Author Topic: 1973 CB750 restore (Read 1998 times)

Schnell · « **on:** February 07, 2023, 05:23:10 PM »

My second CB750 ever. Bought on a cold Winter day in February. Parked for 20 years, luckily in a dry workshop. So far, only sissy bar and highway pegs have been removed. Have to wait for warmer weather in the Spring.

IMG_4028 by frank scheitrowsky, on Flickr

Schnell · « **Reply #1 on:** February 07, 2023, 05:41:48 PM »

Tank is rusty. I'll be doing reverse electrolysis to it. I've done this once before and it works great.

IMG_4052 by frank scheitrowsky, on Flickr
Here's a view under the seat, which has been recovered.

IMG_4054 by frank scheitrowsky, on Flickr
Bike is complete except for left side cover.

bek1966 · « **Reply #2 on:** February 07, 2023, 08:40:18 PM »

Fantastic! There's something special about breathing new life back into a dormant motorcycle. Thanks for sharing and looking forward to following your progress.

Regards,
Brad

newday777 · « **Reply #3 on:** February 08, 2023, 02:43:33 AM »

Quote from: Schnell on February 07, 2023, 05:41:48 PM

Tank is rusty. I'll be doing reverse electrolysis to it. I've done this once before and it works great.

https://www.flickr.com/photos/197675500@N06/52676049804/in/dateposted-public/

Here's a view under the seat, which has been recovered.

https://www.flickr.com/photos/197675500@N06/52676193895/in/dateposted-public/

Bike is complete except for left side cover.

It does look to be in very nice condition having been kept in a dry storage area. That will be a fun rebirth for you!
Electrolysis works great. I've done probably a dozen tanks, the last 3 I have followed up with a couple days filling the tanks with Evaporust, I bought a 5 gallon bucket of Evaporust, then rinsing out 4 times with diesel fuel(the oil in diesel fuel protects from flash rust apposed to rinsing with water, to get all the Evaporust out, then put in 8 Oz of 2 stroke oil to swish around and coat the metal so it doesn't flash rust until I'm ready to use the tank.
I store my bike tanks empty each winter here in NH with 2 stroke oil coating. Come spring I empty the 2 stroke oil before filling the tank. I think Honda used to recommend long term storage for the tanks to be emptied and coating with oil. It works great.

Here's a before and after of a K0 CB500 tank I cleaned with electrolysis process followed up with Evaporust.

Stev-o · « **Reply #4 on:** February 08, 2023, 07:34:18 AM »

Quote from: Schnell on February 07, 2023, 05:23:10 PM

My second CB750 ever. Bought on a cold Winter day in February. Parked for 20 years, luckily in a dry workshop. So far, only sissy bar and highway pegs have been removed. Have to wait for warmer weather in the Spring.
https://www.flickr.com/photos/197675500@N06/52675254142/in/dateposted-public/

Looks good!

BTW - I see you have a Flickr acct. Rather than posting the link, you can click on the share photo arrow [bottom right], then copy the BB code, and paste it on your post:

Schnell · « **Reply #5 on:** February 08, 2023, 07:40:01 AM »

Thanks Steve! I'll try that.

Got it, thanks! An old dog can learn new tricks.

CycleRanger · « **Reply #6 on:** February 08, 2023, 11:30:34 AM »

Very nice! That looks like a great candidate to restore.

Schnell · « **Reply #7 on:** February 08, 2023, 12:00:01 PM »

Thanks, I'm hoping so. Never know what you'll find but it did "ran when parked."

Stev-o · « **Reply #8 on:** February 08, 2023, 02:02:19 PM »

Quote from: Schnell on February 08, 2023, 12:00:01 PM

... but it did "ran when parked."

I always laugh when I read that in a listing!

j343my · « **Reply #9 on:** February 08, 2023, 05:53:40 PM »

Pretty sure I saw that bike on FB Marketplace recently. Glad it was picked up by someone who's going to restore it.

Here is my '73 I picked up in November. Also in Ontario.

Schnell · « **Reply #10 on:** February 14, 2023, 12:10:14 PM »

Valentine's Day: got her naked.

IMG_4082 by frank scheitrowsky, on Flickr

IMG_4085 by frank scheitrowsky, on Flickr

Stev-o · « **Reply #11 on:** February 14, 2023, 12:17:28 PM »

Quote from: Schnell on February 14, 2023, 12:10:14 PM

Valentine's Day: got her naked.

Ha...hope you kissed her first!

bek1966 · « **Reply #12 on:** February 14, 2023, 01:20:37 PM »

Nice! It looks like the frame and battery box has little to no rust.

MauiK3 · « **Reply #13 on:** February 15, 2023, 06:56:09 AM »

Good shape!
Do you know what exhaust you will use?

RAFster122s · « **Reply #14 on:** February 15, 2023, 12:58:35 PM »

If you are gonna ride her ass, remember to pull her hair...

Schnell · « **Reply #15 on:** February 16, 2023, 12:06:32 PM »

Incremental progress - it is February in Canada! Removed the airbox. Was able to remove #1 and 4 spark plugs. #2 and 3 were a different nut size and very hard to turn so I left them for now. Was able to turn the engine over with the kick start to determine that it was not seized. Felt and sounded good. I notice that the valve cover has Allan bolts instead of the original Philips head screws. Also, the engine has been painted, and the paint is now in poor condition. I'll clean that up.

The bike is in great condition given its age. It had been stored for 20 years in a dry garage/shop, so little rust and the chrome is in good condition. I'll use the exhaust that's on it. My finances are limited.

IMG_4092 by frank scheitrowsky, on Flickr

IMG_4113 by frank scheitrowsky, on Flickr

IMG_4105 by frank scheitrowsky, on Flickr

IMG_4107 by frank scheitrowsky, on Flickr

Stev-o · « **Reply #16 on:** February 16, 2023, 12:35:59 PM »

Good to hear it is not "stuck" after 20 years. Those engine covers would look great polished rather than painted, but that is up to you.

Schnell · « **Reply #17 on:** February 16, 2023, 01:33:41 PM »

Oh yes, Steve. I don't plan on repainting. But I won't go as far as mirror polishing.

I plan to paint the mufflers black. They're ugly. Hoping the headers clean up but if not, they're black too.

Schnell · « **Reply #18 on:** February 19, 2023, 12:23:09 PM »

The motor (and mufflers) cleaned up really well with steel wool and scotchbrite pads. This makes me very happy.

Before and after pics:

IMG_4122 by frank scheitrowsky, on Flickr

IMG_4120 by frank scheitrowsky, on Flickr

Mark K · « **Reply #19 on:** February 19, 2023, 08:25:46 PM »

Quote from: Schnell on February 16, 2023, 12:06:32 PM

Incremental progress - it is February in Canada! Removed the airbox. Was able to remove #1 and 4 spark plugs. #2 and 3 were a different nut size and very hard to turn so I left them for now.

I've been working on a '73 CB750 for the past 2 years. My spark plugs are all the same size (18mm), but the issue for me was the spark plug opening in the head. My 18mm deep well socket got stuck after tightening the spark plug and I wasn't able to get the socket back out, except by removing the plug. I've heard some people grind down the outside of the socket to make it fit the opening in the head. I ended up buying a spark plug socket from the toolkit (eBay) and it works great.

Good luck with your restoration. Mine looked like this when I bought it.

Schnell · « **Reply #20 on:** March 02, 2023, 11:20:38 AM »

Incremental progress due to Winter in Canada. Warmer temp today just above freezing so with the help of a heat gun, I removed the carbs today and checked into the float bowls. Look not too bad. They'll be going into an ultrasonic cleaner soon.

IMG_4140 by frank scheitrowsky, on Flickr

IMG_4143 by frank scheitrowsky, on Flickr

IMG_4145 by frank scheitrowsky, on Flickr

Schnell · « **Reply #21 on:** March 06, 2023, 07:56:33 PM »

bath time

IMG_4157 by frank scheitrowsky, on Flickr

HondaMan · « **Reply #22 on:** March 13, 2023, 12:09:39 PM »

The right-side crankcase (by the points cover) looks like it had an 'incident' of some kind, welded back together?

Schnell · « **Reply #23 on:** March 13, 2023, 04:01:20 PM »

Sharp eyes! Yes, there is a weld there. I'll take a pic and post it tomorrow.

Schnell · « **Reply #24 on:** March 14, 2023, 02:07:06 PM »

Damaged and repaired by a previous owner. I believe that I'm the 3rd owner.

853443AC-C115-4471-8B5F-E3D890F12FD2_1_105_c by frank scheitrowsky, on Flickr

D1F782CA-6643-4AA1-B33D-EE30E1CED900_1_105_c by frank scheitrowsky, on Flickr

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Author Topic: 1973 CB750 restore (Read 1998 times)