(80/66cc) just bought a motorized bicycle.

use whatever will work, just to make sure the air is being filtered. I used a large hose clamp.
 
Links to eBay may include affiliate code. If you click on an eBay link and make a purchase, this forum may earn a small commission.
You'll probably have to work something out with a foam filter like jaguar suggested because I don't think you'll have room for the stock air filter. That's probably why there wasn't one on it when you bought it. It wouldn't fit so they took it off!
 
yes, turn it off whenever motor is not running - the carb float is supposed to turn flow off when carb is full, but often fails due to angle bike is at when on kickstand or hitting a bump while just pedaling - if not off, then the motor may fill up with fuel and be VERY hard to start again
 
Here is what your cylinder will look like if you ride without an air filter:

full


I was using the stock air filter but riding on sandy trails. The stock filter is not up to the task.
Here is what I am now running:
full


full


This is a plastic jar cap with a copper pipe glued into place with epoxy putty.
The plastic water bottle neck was heated in boiling water to make fit.
The foam is a kitchen "scrubbie". Make sure you can breath through it, some are more closed cell.
Notice the pipe is centered with the carb throat.

Also notice the twisted wire "clamps" on the fuel line. 2 wraps will keep it sealed tight.
full


Steve
 
Guess I better run an air filter:)

Ha! And a darned good one too!
Hey Frankfort, I'm still running this cylinder until it dies. What have I got to lose?
Although I do have a good filter on it now. Did about 50kms of dirt trail today, much of it deep fine sand.
Nice to have a good filter and the high torque head on to power through that stuff.
Jeff gave me the idea to bring the "High Torque" air filter (Perrier plasic water bottle!) along for these conditions.

Steve
 
I just ride on the road but they are back roads that are very dirty and bumpy. I need to rejet my bike so the only way I can get it not to 4 stroke is without the air filter...
 
I didn't realize the stock one did such a poor job. But I suspected it was crap at the very first so I cut up and glued together a lawnmower foam air filter because oiled foam is what I was used to from riding dirt bikes (motorcycles).

ps- Steve, my first bike was a Penton 125 which was kinda the forerunner to the KTM. (After that a Honda XL250, then a Husqvarna 125 that I raced about 10 times in Austin)
 
Yeah, I suspected the stock filter was crap too, but hey, "they gotta know what they are doing", run with it I figured.
Worse than a K&N. Never, ever use a K&N if you are running in the dirt, unless you are going to pull a serious filter over it.
I've been disappointed to find grit on the inside of my intake after using K&N.

Saying that, the gauze filters are probably fine for street use if well oiled. I'd like to hear some opinions.

The Penton is the grand-daddy of KTM. I took a long road to get here.
67 Honda Dream, 74 XL250, 74 CR250, 76 DT250, 78 XL500, 85 XT600, 87 DT200.
Owned a lot of short timers too, including a Kawi triple. Bought the EXC125 slightly used in 2000 and love it.
I have a 2003 300EXC but love the 125 for the ride. The 300 is actually lighter but feels heavier.
A friend of mine has a Huskie 125 (2000?) that I ride. Nice bike. My KTM has broader power but the Huskie feels lighter.

Good advice, ditch the stock foam. Install something better.

Steve
 
Back
Top