oldaz Posted July 3, 2019 Report Share Posted July 3, 2019 I finished the rebuild on my 247 a few months ago, dropped a bit of fuel in it and rode it around the back yard then put it away in the shop with a view to sell it. I figured one ride at my 74 years was enough for this old body. A friend wanted to have a look at it (the bike, not the old body) and to my dismay the paint on the fuel tank had bubbled in several places. I had sealed and refinished the tank, so expected it would be good. This bike had been worked hard, then sat out in the weather for 30 odd years before I got it and apparently our Australian sunshine didn't do the fiberglass any favors. After inspecting as much as I could I decided the only way to fix it properly would be to take the tank apart and fix from the inside. I used a Dremel type tool to carefully cut the base out of the tank assembly and I'm now glad I made this decision. The inside of the top section is all cracked and crazed and no way would a sealer ever have "fixed" it. I now have the dilemma, do I use the base to make a new fiberglass tank that will fit inside the original cowling, or do I re-fiberglass the inside of the cowl section and glass the bottom back in? The bottom is much thicker and no signs of cracking, so I'll at least use it. Attached picture of the bike when I finished it 1 Quote Link to comment Share on other sites More sharing options...
feetupfun Posted July 3, 2019 Report Share Posted July 3, 2019 If it was me I'd fix the top part and put it back together 2 1 Quote Link to comment Share on other sites More sharing options...
mattylad Posted July 3, 2019 Report Share Posted July 3, 2019 (edited) I would fabricate an alloy tank to sit inside the cover as they did on UK bikes. See the "Shedworks" site for examples. PS lovely bike Edited July 3, 2019 by mattylad addition 2 Quote Link to comment Share on other sites More sharing options...
sherpa325 Posted July 3, 2019 Report Share Posted July 3, 2019 Resin and glass mat are relatively cheap and I assume you are retired so you have the time to do a thorough repair job. Just remember not to use any fuel with ethanol in it. 1 Quote Link to comment Share on other sites More sharing options...
oldaz Posted July 5, 2019 Author Report Share Posted July 5, 2019 On 7/3/2019 at 5:50 PM, mattylad said: I would fabricate an alloy tank to sit inside the cover as they did on UK bikes. See the "Shedworks" site for examples. PS lovely bike Thanks for the heads up on shedworks and thanks for the nice comment. I've decided to go fiberglass, but yet to decide which way. Quote Link to comment Share on other sites More sharing options...
oldaz Posted July 5, 2019 Author Report Share Posted July 5, 2019 On 7/3/2019 at 8:52 PM, sherpa325 said: Resin and glass mat are relatively cheap and I assume you are retired so you have the time to do a thorough repair job. Just remember not to use any fuel with ethanol in it. Not officially retired as I'm still farming, but do have time to do a good job. I've decided to go fiberglass, just haven't made up my mind as to whether the repair will be like the original or whether the base of the original will be the base for a stand alone tank to fit in the original fairing. Non ethanol fuel isn't a problem here in Oz, but I'll look into ethanol resistant resin as used in the shedworks glass tanks. Quote Link to comment Share on other sites More sharing options...
oldaz Posted July 5, 2019 Author Report Share Posted July 5, 2019 On 7/3/2019 at 4:04 PM, feetupfun said: If it was me I'd fix the top part and put it back together Since looking at the shedworks site, my thoughts are heading in this direction using ethanol resistant resin. I don't think the extra glass and resin will add much weight (smiles) or reduce the fuel capacity much for the extra strength and security. I was interesting to see the amount of cracking inside and how much the fiberglass had deteriorated from uv exposure, the new lining was never going to do a good job. Disappointed that I'll have to repaint the outside again and now have to find another set of stickers, not a cheap exercise. Quote Link to comment Share on other sites More sharing options...
brownie001 Posted July 5, 2019 Report Share Posted July 5, 2019 Hi Oldaz, bit late for you now but I bought an earlier model than yours a few months ago and have been faced with just about the same set of problems as you. My tip to everybody would be, go out and spends wads of cash on an endoscope before you do anything else. Mine fits my android phone and a windows 7 notebook/laptop. You can look inside tanks, bores, gearboxes, you name it. Mine came with a 90 degree mirror ad adapter, a magnet attachment and a small hook. The software allows you to take stills and make videos. There are loads available for all sorts of end devices and the wads of cash was € 20. Well worth it as far as I'm concerned. Phil Quote Link to comment Share on other sites More sharing options...
oldaz Posted July 5, 2019 Author Report Share Posted July 5, 2019 8 hours ago, brownie001 said: Hi Oldaz, bit late for you now but I bought an earlier model than yours a few months ago and have been faced with just about the same set of problems as you. My tip to everybody would be, go out and spends wads of cash on an endoscope before you do anything else. Mine fits my android phone and a windows 7 notebook/laptop. You can look inside tanks, bores, gearboxes, you name it. Mine came with a 90 degree mirror ad adapter, a magnet attachment and a small hook. The software allows you to take stills and make videos. There are loads available for all sorts of end devices and the wads of cash was € 20. Well worth it as far as I'm concerned. Phil Great idea Phil, would also pay to expose the tank to bright light/sunshine while you look with the scope, cracks/holes show as a dark color. I've wanted to get a long scope for a long time to explore inside some pipes and also under a rock overhang on farm that may be of indiginous interest. Now might be too late for the tank, but a good time for the farm. Quote Link to comment Share on other sites More sharing options...
feetupfun Posted July 9, 2019 Report Share Posted July 9, 2019 Most of the 1970s spanish bike fibreglass tanks that have come into my possession have had extremely poor condition internals with bare glass visible in many areas. You could see areas of thin resin in the dark using a strong torch shone inside the filler hole and can see the exposed glass using a torch and a small mirror. There is no way that I was going to paint a tank in that condition. I have found that after a thorough degrease process then an internal coating of brushing epoxy resin binds perfectly to the old polyester resin and the exposed glass and the epoxy is also highly resistant to the weird stuff they put in petrol nowadays. It adds a couple of hundred grams to the tank and great peace-of-mind to me. The oldest one of mine is an Alpina tank done in the early 2000s and it has had petrol sitting in it since then. The colour of the epoxy inside has gone from light brown to mid brown in that time but otherwise looks unchanged. I've done 5 or 6 old spanish fibreglass tanks so far like this and they are all still going very well and they all have petrol left in them between rides. 2 Quote Link to comment Share on other sites More sharing options...
oldaz Posted July 9, 2019 Author Report Share Posted July 9, 2019 2 hours ago, feetupfun said: Most of the 1970s spanish bike fibreglass tanks that have come into my possession have had extremely poor condition internals with bare glass visible in many areas. You could see areas of thin resin in the dark using a strong torch shone inside the filler hole and can see the exposed glass using a torch and a small mirror. There is no way that I was going to paint a tank in that condition. I have found that after a thorough degrease process then an internal coating of brushing epoxy resin binds perfectly to the old polyester resin and the exposed glass and the epoxy is also highly resistant to the weird stuff they put in petrol nowadays. It adds a couple of hundred grams to the tank and great peace-of-mind to me. The oldest one of mine is an Alpina tank done in the early 2000s and it has had petrol sitting in it since then. The colour of the epoxy inside has gone from light brown to mid brown in that time but otherwise looks unchanged. I've done 5 or 6 old spanish fibreglass tanks so far like this and they are all still going very well and they all have petrol left in them between rides. Pretty much describes what I found inside mine, how did you degrease yours to be sure the resin would stick properly? I'm now sanding/grinding the remains of tank sealer and unfinished glass inside the 2 halves. Plan is to re-glass both halves to strengthen and repair, then glass it back together. Only other avenue I'll check out first is I have access to a small 3 litre metal fuel tank that may fit inside the fairing, just got the dimensions late tonight, so I'll check it out tomorrow. Quote Link to comment Share on other sites More sharing options...
feetupfun Posted July 9, 2019 Report Share Posted July 9, 2019 Degreasing using kero inside and out then hot water with dishwashing detergent then dry it out then quick rinse with acetone and dry it out quickly 1 Quote Link to comment Share on other sites More sharing options...
oldaz Posted July 17, 2019 Author Report Share Posted July 17, 2019 Been on to several fiberglass places and for those who may be interested the recommendation is to use a vinylester laminating resin. It has a maximum service temperature of 60 degree C when in contact with pure petroleum, and 50 degree C with 10% Ethanol. Their words "As long as the overall temperature of the tank does not exceed 50 degree C, it will be fine" are the best response I got. I know it can get 50C in my workshop in the summer, so not much safety margin even without E10. Quote Link to comment Share on other sites More sharing options...
feetupfun Posted July 17, 2019 Report Share Posted July 17, 2019 6 hours ago, oldaz said: Been on to several fiberglass places and for those who may be interested the recommendation is to use a vinylester laminating resin. It has a maximum service temperature of 60 degree C when in contact with pure petroleum, and 50 degree C with 10% Ethanol. Their words "As long as the overall temperature of the tank does not exceed 50 degree C, it will be fine" are the best response I got. I know it can get 50C in my workshop in the summer, so not much safety margin even without E10. That's why I line my tanks with epoxy resin Quote Link to comment Share on other sites More sharing options...
oldaz Posted July 17, 2019 Author Report Share Posted July 17, 2019 3 hours ago, feetupfun said: That's why I line my tanks with epoxy resin So you're saying epoxy resin rather than vinylester? Fiberglass mob have poly, VE and epoxy, but say the VE is best for petrol? Quote Link to comment Share on other sites More sharing options...
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