High leak down on fresh build before break in

[user-23911]

If you want to check where it all touches together, you use that blue dye on the seats or valve faces.

[Schurkey]

I made a leak down testers I/A/W AC43-13 and I too wondered about the need for a smaller oriface. My oriface my be a bit too long, a 41 caliber bullet swedged into a pipe nipple nicely and added a bit of locktite to make sure the lead sealed to the pipe. What would you suggest for an oriface for automotive work? Mine seemed to be a bit low. I've had several motors read 2-4% leakage after break in. This was with convention moly rings with the gaps on the tight side.

Far as I'm concerned, the .040 main orifice design and size is just fine per the FAA. My concern is with the size of the "Master Orifice" as spec'ed by Teledyne Continental. The Master Orifice produces about 25--30% leakage as interpreted from the gauges, and that's too much for performance automotive use.

But main point was that GSX-R valve job isn't even supposed to seal after assembling, final sealing is achieved after engine running.

Wild Guess: This is C-Y-A for Suzuki due to poor dealership tooling. The valves would/could seal properly on-the-bench if the Suzuki-supplied seat-cutting (and valve guide repair???) equipment were more precise. Alternatively, perhaps this is an artifact of the titanium valve's "oxidized membrane coating".

[dhidaka]

[/quote]

After cutting valves could seal fine, but nobody could guarantee that. Specially on bike engine with hard steel seats, very hard valve coatings, very tight valve stem clearances and very light seat pressures. After running engine valve clearance will tighten up few hundreds and valves stop leaking.

http://www.suzukigsxr.org/valve_seat_repair-293.html

It's a fact that valve seal is not achieved after assembly but only after engine running which seems to be original posters problem.
[/quote]

GSXR Suzuki shop manual quote from above:

Caution
the valve seat contact area must be inspected after each cut.
Do not use lapping compound after the final cut is made. The finished valve seat should have a velvety smooth finish but not a highly polished or shiny finish. This will provide a soft surface for the final seating of the valve which will occur during the first few seconds of engine operation.
The titanium valves are coated with an oxidized membrane treatment to resist wear but the membrane tend to removed if lapped after valve seat servicing.

Here is where I am from my original ST post inquiry.
Seats were cut on a Serdi along with full porting by APE.
Valves are new oversize SS (not titanium) and had been lapped in to factory seats, not by APE.
On my end, I checked leakdown on two different testers. Same results.
I checked leakdown with the head torqued at 38 lbs and 20 lbs. Same results.
Finally, pressurized the chamber with full valve train and 100 lbs. Sprayed Windex in both intake and exhaust ports. Bubbles did not spray, but were very much arising around the valve peripihery.
Therefore, the head went back to APE. APE is graciously going to take a complete look over and said they will definitely make things right. They vacuum test all heads with .8 bar vacuum before anything ships. But, customer was told that he would probably have to run his engine, thinking everything will seat in.
Waiting news of final "looksee" from APE.

[Schurkey]

Seats were cut on a Serdi along with full porting by APE.
Valves are new oversize SS (not titanium) and had been lapped in to factory seats, not by APE.
On my end, I checked leakdown on two different testers. Same results.
I checked leakdown with the head torqued at 38 lbs and 20 lbs. Same results.
Finally, pressurized the chamber with full valve train and 100 lbs. Sprayed Windex in both intake and exhaust ports. Bubbles did not spray, but were very much arising around the valve peripihery.
Therefore, the head went back to APE. APE is graciously going to take a complete look over and said they will definitely make things right. They vacuum test all heads with .8 bar vacuum before anything ships. But, customer was told that he would probably have to run his engine, thinking everything will seat in.
Waiting news of final "looksee" from APE.

I hope you get better service from them than I did. I'll NEVER go back to APE.

[Dan Timberlake]

"Bubbles ... were very much arising around the valve peripihery."

All Intakes, all the exhausts, all of the above?

All the way around every bubbling valve?