rearenginekarts.com

Some time back on Ebay i seen o/s pistons for the US820 now most US820's are chrome bore so what was the story to the o/s pistons and there use ??

McBob.

Hi, Bob! Used to be that a lot of the real hot 820's had a sleeve installed, sometimes because they wanted to save a good block, but most times because they wanted a large overbore. There were quite a few +.100 Benders. The sleeved blocks were stronger, too. Nowadays you can send a scored chrome bore block off to Scott Reath at U.S. Chrome in Fond Du Lac, Wisconsin for a Nickasil treatment. They can repair scored/needled blocks and apply the Nickasil coating. Supposed to be better than chrome. They have done thousands of snowmobiles, karts and others. I've never asked Scott if he can bore the aluminum oversize and then apply his magic.
US Chrome
650 Oak Park Ave.
Fond du Lac WI 54935
http://www.usnicom.com
866-922-5066 ext 101
TJ

Looks as a fella will have to write and ask Scott.

Thanks ol mate i told ya you were more than a pretty face .......... McBob

Darn good thing I'm more than a pretty face, Bob! Wouldn't get far on this kisser!
U.S. Chrome's website will tell you a lot about what they can do. I have to admit that I haven't used them yet, but I will! www.usnicom.com Ted

There were also some that were done as a R&D project for drone use. They were like 60 or 80 over and then rechromed with some port changes so the drones could boost hp without a weight gain. I gathered this info form Dave Bonbright who was involved in the R&D. I doubt any of those have turned up but who knows.

But what you're saying about the others, Ted, is that they were first bored big enough to install a sleeve which was itself large enough to be bored out over 0.100"? I'll bet it was fun trying to get the ports/scavenging correct!

I just had one of my 820s nikasil treated after a repair and, if there is no actual damage during a season, it should be good to go for more than one with no problem. There are anecdotes about wear on the order of .0005" during a season but ??? I guess I'll find out; we're gettin close now.

Andy

Andy, I knew of a number of 820's in the day with a Horstman stroker and a Fairfield Machine Services +.100 sleeve job. My pal, Charlie had one on the same '61 Bug Scorpion that he still drives. It was near 12 C.I., and ran like the wind. S&S Oil (Dick Collier) was a pioneer in the siamese porting like dave B. does now, and a lot of them were ported that way. Fairfield was known for their sleeve jobs with corrected port timing. TJ

Nikasil, electrodeposited lipophillc nickel matrix silicon carbide coating, requires a diamond impregnated hone. German cars have Nikasil bores, F1 engines used Nikasil bores, and might still be using Nikasil, I don't know. BMW switched to Alumasil a few years ago.