Air filter By mthomas (Read 1,594 times)

[mthomas]

Hey JR,
Since you are the expert on 250's, my Duke does not have air filter and I am gonna order one, what should I expect as far as performance gains. I am more familiar with 2 strokes.

[JR]

Hey MT where ya been? Have you been yakking at that other place?

Ok here is your filter;

.ebay.com/itm/54mm-Air-Filter-for-HONDA-CN250-HELIX-Scooter-CF-250cc-Moped-Go-Karts-Cart-Buggy-/180874627084?pt=Motorcycles_Parts_Accessories&hash=item2a1cf7c80c&vxp=mtr" rel="nofollow" target="_blank">.ebay.com/itm/54mm-Air-Filter-for-HONDA-CN250-HELIX-Scooter-CF-250cc-Moped-Go-Karts-Cart-Buggy-/180874627084?pt=Motorcycles_Parts_Accessories&hash=item2a1cf7c80c&vxp=mtr

Now since you've been running without one you'll probably experience a performance loss unless you adjusted the carb to compensate for the extra air with no filter? So when you put the filter on if you made no adjustments you should have a better air/fuel mix and may notice the scooter running a little cooler.

It all depends on if you did or didn't adjust it with no filter? How long have you been running it like this? Hope it wasn't really dusty and dirty? Dirt doesn't do the rings any good.

More air equal leaner equal more power equal more heat. Let's see how she acts when you put the filter on?

JR

[mthomas]

Really have not been yakking anywhere, just working on mopeds. I just got the scoot out the other day since riding season is here. There has never been an element in the airbox since I owned the bike. I did set the carb a while back and I think it was 2 1/2 turns out. I can tell you the exhaust always seemed rich to me so I am sure I will need to readjust after putting the element in. While I was riding yesterday, I noticed a slight hesitation under load, kind of reminded me of the 150 when I had an airleak in the snorkel hose. Also a little disappointed in the performance as the bike tops out about 55-60 according to the Chinamometer and a big hill near me would only go 35-40, so I figure the element is the issue.

[JR]

Don't think so MT? 2-1/2 turns is generally the sweet spot on this carb give or take a touch. With no air filter it would not make sense you are rich but with the extra air you should be lean. That scooter should easily hit 65 to 70 on the Chinameter.

Sounds like a partially clogged high speed jet and/or a vacuum leak.

JR

[mthomas]

I was thinking the same, if it smells rich, it should be worse with the element. I guess it is time for a good carb cleaninig, I will also have to check for leaks....always fun.

[alleyoop]

Yep, that sucker should be Cruiseing 60+ with some left over. Your currently runnning like a 150.
If your smelling gas your way to rich that probably is why your power is way down. Have you up jetted the carb or anything? Also when was the last time you adjusted the valves. Those will also make you loose a lot of power.

Before adjusting the Carb I would adjust the Valves then adjust the Carb otherwise you wind Compensating the tight Valves with Carb adjustments. Then if you adjust the Valves after you adjust the carb you will wind up re-adjusting the carb. So doing them in the right order saves you some re-doing.
Alleyoop

[mthomas]

Alley,
I adjusted the valves about a month ago. Big difference between this and my 150, I did it more by feel because I could not hear any clicking of valves so I just loosened them up a bit. Really though, same performance as last year prior to the valve adjustment. I have not done anything to the carb other than cleaning it last year. It also hesitated and almost like backfired on me. I also went for about a 20 mile ride tonight and opened it up an a stretch and barely 60 mph. Although...the wife did go for a short ride with me and yelled when I hit 40...kinda like my own radar detector.

[cruiser]

It sounds like there may something else going on besides a missing air cleaner. It should be running very lean especially at higher speeds.

You said it seems to be running rich? Unless the main jet was changed to make up for the lean running with out the air filter, and it is too large, then it will really be running over rich with the air filter.

Maybe the air filter was removed because the scoot was running too rich to start with? Did you check to make sure the auto enricher is connected and operating OK? If not, you will be rich all the time.

[richardthescooter3]

mthomas, I had trouble with my recently lossing power at 50+ got checking and found out the clamp from carb to air box was bad, changed both intake and air box, running good now, still rough idle, would the bad auto enricher cause a rough idle?
Hope you fine the problem

[mthomas]

I would love to be, "rich" anytime.
The choke was hooked up the last time I cleaned the carb. What would the stock jet be? I will have to pull the carb and check. The PO barely knew how to tie his shoes, I would be SHOCKED if he changed the jet.

[mthomas]

OK guys...I was TOTALLY wrongo. There is an element in the air box and it looks like new, clean and free flowing. All the hoses are hooked up and I cleaned the carb. It was clean as a whistle but I pulled out all the screws and sprayed with cleaner. I also cleaned both jets with wire and one was #38 and one was #110. Put the carb back in and got it started. I also checked the unreachable air/fuel screw and it was 2 1/2 turns so I put it back the same. I did not take it for a ride because it has been raining all day, maybe tomorrow. It still smelled rich to me while it was sitting there idling. What else should I be looking for if there is no performance gain.

[JR]

You didn't mention if you tested the autochoke? If it has no power or is shot then it's going to be rich all the time.

Since you cleaned the carb I'll rule out stuck but again the question is does it even work?

Need to ride her and see how it responds. Also how many miles on her and have you ever adjusted the valves?

JR

[mthomas]

OK to check the choke. pull it out and turn the key on, wait a few minutes and see if the plunger withdrawls...correct?

I also adjusted the valves a few weeks ago. There was no valve clatter so I just backed them off a bit, loosened the bolt and moved the lever counterclockwise a bit.

[JR]

Nope the autochokes are normally non-functional without the engine running. 99% of the time they tie into the AC on the stator and are not wired to the 12Vdc with the key on. Simply pull it out unplug it and hook it up to any 12VDc battery and watch to see if the needle slowy extends and it should get warm. It will only extend aroung 1/8 to 3/16" .

jr

[mthomas]

Checked the choke today. Pulled it out, plugged the hole with a rag, started the bike and let it run for about 5 minutes and it extended about 1/4 inch so it is good. I adjusted the valves again this time letting the motor warm up to operating temperature and they needed a bit but were close. I pulled the plug and it was black which idicates a rich setting so I tightened up the A/F screw about 1/2 a turn. Put the snorkle back on and took it for a short spin as it is only in the low 60's today but seemed to be better. Gave it wide throttle and no hesitation or backfire. I will try it for a little longer run soon, oh and the exhaust did not seem so rich.