Author Topic: brandEn's leak free top end thread = Tips, Tricks and Suggestion encouraged  (Read 64821 times)

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Offline bytio

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That's it

Offline bytio

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You can see the front two o rings on ready for cylinder

Offline NobleHops

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Adding nothing but thanks for a great thread. Thanks to all that contributed to this.
Nils Menten * Tucson, Arizona, USA

I have a motorcycle problem.

My build thread: NobleHops makes a 400F pretty for his wife: http://forums.sohc4.net/index.php?topic=131210.0

Offline MessnerMoto

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Great thread!

Just one question... I am rebuilding f2 engine with 836 wiseco kit... I Have MLS head gasket and HD studs.

I know I should leave rubbers out(part 2 from picture)... I am just not sure should I leave pins(part 3 from picture) out also?

Offline flybox1

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Definitely leave those in.  Locating dowel to help align the head to the cyls.
If you have had your head decked, you will run into clearance issues and need to adjust these to ~10-11mm.
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

"This is my CB. There are many like it, but this one is mine…"

Offline madmtnmotors

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Great thread!

Just one question... I am rebuilding f2 engine with 836 wiseco kit... I Have MLS head gasket and HD studs.

I know I should leave rubbers out(part 2 from picture)... I am just not sure should I leave pins(part 3 from picture) out also?

Definitely leave those in.  Locating dowel to help align the head to the cyls.
If you have had your head decked, you will run into clearance issues and need to adjust these to ~10-11mm.

Item #3 is optional if you leave out the barrel seals #2. #3 just helps the seal hold its shape. Do not leave out the four locating dowels #9 (two on top, two on bottom).
TAMTF...


Wilbur



Projects:
"Evolution": http://forums.sohc4.net/index.php?topic=100352.0
"P.O. Debacle": http://forums.sohc4.net/index.php/topic,126692.msg1441661.html#msg1441661
F2/F3 O-rings: http://forums.sohc4.net/index.php?topic=113672.msg1300721#msg1300721
Cam Tower Studs: https://www.mcmaster.com/#93210a017/=t19sgp
Clean up that nasty harness: http://forums.sohc4.net/index.php?topic=137351.msg1549191#msg1549191
http://forums.sohc4.net/index.php/topic,148188.msg1688494.html#msg1688494
http://forums.sohc4.net/index.php/topic,139544.msg1579364.html#msg1579364
                                          
Charging system diagnosis: http://forums.sohc4.net/index.php?topic=1012.msg8345#msg8345
Get the manuals: http://manuals.sohc4.net/cb750k/
The Dragon: http://forums.sohc4.net/index.php?topic=45183.msg1571675#msg1571675
Headlight Switch: http://forums.sohc4.net/index.php?topic=113986.msg1283236#msg1283236
Branden's leak free top end thread: http://forums.sohc4.net/index.php?topic=107040.0
Engine Lifting Made Easy: http://forums.sohc4.net/index.php/topic,58210.msg1684742.html#msg1684742
                                      http://forums.sohc4.net/index.php/topic,100352.msg1675840.html#msg1675840
Static and Dynamic Timing: http://www.hondachopper.com/garage/carb_info/timing/timing1.html
Airbox Gasket Replacement: http://forums.sohc4.net/index.php/topic,114485.msg1290000.html#msg1290000
"Café" : http://forums.sohc4.net/index.php/topic,84697.msg953814.html#msg953814
PD Carb Choke Linkage: http://forums.sohc4.net/index.php/topic,100352.msg1669248.html#msg1669248
                                    http://forums.sohc4.net/index.php/topic,110931.msg1248354.html#msg1248354
                                    http://forums.sohc4.net/index.php/topic,48858.msg515204.html#msg515204
Follow up on your damn posts: http://forums.sohc4.net/index.php/topic,144305.msg1791605.html#msg1791605
Taiwanese Cam Chain Tensioners:  http://forums.sohc4.net/index.php/topic,155043.msg1774841.html#msg1774841
Gumtwo Seat Cover: http://forums.sohc4.net/index.php/topic,164440.msg1897366.html#msg1897366
Primary Drive: http://forums.sohc4.net/index.php/topic,166063.msg1919278.html#msg1919278
Tank Latch: http://forums.sohc4.net/index.php/topic,165975.msg1919495.html#msg1919495
Shorten your forks: http://vintage-and-classic-honda-s.456789.n3.nabble.com/How-to-shorten-forks-td4042465.html DO NOT CUT THE SPRINGS!
Clutch How To: http://vintage-and-classic-honda-s.456789.n3.nabble.com/How-to-change-and-adjust-a-clutch-SOHC-td4040391.html
Late model K7/K8/F2/F3 front sprocket cover removal: http://forums.sohc4.net/index.php/topic,178428.msg2072279.html#msg2072279
630 to 530 conversion: http://forums.sohc4.net/index.php/topic,180710.msg2094423.html#msg2094423

Sent from my Tandy TRS-80!

Offline flybox1

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Item #3 is optional if you leave out the barrel seals #2. #3 just helps the seal hold its shape. Do not leave out the four locating dowels #9 (two on top, two on bottom).
Thanks for the correction, mad.  ;D
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

"This is my CB. There are many like it, but this one is mine…"

Offline madmtnmotors

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Item #3 is optional if you leave out the barrel seals #2. #3 just helps the seal hold its shape. Do not leave out the four locating dowels #9 (two on top, two on bottom).
Thanks for the correction, mad.  ;D

Happy to help. I know I have trouble keeping all of the little bits straight from time to time.

Don't forget those four fat little 5.5x3mm o-rings (#6) at the base of the cylinders on the studs where the abandoned oil returns are as well.  ;)
TAMTF...


Wilbur



Projects:
"Evolution": http://forums.sohc4.net/index.php?topic=100352.0
"P.O. Debacle": http://forums.sohc4.net/index.php/topic,126692.msg1441661.html#msg1441661
F2/F3 O-rings: http://forums.sohc4.net/index.php?topic=113672.msg1300721#msg1300721
Cam Tower Studs: https://www.mcmaster.com/#93210a017/=t19sgp
Clean up that nasty harness: http://forums.sohc4.net/index.php?topic=137351.msg1549191#msg1549191
http://forums.sohc4.net/index.php/topic,148188.msg1688494.html#msg1688494
http://forums.sohc4.net/index.php/topic,139544.msg1579364.html#msg1579364
                                          
Charging system diagnosis: http://forums.sohc4.net/index.php?topic=1012.msg8345#msg8345
Get the manuals: http://manuals.sohc4.net/cb750k/
The Dragon: http://forums.sohc4.net/index.php?topic=45183.msg1571675#msg1571675
Headlight Switch: http://forums.sohc4.net/index.php?topic=113986.msg1283236#msg1283236
Branden's leak free top end thread: http://forums.sohc4.net/index.php?topic=107040.0
Engine Lifting Made Easy: http://forums.sohc4.net/index.php/topic,58210.msg1684742.html#msg1684742
                                      http://forums.sohc4.net/index.php/topic,100352.msg1675840.html#msg1675840
Static and Dynamic Timing: http://www.hondachopper.com/garage/carb_info/timing/timing1.html
Airbox Gasket Replacement: http://forums.sohc4.net/index.php/topic,114485.msg1290000.html#msg1290000
"Café" : http://forums.sohc4.net/index.php/topic,84697.msg953814.html#msg953814
PD Carb Choke Linkage: http://forums.sohc4.net/index.php/topic,100352.msg1669248.html#msg1669248
                                    http://forums.sohc4.net/index.php/topic,110931.msg1248354.html#msg1248354
                                    http://forums.sohc4.net/index.php/topic,48858.msg515204.html#msg515204
Follow up on your damn posts: http://forums.sohc4.net/index.php/topic,144305.msg1791605.html#msg1791605
Taiwanese Cam Chain Tensioners:  http://forums.sohc4.net/index.php/topic,155043.msg1774841.html#msg1774841
Gumtwo Seat Cover: http://forums.sohc4.net/index.php/topic,164440.msg1897366.html#msg1897366
Primary Drive: http://forums.sohc4.net/index.php/topic,166063.msg1919278.html#msg1919278
Tank Latch: http://forums.sohc4.net/index.php/topic,165975.msg1919495.html#msg1919495
Shorten your forks: http://vintage-and-classic-honda-s.456789.n3.nabble.com/How-to-shorten-forks-td4042465.html DO NOT CUT THE SPRINGS!
Clutch How To: http://vintage-and-classic-honda-s.456789.n3.nabble.com/How-to-change-and-adjust-a-clutch-SOHC-td4040391.html
Late model K7/K8/F2/F3 front sprocket cover removal: http://forums.sohc4.net/index.php/topic,178428.msg2072279.html#msg2072279
630 to 530 conversion: http://forums.sohc4.net/index.php/topic,180710.msg2094423.html#msg2094423

Sent from my Tandy TRS-80!

Offline MessnerMoto

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Great thread!

Just one question... I am rebuilding f2 engine with 836 wiseco kit... I Have MLS head gasket and HD studs.

I know I should leave rubbers out(part 2 from picture)... I am just not sure should I leave pins(part 3 from picture) out also?

Definitely leave those in.  Locating dowel to help align the head to the cyls.
If you have had your head decked, you will run into clearance issues and need to adjust these to ~10-11mm.

Item #3 is optional if you leave out the barrel seals #2. #3 just helps the seal hold its shape. Do not leave out the four locating dowels #9 (two on top, two on bottom).

Thanks to all for help . I was also thinking that #3 is just there because of #2. So I don't see the point of putting #3 if I leave out #2. So I will leave #2 and #3 out

Offline RAFster122s

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Wouldn't you need to resize both #3 and #9 if the head and or block were milled to flatten the mating surfaces?
David- back in the desert SW!

Offline madmtnmotors

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Wouldn't you need to resize both #3 and #9 if the head and or block were milled to flatten the mating surfaces?

Possibly. Depending on how much was removed from the head and/or cylinders the dowels can require shortening. I usually put the calipers to them and measure the bores to determine whether they need ground/filed/cut down.
TAMTF...


Wilbur



Projects:
"Evolution": http://forums.sohc4.net/index.php?topic=100352.0
"P.O. Debacle": http://forums.sohc4.net/index.php/topic,126692.msg1441661.html#msg1441661
F2/F3 O-rings: http://forums.sohc4.net/index.php?topic=113672.msg1300721#msg1300721
Cam Tower Studs: https://www.mcmaster.com/#93210a017/=t19sgp
Clean up that nasty harness: http://forums.sohc4.net/index.php?topic=137351.msg1549191#msg1549191
http://forums.sohc4.net/index.php/topic,148188.msg1688494.html#msg1688494
http://forums.sohc4.net/index.php/topic,139544.msg1579364.html#msg1579364
                                          
Charging system diagnosis: http://forums.sohc4.net/index.php?topic=1012.msg8345#msg8345
Get the manuals: http://manuals.sohc4.net/cb750k/
The Dragon: http://forums.sohc4.net/index.php?topic=45183.msg1571675#msg1571675
Headlight Switch: http://forums.sohc4.net/index.php?topic=113986.msg1283236#msg1283236
Branden's leak free top end thread: http://forums.sohc4.net/index.php?topic=107040.0
Engine Lifting Made Easy: http://forums.sohc4.net/index.php/topic,58210.msg1684742.html#msg1684742
                                      http://forums.sohc4.net/index.php/topic,100352.msg1675840.html#msg1675840
Static and Dynamic Timing: http://www.hondachopper.com/garage/carb_info/timing/timing1.html
Airbox Gasket Replacement: http://forums.sohc4.net/index.php/topic,114485.msg1290000.html#msg1290000
"Café" : http://forums.sohc4.net/index.php/topic,84697.msg953814.html#msg953814
PD Carb Choke Linkage: http://forums.sohc4.net/index.php/topic,100352.msg1669248.html#msg1669248
                                    http://forums.sohc4.net/index.php/topic,110931.msg1248354.html#msg1248354
                                    http://forums.sohc4.net/index.php/topic,48858.msg515204.html#msg515204
Follow up on your damn posts: http://forums.sohc4.net/index.php/topic,144305.msg1791605.html#msg1791605
Taiwanese Cam Chain Tensioners:  http://forums.sohc4.net/index.php/topic,155043.msg1774841.html#msg1774841
Gumtwo Seat Cover: http://forums.sohc4.net/index.php/topic,164440.msg1897366.html#msg1897366
Primary Drive: http://forums.sohc4.net/index.php/topic,166063.msg1919278.html#msg1919278
Tank Latch: http://forums.sohc4.net/index.php/topic,165975.msg1919495.html#msg1919495
Shorten your forks: http://vintage-and-classic-honda-s.456789.n3.nabble.com/How-to-shorten-forks-td4042465.html DO NOT CUT THE SPRINGS!
Clutch How To: http://vintage-and-classic-honda-s.456789.n3.nabble.com/How-to-change-and-adjust-a-clutch-SOHC-td4040391.html
Late model K7/K8/F2/F3 front sprocket cover removal: http://forums.sohc4.net/index.php/topic,178428.msg2072279.html#msg2072279
630 to 530 conversion: http://forums.sohc4.net/index.php/topic,180710.msg2094423.html#msg2094423

Sent from my Tandy TRS-80!

Offline turkey4me

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Re: brandEn's leak free top end thread = Tips, Tricks and Suggestion encouraged
« Reply #86 on: September 22, 2016, 03:46:13 AM »
No 8 O-rings on are listed as being 11 x 2.5mm.  Can anyone confirm if 11mm is the inside or outside diameter?  Buna or Viton?

Offline Bailgang

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Re: brandEn's leak free top end thread = Tips, Tricks and Suggestion encouraged
« Reply #87 on: September 22, 2016, 04:00:54 AM »
No 8 O-rings on are listed as being 11 x 2.5mm.  Can anyone confirm if 11mm is the inside or outside diameter?  Buna or Viton?

Can't say whether the 11mm is the OD or ID but I used viton o-rings everywhere I could on my F2 3 years ago while following many of the tips on this thread. The only oil leak I had was from the rubber pucks under the cam cradles due to the thin pucks in the aftermarket gasket set I used, I swapped them out for genuine Honda pucks and no leaks at all since.
Scott


71 cb350 twin
77 cb750 F2
83 gl1100 Interstate

Offline lightsareout

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Re: brandEn's leak free top end thread = Tips, Tricks and Suggestion encouraged
« Reply #88 on: September 22, 2016, 05:28:21 AM »
this is awesome, thanks for sharing

Offline flybox1

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Re: brandEn's leak free top end thread = Tips, Tricks and Suggestion encouraged
« Reply #89 on: September 22, 2016, 06:29:28 AM »
No 8 O-rings on are listed as being 11 x 2.5mm.  Can anyone confirm if 11mm is the inside or outside diameter?  Buna or Viton?
11mm is the ID.  Use viton.
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

"This is my CB. There are many like it, but this one is mine…"

Offline MCRider

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Re: brandEn's leak free top end thread = Tips, Tricks and Suggestion encouraged
« Reply #90 on: September 22, 2016, 07:59:59 AM »
No 8 O-rings on are listed as being 11 x 2.5mm.  Can anyone confirm if 11mm is the inside or outside diameter?  Buna or Viton?
11mm is the ID.  Use viton.
I think the 2.5mm is the cross section of the ring material. That makes the OD 13.5mm. OCICBW
Ride Safe:
Ron
1988 NT650 HawkGT;  1978 CB400 Hawk;  1975 CB750F -Free Bird; 1968 CB77 Super Hawk -Ticker;  Phaedrus 1972 CB750K2- Build Thread
"Sometimes the light's all shining on me, other times I can barely see, lately it appears to me, what a long, strange trip its been."

Offline flybox1

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Re: brandEn's leak free top end thread = Tips, Tricks and Suggestion encouraged
« Reply #91 on: September 22, 2016, 10:40:00 AM »
No 8 O-rings on are listed as being 11 x 2.5mm.  Can anyone confirm if 11mm is the inside or outside diameter?  Buna or Viton?
11mm is the ID.  Use viton.
I think the 2.5mm is the cross section of the ring material. That makes the OD 13.5mm. OCICBW
You are almost correct.  2(CS)+ID = OD   
2(2.5) + 11 = 16mm in this case  ;)
« Last Edit: September 22, 2016, 10:42:29 AM by flybox1 »
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

"This is my CB. There are many like it, but this one is mine…"

Offline MCRider

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Re: brandEn's leak free top end thread = Tips, Tricks and Suggestion encouraged
« Reply #92 on: September 22, 2016, 11:58:49 AM »
No 8 O-rings on are listed as being 11 x 2.5mm.  Can anyone confirm if 11mm is the inside or outside diameter?  Buna or Viton?
11mm is the ID.  Use viton.
I think the 2.5mm is the cross section of the ring material. That makes the OD 13.5mm. OCICBW
You are almost correct.  2(CS)+ID = OD   
2(2.5) + 11 = 16mm in this case  ;)

Oh yeah, silly me.  :D
Ride Safe:
Ron
1988 NT650 HawkGT;  1978 CB400 Hawk;  1975 CB750F -Free Bird; 1968 CB77 Super Hawk -Ticker;  Phaedrus 1972 CB750K2- Build Thread
"Sometimes the light's all shining on me, other times I can barely see, lately it appears to me, what a long, strange trip its been."

Offline PeWe

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One more thing that most likely is the bandit on oil weeping CB750 K6 setups. Crank case breather
Crank case breather is connected to oil tank via a 1/2" hose, oil tank itself is sealed, no breather. Honda made a mistake here. This will cause oil weeping engine, more cc and rpms more it will weep/leak.

I found out after over 30 years! I have blamed versions of case seal when the biggest cause is no ventilation of the crank case. I trusted the Honda design. Even cars will run as crap with crank case breather problems.

I'll cut the hose between crank case spigot and oil tank, connect with a T-pipe where I'll add another 1/2"  hose going upwards and connect with the breather hose from valve cover. Cut that hose too and add a second t-pipe. Top breather hose from valve cover will still end up beside the exhaust as before.

Hondaman recommend to route that hose to the front drive sprocket to lubricate with the oil drops coming here. The hose must be slimmer where it enters the cover opening.
http://forums.sohc4.net/index.php/topic,147504.msg1680491.html#msg1680491

Edit: My K6 has not the later breather as K7 has and shown beside the airbox. Also shown in Hondamans post above.
https://www.cmsnl.com/honda-cb750k7-four-european-direct-sales_model14391/partslist/F15.html#results
« Last Edit: July 23, 2017, 01:37:59 AM by PeWe »
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline Scott S

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 Since this one is referred to so often and I go back to it myself, I'm setting it as a sticky. If anyone does a top end, can you take pics and add them to this thread, since Photobucket is holding the pics hostage?
'71 CB500 K0
'17 Triumph Street Scrambler
'81 Yamaha XS650

Offline Niels Bull

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how do you view these pictures??

Offline HondaMan

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No 8 O-rings on are listed as being 11 x 2.5mm.  Can anyone confirm if 11mm is the inside or outside diameter?  Buna or Viton?

Just one addition: all modern head gaskets are thicker than the OEM gasket upon with the 2.5 mm thickness was established. The modern gaskets are 1.0mm thick (some are even more) where the OEM version was 0.8mm thick, and you need to use an O-ring that is THICKER BY THAT AMOUNT. I use the Parker #01-111 that is listed as 2.62x10.77mm size, but is usually thicker than that, to seal the oil passages between the cylinders and head, AFTER having the cylinder top surface decked 0.010" during boring (which also ensures it is flat) - the head gets decked up to that amount, also.

I have a LOT of these O-rings: if you need a pair, I will send them to you for a donation to our website. PM me for details.
See SOHC4shop@gmail.com for info about the gadgets I make for these bikes.

The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
Hondaman's creed: "Bikers are family. Treat them accordingly."

Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

Link to My CB750 Book: https://www.lulu.com/search?adult_audience_rating=00&page=1&pageSize=10&q=my+cb750+book

Link to website: www.SOHC4shop.com

Offline jnymdnyt

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  • Posts: 8
Thank you so much for this very detailed post and thank you as well for everyone that contributed.  You all just saved me a bunch of time doing research.

Offline PeWe

  • Really Old Timer ...
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  • Posts: 15,572
  • Bike almost back to the 70's 2015
O-ring size: Usually inner diameter x cross section (thickness)
11 x 2.5 has outer diameter 16mm.

So when change to a thicker, inner dia must be smaller to not increase outer dia too much so it still fits. Here inside the gasket holes.

Same with oil feed o-rings. The inner dia can not be too small either so it block the oil feed when compressed.
Here just a few 0.1mm to compensate for thicker gasket.

I used 8 THICK o-rings with late CB750 head gasket and early cyl/head. I had to re-torque the head 3 times until it stopped compressing, nuts moved after 24 hours!!
I used thinner viton O-rings next time (changed head), something like Hondaman recommend. Re-torqued once after 24 hours was enough. (I tested once more)
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline ADW

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  • Posts: 218
Here's my experience and suggestion(s) on my 350F from summer of 2019. Reference to gasket sets with taller O-rings and etc. included.

http://forums.sohc4.net/index.php/topic,179085.msg2077683.html#msg2077683