Author Topic: 1978 CB750K — Post 836 OIL PRESSURE - not good (Read 247715 times)

SKTP · « **Reply #1350 on:** November 10, 2020, 09:52:30 AM »

Finally got the Black Bomber tach/speedo back from Foreign Speedo...I really hope it works properly this time. I know they have tried their best, but they clearly gouged the face of the gauge this time, I assume prying off one of the needles. Since the unit sit much lower than stock, I am thinking shorter cables might help out...maybe the CB350s have shorter speedo and tach cables...anybody have or know where I can get cable length info?

Tintop · « **Reply #1351 on:** November 10, 2020, 07:02:23 PM »

Motion Pro may have that info on their site - https://www.motionpro.com/

SOHC4 Cafe Racer Fan · « **Reply #1352 on:** November 11, 2020, 08:36:03 AM »

Quote from: SKTP on November 10, 2020, 09:52:30 AM

Finally got the Black Bomber tach/speedo back from Foreign Speedo...I really hope it works properly this time. I know they have tried their best, but they clearly gouged the face of the gauge this time, I assume prying off one of the needles. Since the unit sit much lower than stock, I am thinking shorter cables might help out...maybe the CB350s have shorter speedo and tach cables...anybody have or know where I can get cable length info?

Jay can make you custom length cables.

SKTP · « **Reply #1353 on:** November 25, 2020, 11:36:42 AM »

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

SOHC4 Cafe Racer Fan · « **Reply #1354 on:** November 29, 2020, 06:03:21 PM »

Quote from: SKTP on November 25, 2020, 11:36:42 AM

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 · « **Reply #1355 on:** January 18, 2024, 11:17:17 AM »

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

denward17 · « **Reply #1356 on:** January 18, 2024, 12:36:51 PM »

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 · « **Reply #1357 on:** January 26, 2024, 07:10:23 AM »

Quote from: SOHC4 Cafe Racer Fan on June 26, 2017, 11:15:39 AM

Quote from: SKTP on June 26, 2017, 10:50:20 AM
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. · « **Reply #1358 on:** January 26, 2024, 07:33:37 AM »

https://bornfreeshow.com/

SKTP · « **Reply #1359 on:** February 01, 2024, 09:28:16 PM »

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 · « **Reply #1360 on:** February 02, 2024, 07:08:11 AM »

Quote from: SKTP on February 01, 2024, 09:28:16 PM

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 · « **Reply #1361 on:** February 05, 2024, 02:25:08 PM »

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 · « **Reply #1362 on:** February 05, 2024, 04:59:33 PM »

Quote from: SKTP on February 05, 2024, 02:25:08 PM

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 · « **Reply #1363 on:** February 05, 2024, 05:57:41 PM »

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 · « **Reply #1364 on:** February 05, 2024, 07:12:47 PM »

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 · « **Reply #1365 on:** February 05, 2024, 09:12:16 PM »

Quote from: HondaMan on February 05, 2024, 07:12:47 PM

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 · « **Reply #1366 on:** February 05, 2024, 09:13:13 PM »

Quote from: SKTP on February 05, 2024, 05:57:41 PM

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 · « **Reply #1367 on:** February 05, 2024, 09:19:43 PM »

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

SKTP · « **Reply #1368 on:** February 27, 2024, 09:35:53 AM »

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 · « **Reply #1369 on:** February 28, 2024, 07:27:57 AM »

Quote from: SKTP on February 27, 2024, 09:35:53 AM

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 · « **Reply #1370 on:** February 28, 2024, 07:58:53 AM »

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

Stev-o · « **Reply #1371 on:** February 28, 2024, 08:16:09 AM »

Quote from: SKTP on February 28, 2024, 07:58:53 AM

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 · « **Reply #1372 on:** February 28, 2024, 09:49:36 AM »

My entire bottom end is stock

PeWe · « **Reply #1373 on:** February 28, 2024, 10:10:23 AM »

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 · « **Reply #1374 on:** March 01, 2024, 09:24:19 AM »

Adding an oil cooler to the mix…

News:

Author Topic: 1978 CB750K — Post 836 OIL PRESSURE - not good (Read 247715 times)