I recently purchased the XIU aftermarket cylinder head for my Gas Gas EC250 from Spain
http://www.xiurdi.com/portfolio-item...250cc-y-300cc/. Communication was prompt and friendly, the price was reasonable at around $130 USD shipped and the item arrived in less than ten days.
Squish measurement on the stock head was 1.6mm, with the XIU head the measurement was 1.2mm, so this was positive.
Installation should have been straight forward, but it was actually a pain in the ass. The earlier Gas Gas models have a head stay that bolts to the frame via brackets. There is no provision for this on the XIU head. Fair enough, just had to make a spacer to hold the radiator guards together. On to the next issue, the cylinder head, being much thinner than the stock item, requires the installer to find proper length bolts in order to avoid bottoming the stock ones out in the cylinder, throwing off torque values. This would be easy to miss, as the stock bolts appear to work properly. There was no mention of this from XIU, in fact there were no installation instructions at all. Still, not a huge issue once sorted.
Upon attempting to install the radiator hoses in the XIU head, one realizes that the spigots are remarkably smaller than the stock Gas Gas items. This means the stock rad hoses will not work with the XIU head. Again, there was no mention of this prior or after purchase from XIU. They leave the installer to figure this out as well. After some creative hose solutions, the head was installed. Bolts sequentially torqued to Gas Gas specs and re-torqued after a heat cycle.
As with any 2-stroke getting closer to the optimal squish measurement, a correlating increase in performance was noted. Not exceptional, but noticeable. A good sign. I was happy at this point, despite the installation issues.
Fast forward, after ten hours of use I am not happy at all. Two small coolant leaks were observed on the left side of the head. Upon inspection it was discovered that the cylinder cover casting was cracked in two separate locations, resulting in the leaks. Fortunately this was found before complete failure. An email has been sent to the company with pictures, I await a response and will update as information becomes available.
