Author Topic: I bought my first CB750 SOHC K7😍😀 (Read 2615 times)

MDC69 · « **on:** December 19, 2019, 04:59:07 AM »

Hello everyone,
Thanks for letting me join you. I have realised there are some benefits to turning 50. I spotted a really original 77 CB 750 SoHC on eBay. So I bought it. It was sold as a runner. I have always admired the CB of the 70s. As a young boy I would look in admiration at them flying about my neighborhood in Nottinghamshire. I now have one YAY!!! The bike doesn't run tuck delivery yesterday, I have put the battery on charge and I am hoping and praying that's the only reason it's not starting. Please pray to the bike god's for me.

Thanks again.

BenelliSEI · « **Reply #1 on:** December 19, 2019, 05:29:03 AM »

Welcome and good luck! I started with a K8, years ago. Wonderful machines....... put some fresh gas in it too.

rocket johnny · « **Reply #2 on:** December 19, 2019, 06:33:20 AM »

welcome to the club ! happy holidays ! !

Stev-o · « **Reply #3 on:** December 19, 2019, 07:17:33 AM »

Welcome from Texas.

Fully charge battery and use this starting procedure: Give full choke and no throttle 'til she fires.

Good luck

MDC69 · « **Reply #4 on:** December 19, 2019, 10:16:38 AM »

thanks for the tips guys, just tested the compresion on cylinder 1, only getting 60 psi. surely that would never run

jakec · « **Reply #5 on:** December 19, 2019, 10:46:10 AM »

compression test is pointless if you already bought it. you might have done the test wrong anyways if it's that low.

Stev-o · « **Reply #6 on:** December 19, 2019, 02:05:25 PM »

If you are using an automotive tester, that will not be accurate. Did you have the throttle fully open?

More important than the pressure number is how they compare to each other.
What were the others?
All should be within 10%

MDC69 · « **Reply #7 on:** December 19, 2019, 02:53:04 PM »

I will do the test on all cylinders with throttle full open and report back to you. thanks

seanbarney41 · « **Reply #8 on:** December 19, 2019, 04:51:35 PM »

If the bike has not been run in years, compression numbers don't mean much, even if correctly obtained. Rings are probably slightly stuck in the piston ring lands and will free up quick with some heat, movement, vibration, and fresh oil.

Stev-o · « **Reply #9 on:** December 20, 2019, 02:50:34 PM »

Quote from: seanbarney41 on December 19, 2019, 04:51:35 PM

If the bike has not been run in years, compression numbers don't mean much, even if correctly obtained. Rings are probably slightly stuck in the piston ring lands and will free up quick with some heat, movement, vibration, and fresh oil.

So true, Sean. But in his first post, he states the bike was bought as a "runner"...

tool14 · « **Reply #10 on:** December 20, 2019, 03:20:17 PM »

welcome aboard and good luck with bike.

MD · « **Reply #11 on:** December 20, 2019, 03:27:19 PM »

Welcome from Lake Superior,

-MD

MDC69 · « **Reply #12 on:** December 21, 2019, 01:39:41 AM »

Johnie · « **Reply #13 on:** December 21, 2019, 08:28:19 AM »

Nice...another one saved. Don't run it to long without a fan on this air cooled engine. My first new bike was the K7. Here's a pic of when I brought it home from the dealer.

MDC69 · « **Reply #14 on:** December 21, 2019, 10:51:25 AM »

Thank you for the advice. Nice bike 👍

Kevin D · « **Reply #15 on:** December 21, 2019, 03:56:57 PM »

HAH MDC, you have brought the CB into the family room, with the Mrs. consent! How did you manage that?!?!

Erny · « **Reply #16 on:** December 22, 2019, 11:09:04 AM »

MDC, congrats!

Another beautiful K7 saved!
I'm happy owner of one too (the same black excell color) so just ask if you will need something, folks here are always willing to advice and help.
If not a secret how much you paid for her?

MDC69 · « **Reply #17 on:** December 27, 2019, 05:02:21 PM »

Quote from: Kevin D on December 21, 2019, 03:56:57 PM

HAH MDC, you have brought the CB into the family room, with the Mrs. consent! How did you manage that?!?!

Its not the family room, its my man cave

MDC69 · « **Reply #18 on:** December 27, 2019, 05:05:13 PM »

Quote from: Erny on December 22, 2019, 11:09:04 AM

MDC, congrats!

Another beautiful K7 saved!
I'm happy owner of one too (the same black excell color) so just ask if you will need something, folks here are always willing to advice and help.
If not a secret how much you paid for her?

Thank you. 4k sterling

JamesReid · « **Reply #19 on:** January 05, 2020, 07:47:42 PM »

Hi mate welcome to the forum, i hope you enjoy the community and we learn a lot from each other.

MDC69 · « **Reply #20 on:** January 11, 2020, 08:44:40 AM »

thanks for the warm welcome.

I have question, Speaking with a chap in the pub and he says that the Pilot Screw isnt a pilot screw its a mixture screw and it doesnt need the washer O ring, these for other models. is this true? I am currently struggling with the idle speed.

valve clearance, timing, carb floats checked, carbs cleaned and passage ways checked, new pilot screws and float valves fitted.

thanks

BenelliSEI · « **Reply #21 on:** January 11, 2020, 09:42:09 AM »

Not sure about the pilots screw “0” ring, check the K7/8 parts list. If it shows it, use it......
Another cause of hanging idle is a sticking mechanical advancer. Staying to long at full advance makes the idle stay up, and then drop when the advancer shakes loose and retards ignition. It needs to be clean and free on the spool.

Stev-o · « **Reply #22 on:** January 26, 2020, 02:35:51 PM »

Quote from: MDC69 on January 11, 2020, 08:44:40 AM

I have question, Speaking with a chap in the pub and he says that the Pilot Screw isnt a pilot screw...

Was he drunk?!

The "pilot" screw is not for adjusting idle, it is for mixture. Do you have a manual?

MDC69 · « **Reply #23 on:** February 01, 2020, 05:31:29 AM »

Hi Steve-o

I have since figured out its a mixture screw. yes I have a Haynes manual. not much detail on the K7.

I am finding that the screw on carb 2 doesnt need to be turned out as far, 3 quarters to 1 turn out. whilst carbbs 1,3 and 4 are between 1.5 to 2 turns out. is this the same everyone else experience?

BenelliSEI · « **Reply #24 on:** February 01, 2020, 10:40:07 AM »

MDC....... I usually set them all at whatever the manual suggests for your year. Then use my manometer set to do a carb sync. After that, in and out 1/2 to 3/4 of a turn makes no difference, so I leave them alone.......

MDC69 · « **Reply #25 on:** February 17, 2020, 01:54:50 AM »

Thanks, I have done an air leak test with carb cleaner, all fine on the engine side, there is an air leak on he air box side. Do I need to replace the rubbers?

BenelliSEI · « **Reply #26 on:** February 25, 2020, 01:51:02 PM »

Really, those are just a push fit. Don’t worry about it. If you’ve done a sync with a manometer of some kind, you are fine!

MDC69 · « **Reply #27 on:** February 27, 2020, 01:30:41 AM »

thanks BenelliSEI

newday777 · « **Reply #28 on:** March 12, 2020, 03:31:42 AM »

Howdy MDC69
Welcome and congratulations from San Diego.
Did you get it sorted? It's been a couple weeks since you last posted on it here.
I'm not familiar with the 77 carbs. I've always had 75 and 76 750s which have the roundtops.

HondaMan · « **Reply #29 on:** April 02, 2020, 05:41:28 PM »

Quote from: Johnie on December 21, 2019, 08:28:19 AM

Nice...another one saved. Don't run it to long without a fan on this air cooled engine. My first new bike was the K7. Here's a pic of when I brought it home from the dealer.

That's when the SS was new!

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Author Topic: I bought my first CB750 SOHC K7😍😀 (Read 2615 times)