Hi all,

I,m new to the site and this is my first post.I just picked up a 199A.The air box isn,t stock or really any good.I have re-engineered an old style model 92 ai box to fit.It,s pretty small compared to a stock one and I,m wondering if it will affect performance or jetting? I will probably by a new one when I can afford it as all my mad money went into getting the bike.

Thanks in advance and man,what a great site!

hi mate wellcome to the site. i would say yes it would affect the running off the motor and the jets. you would probley have to ajust the carb. ive never come across this before but im sure there will be guys on hear to tell you more. i have a new air box on my 199A you would be beter buying a new one. ive just bought a new box for my 199b the old 1 is in not to bad condtion but not sure if it will fit a 199A because its bigger.

Edited January 11, 201313 yr by bondy

Hi Scot, a model 92, also 325cc, in good fettle puts out oceans of power, pulls like a train and breathes just fine through that airbox so I can't see any reason it won't work efficiently on your bike. As long as an airbox doesn't stop the engine getting the air it needs it will work. You should see how small a KT250 airbox is but they will rev their nuts off - contradicts all this stuff about large volume being required. It's only my personal opinion, but the flow of air being unrestricted is more important than fitting the largest volume airbox possible

Thank you both for the input.I guess for now it,s my only option so we will see how it works.

What filter are you using Scot? My 199A has an original box but I use the one-piece filter/hose on it and it runs fine. As has already been said the volume of the airbox shouldn't really be an issue and it only exists to protect the filter, it's more about flow into the box.

The size and the geometrical size of the does matter if you have a standard two stroke engine without any reeds or or disk valve to steer the intake air gasoline mix as the piston revolutions produces resonances and therefore the gas-mixture will oscillating inside the intake and the air box. When the periods of these resonances doesn't fit to the frequency of the engine revolution this will lead to a worse filling of mixture during the suction stroke.

To prevent this the size of the hollow of the air box has to be adjusted. If this is not possible you need tubes inside the airbox that work as Helmholtz resonators to get rid of these "bad" resonances.

If you look inside many airboxes you often find there two or three tubes that work as resonators just to prevent bad airflow.

I just came in from a little more work on the fitting of the air box.It mounts up pretty good with the exception of the bottom fender bracket that will have to be bent up.The only real problem I see so far,other than possibly what pschauber was explaining,is that it wont be real water proof.That may not be too big of a problem as the trials around here don,t really have many, if any water sections and I have two other bikes I could ride if it was a rain day.

I also have to admit that it bugs me a little that it,s some what cobbled and not a stock set up.Thanks again to all for the replies.

P.S. I don,t know if it,s ok to mention the publications name,but I picked up a magazine yesterday with a spread on Vesty and Saunders Buls.Pretty neat article!