Engine installation and ancillaries

With the engine fully built up we’re now approaching a pivotal moment; the installation of the engine into the chassis.

On the presumption that what we are looking at is a total restoration here then, ideally, you will have a bare and freshly restored frame ready to hand. With most single and twin cylinder engines, it should be possible to lift the engine into the chassis with the assistance of a mate even when the bike is on its wheels. To avoid damaging the fresh paint or powder coating it’s advisable to wrap key areas of the frame with some form of protection. Plumbing pipe wrap is the default here normally but cardboard or old carpet can also be used; any and all will work well. Such protection is best secured with cable or zip ties as any form of adhesive tape may mark the frame. First off aim to get one of the lower engine mounting bolts in place then, with that good mate, swing the motor into position and add the rest of the fixings. There may also be a need to install the carburettor(s) before the engine is fully in place but we’ll look at that in a moment.

If the engine is a big weighty twin, triple or four there’s a much better and less fraught way of bringing the engine and frame together. You’ll be needing that mate again plus some cushioning and possibly some clean wooden blocks. Prop the engine on its side so that it’s parallel to the ground and not going to fall or tip. With said mate now lower the frame over the engine and carefully jiggle it into place. Frames are substantially lighter than engines! Once again add mounting bolts and consider critically the installation of the carburettors before you proceed much further. Fresh or supple carb rubbers are a must, ditto for the carb to air box rubbers. The airbox may also be better installed now as space here is pretty damn tight.

A couple of things to remember when installing engines. Firstly always grease each and every engine mounting bolts, stud or nut with something like copper grease. This will ensure that should you ever need to remove the engine in the future it will be a breeze with nothing corroded tight. Second key area and one often overlooked… the engine needs to be properly earthed or you’ll spend forever chasing your tail over electrical faults. Some motors rely on simple metal to metal contact at various mounting points which is fine until corrosion gets in the way. Other engines run a proper earth strap from a mounting bolt back to the chassis. This scenario is ideally the best and it’s not rocket science to make up an earth strap. Alternatively carefully grind off a small portion of the paint or powder coat at a mounting point to ensure proper metal to metal earthing then spray the joint with a corrosion inhibiting product.

With the engine now properly rehomed the protective carpet, pipe wrap or cardboard can be removed. If you’re working off a bare frame and engine, now would be a good time fit the centrestand if there is one, along with the spring/lever arm that goes with it. These units can be real pigs to fit so it pays to do it now while you have unfettered access unencumbered by wheels, exhaust and the like. Top tip here… invest in a spring hook, you’ll never struggle with pliers and springs ever again.

So moving on you can now raise and secure the engine/frame combo so that it’s stable. Before leaping in with new found enthusiasm, take five and look at what else can go or must go on now while your bike is in its bare bones state. The aforementioned carbs, inlet rubbers and air box are much easier fitted now. Next up have a careful look at the wiring loom as it may be easier to fit the bulk of it now when there are no panels, plastics or seats in the way. Even if you only place in the main parts of the loom such as the generator, battery connections, coil connection and ignition module(s) you’ll be saving yourself a whole lot of heartache. These sites are the major determinants of how the rest of the wiring will sit on the bike. Getting these laid in properly now when there’s nothing else in the way will aid the later rewiring process enormously. Collect and collate the inevitable loose bundles or wires and terminals into plastic bags and cable tie each lot up neatly.

Next up it’ll be time to convert the engine/chassis unit into something more akin to a motorcycle... the end might just be in sight!