CV carb
Thread Starter
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Intermediate
Joined: Oct 2010
Posts: 33
Likes: 0
From: McAllen, Texas
CV carb
What do you suppose would cause my bike to run horrible in the morning then smooth as silk when warm. In the morning it has no acceleration, coughs and backfires. After about 15-20 minutes it smooths out. The choke is fine. Thanks for your input.
Grand HDF Member
Joined: Mar 2007
Posts: 4,920
Likes: 264
From: Deep in the heart of New Jersey
My wife's Sportster coughs and sneezes when cold,and has done it since it was new. My '96 doesn't do it too badly. But the key in cold weather is to let it warm up first. Or you can try leaving the choke on for a while when you ride.,
Ultimate HDF Member
Joined: Jun 2007
Posts: 9,193
Likes: 494
From: Richmond, VA
I agree with the above answers. I would check the mixture screw on the carb. Is it 2 1/2 turns out? If not I would open it up 2 1/2 to 3 turns. And in really cold weather its totally normal to have to run with the choke part way out for a solid 10 or more miles.
Tourer
Joined: Sep 2010
Posts: 471
Likes: 9
From: Far NorCal
What I have found in the winter is to leave the choke on until it closes on it's on, at least my Mikuni does. If not, like b-law said, 10+ miles.
Your problem is very common for cold blooded carb-evos, they like to be warm or hot.
Also, if you don't know it. Don't force the trans in gear when cold, pull the clutch in during your last part of warm-up (approx 30sec), it will then go into gear without any problems, saves your stuff too!
Your problem is very common for cold blooded carb-evos, they like to be warm or hot.
Also, if you don't know it. Don't force the trans in gear when cold, pull the clutch in during your last part of warm-up (approx 30sec), it will then go into gear without any problems, saves your stuff too!
Thread Starter
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Intermediate
Joined: Oct 2010
Posts: 33
Likes: 0
From: McAllen, Texas
Thanks for everyone's suggestions. Our temps done here, south Texas, aren't that cold. Our recent am temps have been in the 50's. The bike had been sitting awhile so I cleaned the main jet in the bowl. I noticed yesterday the plugs were badly fouled so replaced them and it's running like it should again. It must have been dumping a bunch of fuel. I'll see how the new plugs work out and keep you posted. You sure can't let these things sit.
Road Warrior
Joined: Sep 2006
Posts: 1,826
Likes: 87
From: Cookson, Ok
Thanks for all those reassurances. I've been following this thread. This is my first winter with the stock CV carb and had noticed the problem below 45 degrees. Mods to fatten things up are on their way.
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Stellar HDF Member
Joined: Apr 2009
Posts: 3,039
Likes: 11
From: Northern Ontario
My bike takes quite a while to warm up before it will run smooth even then its a couple miles down the ride before it runs smooth and even that depends what kind of mood its in, and my wifes sporty is about the same.
This winter I will be soaking both carbs in a carb cleaning solution, just because.
This winter I will be soaking both carbs in a carb cleaning solution, just because.
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Elite HDF Member
Joined: Sep 2007
Posts: 4,468
Likes: 12
From: Bluffton, South Carolina
If the "cold heartedness" is not caused by a vacuum leak, then try richening up the idle by turning the screw out to 2 1/2 turns as mentioned previously. If that fails to cure the problem then go one step richer with the low speed jet. While you are in there you might as well put the needle from non-accellerator pump sporty in as well. Sometimes in cold weather you can also get problems from having done modifications to the slide/slide spring that causes the slide to open sooner. Engines running in cold conditions do not like this until they are good and warm.
Running with the choke/enrichner out can cause an overly rich condition which could wash some of the lubrication from the cylinder walls causing premature ring wear. On a Mikuni it isn't as bad as the enrichment circuit shuts off as the throttle is applied. This does not happen with the CV, the enrichment circuit stays on. Hope this helps.
Running with the choke/enrichner out can cause an overly rich condition which could wash some of the lubrication from the cylinder walls causing premature ring wear. On a Mikuni it isn't as bad as the enrichment circuit shuts off as the throttle is applied. This does not happen with the CV, the enrichment circuit stays on. Hope this helps.
Stellar HDF Member
Joined: Apr 2009
Posts: 3,039
Likes: 11
From: Northern Ontario
If the "cold heartedness" is not caused by a vacuum leak, then try richening up the idle by turning the screw out to 2 1/2 turns as mentioned previously. If that fails to cure the problem then go one step richer with the low speed jet. While you are in there you might as well put the needle from non-accellerator pump sporty in as well. Sometimes in cold weather you can also get problems from having done modifications to the slide/slide spring that causes the slide to open sooner. Engines running in cold conditions do not like this until they are good and warm.
Running with the choke/enrichner out can cause an overly rich condition which could wash some of the lubrication from the cylinder walls causing premature ring wear. On a Mikuni it isn't as bad as the enrichment circuit shuts off as the throttle is applied. This does not happen with the CV, the enrichment circuit stays on. Hope this helps.
Running with the choke/enrichner out can cause an overly rich condition which could wash some of the lubrication from the cylinder walls causing premature ring wear. On a Mikuni it isn't as bad as the enrichment circuit shuts off as the throttle is applied. This does not happen with the CV, the enrichment circuit stays on. Hope this helps.