MC Tested: Millennium Technologies Cylinder Replating Service

ENGINE REBUILDING: Refinishing a pair of hard-to-find cylinders for half the cost of one new-old-stock part.

Associate Editor Zack Courts and I have a side project that we've been chipping away at in our spare time: We're rebuilding a pair of Honda RS125 two-stroke GP bikes. These little racebikes where hugely popular throughout the 90s but Honda stopped making them in 2004 and parts—especially consumable items like pistons and cylinders—are getting very hard to find.

?The boxes of parts that came with the bikes contained several old cylinders, but none were serviceable. I prefer to repair things rather than simply replace them, and with new cylinders difficult to come by and commanding top dollar ($700-$800!), I was eager to find a way to get the old jugs refurbished.

A little online research led me to Millennium Technologies. Located in Plymouth, WI, Millennium has been repairing and replating cylinders since 1997. I called to see if they could fix up the RS cylinders—one of which was severely scuffed and coated in slag from a scorched piston, the other with deep gouging from a broken ring—and the woman I spoke with assured me that neither scenario posed a challenge for Millennium’s techs. If necessary, Millennium welds up damage before boring, replating, and honing. Check out the video below to see how it’s done.

I received my repaired cylinders about three weeks after sending them out. I’d sent them off with a new piston that Millennium used for sizing, honing the cylinder to the exacting 0.002” piston-to-cylinder clearance that the HRC manual calls for. And the cost? The gouged cylinder required welding and cost $220, while the other jug just needed a standard replate which costs $180. That’s two refinished cylinders for about half the cost of one new-old-stock part. Awesome.

Millennium Technologies bores, hones, repairs, and replates cylinders for all kinds of motorcycles, watercraft, snowmobiles, and cars. If it’s internal combustion, odds are they can handle it. They repair crankcases, too. Millennium also offers porting and valve-job services, and even has an entire division dedicated to rebuilding crankshafts. So if you’re a repair-it or rebuild-it guy instead of a replace-it kind guy, keep Millennium’s number handy. It’s 888.779.6885, and their website is

The worse off of the two cylinders I sent to Millennium had deep vertical gouges from a broken piston ring. This picture shows the stripped cylinder with freshly laid aluminum beads filling in the gashes. Cylinder repairs (as well as port and crankcase repairs) are Millennium’s specialty.


PRICE: $180 and up


Verdict: Quick, affordable, expert repairs for rare or hard-to-find engine parts.