hi, whats the best way to sort out a heavily rusted tank, inside? will sand blasting do the trick

Electrolysis would be what I'd do.

See this thread on BCF:

http://www.bikechatforums.com/viewtopic.php?t=257171

looks a bit hectic

Yeah but sand blasting might just end up putting a hole in your tank, plus how much of the inside can you actually see from the filler?

Not much, so you could easily miss rust patches sandblasting. At least electrolysis will get everything in the tank

I have done 2 NC30 tanks now with the POR15 kit and have great results both times. The last one was particularly shitty.

electrolysis is ok to an extent.

You still need to seal the tank with something afterwards.

POR15 complete kit is really good but you have to follow the instructions exactly, no cutting corners.

The kit isnt cheap and not permanent either, if you can its often cheaper to get a new tank and keep water out of it.

I've used something like por15, tho i cant remember wat it was called, its works very well and is still on (in) me bro-inlaws tank on his gpz a good few years later.
But its all in the prep, you have to totally degrease it fist and get rid of the loose rust, use washing powder and very hot water, with a bit of old chain chucked in there and shake the tank about till your arms hurt, then change water and do it again till its mega clean inside.
Dry it very well (a hair dryer helps) then apply the resin.
The stuff i used made the petrol turn red for a few tanks, but works really well.
Cheers
Ian

Acid dip.

Thats what I just did with my 2MA tank. Then I got the holes repaired before sending it for paint.

try nitric acid,works a treat.