Vintage Dirt Bike Q & A

I just installed my motor into the 1980 frame, and the airbox I have is from a 79, how much different is it from a 1980? (other than the upper front tab.) The parts fiche shows a separate part number for 1980. What is the easiest way to install it, even with a bare frame / motor and swingarm it does not want to go in easily. Thanks for any answers and suggestions.

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I have too many....
my wife thinks I should join motorcycles anonymous.......

I am only directly familiar with the 1978-1979 bike, but I believe the airbox is common apart from the mounting bracket. But Honda made it so you can only install the airbox with the engine out of the frame.

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Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF

I agree with Michael, it's next to impossible to install the airbox on these
bikes with the motor in the frame. The only hole really big enough to
install it through, is from the front. The '79 box is identical to the '80
from a fitment standpoint.

I recommend you pull the motor then install the airbox. With the motor
out, it's a piece of cake. Also, it is a good idea to install the rubber
airbox bushings in the frame before putting the airbox in.

dogger

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1973 CR250M
1979 CR250R
1993 CR250R
2008 CR500R
2009 CR250R

While we are on air boxes, get one of those aluminum rings that mounts to the front of the box and provides some more rigidity when you bolt in the air filter and its cage. Lots of air boxes have cracks around the holes and/or have warped the front side. Fox made them back in the day and I think VMX does them today.

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Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF

Motor came out last night, airbox in, motor back in. If the drain tube was not there, it would have gone in.
Dogger - what airbox rubber bushings? - My airbox has the threaded inserts pop riveted to the airbox, is there a flat rubber washer between that and the frame mount?

My top mount on the frame was missing, hence my thinking that the airboxes were different.
I'll look into the aluminum stiffener, this airbox is OK, another one I have has the stress cracks starting.
Thanks for everyones help.

_________________
I have too many....
my wife thinks I should join motorcycles anonymous.......

The box is secured to the frame via three fender washers and collars (item numbers 12
and 13 in the diagram) and three 6X22 flange bolts and one 6mm flange nut. Two of
the fender washers mount on the frame itself and the third mounts in the hole on top
of the airbox. As the name implies, these are the same fender washers (and collars)
used on the front and rear fenders and the side panels.

dogger

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1973 CR250M
1979 CR250R
1993 CR250R
2008 CR500R
2009 CR250R

My 78's have the grommet and washer set up, with a larger hole in the frame tab to hold the grommet. The fiche doesn't show any differences on the 80, then it came to me- the 80 was made in the USA factory, so they may have made them different, with only a 6.5 mm hole. I guess they just bolt up without any grommets.

_________________
I have too many....
my wife thinks I should join motorcycles anonymous.......

Interesting. I wonder how you are supposed to
buy parts if the fiche isn't accurate.

That's one to file in the good to know book or, as
Roseanne Roseannadanna would say, "never mind".

dogger

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1973 CR250M
1979 CR250R
1993 CR250R
2008 CR500R
2009 CR250R

my parts catalogue for 78-80 model shows a difference between the models.
78-79 with gommets, collars and longer screws.
80 no gommets, washer and short screw.

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