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View Full Version : 85 125M Runs great with air box lid off.



BrianD
10-08-2012, 05:51 PM
My 85 125m runs great when I take the air box lid off. With the lid on, it just bogs out and will not run other than at idle. It does have a new carb, but did the exact same thing with the old one. Is this simply a air flow issue? The air tube looks ok. Or is this maybe a engine issue? Really need some help here. Thanks.

Keepah Rolln
10-08-2012, 06:09 PM
Does your black air tube connect to your frame? Look inside with a flashlight. maybe something got in there and plugged it up. Check your compression. Maybe a choke problem also...

tri again
10-09-2012, 02:31 AM
My 125m frame was full of hazlenut shells and
stuffing from the seat.
See where your airbox gets it's air from the outside world and work backwards.
Mice just love 'em.

BR air intake is up under that gas tank.
I've seen those plugged beyond belief too.

BrianD
10-09-2012, 06:58 PM
I looked inside the air tube with the box off and it is clear. The choke also works fine. I also adjusted the valves and checked the timing with no changes. Any other ideas??

Keepah Rolln
10-09-2012, 09:31 PM
I looked inside the air tube with the box off and it is clear. The choke also works fine. I also adjusted the valves and checked the timing with no changes. Any other ideas??

Double check your carb. Jet or somethings worn and possibly causing you to get to much gas or something...Did you notice gas in your airbox before?

BrianD
10-11-2012, 03:38 AM
No gas in the airbox. The carb is new. I had the exact problem with the old carb. I rebuilt the old carb and even switched it back with no change.

tri again
10-11-2012, 03:47 AM
No gas in the airbox. The carb is new. I had the exact problem with the old carb. I rebuilt the old carb and even switched it back with no change.

Are you sure the inside of the actualy pressed steel frame of the trike isn't plugged with
a nest of some sort? Bees, mice, squirrel etc.
I think the airbox sucks air from the inside of the frame.

Seems odd that the lid blocks off the airflow somehow, but I guess that's
why we're both posting.
Any chance putting the lid on flips the choke on somehow?
or sucks up a clump of leaves stuck inside the frame?
Just grasping at straws here but we all know that kind of frustration.

Just rethinking, of all the different honda's we have, seems like some want the choke lever up and some down and the gas on/off is different on all of them too.

Any chance it's running fine with the choke on and the airbox just makes it richer?
Is there an air filter on it?
My 90-110's don't seem to care if they have an aircleaner on them or not, running wise.


I remember someone sprayed my uncle's air filter with clear shellac.
Messed him up for days.

fabiodriven
10-11-2012, 08:02 AM
I bet the frame is plugged.

BrianD
10-11-2012, 03:47 PM
I will check the frame tube again. I will let you guys know what I find. Thanks.

tri again
10-11-2012, 04:03 PM
As always, it's not uncommon for absurd stuff to fool with the greatest of plans.

Is there any chance putting the airbox lid happens to stress some electrical connection somehow making it run lousy?
OR the cosmic timing of your procedures just HAPPENS to correlate with the gas tank
vent creating a vacuum and not letting gas flow at the exact wrong time?

Stranger things have been known to happen.
I have one helper here that always grabs the kill switch side of the handle bars when
he tries to pull start a 90, and of course, it won't start.

I also just had a 90 the other day that would not rev, no way no how
but it started instantly. and would kinda wanna rev with the choke on.
Of course, i took the carb apart (again) and that wasn't it.

I nipped the last tiny bit off the coil wire so it had some fresh copper for
the spark plug cap to screw into and viola'!
starts and runs like a dream
(but still aggraviting)

Jon Boy
10-11-2012, 05:31 PM
I looked inside the air tube with the box off and it is clear.

gotta agree with the tri and fab. how are you able to look in that tube? it makes a hard 90deg bend inside the frame and runs up under the tank area just after the headtube. i'm thinking you might be looking up the wrong tube maybe? :beer

btw: i have an old metal coat hanger with a sock twisted onto one end with the hanger wire itself just for cleaning and keeping mine clear. might try something along those lines, just don't lose the sock or rag in there if you use one. don't ask. :lol:

swampthang
10-11-2012, 06:10 PM
gotta agree with the tri and fab. how are you able to look in that tube? it makes a hard 90deg bend inside the frame and runs up under the tank area just after the headtube. i'm thinking you might be looking up the wrong tube maybe? :beer

btw: i have an old metal coat hanger with a sock twisted onto one end with the hanger wire itself just for cleaning and keeping mine clear. might try something along those lines, just don't lose the sock or rag in there if you use one. don't ask. :lol:

Jon Boy you can't use the long wool tube socks in the 125's got to use the low cut crew socks.:lol: JK

As everyone has said check that air intake in the frame GOOD. I once got a smokin deal on a 200 that ran like crap. 5 seconds with the air blower and the mud dopper nest where history from the intake. It ended up being one of the best running bikes I've had. Now when I get a new machine thats the first thing I do.

dustrunner
10-11-2012, 06:34 PM
my big red had the same problen. nuts in the frame and i couldnt blow them out and ended up drilling a bunch of holes in the lid. good luck...

tri again
10-12-2012, 05:07 AM
my big red had the same problen. nuts in the frame and i couldnt blow them out and ended up drilling a bunch of holes in the lid. good luck...

I wondr if you flipped the trike over and filled the frame with water if the nuts would float out.?

Now they say that fabric softener dryer sheets keep mice away too.
I know I hate 'em.
They choke up my throat.

Maybe we should make air filters outta that stuff.

BrianD
10-16-2012, 05:45 PM
Well I checked the air tube inside the frame with a plumbers camera snake so I can rule it out as the issue 100%. I could see carbon build up inside the exhaust tip to the baffle using the camera, so I removed the exhaust and blew it out with compressed air. I got a ton crap out. I will take it out tonight for a run and see what happens.