Honda-SOHC
SOHC.co.uk Forums => CB750 => Topic started by: bobthebuilder on March 06, 2010, 01:30:47 PM
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Hi Guys,
Anyone out there know how to clean rust of inside of tank, or is it that a daft question, should I bin it
Jock. :-\
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Never bin a tank!
I've never tried it but I hear that a selection of old nuts and bolts, together with some old fuel, is a good way of getting the rust out.
Unfortunately, unless you are going to keep it full of fuel, you will need to coat the inside with one of the proprietary tank liners.
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Have read on "tinternet" about people doing this by electolysis method. get rid of this worst with shaking / bolts method, the basically filling tank with water some salt and and setting up anode and diode connected to a battery. I'm no scientist but there were possitive reports. May have been on US sohc site, don't know. Google it!
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Jock - if it has wrinkles visible through the filler cap then keep it and restore it whatever, as these are ultra rare. Mine does not have this feature although it was built in Oct 1969 and I am convinced it is the original tank shipped with the bike to the UK in Jan 1970.
The painter I used recommended Flowliner if the inside is rusty but you need to treat the rust first. I think some of the tank preps come with a rust remover (possibly phosphoric acid).
http://www.flowliner.co.uk/
Look here for help on the SOHC4 Us site. This is always your first stop for info.
http://forums.sohc4.net/index.php?action=search2
Search for tank, rust, etc there is lots on there but it can take a bit of finding
If it is really bad and non wrinkle then a later tank should be available to restore on Ebay but make sure the tap is on the same side as yours as Honda switched sides on later bikes.
cheers
Ash
PS who is rebuilding your motor? what kind of condition was it in?
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A friend of mine used to swear by this stuff, never tried it myself though.
http://www.mandp.co.uk/productinfo/501102/Workshop/Workshop-others/Petseal
Cheers
Den
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There was a good article in last month's Classic Bike about treating the inside of a tank.
Can't remember all the instructions off-hand, but something about cleaning the inside with a handful of gravel and a cement mixer - and electrolysis using a cold chisel and a battery charger to sort out any rust.
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I used flowliner on my F1 tank and it was quite bad with a leak in the side, Flowliner is an epoxy kit that coats the inside of the tank and traps any loose crap and fills hole when it hardens.
One tip, you will need to block the fuel outlet, don't do what i did and just blank it off or you will be drilling out the hole.
But on the whole a good product.
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I've used Petseal on a tank with a leaky seam, it was fine for a couple of months then I used BP Ultimate and it reacted. (also rotted the seal on the petrol tap on both that bike and my minimoto.)
I've hared of people putting old nuts and bolts in the tank, wrapping it in towels and putting it in the tumble dryer.
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Hey Jock - take a magnet to your filler flap- if it is non-magnetic then on no account bin it because these are really rare K0 items and cost a fortune (LIKE 180 Euros !!! from Yamiya who call them 'Antimon'). Mine had one on and I have had it rechromed but its not perfect. Evidently they pitted very quickly and replaced by the steel one.
http://www.yamiya750e.com/index.php?main_page=product_info&cPath=32_80&products_id=654
This tank has appeared on Ebay BTW
http://cgi.ebay.co.uk/HONDA-CB750-SOHC-Fuel-Tank-1973_W0QQitemZ150421122335QQcmdZViewItemQQptZUK_Motorcycle_Parts?hash=item2305cc2d1f
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Honda KO Tank.
Hi Guys thanks for all the info on tank rust much appreciated.
Got a K2 last year from EBay which turned out to have K7 engine. Along with K2 came F2 in basket case condition and 2 boxes spare parts, and 2 petrol tanks sprayed black [very badly ]. Put them at back of garage and forgot about them till yesterday.
Went and dug them out and found one was originally pearl blue and other gold, both have wrinkles on spine at bottom but only visible if turned upside down, Gold tank is immaculate inside so appear to be lucky them.
Ash. KO engine.
My nephew has a car repair garage in Doune Stirling.
They also customise Harleys ect. turns out mechanic has had SOHC. 750 from K1-K7, sold one last year to a guy in Malta. Engine is soaking in releasol at present time will keep you up to speed when he starts to dismantle same
Cheers Jock.
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Hi Ash,
Just read your last post. Tank that was on bike has non magnetic filler cap.
Other tanks have magnetic filler caps so perhaps had better sort the rust inside which is really only on spine below filler cap [ do you think]
Cheers again Jock
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All of the later tanks have some wrinkling but the original Sandcast ones / some K0 you can see the wrinkles whilst looking in the filler cap hole.