1972 Honda CB750. *update* overflow leak fixed for $0

V

VintageMBike

Been Around the Block
Maybe I had my priorities mixed up. The carbs havent been worked on in AGES, but the bike runs great. So I bought a $1200 tank set from Yamiya.

Im pretty sure when I put it on that I didnt distrub anything.

Now, when i turn off the bike and shut the petcock off, one of the overflow tubes leaks fuel, as much as you see in the photo, for about a minute, and then stops.

A guy I know has a new carb rack and he would sell it to me for $400 (he rebuilds carbs and is amazing!). Im tempted to just get the new rebuilt rack from him, but I dont have any experience changing carbs, and I hear it can be a nightmare.

So, stuck float? What do you think? Pics below:
 

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Re: 1972 Honda CB750. Mixed Up Priorities?

Damn that bike sure is purdy. What's a tank set?
 
Re: 1972 Honda CB750. Mixed Up Priorities?

Jimbonaut said:
Damn that bike sure is purdy. What's a tank set?
Click to expand...

Thanks. A "tank set" is this. Equivalent to $1,250 with shipping:

http://www.yamiya750.com/index.php?main_page=product_info&cPath=246_157_271_242&products_id=2657
 

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Re: 1972 Honda CB750. Mixed Up Priorities?

Gotcha. Might the overflow in the carbs have something to do with the new petcock on that tank then?
 
Re: 1972 Honda CB750. Mixed Up Priorities?

Jimbonaut said:
Gotcha. Might the overflow in the carbs have something to do with the new petcock on that tank then?
Click to expand...

I know some things but not as much as a lot of guys on this forum.

The petcock and tank are new.

May I ask how would the new petcock make one carb overflow? To be fair I NEVER had this problem until I put the new tank on.
 
Re: 1972 Honda CB750. Mixed Up Priorities?

Mate I'm just spitballing here, but if your carbs were fine before and now they're overflowing with a new tank/petcock set up then that could be your smoking gun. I know bugger all about the SOHC carbs however, just for the record. What position settings does the new petcock have? On/off/reserve kinda thing?
 
Re: 1972 Honda CB750. Mixed Up Priorities?

Jimbonaut said:
Mate I'm just spitballing here, but if your carbs were fine before and now they're overflowing with a new tank/petcock set up then that could be your smoking gun. I know bugger all about the SOHC carbs however, just for the record. What position settings does the new petcock have? On/off/reserve kinda thing?
Click to expand...

No worries. I will figure this out.

Thanks.
 
Re: 1972 Honda CB750. Mixed Up Priorities?

You will, but probably after getting some better help than I just offered ;)
 
Re: 1972 Honda CB750. Mixed Up Priorities?

Jimbonaut said:
You will, but probably after getting some better help than I just offered ;)
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Im replacing the entire carb rack anyway so the problem will be sorted soon.

I know enough to know its probably a stuck float or the needle isnt seating properly.
 
Re: 1972 Honda CB750. Mixed Up Priorities?

That would be easy to check, certainly if it's a stuck float. Pull the rack, check the needles and give the seats a polish. A very small amount of AutoSol polish on a Q Tip will do it, and then a clean with some carb cleaner. Check the rubber tips of the needles too, and also the tiny spring-loaded pin on the tother end. It should depress and spring easily.

Or just buy a new rack haha
 
Re: 1972 Honda CB750. Mixed Up Priorities?

Jimbonaut said:
That would be easy to check, certainly if it's a stuck float. Pull the rack, check the needles and give the seats a polish. A very small amount of AutoSol polish on a Q Tip will do it, and then a clean with some carb cleaner. Check the rubber tips of the needles too, and also the tiny spring-loaded pin on the tother end. It should depress and spring easily.

Or just buy a new rack haha
Click to expand...

yeah ill get a new rack. the carbs on there now are originals.
 
Re: 1972 Honda CB750. Mixed Up Priorities?

Why drop $400 on a new rack when approx. $50 in parts will fix your problem?
This is like buying a new motor because your battery is dead.
 
Re: 1972 Honda CB750. Mixed Up Priorities?

Can I have the originals? Pretty please?
 
Re: 1972 Honda CB750. Mixed Up Priorities?

Does the carb overflow if you don't turn off the petcock?
 
Re: 1972 Honda CB750. Mixed Up Priorities?

Redbird said:
Why drop $400 on a new rack when approx. $50 in parts will fix your problem?
This is like buying a new motor because your battery is dead.
Click to expand...


The rack has BEEN in there since 1972 and was never gone over.

Youve assumed the fix is $50. It may not be. I could open it up and find all sorts of chaos. In my city, to rebuild carbs is $400. In my city, rebuilds dont always turn out well. Personally, I dont have time to do it and dont want to do it.

So lets say it turns out it costs $400 to rebuild my carbs and its NOT a $50 problem like you say.

Im better off getting a pretty much BRAND new rack from the same guy who sold me a beautifully rebuilt set for my CB500 rather than rolling the dice with a local rebuild.

I think thats the way to go, no hassles, and no fiddling other than taking the rack out and putting the new rack in.
 
Re: 1972 Honda CB750. Mixed Up Priorities?

VintageMBike said:
he gives me $100 for my core
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I bet he does. Seriously though, a rebuild kit could well be all you'll need. Some new rubber in there, maybe some new float valves and a good clean of the jets and carb bodies. Sure it's a bit of work but it is satisfying when you're back on your ride knowing that all those bugs in your teeth are only there 'cause you made it happen. You've got a few bikes, right? Bet you could work on these carbs over an evening or two and you'd be right as rain.

But sure, it's not for everyone. And it's up to you how you spend your money needless to say.
 
Re: 1972 Honda CB750. Mixed Up Priorities?

Jimbonaut said:
I bet he does. Seriously though, a rebuild kit could well be all you'll need. Some new rubber in there, maybe some new float valves and a good clean of the jets and carb bodies. Sure it's a bit of work but it is satisfying when you're back on your ride knowing that all those bugs in your teeth are only there 'cause you made it happen. You've got a few bikes, right? Bet you could work on these carbs over an evening or two and you'd be right as rain.

But sure, it's not for everyone. And it's up to you how you spend your money needless to say.
Click to expand...

I went through this with my CB500. Had a guy in NYC rebuild them. He did a shit job

Then my dude in cali sold me a set he rebuilt and I havent had a problem since.

Not only to I have multiple bikes, but I have multiple kids.I dont have time to rebuild carbs. id rather just buy the new rack from a dependable dude instead of:

Ordering a kit
Taking the carbs out
Hoping the kit has the right "rubber" as some dont and are shit quality

etc etc

F that lol. The shortest distance between the two points in this issue is the new rack. Wham bam, its in, im good.
 
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