Question about prep&etch

[Guest]

I just bought an 85 gs450 bike has sat since 09 there is still a little gas in the tank. The tank does not seem that rusty but there is a black layer on most of the inside almost like carbon or something. It will leave your finger black if you rub your finger over it. Tank does not look like it has been sealed still some shiny metal parts. Was wondering if prep & etch will remove it. I know i have to remove the petcock and fuel sender. I have done electrolysis on tanks before and it works well with rust but this does not look like rust maybe pre rust i am not sure. Also does anyone make a mechanical petcock i am not a fan of the vacuum ones i almost lost a motor on a v twin from it.

[tkent02]

I just bought an 85 gs450 bike has sat since 09 there is still a little gas in the tank. The tank does not seem that rusty but there is a black layer on most of the inside almost like carbon or something. It will leave your finger black if you rub your finger over it. Tank does not look like it has been sealed still some shiny metal parts. Was wondering if prep & etch will remove it. I know i have to remove the petcock and fuel sender. I have done electrolysis on tanks before and it works well with rust but this does not look like rust maybe pre rust i am not sure. Also does anyone make a mechanical petcock i am not a fan of the vacuum ones i almost lost a motor on a v twin from it.

The vacuum petcocks on these bikes are good, no losing motors. Replace once every thirty years when they start leaking and call it good. I haven't found a mechanical one that fits, other than the Pingels. You can also make the vacuum ones work mechanically.

Maybe the black stuff is from someone else's electrolysis? I get the black stuff sometimes.

[Nessism]

Think you need to clean the varnish slime out before using that etch and prep stuff (which most likely is phosphoric acid). Por-15 tank sealing kits come with some stuff they call "Marine Clean" which is designed to remove that kind of stuff. Sort of like water soluble carb dip. After the varnish and gunk is gone, that etch and prep should take care of any corrosion remaining in the tank.

[chuck hahn]

Laquer thinner or paint thinner will remove it..but dont get it on any paint cuz that will be gone too.

[cutlass79500]

The vacuum petcocks on these bikes are good, no losing motors. Replace once every thirty years when they start leaking and call it good. I haven't found a mechanical one that fits, other than the Pingels. You can also make the vacuum ones work mechanically.

Maybe the black stuff is from someone else's electrolysis? I get the black stuff sometimes.

Got the tank off has 1/2 tank of gas still liquid. I cant get anything out of the petcock at all prime on and reserve i did not put vac to it because if i am not getting anything on prime. The diaphragm on the petcocks on older yamahas split and fill the cyl thru the vac hose figured these were no different. I know i am gonna have to replace it but was hoping i could get most drained thru the petcock. Even the gas in the float bowl was still gas no varnish and they were clean with no corrosion. Of coarse the carb to motor boots shrank to the point the clamps would not tighten and were kinda loose still. put a screw driver between the carb bodies and boots worked it a little and the boots fell off the metal bracket that attaches to the head. Got plenty to do rebuild the carbs check valve clearances ect want to make sure it runs before pulling the valve cover

[cutlass79500]

tank

Carbs are apart look really well and are surprisingly clean i have cleaned all the passages next into the sonic cleaner and another blow out before the get put back together. The pics of the carbs before starting. Gas was still in there after almost 5 years. New petcock is on the way.I think something went wrong with the petcock you cant blow thru it even with a compressor on prime or anything. I think thats why it died screen is still white with nothing stuck to it. 1 float bowl completely dry no corrosion or anything. Tank is cleaning as we speak figured i would try electrolysis see how it does. Have plenty of time. If it does not work to well will try prep&etch next. I am hoping i do not have to line the tank it was still 1/3 of the way full of what used to be gas smells like alcohol