Topic: CB750 MLS head gasket - 8 holes for dowels and fat o-rings too small?

[PeWe]

I see now in the last minute that the MLS head gasket has small holes were it normally are much bigger for the 8 dowels  with fat o-ring around. 4 on each side around the cyl studs between cyl 1-2, 3-4.

I have searched the forum and did not find a clear case explaining this.
- The 8 dowels with o-rings should not be used with this gasket? Really no oil leak?

The height of the dowels is appr13.9mm and they seems to have a small stick-out over the cyl surface, enough together with o-ring guide oil thru the OEM style head gasket.

I have searched around to verify eventual wrong model for older CB750 without these dowels. Could not find any other design. Saw photos from Dynoman as well as CycleX which I have which look similar with small holes.

[MCRider]

The fat ORings were added somewhere around K4, maybe earlier. Might have been a mid-K2 upgrade.

Anywho, they are not necessary. Early models did not have them. They were thrown in to try and reduce the number of headgasket leaks fixed under warranty. But by then the leaks were very rare anyway.

The MLS gasket with no Orings should be comparable or better than an OEM gasket with ORIings. Especially if you have HD studs and are cranking a little more torque on the head nuts anyway,

IMO, OCICBW, its your bike. My rebuild didn't have them and didn't leak.

[PeWe]

OK, NO 2x4 dowels with o-rings/sealers then. I have the APE HD cyl studs
Only the 2  O-rings (11,5x2,5mm) on each side of the cam chain tunnel on rear side (carb side), right?

Hondaman explained the dowels rather well here, MLS was not involved in this case.
http://forums.sohc4.net/index.php?topic=81643.0

Problems with Wiseco head gasket at the end of this page: http://forums.sohc4.net/index.php?topic=88926.0

- More MLS users without these 8 dowels and orings? No problems at all or additional sealer to be used?

I'm not completely convinced yet and have time to make it properly without leak.

[iron_worker]

I talked with Ken at Cycle X about this when I ran into the same issue. Here is what came out of that conversation:

-Install the MLS head gasket DRY.
-The rubber packing on the 8 outside studs was an attempt to fix head gasket leak problems (as mentioned). What the bikes really needed was a better head gasket design.
-O-rings on the inner two studs only (these are the oil feed ports, the other 8 are the oil return ports)

Ken claims he gets no leaks on a properly surfaced head and cylinders.

IW

[MCRider]

I talked with Ken at Cycle X about this when I ran into the same issue. Here is what came out of that conversation:

-Install the MLS head gasket DRY.
-The rubber packing on the 8 outside studs was an attempt to fix head gasket leak problems (as mentioned). What the bikes really needed was a better head gasket design.
-O-rings on the inner two studs only (these are the oil feed ports, the other 8 are the oil return ports)

Ken claims he gets no leaks on a properly surfaced head and cylinders.

IW

My conclusion too. Combo of Ken, Mark (HondaMAn) Mike Rieck, and reading many threads on the subject. My firsthand knowledge is from K1 and early K2 which didn't have the ORings to begin with and they didn't leak upon rebuild w/ HD studs.

[PeWe]

Thank you all for the good news. 
Dry MLS gasket + "O-rings on the inner two studs only".
Head on with cam timing later today when back home from my job

[brandEn]

So did you fit the dowels without the o-rings or just leave all that stuff out all together? Im kinda confused. It seems its ok to leave the 8 rubber thick o-rings out but what about the dowels? Leave em in or chuck em?

[iron_worker]

I put the dowels back in. Not sure if it would matter.

IW