Author Topic: CB750K4 what did I get myself into? (Read 12160 times)

BrockCB750 · « **Reply #225 on:** March 26, 2024, 06:27:03 AM »

Thanks! It's coming along fast. I am so stretched for time between work/life responsibilities it's hard to keep up with posts here.

There is one snag so far. The Swingarm pivot bolt with the rearsets... The nut doesn't thread on nearly enough for me to be comfortable. Is it common to need to buy a new longer one? I am scratching my head. Sent an email to CognitoMoto to see what they say...

Seems not ideal.

willbird · « **Reply #226 on:** March 26, 2024, 07:05:46 AM »

I did see somebody selling custom made engine bolts who said to tell them if you have rear sets due to this issue.

https://www.zed-parts.com/product-page/honda-cb750-sohc-engine-mount-kit

The overall price IMHO for the product was awesome but international shipping usually scares me off ;-). Hmm $118 shipped...not terrible overall really. Buying just one longer stud should not be too bad.

Bill

BrockCB750 · « **Reply #227 on:** March 26, 2024, 07:30:18 AM »

Thanks for the suggestion! Just sent them an email with some pictures to confirm.

BrockCB750 · « **Reply #228 on:** March 27, 2024, 04:40:53 AM »

Looks like the just make the engine mount bolts and not swingarm.

Also, went to get the rear brake all connected up to the lever and realized I installed the actuator part the brake lever connects to upside down?!? Didn't even know I could do that by accident. Rear wheel coming back out tonight...

BenelliSEI · « **Reply #229 on:** March 27, 2024, 08:44:51 AM »

Might be easier to open up the ID of the rear set bracket and have a machine shop make you a “tube nut” that reaches down to contact the frame?

willbird · « **Reply #230 on:** March 27, 2024, 08:57:39 AM »

I did do a little googling on this and I am finding info that a DOHC 750 swing arm bolt was born longer. Looks like they had gone to needle bearings by then so in ebay pictures anyway they are not drilled for a grease zerk. That is a 1979, they say an 80+ is a bigger bolt.

here is where I found the info

https://www.cb750.com/threads/will-a-79-swingarm-fit-my-70-frame.4389/

Bill

HondaMan · « **Reply #231 on:** March 27, 2024, 07:17:13 PM »

You might want to use the swingarm bolt from the 1977/78 750F2/3 bikes. It is the same diameter, but a little longer.
Honda's partnumber for it is: 90121-393-770.

BrockCB750 · « **Reply #232 on:** March 28, 2024, 05:46:29 AM »

Thanks for the suggestion HondaMan! I snagged one from eBay for cheap.

I also emailed that company linked before and they offered to make one to whatever length I need once they get the correct metal/bar/whatever in stock.

Hopefully will make good progress tonight. I want to attempt to start the bike this weekend.

HondaMan · « **Reply #233 on:** March 29, 2024, 07:15:36 PM »

The only 'down side' to the longer swingarm bolt is their lack of greasing passages. I drill them in: it uses up 4 drill bits. Then the collar in the arm either needs to be the early style with grease passages and grooves, or make them yourself: just be sure their feed holes align with the ones you put into the long bolt!

BrockCB750 · « **Reply #234 on:** March 30, 2024, 05:53:58 AM »

Thanks for the heads up HondaMan.

Got the rearsets on. It took literally all day yesterday. When you're first folding with rear brakes and trying to figure that all out... Let's just say it would take anyone with even a little experience much less time and I struggled.

Today is going to be hooking up the controls, getting oil tank in place and priming oil through the engine.

BenelliSEI · « **Reply #235 on:** March 30, 2024, 11:18:26 AM »

Looking very nice!

denward17 · « **Reply #236 on:** March 30, 2024, 12:40:05 PM »

I like those sets, they look comfortable.

HondaMan · « **Reply #237 on:** March 30, 2024, 09:31:53 PM »

Quote from: BrockCB750 on March 30, 2024, 05:53:58 AM

Got the rearsets on. It took literally all day yesterday. When you're first folding with rear brakes and trying to figure that all out... Let's just say it would take anyone with even a little experience much less time and I struggled.

...no, it wouldn't...

You might find that the shifter toe pawl needs to be lower. Quite a bit lower.

BrockCB750 · « **Reply #238 on:** April 04, 2024, 06:23:59 AM »

Yeah there will definitely need to be some adjustments to the shifter and brake now that I have sat on it a few times.

Threw the exhaust, tank and seat on. Nothing painted yet obviously but first real look at what the final product will be:

Need to get the oil lines completed and then its time for wiring.

BenelliSEI · « **Reply #239 on:** April 04, 2024, 07:52:01 AM »

Looks tidy. Lic. plate on the other side?

BrockCB750 · « **Reply #240 on:** April 04, 2024, 07:52:43 AM »

Yeah. Didn't consider the exhaust at all when I put it on. Haha. Easily swapped though.

denward17 · « **Reply #241 on:** April 04, 2024, 08:20:16 AM »

Looking good Brock!

BrockCB750 · « **Reply #242 on:** April 04, 2024, 08:28:51 AM »

Thanks!

Is it normal to be terrified to start the engine for the first time? I have come this far and just keep thinking I did something terribly wrong and I will hear awful metal thrashing noises and trash the engine on that first startup. I don't think that's reasonable. It turns over fine.

BenelliSEI · « **Reply #243 on:** April 04, 2024, 08:52:16 AM »

Quote from: BrockCB750 on April 04, 2024, 08:28:51 AM

Thanks!

Is it normal to be terrified to start the engine for the first time? I have come this far and just keep thinking I did something terribly wrong and I will hear awful metal thrashing noises and trash the engine on that first startup. I don't think that's reasonable. It turns over fine.

Don’t feel bad, I worry every time. If it cranks nicely with the plugs out, and generates oil pressure, go for it!

PeWe · « **Reply #244 on:** April 04, 2024, 10:33:22 AM »

Yes, should the red oil pressure warning stop lit in time?

Good idea to spin without plugs first to get oil pressure.
Around 20sec and no pressure, prime the oil pump that must have air inside.
If crank bearings, cam with rockers are lubed with assembly lube they might keep up longer?

Maybe possible to remove the oil pump pressure relief valve, 14mm nut , spring and steel valve under, spin engine with starter a few sec and oil will hopefully flow when air could exit.
Valve back on, oil pan + exhaust.

I'll test that next time. I removed pump on my CB750K2 due to no pressure. I found that the 3 knock pins for pump fasteners are very fragile, pump must go on leveled with case, not tilted anything.
I ordered some spare knock pins after that adventure.

BrockCB750 · « **Reply #245 on:** April 04, 2024, 06:02:18 PM »

Swapped the license plate to the other side tonight and put the chain on.

Either its been so long that I have forgotten or I never actually ever put a chain on but... is it normal for it to be really tight? The chain tension bolts are backed out pretty far. I know it will loosen over time but I can barely get the lock nuts back on. This seems off to me...

Is that normal?

Its a PARTS UNLIMITED Heavy Duty O-Ring Chain 100 links. I thought this was the correct length maybe I am wrong?

BenelliSEI · « **Reply #246 on:** April 04, 2024, 06:39:08 PM »

You running 18 X 48 stock sprockets? 530 X 100 should be correct.

BrockCB750 · « **Reply #247 on:** April 05, 2024, 04:26:32 AM »

Yep all stock sizes. I switched to an aluminum wheel sprocket but it's identical size.

BrockCB750 · « **Reply #248 on:** April 05, 2024, 04:59:08 AM »

Some photos for reference.

Its pretty for off. Really feels like I need another link or two. haha

denward17 · « **Reply #249 on:** April 05, 2024, 05:45:47 AM »

Is that a different swing arm? Longer perhaps?

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Author Topic: CB750K4 what did I get myself into? (Read 12160 times)