O-Ring mod for $100ish USD - hope it works

[motosapien]

Earlier this year I started restoring my RZ350, and opted for a +4 wicked stroker with 795series wiseco pistons. After mocking it up, the piston was sticking out about 2mm at the top, and first thing that came to my mind was wicked head. But then I was running low on funds so this encouraged me to scout for machining help.

5533c9891dd6a85a59d11f22b8bdc072.jpg (55.19 KiB) Viewed 8099 times

Also I did not want to use the spacer plate the the bottom as I had matched the ports with no plans of using them. Then I got some help from a friend as I am not good in cad software to come up with this

CAD.jpg (97.63 KiB) Viewed 8099 times

After a long search my friend Rick Lance suggested me to check with Eric Gorr and shared his contact http://www.eric-gorr.com. After speaking with Eric Gorr I sent the head and the drawings, got them back in the mail today and they look perfect.

head.jpg (126.79 KiB) Viewed 8099 times

The O-ring groove details are 69mm-74mm id and od, The groove dimensions are 1.5mm deep and 2.5mm wide.
The o-ring specs can be calculated using this https://oringcalculator.eriksgroup.com/" onclick="window.open(this.href);return false;
and the link for o-ring I bought is https://www.mcmaster.com/#1295N274" onclick="window.open(this.href);return false;

Cost breakdown
Head mod and oring - $70
Logistics - $20
O-rings - $8.82 + $5 shipping

[motosapien]

not sure why the last pic of the head is not loading in the previous post...so I have attached here again

[motosapien]

Also I am no tuner, the head design is similar to what is discussed here on the board in many many posts.

[RuZty]

Nicely done. I can see the last pic in your first post, but not the second one, no matter how many times I reload the page. It is visible if I right click and open in a new tab, definitely something screwy going on here with attached pics.

[motosapien]

Glad that they are visible.
Hope the head works on my motor

[slinger]

Expect it to go boom...the land from o-ring to chamber is super small. Good luck with that one, best 100 bucks you spent right.

[motosapien]

Expect it to go boom...the land from o-ring to chamber is super small. Good luck with that one, best 100 bucks you spent right.

[motosapien]

Expect it to go boom...the land from o-ring to chamber is super small. Good luck with that one, best 100 bucks you spent right.

BTW what is the safe width of the land?
Thanks

[MK]

You use a 70x2 ring and a groove with 0.5 mm “play“ at the inside diameter.
I agree that the bridge width may be a bit too low and I have seen heads with that small bridges broken.
It'll work for a limited time depending on the loads. It's not unlikely that it'll survive normal road use for pretty long.

I use 71x2 with basically no play (1 or 2 10'th) and up to now that works in several RD's.

[slinger]

I wasn't joking about the $100 that is crazy cheap for the machining work!!!!! I don't know what the width is when I did them I never measured them, I know the first one I did broke in that area.

[slinger]

Personally I would fill the o-ring groove with resin and get the cylinders o-ringed, or your be buying new pistons and rebuilding the engine when it brakes.

[motosapien]

The width of the land is 2mm

[JanBros]

for my KR1 I once "emptied" an original head and adjusted it so I could put in changeable inserts.

http://www.kr-1s.co.uk/forum/viewtopic. ... ad+inserts" onclick="window.open(this.href);return false;

sadly outer edges arround the big O-rings for the water were too thin and started cracking, so went full-out and designed a CNC head.

[hondaror]

So what was the solution here? Scrapped head?

[motosapien]

So what was the solution here? Scrapped head?

Rework