The first of the GL1000s have only 'slider' guides on both sides of the primary chain, with no adjustment possible. These have a hard type of rubber face, which wears, as does the primary chain itself. This gives rise to the infamous idling clattering at the rear of the high mileage engines.

This clattering can be mitigated by carefull balancing of the carburettors, but eventually you are are going to have to split the cases and renew the chain.

In the redesign of the GL1000 for the '78 model, a spring loaded tensioner was fitted, which greatly reduced the engine idle noise. A slightly better design went into the 1100 and finally an even better one for the 1200.

Any of these sprung tensioners can be fitted to the early engine; they will simply bolt on place of the left hand slider.

These tensioners do require a modification to the early primary chain bottom oil trough.

It is very important to do this mod before before fitting it. If you forget, the crankcase halves will not go together as the tensioner hits the trough.

You can either cut it away as in the pictures or leave it out as in the 1100, but personally I would always fit it since we all know how the 1000 primary wears even with it. It seems that the wider 1100 primary chain is not so susceptible to wear so it was left out. (actually I think it was left out because there is no space to fit it along with the wider chain. It would have meant (another) crankcase re-design!).