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The 2-Stroke Garage => Turning Wrenches => Topic started by: RDDave on January 26, 2026, 08:00:03 PM

Title: Identify baffled air box vs unbaffled
Post by: RDDave on January 26, 2026, 08:00:03 PM


I am thinking about ordering new Mikuni jets for my '75 RD350 and I have a few questions:

Is the baffled air box a handicap on my stock (except for Bassani chambers) '75 RD350? Is there any real advantage to changing to the earlier style box? I may know where to get one if it is worth the effort.

Do you normally jet up for chambers? If so, how much?

Do you jet a combo like mine as was original given that today's fuel is so much different than 50 years ago? My right hand plug looks good as is. But I am fighting a fouling left cylinder and am just throwing EVERYTHING I can think of at the problem.

How do I identify the baffled from the non baffled? I tried the search, but didn't have any luck.

It currently has the yellow foam air filter, UNI I think. Is that one okay? If not, please recommend one.

Thanks guys!  :thumbs:

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Title: Re: Identify baffled air box vs unbaffled
Post by: m in sc on January 26, 2026, 09:04:29 PM
its not the box, its the filter itself

the later box breathes just fine

earlier ones w an unbaffled filter run 140 mains stock so, its a better option if you still have the baffled air filter in it. I would imagine the stock af is long gone though
 
Title: Re: Identify baffled air box vs unbaffled
Post by: soonerbillz on January 26, 2026, 09:23:27 PM
Wasn't there a factory notice showing how to make the boxes breath better?
 I seem to remember that.
Title: Re: Identify baffled air box vs unbaffled
Post by: RDDave on January 26, 2026, 09:37:26 PM
Quote from: m in sc on January 26, 2026, 09:04:29 PMits not the box, its the filter itself

the later box breathes just fine

earlier ones w an unbaffled filter run 140 mains stock so, its a better option if you still have the baffled air filter in it. I would imagine the stock af is long gone though
 

So, just to be clear; my bike has a yellow UNI filter. So that means that I am not dealing with anything baffled and I need to run the larger main jet. Do I have that right?

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Title: Re: Identify baffled air box vs unbaffled
Post by: m in sc on January 26, 2026, 09:38:08 PM
that was an early tsb, yes. the lid front gets opened up. the later lids have an 'overbite' of sorts. I 'think' it was for r5s though
Title: Re: Identify baffled air box vs unbaffled
Post by: m in sc on January 26, 2026, 09:38:41 PM
yes. correct.
Title: Re: Identify baffled air box vs unbaffled
Post by: RDDave on January 26, 2026, 09:53:21 PM


Thank you very much! That takes the guess work out of much of what I am trying to do.

Do you jet up when any when you install chambers when all else is stock? I will monitor the plugs, but I just wanted to get a sense of what to expect.

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Title: Re: Identify baffled air box vs unbaffled
Post by: m in sc on January 26, 2026, 10:34:34 PM
yes. start at 150 -160 mains all else stock except pipes.
Title: Re: Identify baffled air box vs unbaffled
Post by: RDDave on January 27, 2026, 02:32:05 PM


 :thumbs: Thank you............AGAIN!

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