Baja Engine Failure

LINEAWEAVER · Jan 22, 2005

Regarding the Baja 1K Husaberg USA entry:
As you are likely aware I built and modified a 2004 Husaberg 550 engine for Bergdaddy. Said engine failed. Upon disassembly and inspection I found the following:

Two very bent Lineaweaver 32 mm exhaust valves

as a result of:

a new OEM heavy duty (read early model) cam chain failure.

I have seen plenty of broken Husaberg cam chains the result of some other broken part being wedged in between the drive sprocket and chain. However, this is indeed a first for me regarding an actual chain failure.

The chain of events (pun intended) appear to be as follow:
A roller fractured (such explains the early warning sign regarding bearing race like material spotted during an oil change) allowing the sprocket teeth to rapidly saw through the roller bushing consequently making direct contact with the chain pin. Such contact concentrated the load to the center of the pin resulting in an eventual failure.

With exception of the two bent valves the engine appears otherwise unscathed.

Sincerely,
Dale

Taffy · Jan 23, 2005

as usual dale your too humble to say it but the valves DID NOT break!

what was the manufacturer of the camchain? renolds? regina? DID?

Taffy

Supermoto_Husaberg · Jan 23, 2005

Looks Iris to me :roll:

Mine lasted 40 hours before it had stretched too much

PowerCell · Jan 23, 2005

Hey Dale -

Thanks for keeping us informed about the 1K motor. Did you get the metal fragments that were left in the jet box? They were definately not from the timing chain. I would guess there diameter to be more like 35mm. This could better explain the chain failure...

~ Ken

LINEAWEAVER · Jan 23, 2005

PowerCell said:
Hey Dale -

Thanks for keeping us informed about the 1K motor. Did you get the metal fragments that were left in the jet box? They were definately not from the timing chain. I would guess there diameter to be more like 35mm. This could better explain the chain failure...

~ Ken

Hi Ken,
Tim never forwarded the contents of the jet box. Nothing appears to have wedged in the chain in order to break it as both drive and driven sprockets are as new. Quite honestly I have a difficult time imagining a 35 mm (1 3/8") piece of steel wedging itself between the cam chain and sprocket then finding its way to the sump without damaging gears etc. on the way.

My real point:
The oil drain ID is barely 20 mm. How did they get a 35 mm diameter piece of steel out of a 20 mm hole during an oil change? Is it possible said material was not from the Husaberg at all and already in the drain pan when they dumped the oil? Unfortunately these are questions that do indeed haunt me as I was not there and details from the various attendees are vague at best.

Please do not get the wrong idea as I am in no way questioning what you saw and / or were told. I truly respect and appreciate your insight regarding this matter and shall gladly keep you posted.

Sincerely,
Dale

Ps
I would indeed like to have a peak inside the infamous jet box.

nsman · Jan 23, 2005

Hi Dale,
I recall Bergdaddy making reference to some debris discovered in the oil change in a post from him just prior to the start of the 1000.It would appear that all the parts of the broken cam chain were recovered inside the engine and as per the photo are all accounted for.
Since you stated that in your considerable experience that a camchain to break in this manner is unlikely, it would appear that more investigation is in order.
......nsman

LINEAWEAVER · Jan 23, 2005

Taffy said:
as usual dale your too humble to say it but the valves DID NOT break!

what was the manufacturer of the camchain? renolds? regina? DID?

Taffy

Hi Taffy,
Chain by Regina.

Looks Iris to me
Mine lasted 40 hours before it had stretched too much

Hi Supermoto_Husaberg,
Being a mechanical engineer I know you are well aware of the following.

Clarification for the non mechanical:
"The chain does indeed get longer through use, however, not as a result of yielding side plates. Such length increase is as a result of roller, bushing and pin wear.

Best Regards,
Dale

LINEAWEAVER · Jan 23, 2005

nsman said:
Hi Dale,
I recall Bergdaddy making reference to some debris discovered in the oil change in a post from him just prior to the start of the 1000.It would appear that all the parts of the broken cam chain were recovered inside the engine and as per the photo are all accounted for.
Since you stated that in your considerable experience that a camchain to break in this manner is unlikely, it would appear that more investigation is in order.
......nsman

Hi Nsman,
More than a single roller split and was lost. The picture is simply that of the single pin which broke and consequently prevented further operation. Multiple pieces of the chain have the pins in tact minus rollers and bushings. (such are unaccounted for on this end and presumed to be that which was discovered during the infamous oil change) To me this indicates the chain failure was self motivated and accumulative.

Until 2004 I was never witness to a broken valve spring and / or main bearing failure. Based on what I have to work with I can only speculate that the chain did indeed fail. If so, it is a first for me.

Note:
Study the photo and you shall notice one and one half rollers are pictured.

Sincerely,
Dale

nsman · Jan 23, 2005

Thanks for clearing that up for me Dale.

PowerCell · Jan 23, 2005

Hey Dale -

The debris I'm refering to was approx. 15mm long and attached to the drain magnet. It appeared to be the edge of a bearing race. I estimate the bearing diameter based soley on the curvature of the fragment...

Best of luck... Ken

LINEAWEAVER · Jan 23, 2005

PowerCell said:
Hey Dale -

The debris I'm refering to was approx. 15mm long and attached to the drain magnet. It appeared to be the edge of a bearing race. I estimate the bearing diameter based soley on the curvature of the fragment...

Best of luck... Ken

Hi Ken,
I honestly cannot say as everything visible short of splitting the cases looks good. A shift fork or bearing from the transmission side could possibly have failed and a piece come loose. However, making its way to the camchain and back to the transmission magnet without doing other damage is hard for me to buy.

I did take a peak inside the transmission via a boroscope.

In any event Tim can split the cases just for insurance as their is nothing special about the gearbox. I was concerned more for the crankshaft and head as many hours were invested.

I shall keep you posted.

Sincerely,
Dale

BD · Jan 24, 2005

cam chain failure

Dale, if you flip those pin pieces up on end and take a closeup pic, I can determine from the fracture faces if it was a fatigue failure or a rapid fracture from an "interference" problem or otherwise. Just post them here. BD

LINEAWEAVER · Jan 24, 2005

Re: cam chain failure

BD said:
Dale, if you flip those pin pieces up on end and take a closeup pic, I can determine from the fracture faces if it was a fatigue failure or a rapid fracture from an "interference" problem or otherwise. Just post them here. BD

Hi BD,
This is the best shot I could make. I have forwarded the broken pins, bushings and roller fragments to you via USPS. I have also enclosed one complete pin, bushing and roller assembly for reference.

I should mention said failure occurred on the driving side of the sprocket set mid point as the chain was still engaged to said sprocket set on both ends. In addition another pin was broken though had yet pulled from the side plates.

Note:
All previous chain failures have been as a result of lodged material between chain and sprocket teeth resulting in actual side plate failure.
In this case the side plates are intact.

Thank you for your interest and much appreciated assistance.

Link pin on end

Sincerely,
Dale

BD · Jan 25, 2005

Hi Dale. That's a pretty good pic! Just what I needed, but seeing the actual parts will be even better as I can magnify the fracture face without distortion. It looks like a carburized pin from the pic, but I can characterize it more accurately after I get the pieces. BD

Cheesy · Jan 26, 2005

Just a thought on this which may be way off the mark but is it possible that the said piece of metal was part of the auto decompressor. I have had two of these brake in my engine, first time the 'pin' end broke leaving the weight in the cam, the pin then got draged between the chain and the cam sprocket some how and destroyed the Al sproket, the second one the weight broke off and broke off the ends of the pins on the con link. The chains survived both times though

DOLLARS · Jan 28, 2005

Dale would there be any advantage in running the type of chain used in the honda crf 250 with regards to extended chain and sprocket life.

LINEAWEAVER · Jan 28, 2005

DOLLARS said:
Dale would there be any advantage in running the type of chain used in the honda crf 250 with regards to extended chain and sprocket life.

Yes indeed.
Unfortunately Hyvo chain drives (ie silent chains) are quite expensive and do take up a bit more space.

Sincerely,
Dale

LINEAWEAVER · Mar 17, 2005

Engine Update

Two new exhaust valves and a cam chain later I am happy to report the bike is alive and well living the life of riley in Las Cruces New Mexico.

Dale

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