Topic: Reviving a '73 750

[gpzkat]

Couple more rides, just testing brakes and gear shifting, all good so far. Needs some ignition work and carb sync still but it seems to run fine, happy.

[MauiK3]

It took me two tries to get mine sorted out. I rode about 400 miles, rechecked the valve lash and did the whole tuneup again, mostly to satisfy my curiosity. I did find that I did a better job on valve lash. Now, when I’m riding, if I look down with my full face helmet, the sound it captures is a seamless machine sound with no standout tappet sound. It runs pretty smoothly now.
You’ve done a great job, very nice bike. I love to see them put back together.

[BenelliSEI]

Well done. Looking good!

[gpzkat]

Thanks, there's a bit more valve noise than I expected, having adjusted them with the head off and taking great care, but better loose than tight at this point. Nothing sounds 'bad', just a bit clattery.  I will take it off non-op ASAP and ride it a bit, then re-adjust.   I am going from memory of my sweet running '76 that I paid $200 for and rode for 3 years, had a ball on it, it was quieter than this if memory serves.  I sold it only because I was moving to Australia and like nearly every bike I have sold, I regretted it 

It took me two tries to get mine sorted out. I rode about 400 miles, rechecked the valve lash and did the whole tuneup again, mostly to satisfy my curiosity. I did find that I did a better job on valve lash. Now, when I’m riding, if I look down with my full face helmet, the sound it captures is a seamless machine sound with no standout tappet sound. It runs pretty smoothly now.
You’ve done a great job, very nice bike. I love to see them put back together.

[gpzkat]

Thanks! Setting a bad example with no helmet so I put one one. It's a cul-de-sac and I got too comfy perhaps. Always best to be protected so I won't ride sans helmet as the fuzz may bust me and my son will be forever influenced by my bad behavior.

Well done. Looking good!

[Stev-o]

Just caught up on your thread, great job!

[BenelliSEI]

Thanks! Setting a bad example with no helmet so I put one one. It's a cul-de-sac and I got too comfy perhaps. Always best to be protected so I won't ride sans helmet as the fuzz may bust me and my son will be forever influenced by my bad behavior.

Well done. Looking good!

I’ve done the “carefully on the engine stand” valve clearances too. I think that what happens on an engine that’s been sitting, crud and corrosion on valve seats gives false reading. After the first run, I usually have to reset most of them! Good luck.

[gpzkat]

Today I took the first real ride on the CB, bedding in the front brake and giving it some revs after it warmed up.  All seems good, no leaks or suspect stuff going on. I checked out all the gears and no problems, and the idle is set, but still need to sync the carbs and probably replace the plug wires and caps.  Handles well and power is as I remembered from my last CB back in the early 90's - adequate and smooth.  I took a pic of the bikes in my garage.  It is a pretty perfect day here in Southern California and I feel lucky to be able to have a 'stable'.

I also got some racks to to store my parts, another freebie bike, a '79 GS850G and my '66 Norton N15CS project.  Outdoor workshop is cool to have.

[gpzkat]

Checked the valve clearances per the shop manual, they were a bit off but not terrible. But every little thing helps.  It really pulls strong.  Now I'm getting out my old Motion Pro mercury carb sync tool (gasp!) and will dial things in.  I am very happy with the way the bike rides, took a spin with my 16 y/o son on the back and had the shocks set to the softest setting as I need the tool to set more preload.  On a left hander I ground the centerstand and scared the crap out of him, haha.  Brought back memories of my '76 with Mac exhaust, I threw a lot of sparks riding that thing through the Maryland countryside.

My friend with a '74 gave me the racks with the agreement that I'll store his '74 CB750 in boxes while he goes walkabout. He's taking a big chance, not so much leaving a comfy home and living in a camper with his wife and 2 teens, but leaving his parts for me to steal.  He has bought a bunch of nice stuff like electronic ignition and nice new plug wires and NGK caps that will fit nicely on my bike. Hmm, evil Homer is on my shoulder.  He also has a dual disc setup I'm eying.

[wolf550]

those shocks look pretty shiny but you can use angle nose pliers to twist up on those groove notches.

[seanbarney41]

yup, put a rag around them or whatever...doesn't require a huge amount of force if the bike is on the centerstand

[gpzkat]

Yep, can do that, I recall seeing that tool somewhere in the pile but it may have been from my Suzuki, will check and see if it fits.   

Took a nice 15 mile ride after adjusting the valves and synchronizing the carbs.   Valves weren't far off and figured out the clutch basket is rattling. It is at the end of its life so I'll replace soon, but it's fine for now.  The bike rides fantastic, no leaks (yet...) power is good, all systems go.  Just waiting on side covers and will paint to match my better red tank as best I can.

I was going to get an auxiliary tank but just put mine on the trash bin and it was fine.

yup, put a rag around them or whatever...doesn't require a huge amount of force if the bike is on the centerstand

[gpzkat]

I've taken a few nice rides on the CB, and it runs very well, but when putting it on or taking it off the center stand there is fuel overflow through the tubes. So I need to check the float levels. May try the method I've seen on here, doing on bench/vice with a glass tumbler as a float bowl. I carefully measured the height per the manual but no joy.  The #1 carb was leaking out of the top and I sorted that one out with an  in place adjustment but I need to take the rack off and set them all right.

I sort of stalled out a week or two since I picked up a cheap '79 GS1000.  It has a fresh top end and good compression.  The guy could never get it running right, am going through the carbs with the ultrasonic etc.  It has a Dynojet stage 3 kit (plus K&N pods and V&H pipe).  The seller admitted he had no idea about carb tuning, I can see by the plugs and blued pipes, and the position of the clip on the needle that he was way off, all over the place.  I'd prefer stock airbox and pipes, but should be able to get it running well.

[PeWe]

That GS1000 look good. Pipes really blue. Carbs must have wrong setup.
Correct setup for pods and 4-1 must be known and common info on forums with GS1000.

I knew one guy that had one in the 80's. He rebuilt it a lot with fairing, stronger swing arm, fork etc since it ran very fast after he added a turbo that added lots of power. I wonder if top speed was tested. Wheelies in high speed.

[gpzkat]

The good thing is I have a complete set of stock spare VM26SS carbs in case these are botched, I can't see anything wrong but they've been drilled out, will see how I get along with them after rebuild and if not good try the others.

I have the '82 Mr Turbo GS1100, had a ride yesterday, it really comes on strong at 7K. It recently put out 183 HP at 18lbs boost, but will do better.  It was about 110 out when dyno'ed and the rear wheel threw a weight and was unbalanced and skipping (!) on the dyno at 125 mph...scary.  The top end's tired, so I'll sort that out but no huge hurry  It ran 183.9MPH at Bonneville in '96 with 25lbs of boost.  Built by Don Vesco, have lots of documentation/receipts/pics.   It drives fine but I will ride the CB and GS1000 more I'm sure.

That GS1000 look good. Pipes really blue. Carbs must have wrong setup.
Correct setup for pods and 4-1 must be known and common info on forums with GS1000.

I knew one guy that had one in the 80's. He rebuilt it a lot with fairing, stronger swing arm, fork etc since it ran very fast after he added a turbo thst added lots of power. I wonder if top speed was tested. Wheelies in high speed.

[PeWe]

WOW!
That bike look really nice!
Its history make to something very special!
The salt look like my area now with snow

[gpzkat]

I fixed the carb float levels properly today, hate to do re-work but sometimes I'm ignorant and forge ahead thinking I know what's up. I made a gauge with credit card like Spanner1 - I believe it's the same guy based on his name and presence here on the forum, what are the odds...

I found a spare float bowl without a leaky overflow tube, and was meticulous about the float adjustment, both on the gauge and the setting. I blew through the fuel tube and found that one of the float housing washers wasn't sealed well, it's aluminum not fiber. I wet sanded it with 1000 grit and it is sealed up tight now. Fired up right away and has no leaks, woohoo!  it's going to get the sync treatment tomorrow but is already pretty good.  As a bonus my registration tag arrived just after my quick ride around the block 

Lesson learned is to do it right the first time, maybe some day it'll sink into my thick head!

[gpzkat]

First real ride, about 45 minutes, mix of city and highway speeds (max 80 or so). Really good shakedown ride, no issues. Main thing concerning me was leaks, blowing smoke, etc.  None of that happening, hallelujah.

First couple rides there was fuel and oil drips but now it's clean as can be.  Next step is to address the cosmetics.  The blue side covers are original (not for '73) and will probably go up for sale to fund paint on the reproductions I got.

#2 pipe a bit blue but that was there from the first startup and hasn't gotten worse. Now that the floats are set properly, I will sync, check ignition/plug and see how it goes. It runs quite well and I think it's just minor adjustments from here on out.

[newday777]

Good to hear no more leaks!

[gpzkat]

Going Orange.  Found a tank, a bit less of a bright orange 'pop' than it could be but I'm financially challenged and it was a good deal.  I have the blue side cover on it currently, but will be selling those as they are original planet blue, and I have originals I'll match to the tank as best I can.  I have paint on order. 

The brakes are my only mechanical concern now.  I have the issue of turning the bars and the brakes drag.  Not an issue when riding as it is only at the limit. The brake lines are not biding so it may be the MC.  I need to address it, and will also be putting better lines on it. 

OEM grips and the trim strip on the bottom of the tank are on the way. Getting close.

[newday777]

Good looking tank. Patina is a good thing.

On the brakes... Did you clean out the master cylinder return port? It's the tiny hole. Use a wire from a wire brush held with needle nose pliers.
How about did you change out the rubber hose for a new stainless steel hose? The flex of old hoses can be a huge loss of breaking power and also introduce pressure to the caliper when bent.

If I had the cash I buy the sidecovers for my blue 75. I have good covers but a spare set would be good too.

[gpzkat]

I will clean that return port, have read about that.  I need to make up some lines, have done Earls with success before.  The ones I have are not good quality but they hold pressure OK.  They came with the bike in a box but are cheap junk.

Good looking tank. Patina is a good thing.

On the brakes... Did you clean out the master cylinder return port? It's the tiny hole. Use a wire from a wire brush held with needle nose pliers.
How about did you change out the rubber hose for a new stainless steel hose? The flex of old hoses can be a huge loss of breaking power and also introduce pressure to the caliper when bent.

If I had the cash I buy the sidecovers for my blue 75. I have good covers but a spare set would be good too.

[gpzkat]

Inching closer to done.  I got the trim for the bottom of the tank, was on eBay but was a David Silver Spares product sold by Everett Powersports.  Interestingly DSS was out of stock.

I couldn't really dial in the idle and could see the inner two cylinder plugs were wet with fuel - not good!   I had a spare coil for a #1/4 which had better HT leads than my #2/3.  It looks the exact same but with a different color wire and longer leads.  As soon as I swapped it in I could tell that was the issue. I re-synced and got it to idle right around the 1K mark with even vacuum.  I also did a compression check warm but not hot (long story involving removing #2 spark plug problem) and got the same 150 across all cylinders.  Not perfect but I'll take it. I am not positive my gauge is really accurate, but at least it tells me no variation.  New rings and lapped valves is all I did to this engine, and I'm pleased with the performance now, it is peppy and smooth.  And no pesky leaks, fuel and oil are staying in their correct locations.

Now I'll tackle the front brake and painting the side covers.  I have a '79 GS1000E in progress too, had to pull the head to get an exhaust bolt pulled and do some thread fixes.  And the GS1100E Mr. Turbo has a couple of minor needs as well.

[gpzkat]

Long time no post, been having fun riding but also travelling a bit to help my dad who lives in another state.  You can read that multiple ways haha.

I am extremely pleased with the overall ride quality, the shocks and forks are really good, and the seat is comfy.  Problem areas are front brake and clutch, and a really long warmup time that I need to sort out. 

The front brake hose is a cheap junk one I got off eBay in a moment of stupidity.  I run braided lines on my GS1000E and GS1100 Mr. Turbo, and will be doing the same for the CB.  My bars are lower '72 (?) versions which I like better, so I'll make them up myself so they aren't too long.  Right now when I turn the bars to the right they bind, ugh.   I have a dual disc setup ready to put on, maybe will get cast iron rotors but need to research.  Rear brake is great, front is just terrible. 

For the clutch I am going to put Barnett HD springs and EBC friction discs on, that should solve the issue which is really just worn out clutch, at the end of its play.

The engine has plenty of power and 150 compression on all cylinders, and zero oil leaks which is great. Honing the cylinders, new rings, and lapping the valves was all it needed.  But it is very cold blooded.  I think the ignition (stock points) is a weak spot.  I didn't even put new points on it yet, just dressed the points and went for it.  Time to get out the dwell tach and put new points on or maybe go Dyna.

Turning into a blog here, oh well.

[gpzkat]

On the brakes.... thought I'd provide an update, been a while I know.  Well, this is a bit embarrassing but the bolts that join the calipers were loose (!).  I am embarrassed to admit that I must have overlooked this but can't figure out why I'd basically hand tighten them and not torque to spec, since that's my  normal M.O.  Thankfully there was no mishap and the brakes are fine now.  Relatively speaking.

Good looking tank. Patina is a good thing.

On the brakes... Did you clean out the master cylinder return port? It's the tiny hole. Use a wire from a wire brush held with needle nose pliers.
How about did you change out the rubber hose for a new stainless steel hose? The flex of old hoses can be a huge loss of breaking power and also introduce pressure to the caliper when bent.

If I had the cash I buy the sidecovers for my blue 75. I have good covers but a spare set would be good too.