Anyone know the best way to repair exhaust manifold, broken/missing studs on a CBR600 F?
Answers:
I take it that by manifold, you mean the exhaust stud lug on the cylinder head?
If so, then the correct way would be to remove the engine and take it to a specialist in aluminium welding, where a new lug can be built up, filed to shape, drilled and re threaded.
If the broken stud is still in the head, then you would need a cobalt drill bit to drill it out, as it will be very heat hardened and most HSS drill bits will not touch it.
Once the stud is out, then a recoil tap and insert should soon restore the damaged threads.
Epoxy based compounds such as plastic metal cannot take the heat in this area, which can regularly be close to cherry red when viewed in the dark, when stationary.
you need to drill it out the re tap it
YES GET A TOOL CALLED A STUD EXTRACTER YOU WILL KNOW HOW IT WORKS WHEN YOU SEE IT
The only successful way is to weld the joint. If you have a cast iron manifold, the parts must be heated to at least 100 deg c before the welding process is started. The temperatures and vibration involved are too high in both cases to expect a compound to repair such a break. In an emergency situation compounds will get you back home. Long term, do it the correct way.
After you get the broken bolt out, try using "JB Weld" to repair the manifold. What's the worst that can happen? The JB Weld breaks off and you get an exhaust leak. You would've had to fix it the right way in the first place.
To repair the manifold you need it welded, I doubt very much it's cast iron on a bike. Any good welder will be able to fix it in a few mins.
The broken stud is quite tricky and if you're not careful can end up very tricky.
Is the stud broken off in the cylinder head? If so, be very careful with stud extractors: They work by drilling a pilot hole into the broken stud then running the extractor into this hole either by a left hand thread Or by a square taper you hammer into the hole. Be very careful - break one of these off and you are in for a hell of a job - they are too hard to be drilled out & you'll need to get your hands on a "Dremmel" and grind it out VERY EVRY carefully.
Try soaking the stud in penetrant, then get hold of some left hand drill bits, starting off small and successively drilling larger & larger, say 0.25mm at a time. if you are lucky, by the time you get close to the broken stud's thread roots it will spin out with the action of the drill. if not the best bet is to drill out completely to a larger hole size, tap it & insert a helicoil.
Probably the best advice is unless you really are confidenet, and are able to remove the engine to do this, have th tools available - take it to a workshop, or you really could make a mess of it.
If the broken stud is partially exposed you can double nut it, tightening the nuts in opposite directions against each other making a firm head to grip. If ther is not enough room to double nut , one nut a red locktite. If no exposure drill and easy out, but this can be tricky and is best left to one with experience. Regarding the manifold, do'nt screw around get a replcement. An air leak will suck performance and can cause major damage to your motor.
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