How to widen a tank tunnel

nixon

nixon

Active Member
After searching quite a lot, there's mention of widening tunnels on various bikes..and technique seems to be cold hammering.

Thought id put it out their in general- Whats your opinion on this?

how far can you go safely? whats the risks- can it impact on outside shape? I gather it can with a press of sorts..

Ive got a 74 cb750k tank to put on a 77cb750a..and it needs 2cm increase all along, and id rather someone else uses it before i wreck it
 
Just changing out the tunnel should be pretty straight forward. Just bend a sheet of steel over an appropriate sized metal tube, then cut the old tunnel out and weld the new one in. I don't think you can go wide enough to effect anything other than fuel capacity.
 
Ok cool- i can use the old tank as a template.

what type of welding will work? gas- brazing, tig? Ive got an inverter arc which woudnt work on that thin steel i think
 
o1marc said:
Just changing out the tunnel should be pretty straight forward. Just bend a sheet of steel over an appropriate sized metal tube, then cut the old tunnel out and weld the new one in. I don't think you can go wide enough to effect anything other than fuel capacity.
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o1marc are you fucking retarded, better yet have you ever done^? as far as i can tell you pay other people to work on your bike, buy overpriced junk and hand out bad advice. to the op there is alot to what your tring to do. im not saying you shouldnt or cant. The thing harley dip shit failed to mention is welding on a old gas tank is not eazy and can be dangerous, o yea your mentor bought his tank ::). As always ask a question hear alot of anwsers and listen to a few.
 
Haha...

What Mr.J there is trying to say, is that just bending up some metal and welding it in is a VERY simplified description of the job at hand. For example...

Are you a competent enough welder to handle the task without burning up or severely distorting the tank?

Do you have the tools and skills to cleanly bend the needed radius in a piece of sheetmetal of the correct thickness?

Are you aware of the process of purging gasoline fumes from the tank?

Are you willing to risk the tank?

Are you taking into account that by doing this, you'll lose your stock mounts?

Do you have the skills and tools to make new tank mounts?

In the end, it's up to you as to whether or not you dive into such a project. There are plenty of folks here who've really done this work themselves, and will happily lend a (digital) hand. But know the risks and issues ahead of time.

Oh, and if you really only need about 1cm on either side... Just carefully hammer the tunnel. Triple check wjere you need to change the tunnel though. Oft times it's just a small area that doesnt fit and not the entire length.

Good luck. Keep us posted.
 
bradj said:
o1marc are you fucking retarded, better yet have you ever done^? as far as i can tell you pay other people to work on your bike, buy overpriced junk and hand out bad advice. to the op there is alot to what your tring to do. im not saying you shouldnt or cant. The thing harley dip shit failed to mention is welding on a old gas tank is not eazy and can be dangerous, o yea your mentor bought his tank ::). As always ask a question hear alot of anwsers and listen to a few.
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Well i'm sure the OP is thankful you answered his question, oh wait, you didn't. I didn't give an answer based on him doing the work but for those of us WHO HAVE done it it is not that big of a deal. Sure there are concerns about used tanks and anybody that has worked on them in the past are well aware of these concerns so as to make them not a concern. I didn't buy my tank, it was given to me as a sponsorship package. I have paid people to do some work on mine but much of the build was done by myself. You can hate on my Harley all you want but I dare you to show me a bike you built that is worth 5x's what you have in it. There is no over priced junk on my bike. You haven't a clue to what the fuck you are talking about.
Von Yinzers list seems pretty straight forward and nothing on the list is hard to do, at least not for me.
 
I'm no professional,but I feel the best way for what you want is to hammer the sides in a lil, just take your time n you'll be good. You can puts strips of masking tape in the tunnel so when you test fit it'll show you were to hammer. Most old gas tanks are of high tin content n make em a bitch to weld n the metal is very brittle. It can be done but after a couple hundred miles they may start cracking on ya. Not to mention if there's a shitload of rust in the bottom.
 
Well for starters vonyinzer is nicer than i am. Once again you harley guy go right to value and worth like your bike is a investment and nothing more. 5x huum Will this do you elitist sheep i got 400 bucks in it they sell in the area of 5 ta 6 grand plus. and this very bike has put down more harleys owner than dime draft night poker runs. fucking white trash wet dream
 

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It's not hard to find, unlike $5-$6k Titans. I just did a search and found an abundance of them for half what you claim yours is worth and none for what you say.
 
you guys have made my day! Freezing my ass off in Ontario and waiting for my day to end, and then this banter fell into my lap and its funny as shit

Thank You guys…..its appreciated!
 
o1marc said:
It's not hard to find, unlike $5-$6k Titans. I just did a search and found an abundance of them for half what you claim yours is worth and none for what you say.
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is it your avatar?
 
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