Topic: Bought a '69 diecast, what is this gauge?

[Hondawggie]

My newly acquired '69 diecast cb750 (it's a 101xxx bike, built in late 1969) has a vacuum gauge that appears to be a built-in unit.

I found one on ebay -- this is the picture of exactly the gauge on my bike:




I bought this '69 as part of an estate and the caretaker who knew the bike's (original) owner for many years said the bike came with it, and it was an optional add-on that the dealer could install back then. 

The 4 ports on my bike are connected via tubing to the front of the carbs.

I need a history lesson here, it kinda freaks me out that the exact same day I buy a cb750 with a built-in vacuum gauge, I'm searching ebay for '69 cb750 parts and stumble across an identical vacuum gauge unit for sale.

Anyone know anything about this gauge, was it optional or was it a California dealer thing, or what?  I bought my '69 diecast today in Silicon Valley here in the San Francisco Bay Area.

EDIT:  here is the ebay listing URL:  http://www.ebay.com/itm/Honda-CB750-CB-750-carb-carburetor-vacuum-gauge-Sandcast-69-70-KO-K0-/230931144266?pt=Motorcycles_Parts_Accessories&hash=item35c4919e4a&vxp=mtr

[ekpent]

Have you posted a pic of the bike somewhere around here yet,Id be interested in a peek.

[Hondawggie]

Nope, I parked the truck at home and won't have time to unload it until later today, I bought it this morning before work.  The worst feeling is buying a 1969 cb750 and not being able to attack the sucker immediately.   Real freaking bummer.  My plan is to cut out early from work and I'll post pics then.

It's all stock, but for example does it have a wrinkle tank?  Are the pipes 300's?  Is the seat foam black?  I had no time to inspect it, I had to buy it before work and before anyone else came along, f_ckenaye.  Was that key recessed or was it just broken (he didn't have the keys for it).  The craigslist ad did not have a photo.  Is the chain guard a shorty?  I have questions I have to wait until after work.

It's a stock patina'd red paint job, still has the original red plastic K-version airbox.  Do the carb caps have numbers indicating they're original recalled ones?  I do know the carbs are 4-cable cap carbs.  Its killing me these mysteries.  I did have time to notice that the gauge are the K-version fluorescent green with the plastic lens types.   The seat is the ducktail type and still pliant, soft and flexible, the original seat cover.

Here's the version but mine has faded paint:

[Magpie]

I believe that's an on-board gauge to sync the carbs. Cliff.

[Hondawggie]

I believe that's an on-board gauge to sync the carbs. Cliff.

Thanks Cliff -- was it an option offered by Honda? Or only by, say, dealers in certain areas (like California)?

[754]

 Bowman products..I think..lots of ads for them in mid 70,s mags..

 Same fellow that built the deep sump pil pans..

[Magpie]

Check this out http://www.ebay.com/itm/1969-Honda-CB750-Sandcast-K0-CB-750-H440-carburetor-synchronizer-bike-mounted-/290635651056?forcev4exp=true&item=290635651056&vxp=mtr  cliff

[Hondawggie]

Thanks, not sure how it works (yet), is the rider adjusting the carbs frequently enough to need an on-board carb sync gauge?  Seem like going a bit overboard with preventative maintenance.

"Fred let's get some gas and sync the carbs" what.  Puzzling.   Also the fact that there's only one gauge. I'm going to guess that the knurled knobs on the top allow the panicky card-sync'r man to set which carb he's checking.  Kind of a bike-nerdy deal there.

"Honey you know how nervous I am about this-n-that, so I mounted a carb gauge now I can set my carbs everyday when I get up."  what.  I'm missing something here.

These carbs hold their sync pretty well.

[Johnie]

Subscribed and interested in seeing your new find. Let us know the history if you were able to find anything out about it.

[Greggo]

I wanna see!  I wanna see!

[Hondawggie]

WHEW WHAT A LONG FREAKING DAY AT WORK.
Finally got home, unloaded the beast, what do we have here...

WELL WE HAVE A 1969 DIECAST APPARENTLY



4 CABLE CARBS -- check



PATINA'd YET CORRECT SIDE COVERS -- check



THIS IS A FINE MACHINE MEIN GOTT



BLACK ON/OFF SWITCH -- check



SCALLOPED MASTER CYLINDER WITH CORRECT CAP -- INCREDIBLE



WHAT IF I DIDN'T WANT FINS



THIS IS SUSPICIOUSLY STUBBY-LOOKING



FLUORESCENT-GREEN GUAGES, AND the unfortunate relocated and broken ignition


GRAY CALIPER -- check


SINGLE-CUT FRONT FENDER -- one is better than none here



41 TOO MANY


FERD DID YOU SINK THEM CARBS GET TO IT BOY


GOTT DANG GAS CAP PUSH BUTTON DONT WORK NOW


HE HAD NOT RODE IT IN 30 YEAR
AND HE MUST HAVE PUT STABIL IN IT
THERE WAS NO RUST AND THE GAS WAS NOT VARNISH NOR WAS IT GUMMED UP OR NOTHING
FINALLY GOT THE DANG CAP OPEN THOUGH


WHAT DOES THE TANK CAP BUTTON NEED TO FIX IT?


SHAKA!!!!!!!!



It has outstanding compression -- can't want to hear it run.
AMEN.

[kck3]

Nice score!!  Now the important question.... How much ya pay for her??

[754]

 I have a set of 10,*** cases, and Dennis in Wisconson has. 10*** bike...cool find..
.It was one of the first 4 carb bikes, not everybody. Had a set of 4 guages.. Its not like you would set em everymonth, but check them evey once in a while..

[Hondawggie]

Nice score!!  Now the important question.... How much ya pay for her??

He had it on Craigslist for $200.  He had a couple offers on it so I showed up and he said his current high offer was $300.00 and would I go $400.00 and I said 'Sure.'

[Stev-o]

Stole it...check!    Title?  Doesn't matter but would be a bonus.  Great find.

[Hondawggie]

I have a set of 10,*** cases, and Dennis in Wisconson has. 10*** bike...cool find..
.It was one of the first 4 carb bikes, not everybody. Had a set of 4 guages.. Its not like you would set em everymonth, but check them evey once in a while..

Is the trick to using the gauge that you set those knobs on the body of it so that only one carb is on the gauge at a time?   I can see it would be a real handy setup because you don't have to go find  your guage 'where did I last use it', it's right there on the bike.  I had a primary chain rattling problem that was caused by the carbs being out of sync, I *know* the value of keeping them all in sync, just not quite sure yet how to use it -- I'm not taking it off, that's for sure, it's tucked behind the sidecover and no one will know it's there, but I plan on putting new rubber hoses on it and taking it off the bike and cleaning it.

[Hondawggie]

Stole it...check!    Title?  Doesn't matter but would be a bonus.  Great find.

 
Well it does need some work.   The back wheel is locked up, the back tire's flat, on 2nd inspection the seat's hard in some areas and the cover's marginal and the paint's not quite kosher anymore, but I'm loving it as a great project, not too much work to do, and the title is coming we're getting together tomorrow for it.   It's not perfect but I have been looking for a 1969 bike for a long time.

Couple things I don't get is why it has a black on/off button and a wrinkle tank and 4-cable carbs but 341's on it.  I thought the 341s didn't come on until late 70 and into 71.

[Stev-o]

I'd bet the 341's are not original to the bije and were a replacement for one reason or another.

[kck3]

Soap/water/brake cleaner/chrome polish/steel wool/wd-40 her and then take some new pics.  Sure the bike isn't stuck in gear and rear wheel isnt frozen?

[Hondawggie]

I'd bet the 341's are not original to the bije and were a replacement for one reason or another.

Sounds reasonable.  Sure wish it had 300s, I'm going to buy a used set, I keep reading the bike sounds better with 300s and the early cam.

kck3, I suspect the liners of the rear brake drums have stuck to the inside of the hub, I have seen that and dealt with it on a few other long-not-moved bikes, it will just be a matter of taking the back wheel off and using a rubber mallet, working the brake drum out of the hub.  Probably the brake shoes will separate from the liners and the liners will be sticking to the inside of the hub.  When that happens, even when the brake shoes fully retract, the liners are still stuck to the hub and block the wheel from spinning.  Pretty easy fix, just a hassle getting it unloaded and put into the shop today.

The gearbox shifts fine, seems to anyway, and the chain is really loose, so even if the tranny was stuck, the back wheel would still rock a bit in both directions but it is hard froze up.

[Hush]

You lucky stiff, should be in jail for such theft.

[dave500]

good steal,,err i mean scam,,err i mean purchase,the four guage is way more precise as when you adjust one carb it can affect others,you can see that in real time with four guages,,the single guage only lets you monitor one at a time and i think is somewhat of a gimmick of the time,,like real high tech in the 70s?whoa,a vacuum guage,,that sucks,good buy,well done man!

[Terry in Australia]

Nice pickup mate. That's a Bill Bowman vacuum gauge, they were aftermarket vac gauges and popular on K0's especially, due to them going out of synch, especially with new, unstretched cables.

Honda changed the carb design from from four seperate cables on the K0 to a linkage system from the K1 to reduce the requirement to regularly re-synch the carbs. Personally, I like the K0 carbs as they have a much lighter throttle, which gives you the impression that the K0's have a much more responsive engine.

The Bowman guage is a really cool period gadget, but as it only has the one gauge, isn't as easy to use as a set of 4 seperate gauges. Cheers, Terry. 

[ekpent]

Wow that was a great deal. Bet some guys before you are going to be mad for being so cheap. Gotta buy those when you see them and not fool around. Never saw or heard how many miles its showing.
  I am kinda in your boat.I bought and paid for, 4-bikes so far from a hoarder friend the first of Feb,one of them being a 6800 miles K0 and am getting anxious to get it back to the shop to check it out closer. Other than the crappy repaint looked all there,pipes,ignition etc. but no airbox and dirty    Hopefully this Sunday or Monday weather and or schedules will work out to start hauling.
  Congrats on getting over there and making sure it went home with you.

[tango911]

if you re build it, i have an almost mint set of side cover emblems i might sell ya
My luck id sell them and then find a sandcast that needs them .


great find!!!