4 stroke airbox Mod

Autocycler

New Member
Feb 14, 2008
153
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Metro Washington, DC
I stumbled upon a quick and easy performance boost for the 49cc Honda clone engines. The stock air cleaner inlet is very restrictive, and was causing my engine to bog and hesitate at midrange rpms. I resolved this by simply enlarging the inlet with an exacto knife. I only needed to expand the inlet by about 1/8" across before the engine began to idle more smoothly. Now it runs like a champ. The only downside to this is it made the engine a bit louder, if you consider that a problem;).

Now, if only I could figure out a way to hush the gearbox whine...^5
 

HoughMade

New Member
Apr 15, 2008
624
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Valparaiso, IN
Here's my "high tech" Honda GXH50 airbox...of course I was going for "retro", not performance, but I'll take what I can get. Of course I also had to replace the original airbox because it would not fit.

...and in the spirit of retro, that garish red cover color will be going away soon along with all the stickers- body color, same as the filter housing.
 

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Autocycler

New Member
Feb 14, 2008
153
1
0
Metro Washington, DC
Nice...that's a major improvement on the stock airbox. I'm a fan of the retro look as well.

Is your airbox from one of the small russian engines? I removed the red cowling from my engine, and it looks much better...less like a lawn mower:D

Opening up the intake has really made a difference on my bike. I love riding it now. The gear whine is either quietening down or maybe I'm just getting used to it.

Anyway, I'm becoming a fan of these 4 strokers.
 

HoughMade

New Member
Apr 15, 2008
624
1
0
Valparaiso, IN
I don't want to get away from the air box mod issue, but since you asked, I used the standard tank and fabricated a fiberglass cover to mimic a more vintage look.

I made a form out of foam board, glued fleece on (in the future I would use fiberglass cloth because the fleece required a lot of smoothing), brush on resin, sanded, brushed on more resin, sanded, then filled, primed and painted- it sounds easier than it was. The tank is secured with polyurethane adhesive and polurethane foam.
 

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