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Discussion Starter #1
Hey guys. Need help with a 2003 bonnie that's real hard to start with a cold engine. Uni air filter, slip on pipes, at sea level. I put larger 130 main jets and 42 pilot jets. When it finally starts it runs great. Once the engine is warm it fires up real easy. Please help!
 

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Yes, they're hard to start in colder weather. Use the "choke" properly, and never give it throttle while you're turning it over. That will kill it immediately.

I've found that sometimes I need to set the "choke" at a bit less than fully pulled out to get it to start, but I rarely ride it when it's less than 60F outside, so I can't really speak to weather colder than that.

Someone who knows more than I might be able to comment on your carb settings. I know that at the stock settings, they're notoriously lean and difficult to start when cold, but that doesn't apply to you.
 

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I ran 140 mains with every thing else stock in my 05 T100. Also at sea level with slipons and pod air filters. I would use the choke if the bike was cold, even in summer. Also check your spark plugs.
 

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Discussion Starter #4
Hey guys. Need help with a 2003 bonnie that's real hard to start with a cold engine. Uni air filter, slip on pipes, at sea level. I put larger 130 main jets and 42 pilot jets. When it finally starts it runs great. Once the engine is warm it fires up real easy. Please help!
Replaced with brand new plugs and just did a thorough carb clean. Its intermittent some times which is confusing. Some times it starts right up. Most times its temperamental. Makes me think its float related maybe? Also has 3 needle spacers. Would that effect the hard start condition?
 

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That seems a lot of shims on the needle. Check the needle part numbers too. FWIW most 790cc engi es do not require other than the standard 40 pilot jet.
 

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That seems a lot of shims on the needle. Check the needle part numbers too. FWIW most 790cc engi es do not require other than the standard 40 pilot jet.
I have to disagree on the "standard 40 pilot jet" comment. I think most everyone including myself found going to a 42 pilot improved cold starting and off idle smooth acceleration immensely. They are to lean from the factory.
 

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42 for mine with Thrux needles choke out even on warm days when cold. Only takes maybe 30 sec. before I can reduce the amount of choke and can pull away. Really cold (like 40's and below) I run a little choke for a few miles then full in.
 
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Discussion Starter #8
Thanks for the feedback guys. We'll here's what I noticed. If I open up the throttle it starts easier. What does that mean? Slide being up lets more air in? Or it gives it more fuel? I swapped oily uni filter for stock paper air filter. Not sure if its helped it or not. Help!
 

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Try adjusting the fuel / air screws in [ CW] 1/4 to 1/2 turn at a time and see if that helps or hurts. Also a carb balance should be done to ascertain that both carbs are bringing in the same amount of air and not fighting each other.
 

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take one needle shim out and try it. If it improves but needs a bit more to be right, take out another shim. 3 shims is a bit much. Go slowly, a step at a time. Throwing too many changes at once confuses the situation to the point that you can't tell what's making improvement or not.
 
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