87 430WR - Coolant Leak on Exhaust Side of Head/Cylinder Area

I just had my 430 bored 1st over and after I put it all back together, it has a coolant leak between the head and cylinder area only on the exhaust side of the head/cylinder. I am using all new gaskets and it has never even had head seepage of any kind over its life. No gasket sealant ever used on the bike. I am the original owner and it has only had the cylinder off 1 time for a new ring way way back - I just could not wear out this top end.

I torqued all 4 head bolts (22ft LB) and 4 head nuts (26 ft LB) to what I believe are the correct torque setting. The leak started right on start up before the coolant system was even pressurized. As a test, I tightened only the front 2 bolts and 1 front nut by another 3 ft LB which reduced the leaks but did not stop them (around 10 tiny streams spanning across much of the gasket edge on exhaust side of cylinder).

So I pulled the head and am inspecting things. I can't measure/detect any head or cylinder warp and my bore shop said they would lap the surfaces as needed (now confirmed this was done with a Tuesday call). However, the head does seem to have some very very minor side to side (left foot peg to right foot peg) rock when using my hands - EDIT - no rocking as it was not mounted perfectly. The head passed my primitive feeler gauge check on a few granite counter surfaces so that leaves the cylinder surface - does it easily warp after never leaking? EDIT - painted head and cylinder with black marker and lapped on 600grit on my tested flat granite piece, all looks very flush.

So --- what to do?

Defective head gasket (it's new)?

Are my torque specs to low? Anyone have different service manual specs? (This could be it but I need some new numbers so I don't rip a head bolt stud out of the case)

Reassemble using gasket sealant for the front coolant gasket area?

Get head and cylinder checked for warpage, repair as needed?

All input welcome, time to ride so this bike needs to be 100% like yesterday!!!


EDIT - Hall's is sending me a new head gasket as it appears not quite right. I may also use some of the copper head gasket seal in this thread.

Can someone please confirm the torque settings?


[FYI - the OEM forks almost made me sell the bike so I swapped them for a direct bolt on set of Showa forks off a Husky WR360 1992 model (just bolt on the entire front end with the Brembo brake and no need to change any head bearings etc. Everyone should do this, just magical compression and rebound adjustments!!!]

I always assemble my 430 and like engines with a silicone sealer on both sides of the gasket, not much and it allows me to reuse the gasket most of the time
big benefit it confirms seal
but you might consider checking all surfaces as you said it rocked, typically they don't warp, but if you have not owned it for years you have no history of it's past

I just my cylinder back with a fresh bore from Halls. I checked and my head sits prefecly flat on the cylinder.
I would double check the head and top of the cylinder

For a quick check on flatness - take a magic marker (or machinist dye) and fully mark the top of the cylinder and bottom of the cylinder head - then take a full sheet of 400 Wet & Dry sandpaper on top of a piece of glass (or other very flat surface) and lightly, using circular motions, sand (with wetted surface) for a few moments. Look to see if all the marked ink has been removed. It was mentioned that there was a 'slight rocking' - that would seem to be a warped surface - would not have any 'rock' otherwise.

Per the Husky service manual silicone is recommended on both mating surfaces. I use Permatex Ultra Black on my builds.

Torque value for the big bore is 29 ft-lbs on long studs and 22 on the short ones.

The bike is back together and all ok. The issue was the brand of head gaskets which I consider defective since they have ridges around many of the stamp out areas which cannot be flattened properly under the correct torgue. I purchased another brand of head gasket from HVA that is the old paper material type (not the kevlar metal infused type) and it works perfect.

Who's gasket was it?

The good gasket was sold by HVA-Specialty!!!

I meant the first one. The older paper style gaskets work perfect. But sometimes you have to wet them and let the swell up to fit properly.