Hey Guys, I may be posting this in the wrong thread and it's been covered before, but as far as replace or repair. It looks like the tank was empty and with a light I can see rust in the tank... Should I go with one of these pour in cleaners or a Kreem kit - OR - Can I just pull the tank and put a replacement in Also....even though the tires (TrailWings) LQQK ok, I think I better update - Yes? Throttle cable was froze..... New Cable and rebuild the carb? I know - Lots of questions.... Input and wisdom - much appreciated.... RR
Tank sealers can work as-advertised. I've used the KREEM sealer for the past two decades, now, on my daily-ridden bikes...no problems, at all. The white sealer does yellow, a bit. I like the fact that it makes it very easy to see if there's garbage in the gas and how much. Be forewarned, this sealer doesn't just lack a sense of humor, it's downright temperamental. If the surface prep is less than 100%, it'll peel like Birch bark. Removal is a nightmare. POR-15 tank sealer is quite forgiving but, it's metallic silver. Either way, the entire inside surface must be completely free of rust and petroleum residue(s). That means: chemical degreasing (MEK or acetone), chemical rust removal (phosphoric acid, typically), rinsing/drying, followed by immediate MEK flush, application of the sealer. The KREEM kit includes all the chemicals needed, don't recall if the POR-15 kit still does.
The big stumbling block, for most, is chemical rust removal. There's a lot of disagreement over the "best" solution. Some say Evaporust, others white vinegar (acetic acid). IMO, phosphoric acid should be used, if only as a final stage; it leaves a light phosphate coating that'll give you more working time, before flash rust (the killer of many a sealing job) can form. Plan on a 2-3 day soak period, with frequent agitation (a handful of nuts & bolts, or gravel will improve scouring action), minimum. Some of the worst tanks I've de-rusted have taken as long as 2-3 weeks. Plan the sealer application for a low-humidity day and use hot water to rinse out the phosphoric acid. The sealer usually takes 30-60 minutes to apply, which simply means rolling the tank to distribute the sealer evenly, until enough of it has begun to set-up into a film that won't migrate, once the tank is set down.
Vintage tires are good for display purposes only. Rubber doesn't improve with age, it dry rots.
Plan on replacing the throttle cable, cleaning & lubing the internal twist grip throttle assembly and rebuilding the carb. Old throttle cables are usually too arthritic. The factory throttle assembly, a.k.a. "CT70 cruise control" needs to be completely free-moving to work properly. A stronger return spring also helps.
As long as the throttle slide (inside the carb) is moving freely and the float bowl doesn't look like a scale model of the Great barrier reef, it should be rebuildable. A stuck slide or/and deeply pitted/heavily oxidized float bowl oftentimes mean that the carb is toast.
