Recently acquired a low-hour 2005 WR450 and was faced with having to un-do the half assed attempt at AIS removal the previous owner had done.
A real horror show that leaked badly and it had to go in favor of a proper permanent solution.
The GYTR AIS removal kit for the 2005-6 WR450s is a dodgy solution also, relying on clamping a cap on the 90 degree elbow coming out of the cylinder head.
There used to be pre-made options for AIS removal on these bikes, but now those are all gone except for the GYTR kit.
The solutions that are no longer available consisted of a plug that was driven into the hole in the head left after removing the pipe elbow. A much better solution than the GYTR kit.
Some will say the GYTR kit is nice because it includes a needle and throttle stop, but the value there is dubious considering that you can just cut the throttle stop and many folks (myself included) opt for the JD jetting kit so that makes the GYTR needle and jets unnecessary.
So, faced with not wanting to lay out $50 for the GYTR kit and its weak answer to the problem I set out to find an acceptable substitute for the plugs that are no longer available.
Behold the solution:
Dorman part number 555-106 freeze plugs, a whopping 39 cents each at O'Reilly Auto Parts. These are 12.1mm oil gallery plugs. The hole in the head is 12mm, and these fit perfectly. Actually a bit tighter than the pipe elbow I removed.
One plug installed:
There is a lip at the bottom of the hole that prevents them from being driven in too far. The hole is deep enough to accept as many as three plugs, but that is definitely overkill. As tightly as they fit, one should be plenty but erring on the side of caution and just wanting to fill the hole up so it doesn't collect a lot of mud and dirt I installed a second one:
These are not coming out without a drill and a slide hammer.
This is the proper, permanent solution to this problem!
For the small vacuum fitting on the head near the carb, a standard rubber vacuum cap is sufficient. Also for the airbox, a 1/2 inch rubber vacuum cap took care of that.
Dorman 555-106 plugs: .39 each, .78 total
Pack of assorted vacuum caps: 3.49
Less than 1/10 the price of the GTYR kit, and a MUCH better solution in my opinion!