I am looking at buying a old-school chopper (1969 BSA Thunderbolt). Just talked to guy about it. Said ti was designed as a bar-hopper / cruiser. Now, the only thing that is noticeably wrong is the head gasket is leaking. He says he just got it serviced (less then 200miles ago) and that he used a copper gasket. He mentioned retorqueing / tightening the head bolts. If it is just a leak at the head gasket is it a relatively easy fix it could this be a syumptom of a more serious problem?
If I can fix it with retorqueing or a new gasket and some high-temp sealant that would be great. I wouldn't mind a old-school bar-hopper.
2007-05-23 14:19:08 · 7 answers · asked by PBPhreak 1 in Cars & Transportation ➔ Motorcycles
Afraid this is not an uncommon problem with these old bikes. If the gasket has been replaced recently, and it still leaks, do not expect another new gasket to fix it, or retorqueing. Is it leaking oil, or compression? Best fix is to find a lapping plate, or make one, you can use a piece of plate glass, should be large enough for the head or cylinder to be moved around on it at least 3 or 4 inches. Get a can of coarse valve grinding compound, coat the glass, and lap both the head and cylinder until there is no uneven colored areas on each. Then a new copper gasket, coated with a thin coat of settled aluminum, from a can of aluminum paint should do the job. Be sure to clean both head and cylinder completely. Another step which helps very often, is to heat the head gasket red hot, over a gas stove eye, or with a torch, and drop it in cold water. This anneals copper, and will assist in sealing.
If it is an oil leak, the annealing step is very important. And always be sure the head is lapped perfectly flat.
Good luck.
Tomcotexas
2007-05-23 15:26:49 · answer #1 · answered by tomcotexas 4 · 2⤊ 0⤋
I rode Triumphs and BSA's for many years.
The manual will tell you that a copper head gasket can be annealed with a torch, brush off any scaling, and reuse. At some point, you WILL have to buy a new one, as this can be done only a few times.
You might try retorqueing, and it MIGHT work.
Actually, removing a BSA head to R&R a head gasket is not that hard, if you have any mechanical skills, and a shop manual.
Just remember, as earlier people have answered, some hardware is British Whitworth, not SAE or Metric.
2007-05-23 20:43:07 · answer #2 · answered by strech 7 · 0⤊ 0⤋
These unit twins were never any good when new,in fact one firm in the UK made a living modifying the big ends/cranks.Walk away now if there's no proof of this machine being modified in the crank department.This engine was never as good as the pre-unit that preceded it(yes I know they had their problems too) so it's cylinder head leaks today--big BIG!end problems tomorrow.If your determined to go ahead with the deal then "tomcotex "advice is the best so far.Wallet at the ready-------------------good luck,you'll need it.
2007-05-24 02:51:41 · answer #3 · answered by greeves4t 2 · 0⤊ 0⤋
i would not try any of those sealers, via what you have suggested the slightly milkish could be slightly moisture in the oil, as for the water point each and every so often the water point unearths its very own sort of point, fill the water as much as max returned use for an afternoon or 2 if water has dropped purely below complete difficulty solved. purely save checking daily if dropped decrease then get a storage to tension try the water gadget..
2016-10-05 22:36:04 · answer #4 · answered by carol 4 · 0⤊ 0⤋
I agree with Tomcotexas. if you buy it get a good manual and keep in mind it has whitworth hardware. odd threads and bolt sizes. at least not common in usa
2007-05-23 16:39:50 · answer #5 · answered by Kurt T 4 · 1⤊ 0⤋
re torque the heads but buy new head bolts first
2007-05-23 14:26:57 · answer #6 · answered by honda vtx 3 · 0⤊ 1⤋
Old bike.... ... pay your money ,,take your chances..
but should be a cheap fix.....
2007-05-23 14:22:28 · answer #7 · answered by Anonymous · 0⤊ 0⤋