Topic: Cutting out in windy conditions

[Dave Wyatt]

I was out on the Hondamatic yesterday and it was quite windy.  When heading west with a cross wind out of the south, the bike would cut out from time to time.  This is not the first time, but yesterday was the worst.  In the past it was bad under similar conditions with my feet on the highway pegs.  I could put my feet back on the stock pegs and it would clear up.  I have since removed the highway pegs and was surprised when this happened.  The bike has the stock airbox and filter set up.  I have tried moving the wires around, but nothing happened.  That narrows it down to airflow.  I did notice it a couple times heading east, but not nearly as bad.  Any ideas?

[Jay B]

Check the connections between the spark plug caps and plug wires.  Sometimes it's necessary to unscrew the caps from the wires and cut 1/4" or so off them and screw the caps back on to get good contact. Maybe the wind is jiggling them around and loosing contact.

[TwoTired]

I think I would inspect all the fuel vents and overflow tubes for blockage/restriction.  Seems logical that wind currents are either reducing the pressure in the fuel tank, reducing outflow of fuel.  Or, pressure changes in the carb bowl chambers are effecting flow from the carbs jets.

1 - Fuel tank cap vent
2 - Carb bowl vents
3 - The overflow tubes, too as they behave as vents when the carbs aren't overflowing.

Examine the above tube routing.  Are the exits it in the stock location?

Have you had the oportunity to pull the spark plugs (plug chop), preferably while the event is occurring?  Might be some evidence of what is occurring in those plug deposits.

Cheers,

Oh, and the simple things.  When was the filter last cleaned, and when was it last replaced?

[dusterdude]

if your are running pods thats it,mine does the same thing

[red8657]

I run pods on my CM400, and with my feet on the highway pegs, it will cut out like crazy.  It creates a vacuum somehow, IMHO.     I don't find the highway pegs comfortable for me at 5'8", so I haven't cared enough to find a fix. 

[Dave Wyatt]

Stock air filter and box, no pods.  The filter is in good shape, I had it out at the end of last season to check it.  I didn't stop along the road and pull the plugs, but if nothing else checks out, I'll take a look.  I'll also take a look a the vent hoses and see if I can find anything out of place.  Everything is where it's suppose to be, best I can tell.  It ran like a beast north and south, but the air blowing in the left side created havoc.

[TwoTired]

The filter is in good shape, I had it out at the end of last season to check it.  I didn't stop along the road and pull the plugs, but if nothing else checks out, I'll take a look.  I'll also take a look a the vent hoses and see if I can find anything out of place.  Everything is where it's suppose to be, best I can tell.  It ran like a beast north and south, but the air blowing in the left side created havoc.

Perhaps no direct bearing on your current issue.  But, the stock filter will not last indefinitely.  With use, it gets more and more restrictive as it traps particles that just can't be cleared with the compressed air blast normally used for cleaning.  The maintenance schedule for the filter is clean at 3000 miles of use and replace at 6000 miles of use for this reason.  A very dirty air filter is easy to observe, but a restrictive filter is much less obvious.  I put a strong light on the inside of both a used and new filter which made it more obvious that although cleaned, the used one still had more discoloration and was significantly darker than the new one.

How could a restrictive filter cause your problem?  Well, gas will ignite when mixed with air in ratios of 10:1 to 20:1, with 14.7:1 being ideal in a perfect engine.  If we assume this is what is provided with a new filter, then as the filter becomes more restrictive, the ratio increases.  At some point, there will be too much fuel to sustain combustion.
The carburetors are effected by barometric pressure, too.  High and low pressure weather patterns effect mixture delivery.  Crosswinds can effect barometric pressure in microclimates (also called turbulence) around various parts of the motorcycle.  When this occurs at your carb vent inlets or the air filter inlet, fuel delivery mixtures are effected and may exceed the range that can support combustion and may be exacerbated by a restrictive air filter.

The hoses can be plugged up by insects making homes in the tubes.  Some plug the ends with mud.  Others crawl in and spin a nest from their own secretions.  What ever you do, don't blow crud into the ends of your carburetor vent tubes, unless you enjoy cleaning carburetor innards.  Disconnect each one and blow from the carb end.

Was the cut out you experience coupled with some engine burbling, or was it more like a wheeze or as though the ignition was temporarily cut?

Cheers,

[Dave Wyatt]

It was more of a burbling.  Like a cylinder or two laying down.  Due to other activities and crappy weather, I didn't get a chance to work with it this weekend.

At one point I was wondering if the wind was sucking the fuel out of the float bowels via the vent tubes, if so, that's an easy fix.  I'll try a new air filter while I'm at it, even though I hate to take that air box apart.

[Dave Wyatt]

I think I found the problem.  The left hand boot from the carb to the airbox was not sitting right.  Last year I had the carbs off and when I put everything back together, I did not get the airbox in the correct position.  It had swung back a little and was not letting that one boot seat in the hole correctly.  This may explain the cylinder dropping when riding in the rain too. 

After I loosended and repositioned the airbox, I took the air hose and tried blowing air in araound that boot while I held the throttle open.  The engine did not stumble.  Unfortunately, I have not ridden it in a good sidewind yet, nor a rain.  Time will tell if this fixed the problem.