A fellow trials rider (a very competant one!) has a TY200 Majesty. Although the bike goes OK (he is also a good mechanic), he feels the standard airbox is limiting the performance. He has fabricated a replacement, but still thinks the airflow is stifled. Someone suggested fitting a 'boost box' (possibly from a DT175) Has anyone any experience of this?

Thanks

If i remember rightly, Boost bottles were fitted to the Yamaha majesty I think to divert inlet mixture when the throttle was shut, then, when the throttle was opened again, the engine was fed by this charge held in the boost bottle for a more instant response.

I'm sure someone will correct me but i think that was it's function.

You are correct Twinshock - The Boost Bottle was fitted to the IT 250 Cross Country bike to help with response when riding in tight woods. We did fit this to our IT 175 for the same reason. The TY series has bigger flywheels, and does not require this, However I aggree that the air box is restrictive - we used to drill extra holes in the top to get more air flow.

Here is an article from the late 80's on how they work . Installed on a TY350.

http://www.bjracing.com/aug88.htm

I drilled holes in my airbox towards the top. Being in very dry conditions allowed me this luxury. Figured they could be duct taped up if needed. If somebody has plans or has found a better air box solution I'd sure like to see it.

Standard airbox is very poor.

Use a Gas Gas or similar from a later bike to give more volume.