1979 Suzuki Rm125 Air Box Assembly

Cota247Boy
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Cota247Boy
Edited Date/Time 5/10/2022 12:11pm
Hello Friends,

I'm glad I found this forum. I recently bought 1979 RM125 in almost fully rebuild condition.


I checked the air box assembly and it seems that someone glued the box parts.
There are 3 screws, but I can't separate the box to replace the filter. I also can't remove the filter from the top, because the filter attached to the plastic filter holder with some zip tie.

I am thinking to cut the box with Dremel and glue it afterward, because it is. very hard to find anther box.

But for me cutting is always the last option, so I would like to hear more expert options.

Thank you for any information.

P.S I've searched the forum but best to my ability I couldn't find an answer or information how to replace the air filter. I also have the Clymer guide but it doesn't state if one needs to separate the to part of the box in order to replace the filter.








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Cota247Boy
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Cota247Boy 5/9/2022 11:58am
5/9/2022 11:58am
Thanks Hasletjoe, that's a good idea. I already bought the UNI filter. Maybe indeed cutting the old filter out and installing the new filter is the way to go.
DaveB771
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DaveB771 5/9/2022 2:24pm
5/9/2022 2:24pm
Filter access on that bike is from the top. I had a 1979 RM125 and never had a need to take the airbox apart. Cut the zip tie and unscrew the bolt in the middle of the filter.

I think it came stock with a wing nut to hold the filter in place, but that was a long time ago.
Cota247Boy
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Cota247Boy 5/9/2022 2:40pm
5/9/2022 2:40pm
DaveB771 wrote:
Filter access on that bike is from the top. I had a 1979 RM125 and never had a need to take the airbox apart. Cut the...
Filter access on that bike is from the top. I had a 1979 RM125 and never had a need to take the airbox apart. Cut the zip tie and unscrew the bolt in the middle of the filter.

I think it came stock with a wing nut to hold the filter in place, but that was a long time ago.
Thanks! that was the information I need.

Do I need to use a new zip tie after installing the new filter?

According to the part list, there was a wing nut. Mine has a regular nut, but I will go to my local hardware store to replaced it with wing nut.

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DaveB771
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DaveB771 5/9/2022 2:54pm
5/9/2022 2:54pm
Cota247Boy wrote:
Thanks! that was the information I need. Do I need to use a new zip tie after installing the new filter? According to the part list...
Thanks! that was the information I need.

Do I need to use a new zip tie after installing the new filter?

According to the part list, there was a wing nut. Mine has a regular nut, but I will go to my local hardware store to replaced it with wing nut.
If the airbox and filter cage are undamaged, I don't think there'd be need for a zip tie.

Even 19 year old me would have been too cheap to use a new zip tie every time I cleaned the filter.

Does the bike still have the stock origami inspired fenders?
Cota247Boy
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Cota247Boy 5/9/2022 3:37pm
5/9/2022 3:37pm
DaveB771 wrote:
If the airbox and filter cage are undamaged, I don't think there'd be need for a zip tie. Even 19 year old me would have been...
If the airbox and filter cage are undamaged, I don't think there'd be need for a zip tie.

Even 19 year old me would have been too cheap to use a new zip tie every time I cleaned the filter.

Does the bike still have the stock origami inspired fenders?
Do you mean the "duck" style fenders?
If yes, only the rear fender seems to be like that, as far as I can tell.



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DaveB771
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DaveB771 5/9/2022 4:21pm
5/9/2022 4:21pm Edited Date/Time 5/9/2022 5:20pm
Nice. The style of the 1979 RM was polarizing. I'm more accepting of it now then I was then,

I think the stickers on the side plates lasted about 2 rides.

If you're going to ride it, get a Gunner Gasser throttle or some other aftermarket throttle, Suzuki throttle cables kink with no provocation. And if you haven't already done it, route the front brake cable in front of the number plate.
Cota247Boy
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Cota247Boy 5/9/2022 8:06pm
5/9/2022 8:06pm
This is the throttle the bike has. I don't think it's Suzuki, and it's seems weird that the cable goes from the top and not from the side.
Why the front brake cable should be in front of the plate?

DaveB771
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DaveB771 5/10/2022 5:48am
5/10/2022 5:48am
Cota247Boy wrote:
This is the throttle the bike has. I don't think it's Suzuki, and it's seems weird that the cable goes from the top and not from...
This is the throttle the bike has. I don't think it's Suzuki, and it's seems weird that the cable goes from the top and not from the side.
Why the front brake cable should be in front of the plate?

That's a Gunner Gasser style throttle that someone drilled and tapped so they could install a stock-style Suzuki throttle cable. If the cable doesn't kink first, the metal fitting at the base will break and the throttle will stick wide open.

Before I swapped out to a good throttle I went through many OE cables.

Brake cable goes in front of the number plate so that it doesn't bow out to the side as the forks compress. The tabs on your front number plate are designed to keep the cable from possibly hanging up on the bar mounts.
Cota247Boy
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Cota247Boy 5/10/2022 11:19am
5/10/2022 11:19am
DaveB771 wrote:
That's a Gunner Gasser style throttle that someone drilled and tapped so they could install a stock-style Suzuki throttle cable. If the cable doesn't kink first...
That's a Gunner Gasser style throttle that someone drilled and tapped so they could install a stock-style Suzuki throttle cable. If the cable doesn't kink first, the metal fitting at the base will break and the throttle will stick wide open.

Before I swapped out to a good throttle I went through many OE cables.

Brake cable goes in front of the number plate so that it doesn't bow out to the side as the forks compress. The tabs on your front number plate are designed to keep the cable from possibly hanging up on the bar mounts.
What kind / brand of throttle cable you recommend? and what length?

I also can't adjust the throttle cable to have 1mm free play, maybe it's because the current cable goes from the top of the throttle case?
DaveB771
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DaveB771 5/10/2022 11:40am
5/10/2022 11:40am
They still sell the Gunner Gasser and it shouldn't be hard to find one in a kit with the cable. I used mine on three different bikes - a 1977 and a 1981 RM250 and the 1979 RM125 with the same cable - they're reasonably universal fit. Just make sure the cable is for a round-slide Mikuni, which is what's on your bike unless someone changed that.

Motion Pro sells a cable for Gunner Gasser to Mikuni round-slide carburetors. Most dealers/mail order places can get one for you.
Cota247Boy
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Cota247Boy 5/10/2022 12:11pm
5/10/2022 12:11pm
I just checked Motion Pro website and the cable seems similar to the current one the bike has, with the curved metal in the carb. side.

The carb is indeed round-slide Mikuni.

What is the correct way to adjust the throttle cable on this bike?
DaveB771
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DaveB771 5/10/2022 1:13pm
5/10/2022 1:13pm
The carb side has a curved metal fitting. For a Gasser-style throttle you need one that fits straight into the throttle, without that curbed threaded adjuster in the picture.

There are still supply chain issues, but this ought to work for you.

Google can provide all in the info you need on adjustment. Basically, not too tight, not too loose.

Cota247Boy
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Cota247Boy 5/10/2022 1:42pm
5/10/2022 1:42pm
ok, I appreciate you help. Thanks
elsinor79
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elsinor79 10/5/2025 1:53pm
10/5/2025 1:53pm
Cota247Boy wrote:
Hello Friends, I'm glad I found this forum. I recently bought 1979 RM125 in almost fully rebuild condition. I checked the air box assembly and it...
Hello Friends,

I'm glad I found this forum. I recently bought 1979 RM125 in almost fully rebuild condition.


I checked the air box assembly and it seems that someone glued the box parts.
There are 3 screws, but I can't separate the box to replace the filter. I also can't remove the filter from the top, because the filter attached to the plastic filter holder with some zip tie.

I am thinking to cut the box with Dremel and glue it afterward, because it is. very hard to find anther box.

But for me cutting is always the last option, so I would like to hear more expert options.

Thank you for any information.

P.S I've searched the forum but best to my ability I couldn't find an answer or information how to replace the air filter. I also have the Clymer guide but it doesn't state if one needs to separate the to part of the box in order to replace the filter.








Hi , are these your pictures of the box? I have someone trying to sell me a box using the same pictures

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