Engine vibration on FC550

Hi MAW,
It is indeed possible for said balance unit to be improperly phased and / or of the wrong weight. (ie from a different model)

Dale

Mark,
Such an inspection will indeed require splitting the main cases.
Dale

Just for thought:
1. What if the Counter-Balancer bearings are starting to seize-up and not letting the C-Balance spin freely? Thus creating more friction and draging the C-Balancer alittle slower.
2. Maybe there is no C-Balancer.

Please let us know what you find!!

My motor let go last weekend during a race..no warnings or anything.
My bike had the crank mod done from new but a few weeks ago developed a rattle from the bottom end. Dcr checked it and found the crank end nut had come loose..a week later the same thing happened so it went back to Dcr again. They again redid the crank nut and even fitted a new one. When the motor let go last weekend it happened exiting a 2nd gear turn, couple of bad misfires then power loss, I pulled off and the motor sounded like a bag of spanners so I shut it down immediately.
When Dcr inspected it they found the 2 webs of the crank were slightly out of line and were amazed it wasnt vibrating itself to bits...it did however cause the mains to crumble, they also believe it to be the reason for the loosening crank nut.
They say they havent seen this before but could it be a crank assembly defect ? I would certainly get your bike checked out beofre any serious damage occurs. Mine ended up needing a new crank, all bottom end bearings, piston and liner, fotunately it was covered under warranty.
They did show me the crank spinning and the defect was quite obvious

Gix said:

My motor let go last weekend during a race..no warnings or anything.
My bike had the crank mod done from new but a few weeks ago developed a rattle from the bottom end. Dcr checked it and found the crank end nut had come loose..a week later the same thing happened so it went back to Dcr again. They again redid the crank nut and even fitted a new one. When the motor let go last weekend it happened exiting a 2nd gear turn, couple of bad misfires then power loss, I pulled off and the motor sounded like a bag of spanners so I shut it down immediately.
When Dcr inspected it they found the 2 webs of the crank were slightly out of line and were amazed it wasnt vibrating itself to bits...it did however cause the mains to crumble, they also believe it to be the reason for the loosening crank nut.
They say they havent seen this before but could it be a crank assembly defect ? I would certainly get your bike checked out beofre any serious damage occurs. Mine ended up needing a new crank, all bottom end bearings, piston and liner, fotunately it was covered under warranty.
They did show me the crank spinning and the defect was quite obvious

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Hi GIX,
With all due respect and based upon current and earlier posts
http://www.husaberg.org/modules.php?nam ... ng+failure
I understand DCR to have reworked your engine prior to initial delivery.

If one takes the trouble to install different main bearings and set correct end float one would also insure proper crankshaft alignment. Why then suspect the crankshaft?

This is not intended as a flame for I am truly interested in the nature of your failure and the events leading up to it.

I have seen more than my share of blown up Husaberg lower ends. Quite often such catastrophic failure is the result of accumulative shortcomings. IE Excessive rpm, misaligned main bearing bores, axial mount balance unit loading (rocking couple), etc.

Respectfully,
Dale

Dale.
I totally understand what your saying and to be perfectly honest I have no definitive answer. I too thought that it should of been spotted on the 1st stripdown for the mod, but having never stripped one myself I assumed that the crank mod was done without having to totally strip the motor..but I admit, it was just an assumption.
However having seen the removed crank on a jig and spinning the difference in the webs was obvious....I also thought that it would have caused an vibration...it could be that it spun on the crank pin just before letting go, however no vibes were felt whilst riding, it wasnt revving highly in fact it was just picking up off nearly tickover.
I wasnt trying to say this is the problem with Maws bike just offering up my experience..In fact , if you have a theory as to what occurred in my motor I'd be more than happy to hear it

I have a Fc470 that is leaking some oil between at the bottom of the centre cases at the case halve mating surface.There is no external damage and this engine will be disassembled to reseal .Is this a early indication of an internal bearing or other failure causing outward pressure on the cases or just a case of a poor joint/sealer failure.Anyone have some insight ....thanks ....nsman

Hi Gix,
I am more than happy to help.

If at all possible please forward picture files and / or a list of damaged components.

The crankshaft misalignment is most often the result of a drive side component failure. IE Main bearing, balance bearing, drive gear, etc.

Kind Regards,
Dale

[email protected]

nsman said:

I have a Fc470 that is leaking some oil between at the bottom of the centre cases at the case halve mating surface.There is no external damage and this engine will be disassembled to reseal .Is this a early indication of an internal bearing or other failure causing outward pressure on the cases or just a case of a poor joint/sealer failure.Anyone have some insight ....thanks ....nsman

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Hi Nsman,
I often see such a leak associated with loose front engine hanger bolts.

Dale

Thanks Dale,
I will be sure to check this......nsman