Topic: 77 CB750 F2 Top End Rebuild Advice

[bryanj]

Sorry cant watch videos, with valves only just perceptible play between stem and guide is allowable, if you can see movement its probably too much.
We are talking way less clearance than cars here

[grcamna2]

Sorry cant watch videos, with valves only just perceptible play between stem and guide is allowable, if you can see movement its probably too much.
We are talking way less clearance than cars here

 

[spmc]

If the mating surfaces are clean and flat is there any need for liquid gasket as insurance or could that just cause other issues?

I just think a new gasket should be enough to keep everyone sealed no? Or does most everyone add a little liquid gasket on a rebuild?

[PeWe]

That yellow paint indicated which end of the spring goes on top. When the factory is building hundreds of heads and has thousands of springs it makes it easy to know which end goes up.
 That 45 degree valve face is hammered. The contact width should be .060....that looks to be about double that and it is recessed as well. Dynoman sells F2 valves for cheap and they are better quality. OEM Honda valves are as soft as a grape.

I have used F2 in valves in my K6 head.
The first set got mushroomed tips within 10000 km so the tips had to be grinded to take out.
Engine got new the year after. Same thing shortly.

So stock F2 valves are wrongly made. Cannot be hardened, soft as a mushroom.

Dynoman valves as Mike wrote.
They also have titanium retainers that keep up better.

[spmc]

That yellow paint indicated which end of the spring goes on top. When the factory is building hundreds of heads and has thousands of springs it makes it easy to know which end goes up.
 That 45 degree valve face is hammered. The contact width should be .060....that looks to be about double that and it is recessed as well. Dynoman sells F2 valves for cheap and they are better quality. OEM Honda valves are as soft as a grape.

I have used F2 in valves in my K6 head.
The first set got mushroomed tips within 10000 km so the tips had to be grinded to take out.
Engine got new the year after. Same thing shortly.

So stock F2 valves are wrongly made. Cannot be hardened, soft as a mushroom.

Dynoman valves as Mike wrote.
They also have titanium retainers that keep up better.

Justin installed the Cycle X retainers last night actually! Make it look a little more Mad Max haha.

[spmc]

The second source is the O-rings in the head gasket that [are supposed to] seal the oil fed to the top end. The new head gaskets made after 1990-something are all (ALL) thicker by at least 0.2mm over Honda's version (some of the MLS are even thicker than this) so you need to use a correspondingly thicker O-ring in those 2 ports: 2.6x10.8mm (Parker# 02-111) to make up the extra thickness with sealing pressure.

I'm having a hell of a time trying to find the right O-Ring to address the potential head gasket gap... If I'm correct you're referring to part no. 91310300000 which is 2.5x11? Can't find any source for a 2.6x10.8mm in Canada currently. And to make me more confused the rebuild kit I got from 4into1 has the following listed

91302-001-020 - O-Ring 30.8mm - x8 (tappet rings)
91305-323-000 - O-Ring 5.8 x 1.9mm - x4
91304-286-000 - O-Ring 61.8 x 2mm - x4 (Cylinder)

I'm assuming 2.6 x 10.8 is because you're thickening the ring by .2mm so that means you subtract .2 from the diameter right? Can I order this from a marine store or something?

[grcamna2]

The second source is the O-rings in the head gasket that [are supposed to] seal the oil fed to the top end. The new head gaskets made after 1990-something are all (ALL) thicker by at least 0.2mm over Honda's version (some of the MLS are even thicker than this) so you need to use a correspondingly thicker O-ring in those 2 ports: 2.6x10.8mm (Parker# 02-111) to make up the extra thickness with sealing pressure.

I'm having a hell of a time trying to find the right O-Ring to address the potential head gasket gap... If I'm correct you're referring to part no. 91310300000 which is 2.5x11? Can't find any source for a 2.6x10.8mm in Canada currently. And to make me more confused the rebuild kit I got from 4into1 has the following listed

91302-001-020 - O-Ring 30.8mm - x8 (tappet rings)
91305-323-000 - O-Ring 5.8 x 1.9mm - x4
91304-286-000 - O-Ring 61.8 x 2mm - x4 (Cylinder)

I'm assuming 2.6 x 10.8 is because you're thickening the ring by .2mm so that means you subtract .2 from the diameter right? Can I order this from a marine store or something?

Bump.  Yes,I hope HondaMan will give you a source for these.

[spmc]

The second source is the O-rings in the head gasket that [are supposed to] seal the oil fed to the top end. The new head gaskets made after 1990-something are all (ALL) thicker by at least 0.2mm over Honda's version (some of the MLS are even thicker than this) so you need to use a correspondingly thicker O-ring in those 2 ports: 2.6x10.8mm (Parker# 02-111) to make up the extra thickness with sealing pressure.

I'm having a hell of a time trying to find the right O-Ring to address the potential head gasket gap... If I'm correct you're referring to part no. 91310300000 which is 2.5x11? Can't find any source for a 2.6x10.8mm in Canada currently. And to make me more confused the rebuild kit I got from 4into1 has the following listed

91302-001-020 - O-Ring 30.8mm - x8 (tappet rings)
91305-323-000 - O-Ring 5.8 x 1.9mm - x4
91304-286-000 - O-Ring 61.8 x 2mm - x4 (Cylinder)

I'm assuming 2.6 x 10.8 is because you're thickening the ring by .2mm so that means you subtract .2 from the diameter right? Can I order this from a marine store or something?

Bump.  Yes,I hope HondaMan will give you a source for these.

Closest I can find right now is an SAE version which is

ID 0.437 or 11.09mm
OD 0.625 or 15.875
CS 0.103 or 2.616mm

Which the part number I got from them was also 02-111 so I'm guessing thats the one HondaMan was referencing
https://www.sealsonline.com/sealtech/en/2-xxx/81378-2-111-n70.html?search_query=2-111&results=9

So if that is the one I'll grab it, or rather a little more than 100 of em cause they have a minimum order of $15 haha

[spmc]

Okay can confirm I was able to source that odd oversize o-ring plus the goofy 3mm x 5.5mm ones for the studs on the F at SealTech Supply in Mississauga (sealsonline.com)

For any future lurkers here's the part numbers!