[dANbOT]

There seems to be a collection of very knowledgeable experts in here. Anyone with foundry, casting, or metallurgy experience care to look at my pics and offer an opinion?

Bike is a 2014 Gasgas EC300 running completely stock aside from minor jetting adjustments. Aprox 120 hours on brand new bike since the spring. The engine ran flawlessly right up until the incident.
The short story is:
Last week, a friend and I stopped after a stretch of gravel road high speed cruising between area's to check on the slower guys in the group. As I stopped I saw some steam coming from the engine area, and quickly spotted a visible crack on the top on the cylinder head. After rescuing the bike and taking the top end off, this is what I found:

There is the long crack on the top of the cylinder head I had originally spotted, plus another crack in the combustion chamber.



I cut the head in half vertically to get a look inside the coolant jacket. I know almost nothing about casting, but there are some iffy looking areas inside, leading me to believe this head was flawed leading to eventual failure (whether progressive, or sudden).






The piston, rings, and cylinder all look mint. No signs of det. Anyone care to guess what might have happened? Or have experience to judge the casting?

 

[John Tice]

Dan; I’d suggest that this info be forwarded on to the factory for review. There probably is a shrink problem at the foundry. Maybe the head was pulled from the mould too quickly while cooling. Possibly there is a gating problem with the molten aluminum not flowing correctly. Properly, possibly & correctly are all a characteristic of a new product as your machine is a late model. Sometimes a manufacturer may be inclined to replace a faulty product; there may be other cracked heads floating around somewhere. ope:

 

[dANbOT]

Unfortunately Gasgas has gone bankrupt, and is in a liquidation phase right now so it seems I'm on my own with this.
I have ordered an aftermarket head to install, so I'm basically just trying to get as close to confirmation as I can that the failure was nothing but a flaw in the head. (so I wont worry about some other strange cause as I assemble the engine, and get ready to run it again). If there is suspicion of flawed heads, I wouldn't want to replace the head with another OEM one anyhow. Good thing S3 makes a nice interchangeable dome head kit for my engine!

This really is an AMAZING engine / bike from somewhat of a "boutique" manufacturer, but I have found a couple flaws that I have / will have to address.
-Kick start lever is made of such soft aluminum that it quickly failed (rotating past 90deg on the spindle when I fold it out to kick) Luckily, they copied a Yamaha spline, and YZ/YZF kicker assy's fit right on.
-I have snapped two kick start shafts in the same area (at a narrow spot, just past the outer splines) I have found a shaft from an older EC300 that does not have this narrow spot and looks much tougher.
-And now this head failure.

Once thee few issues have been taken care of, I am still confident that I have one of the best 300cc enduro bikes available, and am happy with my purchase. I do HATE the down time though.

 

[John Tice]

Seems like too many possibilities broke the company

 

[seattle smitty]

If you or those you know with the same bike are cracking heads and running low on replacements, consider having one of you with machining skills and access to a lathe and vertical milling machine make heads of aluminum billet. Easy enough to do; make it in two parts. Basically you turn the combustion chamber and squishband, along with any o-ring grooves, on one side of the chunk of aluminum, and mill water jacket passages in the other side. Make the water jacket cover plate with the second piece of aluminum. You'll never break a billet head. I made my first one forty years ago, for a two-cylinder Konig racing outboard.

 

[dANbOT]

It's an uncommon bike outside of Europe, but I did scour the internet for similar failures with very little to find.
I did see reports of much older versions of the engine that had porous flaws in heads but they did not seem to crack, just weep.

I'm sure the aftermarket head I ordered will do the job, but I sure wish I had machining / welding equipment available to use!

 

[mgty3whlr]

Cool Head makes the billet 2 piece head. but there are others copying their design.
So an aftermarket head should not be a prob.