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Discussion Starter #1
Has anyone who has re-jetted the pilot jet (after market exhausts etc) found that it aided with the T100 cold start issue?
 

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yes, for me it did. Switching to 42 pilots and backing the mixture screws out helped my Bon with cold starts. She still doesn't like the cold but much better now than the overly-lean stock set-up.

Happiness is a warm Bonne.:D
 

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Yes, it helped me, too. Still not the easiest to start when 40F or below, but a significant improvement. Also helps to be sure that the carbs are properly balanced.
 

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Discussion Starter #4
Cold start blues - or air blue at cold start!

Yes, it helped me, too. Still not the easiest to start when 40F or below, but a significant improvement. Also helps to be sure that the carbs are properly balanced.
I have the carbs balanced. I am starting at 30 degree at 1000 feet. Spark plug looks a nice light brown at a few different rev ranges.

The cold start thing has me a bit perplexed. My KLR will start first pop! The Bonny has to be cajoled and fussed with - almost like a garage queen!

I did pop the caps to the mixture screws and played with that. The after burner has been removed.

Any input is germane.
 

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I am somewhat puzzled by the cold start issues some report with Bonnevilles. I am on my second 2007 and not a problem with either. Choke, button, motor starts. Maybe I am just lucky?
It makes me think that it is not the nature of the model but some undiagnosed problem with the bikes that start with difficulty.
Even my old Triumph start fairly easily in the cold - as long as the points and plugs were good. I'd tickle the carbs till fuel poured out, a few key off kicks to get some fuel in the cylinders, a bit more tickle and away it'd go.
I think I'd be doing some close looking at a new Bonneville that won't start at 30 degrees.
 

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cold start

My bike was displaying the cold start issue. The solution that works for me is, I open the petcock, straddle the bike, lean it over to the right to fill the right side carb bowl, I will hold it here for 20-30 seconds, then hit the starter and it fires right up.

I bet the people that have and use the center stand have fewer cold start problems than those of us that do not.
 

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I have found 2 problems which cause the bike to be hard to start. Check your breather hose that comes out the rear of the carbs. is not blocked, this will cause a vacum and not allow the carbs. to get enough fuel. Also check the seals on the enrichener circuit are staying in place when you pull the "choke", mine were coming out with the plunger allowing air in the carb. actualy making it run leaner with the "choke" pulled.
;)
 

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I've been following various threads on this issue. It just HAS to be something maybe like amanger says. If I had not read these threads I'd be thinking that all new Bonnevilles started great in the cold. Yesterday it was 29°F when I started for work. Full choke, one push on the starter and starts right up. That's on the '05 T100. It has 112.5 main jets and the rest is stock. My son's '07 T100 starts very well too in the cold. It has TORS but I am not sure of the jetting.

I'm very curious what is going on with the others who have troubles.
 

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My 2007 T100 was hard to start when I picked it up in April. I brought it back to the dealer and they played around with the carbs. Picked it up and they told me that it starts without the choke. I won't get into all the details but after all summer of having it start on the first hit of the starter I decided to pull the plugs in September. The right plug looked fine. The left one looked like it came out of the bottom of a coal mine, couldn't be any blacker. Had to turn in that screw 1 1/2 turns to get it to where I was happy with the performance. Unfortunatly it is back to hard starting. But it does run much better. Going to update pipes and jetting. Then go on a dyno to get dialed in.

Mike
 

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There is no reason in the world that a Bonnie with properly adjusted carbs won't start right up on choke in cold weather, unless something else is wrong, such as a vacuum leak.
 

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I am somewhat puzzled by the cold start issues some report with Bonnevilles. I am on my second 2007 and not a problem with either. Choke, button, motor starts. Maybe I am just lucky?
It makes me think that it is not the nature of the model but some undiagnosed problem with the bikes that start with difficulty.
Even my old Triumph start fairly easily in the cold - as long as the points and plugs were good. I'd tickle the carbs till fuel poured out, a few key off kicks to get some fuel in the cylinders, a bit more tickle and away it'd go.
I think I'd be doing some close looking at a new Bonneville that won't start at 30 degrees.

Apparently they have corrected the cold start problem on the newer Bonnies.
Mine is an 2002, 790, T100, I bought it new and was there when it was started for the first time, it was hard to start then (cold) and it’s never changed.
The early Bonnies came out of the factory set VERY LEAN to satisfy the EPA requirements.
I just ordered new jets and I’m sure that will remedy the problem.
 

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It shouldn t matter how lean the bike is jetted as soon as you pull that enrichener (choke) lever the bike should start.
It doesn t work like a normal choke (reducing the amount of air available,thus richening the mixture) it actual opens a passage directly from your fuel bowl to a jet on the inlet side of the carb. so it squirts unmixed fuel directly into the manifold.
Remove your carbs and check that when you pull the "enrichener" both slides move with the lever and that the rubber boots on the carbs. dont move with the slides. These boots are only pushed into place and dislodge easily allowing air into the enrichening circuit.
;)
 

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Mine was slow to start in cooler weather from stock. It started much easier after I re-configured filter, silencers, main jets, needles, and mixture screws as listed in my signature, a nice fringe benefit of the project.
 

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Taming of the Hard-Startin' Shrew

My 07 was a hard-starter when I got it. It had Predator pipes and the AI removed, but no jetting changes, so it was way lean. After I chopped the airbox, installed the UNI pods and rejetted, it starts much easier, even cold with the "choke" pulled.

IMHO: If it don't like to start, it's most likely running lean. Back the mixture screws out til the warm engine starts on the first spin with no throttle applied. If about 3.5 turns don't get it, go to the next size larger pilot jet and do 'er again. Amanger's dead right about those choke seal things; check em.

'07 BB. Preds, big-ass Uni pods, 150/42, two shims, 3 turns.
 

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Discussion Starter #15
It shouldn t matter how lean the bike is jetted as soon as you pull that enrichener (choke) lever the bike should start.
It doesn t work like a normal choke (reducing the amount of air available,thus richening the mixture) it actual opens a passage directly from your fuel bowl to a jet on the inlet side of the carb. so it squirts unmixed fuel directly into the manifold.
Remove your carbs and check that when you pull the "enrichener" both slides move with the lever and that the rubber boots on the carbs. dont move with the slides. These boots are only pushed into place and dislodge easily allowing air into the enrichening circuit.
;)
I think that this is how I will spend my time. I like the look of the color of the spark plugs - telling me the mixture is right at the moment. The bike has never liked the cold (as cold as it gets in California!)
I didn't know about the boot.
Thanks for your help!
 
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