Author Topic: Winter Project 1973 CB750 Brat (Read 3563 times)

RHCP4LIFE · « **on:** February 17, 2020, 08:11:57 PM »

Picked up my first bike 1973 Honda CB750 this fall. I paid $1800 for it and drove it home. The previous owner had the motor gone through in 2017 and ended up putting some wisco 836 pistons in it. had a few more things on the paper work as well.

I immediately started working on it.

I replaced the wiring harness, and a lot of the electrical components(regulator voltage controller, flasher, speedo, tacho, starter relay). I bypassed the neutral safety switch, but kept the clutch switch in order to start it. I put new bearings in the Wheels and Steering. Refreshed the front forks and put a new chain on. Had front tire replaced balanced and rear wheel trued up and balanced. Rebuild the brake calipers and replaced the lines. New headlight, taillight and signals. Chopped the fenders and rear section and added a rear hoop, added turn signal mounts in the rear. Nice new leather seat and Grips, with new bars... although im not 100% on the clubman bars. Thinking of going with a 2.5" rise bars. New blank sidecovers and some new shocks

Paint is just primer for now but in the next few weeks i will be painting it Hot Rod Satin Black with a 2K spraymax paint. I need to touch up the frame too.

Planning on changing the oil once tank is finished painted and I get fuel in it and started and warmed up.

Any ideas on how to get the motor to shine up? I also think my master cylinder is leaking...

What do you think of it

Edit: i attached the images as im having trouble embedding photos into the Post with google photos.

Scott S · « **Reply #1 on:** February 19, 2020, 02:13:04 PM »

Pics no worky.

WhyNot2 · « **Reply #2 on:** February 19, 2020, 02:35:14 PM »

Pics really would help a lot...........everything sounds good, but.

C'mon man.

Scott S · « **Reply #3 on:** February 20, 2020, 02:52:39 AM »

Working now!

Gurp · « **Reply #4 on:** February 20, 2020, 05:14:47 AM »

Looks great man. Personally some low ride "superbike" bars are alot more comfy for extended riding IMO. Either way it's going to look good

WhyNot2 · « **Reply #5 on:** February 20, 2020, 05:44:28 AM »

Bike looked great red.

Looks like mine in black.

Actually like the black better.........specially with it being a brat/rat bike.

That's the look I was going with mine.

Don't care much for clubman bars. I have euro style on mine.

Yours would look good with that sort of bar.

SOHC4 Cafe Racer Fan · « **Reply #6 on:** February 20, 2020, 10:06:17 AM »

Quote from: Gurp on February 20, 2020, 05:14:47 AM

Looks great man. Personally some low ride "superbike" bars are alot more comfy for extended riding IMO. Either way it's going to look good

Agreed. I've had clubmans with stock pegs before and it feels awkward, even when I had my adjustable clubmans to a position that was basically flat. Superbike bars or CB400f bars works great with the stock pegs while not being too high.

XC204 · « **Reply #7 on:** February 21, 2020, 05:03:11 PM »

That's sweet!

RHCP4LIFE · « **Reply #8 on:** February 22, 2020, 11:00:03 PM »

I finished painting on Friday night. I put the bike back together tonight. It was like 50 degrees in Iowa today so I rode it around the block.

Its idling high, but i was able to force the throttle more closed and it would drop down to around 1000. i think i just have my preload too high on the throttle cable. I replaced both cables this winter.

Need to do a nut and bolt check, put my plates on... i have a list. I did end up getting custom vanity plates for the bike "CB750" I was surprised it wasn't already taken. I got the cool blackout plates so it should look good with the bike.

RHCP4LIFE · « **Reply #9 on:** February 23, 2020, 05:21:38 PM »

Well I drove it about 50 miles today. It warmed up to 55 today, but Snow storm is coming....

I was able to get the idle down, by just adjusting the idle screw. It seems like it crept higher and higher through out the day. But I could force it lower with the throttle cable.

Front brake feels weak. Likely because of master cylinder I'm guessing. Rear brake is solid.

Definitely not very comfortable with the Clubman bars. Definitely going to look into some alternatives. Also I need to get a mirror. My turn signal is pretty sticky hard to get it back to center.

It leaks a bit of oil(see attachment) not 100% sure it's coming from. also noticed my clutch cable needed tightened with this picture.

Had to make some adjustments to the rear shocks this morning it was bottoming out. Also changed the oil and filter. What a mess that was! I ran rotella T4 15w40. Did a nut and bolt check over and a few minor things.

754 · « **Reply #10 on:** February 23, 2020, 10:24:00 PM »

How can you see the clutch needs adjusting ?

WhyNot2 · « **Reply #11 on:** February 24, 2020, 07:05:35 AM »

Man, she looks nice.

Looks like mine, 'cept my engine is black, thinking of cleaning that off.

Love those fenders, are they store bought, or did you mod them?

Seems you have the same leaks as mine.......still figuring that myself.

Clutch cable on mine is loose at that location, too........go figure.

Hope you get all the answers you need, sorry I can't help much, as I'm having way more issues.

RHCP4LIFE · « **Reply #12 on:** February 24, 2020, 11:57:39 AM »

Quote from: 754 on February 23, 2020, 10:24:00 PM

How can you see the clutch needs adjusting ?

I just noticed the Retaining nut for the preload nut was backed way off.

Quote from: WhyNot2 on February 24, 2020, 07:05:35 AM

Man, she looks nice.

Looks like mine, 'cept my engine is black, thinking of cleaning that off.

Love those fenders, are they store bought, or did you mod them?

Seems you have the same leaks as mine.......still figuring that myself.

Clutch cable on mine is loose at that location, too........go figure.

Hope you get all the answers you need, sorry I can't help much, as I'm having way more issues.

I just chopped the OEM Fenders they were pretty dented so i didnt feel too guilty about it.

WhyNot2 · « **Reply #13 on:** February 25, 2020, 08:52:03 AM »

Thanks for the heads up on the fenders.......just thought I'd show you mine:

RHCP4LIFE · « **Reply #14 on:** February 29, 2020, 06:19:52 PM »

So one of the odd things when i got the bike, is that it has a CB750F front brake caliper. This threw me for a loop when i went to rebuild it as i got a 38mm oring for the piston bore vs the proper 43mm Piston seal. I have been noticing some leaking from my font master cylinder and i plan on replacing it. Also it has felt pretty weak when i have been using it. I come to realize just now its probably because the small bore on my master cylinder that was originally designed for the CB750k3 front brake. 38mm piston 1,134mm^2 Area ////// 43mm 1,452mm^2 Area. if you think about the piston only having to move 1mm then the area becomes the volume. thats 318mm^3. I tried to determine the stock piston bore size on a cb750K3 but i couldnt find it. i think if i go with a 5/8 master cylinder for a single cb750F front brake i should be fine. I did find this little chart which was nice. https://www.vintagebrake.com/mastercylinder.htm

RHCP4LIFE · « **Reply #15 on:** March 06, 2020, 10:36:42 PM »

Swapped out handlebars from Clubman to a more natural feel, a little lower than stock. Swapped out the master cylinder. Front brake feels a lot better. Will take it out for a test drive tomorrow. Got the left hand switch control replaced, as the old one was faded and the indicators would always stick. I shortened a bolt the rear tire was rubbing on over large bumps. Also tightened up the rear shocks to help with rubbing.

I need to clip a few zip ties and I'll be ready to ride tomorrow.

RHCP4LIFE · « **Reply #16 on:** March 06, 2020, 10:42:10 PM »

Quote from: RHCP4LIFE on March 06, 2020, 10:36:42 PM

Swapped out handlebars from Clubman to a more natural feel, a little lower than stock. Swapped out the master cylinder. Front brake feels a lot better. Will take it out for a test drive tomorrow. Got the left hand switch control replaced, as the old one was faded and the indicators would always stick. I shortened a bolt the rear tire was rubbing on over large bumps. Also tightened up the rear shocks to help with rubbing.

I need to clip a few zip ties and I'll be ready to ride tomorrow.

Photos

JW1st4stroke · « **Reply #17 on:** March 14, 2020, 08:24:22 AM »

I guess this is a popular look! Check mine out

RHCP4LIFE · « **Reply #18 on:** March 18, 2020, 01:09:44 PM »

Quote from: JW1st4stroke on March 14, 2020, 08:24:22 AM

I guess this is a popular look! Check mine out

Nice, I like that exhaust!

RHCP4LIFE · « **Reply #19 on:** March 19, 2020, 07:08:34 PM »

Checkout my new plates!

RHCP4LIFE · « **Reply #20 on:** March 21, 2020, 03:11:41 PM »

Swapped out the mirrors. Added some rubber grommets to the front fenders. And made some D washers for the triple tree

RHCP4LIFE · « **Reply #21 on:** March 21, 2020, 03:14:18 PM »

Also tho other day I had fuel leaking out one of the over flow. I pulled the bowl tried to flush out the float and needle. Seemed to do the trick because no more leaks!

WhyNot2 · « **Reply #22 on:** March 22, 2020, 08:12:30 AM »

Looks nice......I really need to get off the duff, and do something with mine.

seanbarney41 · « **Reply #23 on:** March 22, 2020, 10:33:43 AM »

Not a fan of the brat style, or the whole "look mom I chopped the back part of my motorcycle clean off" trend going on these days. But, yours has a good look with the bobbed rear fender. So, good job!...an it should be fun to ride!

RHCP4LIFE · « **Reply #24 on:** May 13, 2020, 07:48:00 PM »

Little more work on the bike. I didn't like how I had to squeeze my hand under the rear tire to remove the 4 wing nuts holding down the custom seat, so I bought some quick latch things made for hoods and bumpers and such. They are quite small, the threaded post with the ball on the end was 6mm. While my Seat had 5/16-18. So I bought some 5/16 studs and drilled and tapped them to m6. Made my own little adapter 5/16 male to 6mm female. Not much room for error. I tried this in my vice with no luck, as I kept drilling through the side. My neighbor stopped over and let me use his drill press and it worked! Now all I have to do is reach under and press a couple buttons and the seat pops off. Much easier to remove the seat so I can pull the gas tank and adjust my throttle cables or mess with the battery.

Link to the US made quik-latch https://www.quik-latch.com/

I'll have to grab some photos later.

News:

Author Topic: Winter Project 1973 CB750 Brat (Read 3563 times)