Boost Bottle Revisited

[cannonball2]

Years back I did some experimenting with boost bottles with some interesting/positive results. Never got one to run to suit me. The other
day, my wife who is a nurse brought home a 60 ml syringe they were throwing out. I immediately thought boost bottle because of its displacement. For a bottle to work properly it needs to match the cylinders displacement. This syringe had enough extra space to estimate 66ccs. I pinned the plunger in place and cut the handle off where I estimated the proper point to be.
This bike is an old test mule that has been used for many experiments, not the least was a wet clutch. I installed the mod and went
t for a test ride. It ran with noticeable improvement. Mainly cleaner smoother running with better low/mid range. What I think made the difference this time was the 15 SHA clone has an adjustable idle circuit. Last time I tried this it was with an old NT. Idle and bottom end never were great. Boost bottles do work, but they must be compatible with the installation. Some good bit of science.
As I remember in the 80s Yamaha and Suzuki had bikes that ran them. At any rate I got enough of an Improvement to continue messing with it. Disregard the crudeness, its all function not looks.

 

[cannonball2]

So have finalized the bottle installation and put a good number of miles on it and conclude its a good improvement. Painted the syringe black to give it a less medical look and cable tied it to the frame rail.
What improved is low to mid range Including a smoother idle. Saw no change in the high end. It makes quite a difference in running if the tube is clamped off. Runs not nearly so well. I live on .7 of a mile of sand and gravel road before I get off our island. Low speed manners are needed to pick my way thru the rough road. Im happy with it.
This is with a basically stock motor. I think there are gains to be made using a bottle, but there are so many variables. Displacement, porting, etc, even hose length affects the out come. Guess I just got lucky. If any one wants to experiment around with the concept, you can get the syringe at Tractor Supply.
Here a pic of Old Ugly the test bike. Has been thru a bunch of mods. Has both manual clutch, and auto clutch. Had had a wet clutch also. The run cool cylinder head really helps. The Arebo SHA is an improvement as its had and adjustable idle circuit. Wouldnt run it otherwise. Gas tank is two bean cans soldered together. Also has a Jaguar ignition which has been flawless. Been riding this thing for the last 5 years. Cheap fun. I have much nicer bikes, but this is the beater that gets all the errands.