Author Topic: Project Migoto. 1973 Honda CB750 rebuild (Read 15037 times)

70CB750 · « **Reply #25 on:** February 28, 2012, 04:28:44 PM »

Check for the marks on the shaft and pedal. They should match two little dimples. That will tell you you got both levers correct and than adjust for play.

gnarlycharlie4u · « **Reply #26 on:** February 28, 2012, 04:30:06 PM »

Quote from: Scott S on February 28, 2012, 03:32:26 PM

Not trying to be a dick, but the way it is in that .gif is borderline dangerous. I think you can get it much "firmer".

I already made adjustments since I made that picture and it is much firmer now that I changed it from the gif. The brake engages after about an eighth of input, but I can still continue to put pressure down on it until it hits the brake pedal hits the exhaust. I'll take more pictures and measurements when I can.

gnarlycharlie4u · « **Reply #27 on:** February 28, 2012, 04:38:31 PM »

Quote from: 70CB750 on February 28, 2012, 04:28:44 PM

Check for the marks on the shaft and pedal. They should match two little dimples. That will tell you you got both levers correct and than adjust for play.

Yes, this exactly.
If the dimples don't match up it is "out of alignment," and will fail inspection.
Also, if the brake arm is less than 180º (pointed forward towards motor from perpendicular to the ground) the bike will fail inspection.

gnarlycharlie4u · « **Reply #28 on:** February 28, 2012, 05:03:32 PM »

Alright I'm home and I took some pictures real quick to help illustrate the situation.

The dimples on the pedal, arm, and corresponding mounts match as they should to pass inspection:

The rear arm is now tightened so tightly that the rear brake is fully engaged with NO pressure on pedal. There is NO slack in this pedal at all. Even fully up it is completely engaged.
I can't spin the rear wheel at all, even with two hands.

But... I can still put enough pressure down on the brake pedal with just my hand to make it touch teh exhaust

so the problem is, I can't actually make it tight enough to keep it off the pipe.
I tried adjusting pedals so they're out of the safety inspection range and I can keep it off the exhaust that way but it presents 2 problems:
1) the pedal is impossibly uncomfortable to operate because it's not horizontal, it's actually sticking up about 8º (edit: you have to remove or flip foot pedal to allow this) and
2) it fails inspection.

brandEn · « **Reply #29 on:** February 28, 2012, 05:14:20 PM »

Hey just as an FYI those headers are for later DOHC CB750's I believe. Thats why you had fitment issues. I was looking into getting that exhaust but after talking to Ken at Cycle X he gave me the heads up. Apparently you might want to be careful turning right because you may have ground clearance issues. I am just going on what Ken and a few other on the board have told me.

gnarlycharlie4u · « **Reply #30 on:** February 28, 2012, 05:36:43 PM »

Quote from: brandEn on February 28, 2012, 05:14:20 PM

Hey just as an FYI those headers are for later DOHC CB750's I believe. Thats why you had fitment issues. I was looking into getting that exhaust but after talking to Ken at Cycle X he gave me the heads up. Apparently you might want to be careful turning right because you may have ground clearance issues. I am just going on what Ken and a few other on the board have told me.

I already know, and I mentioned that in the blog. They're actually kerker 4>1 DOHC headers.
My recommendation was to just get an F 4>1 exhaust and buy cycle-x's shorty cone.

seanbarney41 · « **Reply #31 on:** February 28, 2012, 05:38:53 PM »

Quote from: brandEn on February 28, 2012, 05:14:20 PM

I was looking into getting that exhaust but after talking to Ken at Cycle X he gave me the heads up. Apparently you might want to be careful turning right because you may have ground clearance issues. I am just going on what Ken and a few other on the board have told me.

...yup..."sidewinders" are generally considered drag race equipment...drag bikes don't do much turnin'

gnarlycharlie4u · « **Reply #32 on:** February 28, 2012, 07:48:28 PM »

Well I got that starter solenoid working... it was just being picky.
After I diagnosed that the solenoid was causing the problem, I pulled it apart and cleaned it out real well and now it's fine.
Go figure.

gnarlycharlie4u · « **Reply #33 on:** March 01, 2012, 08:03:02 PM »

Joey your MC was in terrible need of a rebuild. No wonder that front brake felt soft!

I didn't have any spare rebuild kits but I did have the whole brake assembly from my K7. I pulled the MC from that, disassembled and cleaned it up as best as I could until we get a chance to rebuild yours.

Hope it works...

Steel wool on the drill was crucial for cleaning and polishing the hard to reach spots.

Sorry for lack of cleaned up pics I got really into rebuilding it and forgot.

70CB750 · « **Reply #34 on:** March 02, 2012, 04:31:47 AM »

Interesting cleaning solvent you got there, Charlie

gnarlycharlie4u · « **Reply #35 on:** March 05, 2012, 06:18:51 AM »

^^it's actually fuel for my polishing machine.

Got the cleaned out brake master cyl back together and on yesterday.
20sNaRanger helped me bleed the brakes on his bike and my Goldwing.

I also taught him (by demonstration) the dangers of hooking up the starter solenoid with the battery still connected.
DON'T DROP THAT NUT!

gnarlycharlie4u · « **Reply #36 on:** March 12, 2012, 01:28:09 PM »

Quote from: Scott S on February 28, 2012, 03:32:26 PM

If I hold a tape measure at the end of my pedal, it barely moves 1/2" before completely locking up the rear brake.

You say "It will pass inspection for the moment like this but when that new break shoe starts to wear in, the rear brake arm will be out of the allowable adjustment level." That doesn't really make sense to me....why would new shoes already be out of adjustment range?

I think you need to remove the linkage from the drum and remove the pedal. Make sure the arm at the back of the splined shaft for the pedal is positioned properly. I think you'll have to rotate it forward, towards the front of the bike. Reattach the actuator rod on the drum and set the arm on the drum as close to 90 degrees as you can. Readjust and check it again.

Not trying to be a dick, but the way it is in that .gif is borderline dangerous. I think you can get it much "firmer".

I just realized that I forgot to mention that you need about a 1/2" of free play in the brake arm because when your rear shock bounces up and down... your rear brake arm moves. Soooo if it's adjusted to tightly and you hit a bump, you might lock the rear brake for a second.

gnarlycharlie4u · « **Reply #37 on:** March 15, 2012, 12:47:48 PM »

Swapped out that funky kickstand for a more appropriate one:
http://gnarlywrench.blogspot.com/2012/03/tripod-gets-trim.html

70CB750 · « **Reply #38 on:** March 15, 2012, 03:50:44 PM »

Are you on the road, Charlie?

gnarlycharlie4u · « **Reply #39 on:** March 15, 2012, 08:19:31 PM »

Quote from: 70CB750 on March 15, 2012, 03:50:44 PM

Are you on the road, Charlie?

Haha well I almost made it out of the driveway but the goldwing blew up. That's okay though. After I finish painting the tank and side covers, I think I'll take this bike for a little spin

70CB750 · « **Reply #40 on:** March 16, 2012, 06:27:19 AM »

I hear you, for almost a week now I am trying to fix a flat - the only progress is increasing number of patches on the tube:). Off road tire irons are not the best for motorcycle wheels.

gnarlycharlie4u · « **Reply #41 on:** March 16, 2012, 06:46:08 AM »

Quote from: 70CB750 on March 16, 2012, 06:27:19 AM

I hear you, for almost a week now I am trying to fix a flat - the only progress is increasing number of patches on the tube:). Off road tire irons are not the best for motorcycle wheels.

I hear that about the off road tire irons. I prefer to use my short ones + a screwdriver and a crowbar, if needed. The best advice I've ever received is to use a plastic water bottle to protect the rim from the irons.

I don't think I'd go through the hassle of patching a busted tube though. I'd just use a new one.

70CB750 · « **Reply #42 on:** March 16, 2012, 07:06:03 AM »

Blalock cycles will have them on Tuesday - but I got three irons there, should work now.

BTW Blalock cycles have CBX on list on cycletrader. Thats whats missing in your garage:)

gnarlycharlie4u · « **Reply #43 on:** March 16, 2012, 02:28:57 PM »

Quote from: 70CB750 on March 16, 2012, 07:06:03 AM

Blalock cycles will have them on Tuesday - but I got three irons there, should work now.

BTW Blalock cycles have CBX on list on cycletrader. Thats whats missing in your garage:)

yeah my garage is missing a lot of other $10000 things too...

gnarlycharlie4u · « **Reply #44 on:** May 14, 2012, 07:37:24 AM »

Maintaining a blog and several concurrent project threads is hard $:-\$

I repainted teh tank and sidecovers, now I'm trying to figure out what decals to make for the tank.

Any suggestions would be appreciated. Here's some pictures to get you all up to speed:

This is the xs650 motor I also painted. I mixed some gold paint with the "cast iron" (

) engine paint and got that bronze color to paint the Yamaha logo.

Back on topic:

I had some decals made.

First coat of paint sucked.

Then I threw the CR-29's on there and got her running.
Oh cool... it starts. 1973 CB750

Second and third coats looked MUCH better.

I taped the tank to show contours. That way I can more easily draw up decals in Illustrator.

Here's what decals I've drawn up so far. I don't like any of them:

So there we are, pretty much up to speed.
It runs, looks decent, and still needs decals.

Oh I also put a NOS petcock on there last night.

mono · « **Reply #45 on:** May 14, 2012, 08:43:53 AM »

i really like the #7 and #8 for the decals, but maybe use the traditional honda wing like the top 2, but make it a bit smaller?

just brainstorming.

i definitely love the paint color though! great choice - looks mean.

gnarlycharlie4u · « **Reply #46 on:** May 14, 2012, 09:19:10 AM »

Quote from: mono on May 14, 2012, 08:43:53 AM

i really like the #7 and #8 for the decals, but maybe use the traditional honda wing like the top 2, but make it a bit smaller?

just brainstorming.

i definitely love the paint color though! great choice - looks mean.

I was leaning towards those 2.
I think that the logos I printed up actually are smaller than the ones in those pictures so that might work nicely.

I appreciate the encouragement!

gnarlycharlie4u · « **Reply #47 on:** January 18, 2013, 11:20:56 PM »

sorry for the lack of updates but the bike had been suffering from some leaky carbs forever. I finally resolved that it was the #4 float seat (even though gas was coming out the #3 overflow

No sooner did I get the carbs sorted out than it developed a terrible top end problem. Some awful clatter coming from the top end somewhere.
When I turn the engine over by hand the #3 and 4 tappets don't move smoothly: they just stay in place for about 1/4 of a turn then drop. I don't know if the cam is busted or the rocker shafts or what, but I know it isn't good.

I'll post again once I have the motor out and the top end off $:-\$

stewonepot · « **Reply #48 on:** January 19, 2013, 01:38:14 AM »

Hi Gnarly
Where are the carbs connected for this problem to occur?
At the bowl vents?
Regards Stew

gnarlycharlie4u · « **Reply #49 on:** January 20, 2013, 03:49:45 AM »

The #3 and 4 carb share a fuel inlet so I'm assuming that's how it happened. #3 carb was suffering from a weakened (fatigued) float so it wouldn't hold it's height. I'm guessing the #4 carb just filled up all the way through the leaky float seat and fuel backed up the fuel inlet and then started over-filling the #3 carb that couldn't hold a proper float height.

The bike was on it's side stand when this happened so gravity could have easily carried fuel over to the #3 carb from #4 while it sat.
This problem did not occour with the bike on it's centerstand which is all the more reason for me to believe the aforementioned is what happend.

News:

Author Topic: Project Migoto. 1973 Honda CB750 rebuild (Read 15037 times)