Topic: 1978 CB750K — Post 836 OIL PRESSURE - Hopefully Good!?

[SOHC4 Cafe Racer Fan]

UPDATE: The speedo calibration seems to be bang-on this time...it matched from 0-80mph exactly then seems a little slow from 80-100mph when compared to GPS

That must be a relief!

[SKTP]

Guess who's pulling their motor for the 5th time?

[denward17]

Following.....

I haven't read through all 55 pages, what you working on for the 5th time?

I wasn't here when you started this thread but think I browsed it last year when working on mine.

Good Luck..

[Floshenbarnical]

The forks are original to my knowledge. I am thinking I will talk to Race-Tech

http://www.racetech.com/

And yes, I think it will be my last born-free...it is not my scene. It was a fun ride regardless.

It's definitely a different scene.  I like the trackers and invited builder customs.  There are definitely plenty of girls with daddy issues to make it somewhat entertaining.

I'm sorry to drag up a 7-year-old post - where is this?? Asking for a friend

[Alan F.]

https://bornfreeshow.com/

[SKTP]

Ok I am laughing...I actually have gone to many more BornFree shows. At the last one, my bike fell over onto Don's fancy bike. (I have parked on grass many times without issue, but not on that day.)

My bike's motor is currently out and getting new HD studs, new rings, all new top-end rubber, gaskets, surfaces resurfaced, etc...If it leaks after this round I am done.

[Floshenbarnical]

Ok I am laughing...I actually have gone to many more BornFree shows. At the last one, my bike fell over onto Don's fancy bike. (I have parked on grass many times without issue, but not on that day.)

My bike's motor is currently out and getting new HD studs, new rings, all new top-end rubber, gaskets, surfaces resurfaced, etc...If it leaks after this round I am done.

Good luck to you. If my bottom end still leaks after this round then I'll start wearing diapers send it to a pro next season

Think I might check out the Born Free show this year! Probably a bit far to take the bike all the way from NY but I love bikes and hot weather

[SKTP]

Well the original idea was just to redo the top end in hopes of no leaks...but I think I am going to go with Weisco 836cc pistons and a cam...talk me out of this?

[madmtnmotors]

Well the original idea was just to redo the top end in hopes of no leaks...but I think I am going to go with Weisco 836cc pistons and a cam...talk me out of this?

Must... resist...

HA! Who are we kidding? Do it and don't look back! 

[SKTP]

I just realized that I have not posted much at all in years...

Will I be happy with 836cc's and a new cam?

Here's how the bike currently looks. Yes, that is me.

(I need to move that fender back)

[HondaMan]

If you go to the high-compression 836cc engine, I'd feel compelled to ask: do you have the HD engine studs in place?
And, did you use thicke r O-rings in the head gasket, for the oil ports? I can send you some, if not. When rebuilding these engines with modern head gaskets, 100% of them leak oil at the head joint in my experience, unless thicker O-rings are used thru the head gaskets due to their thicknesses today.
With higher-compression pistons this just gets worse.

[SKTP]

If you go to the high-compression 836cc engine, I'd feel compelled to ask: do you have the HD engine studs in place?
And, did you use thicke r O-rings in the head gasket, for the oil ports? I can send you some, if not. When rebuilding these engines with modern head gaskets, 100% of them leak oil at the head joint in my experience, unless thicker O-rings are used thru the head gaskets due to their thicknesses today.
With higher-compression pistons this just gets worse.

Yes. I just bought the "Super Stud, Heavy Duty Stud Nut & Tool Combo" from CycleX. I also will be using an MSL gasket and the top-end rubber that Ken at CycleX sent me. I believe the O-ring are the thicker type (there were some clear almost tube-like rings and I am guessing go over the Dowels?) I am not near the parts at the time of writing this. I will ask him about O-rings. When I call to order the pistons and Cam. Thank you for the info, greatly appreciated.

Due to cost and time I am just going to do 836cc Weisco pistons and a cam. No headwork. I also plan on running my stock carbs.

[PeWe]

Will I be happy with 836cc's and a new cam?
......

Is the head restored? Valves, guides and seats cut.
Exhaust guides goes bad first.

If in need to be replaced, a port job when doing the restore will help if you change cam, pistons.

Race springs can be good anyway.
I should prioritize head to be good if guides are worn.

[SKTP]

The valve-train/head was redone less than 7000 miles ago.

[SKTP]

So I got HD Studs, MLS gasket, Wiseco 836cc pistons and the CycleX/Web CX1 cam. Currently waiting for the machine shop.

Anybody else running this piston/cam combo?

[Stev-o]

So I got HD Studs, MLS gasket, Wiseco 836cc pistons and the CycleX/Web CX1 cam. Currently waiting for the machine shop.

Anybody else running this piston/cam combo?

I used Wiseco 836 piston/rings on my K4 when I blew a hole in the case, but have a Kenny Harmon d grind cam, didnt feel the need for HD studs. This was about 6 years ago and all has been well since.

[SKTP]

Scary! I searched and found the case-hole pic. I hope the 836cc gods are kind to me.

[Stev-o]

Scary! I searched and found the case-hole pic. I hope the 836cc gods are kind to me.

Dont be skeered!  Use new rod bolts, my guess is the PO didnt when he rebuilt the motor

[SKTP]

My entire bottom end is stock

[PeWe]

Here 836 with stock rods. Not F2 rod bolts either
Dyno chart showed 10.000 rpm, maybe a little more.
+9000 rpm before shift gear upwards normal.

It had Action Fours SS1 cam back then. It worked really well, not that steep lift either. 0.361" lift measured when timed. Cam card said 0.360.


A good touring cam. Ran fine between red lights too.

[SKTP]

Adding an oil cooler to the mix…

[HondaMan]

If you go to the high-compression 836cc engine, I'd feel compelled to ask: do you have the HD engine studs in place?
And, did you use thicke r O-rings in the head gasket, for the oil ports? I can send you some, if not. When rebuilding these engines with modern head gaskets, 100% of them leak oil at the head joint in my experience, unless thicker O-rings are used thru the head gaskets due to their thicknesses today.
With higher-compression pistons this just gets worse.

Yes. I just bought the "Super Stud, Heavy Duty Stud Nut & Tool Combo" from CycleX. I also will be using an MSL gasket and the top-end rubber that Ken at CycleX sent me. I believe the O-ring are the thicker type (there were some clear almost tube-like rings and I am guessing go over the Dowels?) I am not near the parts at the time of writing this. I will ask him about O-rings. When I call to order the pistons and Cam. Thank you for the info, greatly appreciated.

Due to cost and time I am just going to do 836cc Weisco pistons and a cam. No headwork. I also plan on running my stock carbs.

OK, here's where you ARE leaking: those tube-like Orings at the top of the cylinders. They ALWAYS leak. These first appeared around 2002 or so as someone's wet dream of stopping the oil leaks from the oil ports, and they NEVER worked, from Day One of their intro.

PM me your address and I'll send you some thicker O-rings for the oil ports. These are 2.6mm thick. The MLS head gasket: there are several types of these out there. Some are just too thick, period. They must NOT be thicker than 1.0mm before installation, or else there is no way to stop the oil feed ports from leaking. I have seen MLS gaskets with little rivets in them for the 836cc engines: they leak 100% of the time, sometimes taking a month or two of riding before they do. This is simple physics: if the head gasket is so thick that there's no way to install a thick-enough O-ring in the oil ports to seal them, then they are going to leak. It really is that simple.

I have been using the 65mm head gaskets from Vesrah and CruisinImage for forged piston engines that come to me for oil leaks, plus milling 0.010" off the top of the cylinders, plus these 2.6x10.8mm O-rings. It works to stop the oil leaks.

[SOHC4 Cafe Racer Fan]

If you go to the high-compression 836cc engine, I'd feel compelled to ask: do you have the HD engine studs in place?
And, did you use thicke r O-rings in the head gasket, for the oil ports? I can send you some, if not. When rebuilding these engines with modern head gaskets, 100% of them leak oil at the head joint in my experience, unless thicker O-rings are used thru the head gaskets due to their thicknesses today.
With higher-compression pistons this just gets worse.

Yes. I just bought the "Super Stud, Heavy Duty Stud Nut & Tool Combo" from CycleX. I also will be using an MSL gasket and the top-end rubber that Ken at CycleX sent me. I believe the O-ring are the thicker type (there were some clear almost tube-like rings and I am guessing go over the Dowels?) I am not near the parts at the time of writing this. I will ask him about O-rings. When I call to order the pistons and Cam. Thank you for the info, greatly appreciated.

Due to cost and time I am just going to do 836cc Weisco pistons and a cam. No headwork. I also plan on running my stock carbs.

OK, here's where you ARE leaking: those tube-like Orings at the top of the cylinders. They ALWAYS leak. These first appeared around 2002 or so as someone's wet dream of stopping the oil leaks from the oil ports, and they NEVER worked, from Day One of their intro.

PM me your address and I'll send you some thicker O-rings for the oil ports. These are 2.6mm thick. The MLS head gasket: there are several types of these out there. Some are just too thick, period. They must NOT be thicker than 1.0mm before installation, or else there is no way to stop the oil feed ports from leaking. I have seen MLS gaskets with little rivets in them for the 836cc engines: they leak 100% of the time, sometimes taking a month or tow of riding before they do. This is simple physics: if the head gasket is so thick that there's no way to install a thick-enough O-ring in the oil ports to seal them, then they are going to leak. It really is that simple.

I have been using the 65mm head gaskets from Vesrah and CruisinImage for forged piston engines that come to me for oil leaks, plus milling 0.010" off the top of the cylinders, plus these 2.6x10.8mm O-rings. It works to stop the oil leaks.

Great tips on the o-rings and MLS gaskets, HondaMan!

[SKTP]

The cylinders are bored. The pistons are in. Currently waiting for the Honda Man O-rings and new/refurbished rocker arms. Getting closer...

[SKTP]

HD Studs and Nuts from Cycle-X. Refurbished Rocker-arms will be going on. Honda Man's O-rings (Thank you Honda Man!)

CX-1 Cam. Weisco 836cc Pistons.

What will be my jetting?