Topic: HondaMan's solution for aftermarket engine gasket kits

[HondaMan]

A great idea! It's definitely necessary as most of the gasket kits don't come fully complete.

Can I also suggest adding the 6 x 2.3 o ring for the points shaft and the o ring beneath the counter shaft retainer.

Yeah, that 6 x 2.3 silicone O-ring is a custom one for Honda. So far only Honda has them. I was quoted $550 setup to have 1000 of them made (ouch!).
The other one is 1.9 x 5.8 size, but the 2x6 that is very common fits it, and the post-750k1 oil jets, perfectly. I have LOTs of them if you need a couple...

[70CB750]

I am definitely interested in this kit.

[lash]

Me too for some kits!

[Trav-i]

I'm glad my thread on newer gaskets has made for some good discussion.  Due to time constraints and other projects like my GL1500, I have yet to finish getting the engine out of the frame.  I did get around to measuring the MLS head gasket I have in the cycle X kit I bought and it measured right at 1mm thick.  So I guess I will be needing the thicker o-rings for oil passages.  Good thing I learned of that now rather than later.  I'm hoping to have the engine later this week, then it will be time to degrease it and then strip off all of the old cheap black paint.  Then I clean up the ports in the head, check the guides and start reassembly.

[PeWe]

My K6 has MLS head gasket, 72mm. I think it does not need any o- rings at all. I gave it 2 o-rings for oil transport going up.I'm sure it should not leak without them either.

 All oil holes in the gasket have raised round rings around them.

Important with flat surfaces. The cylinder was new Billet block Mike Rieck has done, head  surface grinded on my kitchen table. Some rounds of grit 240 until all marks disappeared, then a few rounds of grit 400 paper glued on a flat thick board.

Bike has done over 10.000 km with no head nor cyl base leaks yet. Base gasket RCS that needed 2 o- rings for oil transport. 

[Trav-i]

Hmmmm.  I did notice the raised rings but, never really gave it much thought.  I'll have to look at it again.  Would probably use the o-rings anyway, I'm not in the mood for any more leaks.  I don't want to pull the cylinders unless I have to, I might have the head surface cleaned up to help with overall seal quality.

[PeWe]

The 72mm MLS gasket from Dynoman.
I have other MLS head gaskets from CycleX, 62, 65.5 and 67.5/68mm bores. All look the same, except thickness, some thinner than 1mm.

One thing to check is if the rivets  will sit in mating surfaces head- cylinder. Mine did on 836 K6 cylinder and K6 head ( sa e head my Bullet block has today.) I hammered rivets flat and drilled smal dents on both sides where rivets hit. 8-9mm drill, just hit a little making space for the hammered rivets.

[Trav-i]

Interesting solution to the rivets.  I'll have to check that clearance as assembly time gets closer.

[HondaMan]

My K6 has MLS head gasket, 72mm. I think it does not need any o- rings at all. I gave it 2 o-rings for oil transport going up.I'm sure it should not leak without them either.

Of the 4 CB750 engines I 'repaired' because of oil leaks, each owner was sold the MLS head gasket with the assurance that it would not leak oil from those ports, and the owners (each one) used the standard 2.4 x 12 O-ring in the ports anyway. All 4 leaked, and eventually found their way to me (for whatever reasons) to make them stop leaking, more than anything else. I felt bad for their owners. The MLS gasket is, like you show, 1mm thick, so the O-rings must be correspondingly thicker than OEM, too.

I have to say, though, that the MLS gaskets were so sticky to the surfaces that they took a LONG time to clean off the head and cylinder, as they shred when the head is pulled off! Messy! 

[PeWe]

I have only used 2 MLS to be sure they did not leak. 836cc and latest 1000cc (71.25 mm pistons).
The 836 had around 4000 km, 1000cc now 10.000 km. No leaks.
I saw no sticky residues after the 836 with MLS.

If surfaces were smooth and flat enough for MLS...
- Maybe they added some wrong type of sealer that destroyed the viton rubber on the steel?

Add additional sealer seems to be very common, even if not needed.

 Or the rivets had contact with cylinder and head surfaces?
My K6 hade that with 836.
No problem with billet block Mike Rieck has shaped exact as a gasket, not wider..

I made a mistake once using Permatex copper spray on a Cometic fiber head gasket (graphite). What an oil leak very soon after, despite high tightening torque, several times. Worst oil leak ever on that bike.

I did not use any sealer on the MLS, dry.
I've been told that MLS can be reused several times even if rubber is damaged. Just brush all rubber away and spray Loctite spray gasket, 3020.

[Tews19]

Why is the oil orfice on the top of the cylinder head O ring so difficult to find???

I'm about to toss this freaking engine and bike out of the garage

[Tews19]

I purchased these O rings from Honda and torqued everything to factory spec. I thought I forgot to install the dowels so I pulled the cam towers. The o rings split. Any idea on the proper size as the Honda size are incorrect and all websites are stating these are NLA
 

Sent from my SM-G955U using Tapatalk

[HondaMan]

I purchased these O rings from Honda and torqued everything to factory spec. I thought I forgot to install the dowels sonI pulled the cam towers. The o rings split. Any idea on the proper soze as the Honda size are incorrect and all websites are stating these are NLA
 

Sent from my SM-G955U using Tapatalk

For the K0-K2 engines  with the big oil jets, Honda's size was 1.5x3.0. I use 1.6x3.0 because the large oil jet leaves the O-ring unsupported. I also use 1.6x6.0 around the 1.5x3.0 (or 1.6x3.0) to fill in the recess of the oil jet itself in those engines.

In the early K0 engines (and most sandcast) the recess fits only the 1.5x3.0 (or 1.6x3.0) size, just like the outer 2 recesses under the cam bearings. Don't forget those 2 outboard ones, or the oil pressure in the top end will be zero: I just rebuilt a K0 sandcast head that went through that problem from someone's hand.

In the later engines, starting mostly in the "new factory" K1 engines, the smaller oil jets take the 2x6 size. Honda spec'd this as 1.9x5.9. They always spec'd the MINIMUM acceptable size, as that's how JIS standards worked in the 1970s: you spec'd the smallest acceptable size, and their tolerance rules limited the upper dimensions in that thickness.

If the O-ring is too thick, yep, it can split it under the pressure of clamping it too tightly.

For the K1 engine (which yours appears to be), you will need either 2 or 4 of the 1.6 x 3.0 size, or 2 of those and 2 of the 2x6 size, under the cam bearings. You also need another 2x6 / 1.9x5.9 under the countershaft bearing retainer housing (shifter side of the engine). The O-rings for the oil passages to the head, on top of the cylinders, take Parker's 2.62x10.77 #01-111 in Buna70, while the bottom of the cylinders takes a 2.4x11 or 2.4x12 in a silicone type material (these are usually pink in color in gasket sets).

There's others: that's why I am thinking of making kits for everyone who wants one. I may just offer them for donations to this site, like I used to with the gas cap pins before the 1-1/16 size #4-40 SS screws vanished about 4 years ago. I can't spend hours and hours trimming longer screws to that length for free!

[Bodi]

Seriously? 4-40 x 1 1/18 screws were actually available? Why?

[trigger]

Why is the oil orfice on the top of the cylinder head O ring so difficult to find???

I'm about to toss this freaking engine and bike out of the garage

Not too hard to find. You just need to ask the right person.
You old boys worry too much 

[HondaMan]

Seriously? 4-40 x 1 1/18 screws were actually available? Why?

 
Fixed that typo...

[HondaMan]

Why is the oil orfice on the top of the cylinder head O ring so difficult to find???

I'm about to toss this freaking engine and bike out of the garage

Which model 750? There were 2 sizes, both are widely available. The early ones are 1.5x3.0 (OEM) or 1.6x3.0 (more common) and the later, larger ones are 1.9x5.9 (pretty common) or 2x6 (more common).

[PeWe]

Time for more oil leak issues!
Oil filter cover o-rings sucks or more real, blows!
I used the thickest I could find from my filters on the shelf. KN, Hi-Flo, Emgo and 2-3 different Japanese filters.

I found old threads here about leaking filter covers due to bad o-rings.

Saw the front on my CB750 K6 was sprayed with oil more than expected so I changed oil and replaced filter with o-rings.
Oil filter cover o-ring had not much stick-out over the oil filter groove and was very soft. Measured the o-ring, almost 4 mm thick, 4.5mm wide.
It should be 4.5mm thick, round, not oval. ID 89mm.
The rubber material is too soft.

I have tried to find a little bit thicker or harder with no luck.
I ordered ID 89mm x 4.5 Nitrile 70 from a bearing and seal company. I hope this will be harder than the bad o-rings the filters have. No harder version like Nitrile 90 found. 5 cost around £12.5 GBP, 50 around £17.50 GPB so 50 ordered.

I ordered also a stock Honda  when ordering from DSS (before BREXIT adding customs fee this way) to have something to compare with.

It would be better with harder rubber.
I torqued the filter bolt less this time, too much will probably collapse the o-ring. I hope it will withstand the pressure.

I'll have O-rings for replacement, hopefully an improvement.

Edit: That o- ring was harder in the 80's as I can recall.

[beemerbum]

BTW: since the head gasket O-ring problem is a big one, and since the gasket kits now often have the wrong O-rings in them, I am thinking of making up an "O-ring kit" for the 750. It will have the proper silicone-based ones for the bottom of the cylinders (against the cases), the oil caps on the engine (3 of them), both sizes and the 'backup size' for the oil jets in the head, the correct ones to match these thicker head gaskets at the top-of-cylinders, and the 6 needed for the oil system (3 on the pump, 2 on the oil hoses, one on the oil filter's bolt), and if I can get them, the one for the main oil journal's plug (by the alternator), and one of the properly thick ones for the oil filter housing. The kits always include the ones for the valve caps, so those are not trouble nowadays.

Does this sound worthwhile? The sooner the better!

[lash]

Pewe, where did you order these from?copied below from your post..

I have tried to find a little bit thicker or harder with no luck.
I ordered ID 89mm x 4.5 Nitrile 70 from a bearing and seal company. I hope this will be harder than the bad o-rings the filters have. No harder version like Nitrile 90 found. 5 cost around £12.5 GBP, 50 around £17.50 GPB so 50 ordered

[PeWe]

http://www.bearingshopuk.co.uk/quicksearch/query/result/?category=53&qs_oring_int=89&qs_oring_sec=4.5

Or just enter the startpage
http://www.bearingshopuk.co.uk

I ordered other o-rings and oil seals too.

[Keith]

Yes!!

[HondaMan]

Time for more oil leak issues!
Oil filter cover o-rings sucks or more real, blows!
I used the thickest I could find from my filters on the shelf. KN, Hi-Flo, Emgo and 2-3 different Japanese filters.

I found old threads here about leaking filter covers due to bad o-rings.

Saw the front on my CB750 K6 was sprayed with oil more than expected so I changed oil and replaced filter with o-rings.
Oil filter cover o-ring had not much stick-out over the oil filter groove and was very soft. Measured the o-ring, almost 4 mm thick, 4.5mm wide.
It should be 4.5mm thick, round, not oval. ID 89mm.
The rubber material is too soft.

I have tried to find a little bit thicker or harder with no luck.
I ordered ID 89mm x 4.5 Nitrile 70 from a bearing and seal company. I hope this will be harder than the bad o-rings the filters have. No harder version like Nitrile 90 found. 5 cost around £12.5 GBP, 50 around £17.50 GPB so 50 ordered.

I ordered also a stock Honda  when ordering from DSS (before BREXIT adding customs fee this way) to have something to compare with.

It would be better with harder rubber.
I torqued the filter bolt less this time, too much will probably collapse the o-ring. I hope it will withstand the pressure.

I'll have O-rings for replacement, hopefully an improvement.

Edit: That o- ring was harder in the 80's as I can recall.

Honda still sells the correct O-ring for the oil filter housings, at about $3.50 each. The ones coming in the filter kits only fit Kawis and some Suzys.

[onepieceatatime]

BTW: since the head gasket O-ring problem is a big one, and since the gasket kits now often have the wrong O-rings in them, I am thinking of making up an "O-ring kit" for the 750. It will have the proper silicone-based ones for the bottom of the cylinders (against the cases), the oil caps on the engine (3 of them), both sizes and the 'backup size' for the oil jets in the head, the correct ones to match these thicker head gaskets at the top-of-cylinders, and the 6 needed for the oil system (3 on the pump, 2 on the oil hoses, one on the oil filter's bolt), and if I can get them, the one for the main oil journal's plug (by the alternator), and one of the properly thick ones for the oil filter housing. The kits always include the ones for the valve caps, so those are not trouble nowadays.

Does this sound worthwhile?

HondaMan,
Did you decide to put these kits together for sale?

[HondaMan]

BTW: since the head gasket O-ring problem is a big one, and since the gasket kits now often have the wrong O-rings in them, I am thinking of making up an "O-ring kit" for the 750. It will have the proper silicone-based ones for the bottom of the cylinders (against the cases), the oil caps on the engine (3 of them), both sizes and the 'backup size' for the oil jets in the head, the correct ones to match these thicker head gaskets at the top-of-cylinders, and the 6 needed for the oil system (3 on the pump, 2 on the oil hoses, one on the oil filter's bolt), and if I can get them, the one for the main oil journal's plug (by the alternator), and one of the properly thick ones for the oil filter housing. The kits always include the ones for the valve caps, so those are not trouble nowadays.

Does this sound worthwhile?

HondaMan,
Did you decide to put these kits together for sale?

Not 'officially', since the Kung Flu Shut-in has had me up to my waist in SOHC4 engines since March. If you need some, I have them, PM me with your bike model.