Hi Paul,

While I have not yet hooked up my boost bottle, it is a common for the idle speed to increase fairly substantially when using the boost bottle. This ultimately requires an adjustment to the idle speed screw (RPM's increase because the air/fuel flow is "smoother" and the reversion wave is lessened allowing for more air/fuel into the engine for a given thottle setting)).

The other problem I have heard with the boost bottle, is when the air/fuel in the boost bottle condenses into just a liquid fuel and eventually runs back into the intake manifold.....obviously this can cause problems with running (and possible even after running depending on the amount of fuel pooled) and is one of the main reasons the outlet of the boost bottle must or should be pointed down to the intake manifold....More often than not this is not done and problems can result.

In thinking of the problem more thoroughly, perhaps the ultimate shape for the boost bottle is a somewhat stocky triangle (narrow in profile...relatively squat in height) with the outlet at the very point on the bottom.....this would ensure that any condensed fuel in the bottle itself would always drain out almost immediately....something that the current cylindrical bottle shape may be a little slow at doing at times unless mounted in the vertical position (which for most practical purposes will not happen due to the need to commonly mount it to the top tube of the bike).

Andrew