runs better with air filter off?

[KC Roy]

hey guys thanks for all the good info on this site. i've put together my first motorized bike a couple weeks ago. breaking it in and tweaking things here and there. it runs pretty nice but seems to cut out or surge/bog down a bit when i get going at the high end. it idles great, will rev just fine with the clutch in. i just wonder if hauling my 200 lb carcass is giving the 66cc's a run for the money? i do have to pedal up the steep hills to help the engine out. well i replaced the plug and put a nicer wire and boot on as well. today i took off the air filter (NT carb) just to experiment, and noticed an unusual amount of fuel oil in the sponge and coming out those breather holes. (i realize those sponges are lightly oiled, but this sucker looks like fuel regurgitated out of the carb).

well i took it for a spin without the filter to see how it ran and it ran much better. quicker response, less bogging and seemed to even perform better. that being said, is my fuel air mixture too rich? thoughts? logically i am thinking no filter is more air, so that's why i wonder if the air/fuel mix is the next thing to monkey with.

 

[Nashville Kat]

Maybe just a bit oily- but better that than not, at first. Probably not the reason for the bogging- most stock carb bogging can be cured by using a short intake, depending on the angle your motor is already at. Anyyway- it's a cure for under $20 I've always used since the billet intake was introduced years back, and there was big discussion about bogging before that.

Larger carbs are also much cheaper these days, but I've never used one. Make sure that clutch lever is down- they do get knocked on sometimes.

 

[Venice Motor Bikes]

Hi,
It's totally normal for the filter to be wet with oil.

Yes, you need to help the engine by pedaling up hill (& also pedal whenever you're taking off from a dead stop).

Your carb jetting is a little rich (but that's a good thing for now) because it's a new engine... You'll find that the more the engine breaks in, the better it's going to run.

By the time the engine is fully broken in, it might not even need re-jetting.

 

[crassius]

at 200# with a 44T sprocket, most hills should be doable without peddling, if you got stuck with a 36T sprocket, peddling will be needed a LOT (and your motor will never get over about 1/2 revs)

for tuning. I always recommend starting with things that can be undone easily like changing needle notch setting and float level height to see which way works better - only after that tells you something, should you start changing jets

 

[KC Roy]

View attachment 98594 Maybe just a bit oily- but better that than not, at first. Probably not the reason for the bogging- most stock carb bogging can be cured by using a short intake, depending on the angle your motor is already at. Anyyway- it's a cure for under $20 I've always used since the billet intake was introduced years back, and there was big discussion about bogging before that.

Larger carbs are also much cheaper these days, but I've never used one. Make sure that clutch lever is down- they do get knocked on sometimes.

good suggestion, i never thought of the intake being shorter. i did have to reset the clutch i think that is okay. in fact that was how i obtained the engine free from a buddy. he said he couldn't start it....he said it was electrical, i immediately discovered it wasn't cranking when you popped the clutch lever. once it fired i took it off his bike gave him the bike back and put it on a cruiser.

 

[KC Roy]

Hi,
It's totally normal for the filter to be wet with oil.

Yes, you need to help the engine by pedaling up hill (& also pedal whenever you're taking off from a dead stop).

Your carb jetting is a little rich (but that's a good thing for now) because it's a new engine... You'll find that the more the engine breaks in, the better it's going to run.

By the time the engine is fully broken in, it might not even need re-jetting.

i am glad it is running rich because i was doing 50:1 oil for prob 1/2 tank before i realized i should probably check that mixture. i had gotten lazy with my 2 cycle stuff over the years, more and more i read 50:1 is fine for most engines. yikes, i sweetened the mix after reading a bit on what you guys use to break in and operate with.

 

[KC Roy]

at 200# with a 44T sprocket, most hills should be doable without peddling, if you got stuck with a 36T sprocket, peddling will be needed a LOT (and your motor will never get over about 1/2 revs)

for tuning. I always recommend starting with things that can be undone easily like changing needle notch setting and float level height to see which way works better - only after that tells you something, should you start changing jets

ah good suggestions too, i will count the teeth and see what i am dealing with.