Topic: Tank options for my CB500/4 restoration

[gregwaits]

I am trying my best to do a respectable job of restoring my '73 Honda CB500/4. The fenders are coming along nicely, but the inside of the tank is crap. I have heard mixed messages re: how to deal with this.

Some people swear by Kreem, others say it is bad news. I don't know what to do.

I spoke to someone with a degree in chemical engineering and they said that sulfuric acid would strip the inside perfectly. Anyone heard of this route?

Is there anyone in here that manufactures replacement tanks from sheet metal?

I am not really particularly interested in making the bike look like stock. In fact I will be making it a partial cafe racer with club bars and bobbed fenders. So the tank doesn't need to look stock. That is not a concern.

Are there other Honda models that the tanks would fit a '73 CB500/4?

Suggestions and hints are greatly appreciated!

[hymodyne]

there have been posts on here recently about mounting 750 tanks on our bikes, and lots pf threads about tank cleaning, coating, etc.  there are also fiberglass tanks that come up on ebay pretty regularly, but you get what you pay for. I'd pick up another stock tank, after quizzing the owner about its condition. besides, if you follow the recent interest in knee cutouts, you've got a spare.I'm gonna stick with my stock one until I can afford an alloy or decide to elongate this one.

btw, I'll box up and get a quote on the exhaust system tomorrow.
PM me with what other parts you might need and I'll toss them in the box (so to speak) If I have them.

hym

[dagersh]

Greg,

Do a search for "molassas".  There was a recent thread here about its amazing rust removing properties.  I think the mix was 4:1 water:molassas, let it sit for a few days (?), flush, clean and then treat with Kerosene to keep the interior from flash rusting due to the water.  Many seem to have had great sucess with this method as well as muriatic acid.  You will find some other tank liners that others have had better success with over Kreem.

Good luck,

Gersh

[Jinxracing]

Do a search for "molassas".

And if that doesn't work, try a search for "molasses" 

As far as custom steel or aluminum tanks go, I've been shopping around, and the general price range seems to be in the $800-$1000 area. If you find someone cheaper that does quality work, please let me know!

Jim

[Tim.]

POR-15 for a commercial tank cleaning/prep product.  Hands down better than Kreem.

A CB750F tank looks awesome on a 500/550 and evokes the styling of the CR racing bikes of the past (long square tanks).  Just need to cut 1/4 inch or so off each of the front tank mounting studs on the frame and cut the rubber bumpers down to match.  The 750 tank is a little narrower at the front than the 500/550 ironically.  An early 750 tank with the chrome gas cap looks nice too - bigger than the 500 tank.

The 500T tank looks good too and apparantly fits (haven't done that myself).  This is a pic of someone in the Toronto area with a beauty of a bike - a friend took the picture for me.  I haven't had the pleasure of seeing it in person.

[Peter]

I am in the process molassing my tank, I took a quick peek inside the other day and it seems to be working just fine.

[csendker]

I've used molasses for lighter clean jobs, and "The Works" (cheap bathroom cleaner) for heavier ones.  Ditto the drying, acetone & kero/diesel/gas/whatever for the flash rust, more so when using "The Works".  Be sure to remove your petcock before doing anything.  It seems that POR-15 is more fondly thought of than Kreem, but I've never used either.  My current tank is lined with something, but I don't know which or what (PO did it).  Pinholes are often a sign of imminent tank death.  Yes, there's many threads about all of these and more; try some searches. 

And 500 tanks are different than their 550 cousins.  Different petcocks and different dimensions.  They'll pop on the frame, but they won't match the seat.

[puppytrax]

The 500T tank looks good too and apparantly fits (haven't done that myself).  This is a pic of someone in the Toronto area with a beauty of a bike - a friend took the picture for me.  I haven't had the pleasure of seeing it in person.

Interesting...he has cut/ground the rear peg mounts off, and left the front pegs intact...no rearsets...from the angle of the shift lever, he rides sitting straight up...kind of odd for a cafe seating position...chrome chainguard with drilled holes...chain looks awful slack...   

[Tim.]

Yeah, there are some interesting bits to be sure, but I have always liked the 500T tank, and think it looks really nice on this bike.

[bryanj]

The 550 K0,K1,K2 tanks are identical K3 is different

[Kevin400F]

Once the heavy rust is knocked out by shaking the tank with some large nuts & bolts inside, I like to use electrolysis to remove the rust.  This involves clamping the negative lead of a 12V battery charger to the tank itself, suspending a steel (or stainless steel) electrode in the tank..... insulated from the tank, of course.....with the tank filled with a conductive electrolyte solution.  I typlically use water with "washing soda" added.  Washing soda is sold here in the states as a laundry detergent additive...chemically it is sodium carbonate.  About 1/2 to 3/4 cup dissolved in a bucket of hot water works well, then add enough water to fill the tank completely.  You'll probably see a couple of amps current initially, and the rust will immediately start conveting.  When the current drops down to 1/2 amp or so, remove the electrode, clean off the deposits, reinsert into the solution and go again.  Follow this process with a phosphoric acid flush, then line with POR15.

regards,

Kevin

[Dougy Dougy Dune Buggy]

TinTin,
You are correct, that tank just plain "Fits" that 550..maybe i should getme one of them, contemplating knee cut outs for my CB500
tank while searching for an F model tank to go with e F Model seat i've got..fabbing is no stranger to me though, dad being a mechanical engineer
and always wrenching on Harleys, i leaned towards CB Cafe style..tried the harley scene, but too many cry baby's & WAYYYYYYYY too expensive, took all the fun out of it!
Thanks for posting
DWYJ