Triumphrat

10-11-2006, 05:10 AM

I am a first time motorcycle owner and I went with the Bonneville Black. I made the purchase in May '06. I really love it, but I have noticed that no matter the weather I usually need to extend the fuel heater switch. Also, I rode to work the other night, and for the return trip the temp. was in the low 40's. The Bonnie cranked and fired, but would immediately die. It took about 8 to 10 tries to get her fired up.
Also It seems when I am slowing and down shifting I will sometimes shift to the next lowest gear to start accelerating, and goose the throttle a bit, then I will get a weak backfire through the carbs.
I guess I'm just wondering if this is the norm.
:???:

caspianthruxton · 10-11-2006, 05:28 AM

every once and a while i will also get a small backfire when i clutch it and try and rev match. Anyone else get this?

Geoff · 10-11-2006, 06:08 AM

pardon my possible ignorance, but what is a fuel heater switch? where is it located?
personally, I have not heard of it
G

bgaz · 10-11-2006, 07:45 AM

On my bike, the carb heaters are automatic.
They are only designed to prevent icing.
Stock, the bikes are jetted lean to meet emissions standards, and that hurts the cold running and performance.

If you rejet, or at least adjust the pilot screws a turn out (richer) it should do much better.

I have the off road silencers, no airbox inlet snorkle, no air injection, and a dynojet kit, and other then to start the bike, the choke is off and the bike runs fine in the cold.

Brett

2522 · 10-11-2006, 09:47 AM

I think Roobsta is referring to the choke/fuel richen button. The stock Bonnies, as it has been mentioned, are jetted lean. This will cause poor cold weather performance,...at least until the engine is fully warmed up. Plus cold air is denser which would permit a richer fuel mixture at idle, to be appreciated. To help with your present trouble, use your choke almost all the way out and try turning your idle adjustment knob up 1/2 to 3/4 of a turn before trying to start when it's cold. This helps to keep it running until it becomes stable. (Don't use the throttle when starting) As it warms up while riding, push in your choke, in steps and then turn your idle back down as necessary for correct idle. I use this method in early spring and late fall,...OK, OK I do ride in winter, if the street is clear of ice and snow, but look at my address. 7 months of snow and 5 months of yard work.

[ This message was edited by: Jimi_X on 2006-10-11 07:50 ]

markbvt · 10-11-2006, 01:24 PM

Roobsta, this is completely normal behavior. Below about 50 degrees, I have to hit the starter button a number of times before the engine will stay running. And I need to keep the choke on full for half a minute or so while letting the bike warm up, and then on half-choke for the first mile or two I ride.

I don't have the backfire issue you've mentioned. Are you sure it's actually backfiring through the carbs, and not simply popping from the exhaust the way nearly all stock Bonnies do? My guess is that it's just exhaust popping, which is due to unburned fuel combusting in the exhaust headers (caused primarily by the air injection system -- remove the AI and you'll notice far less popping).

--mark

caspianthruxton · 10-11-2006, 05:11 PM

I have removed my AI and i only have the problem when i pull the clutch in and give it a little bit of gas to match the revs up. it chokes itself out for a second and then it's fine.

bonnieblackinfl · 10-11-2006, 06:09 PM

In the HD world we call that a "carb fart". Do as suggested and counter clockwise on the pilot screws 1/2 a turn.

Greg

caspianthruxton · 10-11-2006, 06:20 PM

sounds good. thanks!

merlin · 10-11-2006, 08:35 PM

The carbs don't have chokes in the traditional sense of a butterfly that chokes off most of the air supply, thereby enrichening the mix. Instead, the 'choke' is actually an enrichening circuit that feeds lots of fuel into the airflow. The relevant point to this though is that any opening of the throttle causes the enrichening circuit to be bypassed, thus defeating it and you suddenly have no 'choke' at all and the engine dies. (The term 'circuit' is used to descibe the routing or piping of the fuel, no electrics involved in this)
So stay off the throttle when starting with 'choke' on.