Thanks in advance.

Milling a head on an overhead cam engine will retard your valve timing. That is a bad thing. You will need to modify the cam chain sprocket to correct the valve timing.

You can increase compression with less hassle via a different piston or connecting rod.

Increasing the compression will increase power through out the entire engine range. Most notably in the low through mid range. Best of all, torque will be vastly improved.

Horsepower sells engines, torque wins the race.

650 Compression Ratio

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