Hi all

I have a 1980 yamaha mx175. It got harder and harder to start.

I check compression was pretty low so i am doing top end.

Had jug bored .25mm over stock. I also replaced both crank seals. (good thing falling apart) So i decided to do a good job clean and painted the whole

bike it is looking good. What I was wondering is can i leave the airbox off. I bought an after market K&N air filter that fits right on my carb. will the bike run like this, if so will it need rejeted, the only mod. has boyseen reed valves.

thanks for your help. :lol::ride::lol:


You can and yes, you will have to rejet. You will not gain any performance by doing so. A bike of that age is worth way more stock than hacked up.

What kind of riding are you going to be doing with it? Street only?

If off road, there's a reason they housed the filter in a box in the first place.

I agree with William. When I see a bike like that with the airbox missing and only an external filter mounted to the carb, I think "Rat Bike". Wonder what else has been hacked up on it. Not ranting on you, just sayin...............

My own 1974 DT100 has the air filter right on the carb. Only because when I got the bike, most of the parts, like the airbox, were missing. If I had it, I'd use it.

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