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New member hello and tank question

Jdlong27

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Hi everyone! Enjoyed reading all the information here and finally registered. I've purchased an 80 cb750c as my first "owned" bike and look forward to riding soon.

I've searched and cannot find some info on the tank. The cap has been drilled out (no key) and when I de-rust the tank I'm going to replace the cap. But, I can't seem to locate any information on the part that holds the cap in. I've searched "inside", "female", "ring", etc. can anyone tell me what this is called and, most importantly, why it just slides out. Should it? Or is something missing/needs welding/needs gasket/etc.

I know a picture is worth a thousand words and I'm about out of words for this one. I've highlighted the part in question with an arrow. Thanks in advance and look forward to being a member!

Jason

Ok, can't find a way in mobile to attach a pic. Might be because I'm new. I'll try the full site and update the thread.
 
Welcome... Sorry fairly new myself and restoring a CB too... I do not recognize that so I would like to see what chimes in... I may not have enough familiarity either them but it doesn't look like anything I've seen on any of my Hondas... BTW pix only seem to use the loader properly on a PC, not mobile devices...
 
Thanks flogger! It appears to be some type of sleeve (searched that too lol) that the cap locks in to. It is notched to fit the notch in the tank opening. But nothing keeps it from pulling out when the cap comes out. It's as if it should maybe go in and turn, but I don't want to damage anything without knowing more. Hoping someone can help! Thanks again!
 
Just had my tank repainted too... On inside? This and my GL650 both appear to just have the tank opening shaped/machined to hold the cap but I will look closer... 750 is at shop for some stuff, will look when I can... If it's inside the opening, how'd you get it out?
 
Both my 83 GL650 and my 81 CB750, neither one has that... I wonder if who drilled it out on your cap, put that in trying to make it hold or make something secure/lockable but never finished it? Aftermarket item?

On both of my cycles above, the tanks look like yours without the ring. Both of these, when you turn the key, the cap pops up, spring loaded, about a half an inch. Ring put on yours to deal with the modified cap as you have in your video? Does your cap still have a movable, spring loaded notch on it?

My factory caps just plug in to my tanks, the cap notch aligns with the tank notch. The cap notch is movable and spring activated too. Press in and the cap clicks down, secure, and sealed. I would be worried with the drilled out cap that water or moisture would get into the tank...
 
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Haha. Yes. Water. That's the issue. I've got a rusted out out tank I'm going to attempt to repair and need a new cap when I do. I didn't know what this thing was so that I could get a new one, but it seems that I don't need it.

No, there are no moving parts left to the actual cap. Seems like a good assessment to me.

Here's what an open cap for a few years will do: https://www.dropbox.com/s/sxpd3jvi73g12rd/Photo%20Feb%2019%2C%202%2020%2048%20PM.jpg?dl=0

Needs a lot of work. In this pic you can see the gas/shellac at this point leaking through; cracked carb insulator boots; rust; etc.
 
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Wow... really rusted... Inside the tank too I bet? I see airpods, could be more issues... Is it running? You have a handful for a first bike... How much did it cost you?

You can post pix right in here, see the icons above the text block when posting? The 3rd icon from the right inserts pic...
 
Yes. A major undertaking. There is a lot of rust inside. I'm going to see what I can do to save it. I bought it for $300. It cranked with a jump and ran a few seconds and died. So the engine is not locked up. I'm not trying again until I've gone through it thoroughly.

The throttle sticks and doesn't return.
The gas is old.
It does shift through gears.
The front caliper locked up so PO just took it off and ziptied it up. ��
The engine looks like it was buried for a while.
The tires are out of date.
There's no key and a switch has been installed under the tank. (The first part of the charging system I plan to check)

I can't add photos here because I don't have access to a computer. Neither the mobile or "full site" add picture is working on my iPhone. Here's a link to the Dropbox of more photos.

https://www.dropbox.com/sh/tc4ltjgy7ubvrnc/AACM3qTA66RKwkyf2kwAY_rCa?dl=0
 
300? Here is my thread link on this site... I put pix there of my project. I paid 300 also but I think I got a better deal.

http://www.cb750.com/threads/3466-Newbie-here-with-just-purchased-81-CB750

It was drivable, just ran rough. No rust anywhere, was always stored in a climate controlled garage. Chrome, seat, frame, most of it were in great shape... Tank had 3 dents, so you will see the later pix where I repaired it and repainted it... New 4 to 2 all chrome pipes, value and carbs have been re-done now... Replaced brake fluid, rebuilt master cylinder, new pads and new shoes... New tires... Still a work in progress but I hope to be on her this Spring, maybe in a month or so...

On yours, you can get a new tank on Ebay easily... Caps sold by themselves or even caps with ignition and helmet locks and keys as a set... Not very expensive...
 
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Wow. Nice flogger! You got a deal! Biggest issue with mine so far, and reason i haven't started, has been an issue getting title. But, I'm close to having that resolved. Once I do I'll start.

I was looking on eBay for a cap and that's what prompted this thread. I couldn't find anything for sale that looked like this and I didn't think I was buying the right parts. I'll get one and see if it works.
 
Your caps are on Ebay... Match your make, model, year, etc and not what PO did... Get the title before you invest much... Bikes without titles are worthless and parts only bikes...
 
So, not worth starting another thread really, but I got the tank drained, off and the Petcock removed. Aren't these things supposed to have some kind of screen or filter on them?
The long part is a very fine round screen. Try cleaning it up, looks pretty bad.... Google petcock under images and you can see what a clean one looks like...

Never seen one that coated, good indicator of what the fuel and the inside of the tank looked like... Got pretty bad...
 
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Yeah flogger. This one looks brass. All the pics I see look white. :eek: I've got it soaking to try and clean it. Possibly will just replace it, but I'm waiting to determine the extent of damage to the tank first. Thanks!
 
New here and wanted to get some info on the Tank as well. How Can I tell if my tank petcock has a vacuum port on it cause I do not see one. And I heard the SOS pump is removable without any side effects other than having to turn it off before storing. Any Help much appreciated.
 
The vacuum unit on a DOHC is separate from the petcock and often mounted on the other side. It has a vacuum hose going to the #2 carb from the left sitting on bike.
 
The vacuum unit on a DOHC is separate from the petcock and often mounted on the other side. It has a vacuum hose going to the #2 carb from the left sitting on bike.

Thank You for the kind reply. That is not however helpful in any manner. I know it mounts on the right hand side of the carb rack and it has a Vacuum port hose from #2 Carb. From the lack of any helpful tips here, I found another forum that said removing the Spawn of Satan Vacuum Pump is easily done with no side effects other than having to manually turn off the petcock after use. To also help prevent vapor lock. I did that and the bike runs. Now to put on the finishing touches and go riding.
 
You have to use english in the right way. You said 'I heard...' rather than 'Can you do this?'. If you heard then why would you be asking the exact same thing again???

'.... is separate from the petcock...' DID answer your question so the not helpful in any manner thing is wrong as the words 'not' and 'any' turns the statement into an absolute. And you go on to thank me then insult me at the same time.

'And I heard the SOS pump is removable without any side effects other than having to turn it off before storing.'

How or even why would you need to turn 'it' off if you removed it? And the part is a valve NOT a pump at all. Once again the english gets in the way. There is NO vapor lock in a gravity fed carb on bikes like that, somebody does not know what he is talking about. You already had the gist of it as well and why repeat myself after others? If you need to be told twice you are your own problem. So by trying to mollycoddle you I apparently caused you to flare up instead. Great, dealing with a child now.

'From the lack of any helpful tips here, I found another forum that said...'

Unfortunately the english used there as compared to post #17 confirms a LIE, poster had already been there according to the earlier post.

Thank you. Learn the meaning of english and how it can kill you. No wonder Florida is so messed up. Go back to your video games where nothing is real.

You will discover on these that running more often than not does not mean running right. Get in line.
 
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