Getting the barrels off of the GT750 engine can sometimes be damn near impossible. What happens is the cylinder head studs corrode, especially the locator studs, and the barrels become firmly stuck. In the past I’ve pulled the cylinder head nuts and then filled the bolts holes with 3-in1 or PB Blaster penetrant from Canadian Tire, left them to soak for a few days or a week and then been able to eventually wrestle the barrels off.
Suzuki actually recognised that getting the barrels off was a problem quite early in the production of the GT750, and made a change to the cylinder head bolt washers (service bulletin GT-5 of May 1, 1975) to try and address the corrosion issues, and also made available a puller (service bulletin GT-25 of August 15, 1975). Both of these service bulletins, and all the others, are available here . The problem with the Suzuki puller, is that if the barrels are REALLY stuck, then you risk stripping the threads you have cut in the barrels per their procedure and then you are totally stuffed !
An alternative is as per the photo to the right which was made by John in the local Calgary Water Buffalo group. Basically its a flat steel plate drilled out in the same pattern as the cylinder head. The plate is bolted the top of the barrels and then threaded rod is run through nuts welded to the plate, down into the cylinder bolt holes till they seat on the studs. Then, if all goes well, you just walk the barrels off by progressively tightening the threaded rod which pushes against the tops of the studs and lifts the barrels up and off.
This is a view showing the barrels pulled up part of the way – you can see the degree of corrosion on the studs which meant they really did not want to let go ! In a case such as this, a puller is almost mandatory.
I was just tearing this specific engine down for parts – it is one of two that was included in the 1973 Suzuki GT750 basket case that I picked up in Kincardine, Ontario. While the barrels, crank and pistons were all scrap (lots of severe damage, and signs of seizure), there was a brand new (or at least virtually unused) nylon water pump gear and as well, the side covers and the actual crankcase halves were in good shape as well. As the pistons were first over size, it looks as if the engine had been rebuilt, and then blown up very soon after putting it back on the road. I’m sure I will be able to use a few of the engine components in other projects at some point.
You can see what the plan is, and follow along on the project progress on the 1973 GT750 project site located here.