XIU Cylinder Head Review
 

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.

http://i68.tinypic.com/iftkie.jpg

http://i66.tinypic.com/eh0rb9.jpg

Darn it, that really sucks big time!

I'm probably missing something here but if you feel the stock head is off why not have it recut... it used to cost me $75

RB quit doing GG heads here in the US, but Motopsycho should be able to hook a European brother up.

I know the stock head is off, but RB stopped doing the heads and I needed a spare anyways. RB's turn around time used to be phenomenal, the other tuners that do this type of work, not so much. I can't have my bike down for weeks waiting, with a race every two weeks. This seemed like a good option.

I received an email from XIU, they are going to "check internally how to answer your problem properly". Sounds like the run around. I hate to do it, but if they do not offer a replacement cover, I will have to file with PayPal.

might be a way of saying nothing, but may also be a way to tell you that they have started working on an answer. I would give them a day or two.

Agreed. :D

I have been thinking about this head myself, as Xiu-Rdi are the only ones that I have found selling a head with separate inserts for the 200. I have cut the OEM head with good results on my lathe, but fancy parts are always of interest :-)
And after all, these spanish guys have been participating in the design of both Ossa and Gasgas, so I think they know what they are doing, engineering wise. Lets hope this cracked head is a unique issue, and not a sign of their normal quality.

Looks like the head cracked from over torquing of the head bolts.

I was waiting for this. I can tell you unequivocally that was not what happened here. Head was torqued in 4 steps in the proper pattern with a quality click type torque wrench to Gas Gas spec of 18 ft lbs and then checked after a heat cycle. I've dealt with plenty of 2 stroke cylinder heads over 20 years of road racing and never cracked one due to over-torquing.

Ok. I apologise if I came off as questioning your ability.

There must be a gap between the insert and the outer head. This would cause the head to flex at the head bolt holes.

No worries. I guess I am anticipating the same response from the company and have my rebuttal ready to go!

Still have yet to hear anything from them. Sending another email today. It seems clear to me the solution is to send another head cover, the only issue is whether it will be sent free or discounted or for the price of shipping or something in between. I understand that with engine components there really isn't much of a warranty once it leaves the manufacturer's hands, but a non-wear item like a cylinder head cover should not be failing either.

I agree with gasgasman, you caused the cracks when it was torqued. Not saying you torqued it incorrect, but for some reason the insert and head are not seating correct. If you get a new cover you might just wind up with the same result another crack.

Point taken. Everything seemed normal upon assembly, went together with no issues, there were no leaks, external or internal, so things were sealing properly. Worked well for about nine hours, five rides. I was in the woods and noticed a small leak around two of the bolts. Got home and inspected and found the cracks.

I don't think this is over torque. This looks like a machining issue to me. The head is high siding towards the center. Like breaking a stick over your knee. By the looks of the cracks it seems to have been torqued very evenly.

I think it is a stress crack from the bolts tightening down on the head but not from over torquing them and that there may have been a fault in the manufacturing of the head. By the looks of it the machining of the inside of the head may of had a little too much meat taken out so that when the two parts are brought together they don't sit flush and hence when they are placed on top of the cylinder there would be a small gap of a tenth of a millimetre between the cap and chamber where the blots go through. Then when the bolts are torqued up the gap would be closed but with alot of stress focused on these points and then with the added stressed of the engine running it leads to the top cap stress cracking around the bolts.

I'd be looking into how well both parts sit together and if they marry cleanly.

Just a theory.

The point that everyone is making to save you more grief, ask for complete matched set insert and cover.
From the pics it doesn't strike me as a high quality part, think I would try for a refund and buy a S3 head.

It sounds like it was not machined properly so if the company is not responding promptly and with the correct answers to address this problem, I would contact PayPal sooner vs later. There may be a time limit.

I believe it's 180 days to file with an international sale. The company has not responded to my email from Wednesday. They are in Spain, so I don't think they are on holiday like the US.

I opened a query with PayPal and received an email almost immediately from the company (funny how that works).

They are going to send a replacement cylinder head cover. I informed them if this one does not mate properly to the insert, I will move forward for a refund. They were OK with that.

Will post further information when I have it.

Glad to hear you are making progress.

As a final update, the replacement head cracked as well, in less than 10 hours of use, despite meticulous installation and set-up. I believe the aluminum on the head cover is too thin to withstand the vibrations. The company refuses to do anything else to assist, so I am left with a hunk of useless aluminum. Go elsewhere for your performance head. Stay away from XIU.

After looking at them ( and the price) I emailed them a few weeks ago, the reply ' sorry the part is out of stock'
lucky!