Technical advice: Loosening corroded bolts

MCN expert Chris Dabbs is here to answer any questions you have on anything bike related.

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Q. want to replace the standard exhaust system on my 12,000 mile Kawasaki ZX-7R with an aftermarket system, but all the fixing nuts and bolts are corroded solid.

I managed to get the larger collector box nuts off with WD40 and a long extension on the socket, but I’m wary of tackling the 6mm thread nuts that clamp the downpipes in place in the same way since I snapped the stud off one on my last bike.

George Slater, e-mail

A. The next step is to apply some heat to the local area. Get a propane or butane canister from a hardware shop and fit the biggest nozzle you can find – 30mm is a good size.

Don’t use an acetylene torch with a welding nozzle because you’re likely to overheat the area. What you’re trying to do is warm the nut, but not the cylinder head or the exhaust pipe.

Give it a blast, then try and loosen it, another blast, another twist. If the nut glows red hot it’s too hot.