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Old 14-10-12, 08:44 PM   #1
Goodfella
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Default Curvy cold starting trouble.

My SV650n (2000) has been fine starting up in the morning for the last few months since I bought it but now the weather is getting cold it's struggling. it will actually fire up ok (battery is new) but then it ticks over for say 5 seconds (lumpy, slow struggling sound) then cut out, I start it again, will run for a bit longer then cut out. By the third time it usually stays running and all is well and good.

Just asking if this is perfectly normal for a bike of this age (non FI) as I was so used to my 2009 DR125sm which was fuel injection and always started first time and stayed running first time, even in the harshest conditions.

Choke doesn't help as it refuses to start at all if I use it.

Just worried that this will get even worse and not start at all when it gets really cold in December/Jan.

Last edited by Goodfella; 14-10-12 at 08:52 PM.
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Old 14-10-12, 10:00 PM   #2
embee
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Default Re: Cold Starting

Cold starts (properly cold) should need choke, if it'll start without choke it's running richer than it should be. The choke is there purely for cold starting, it's not an ornament.

The main thing with the curvy is to make absolutely sure the choke cables and plungers are working properly. The only way you can be really sure of this is to take the plungers out of the carbs and check the cleanliness, that the springs are not broken, and the cables are free and well lubed.
The rear carb is easily accessible, the front one isn't and the only successful way to get to it is to take the carbs off, not a big job.

When starting from cold, apply full choke and DO NOT TOUCH THE THROTTLE. This is important. If you use the throttle when using full choke it will mess up the fuelling and then becomes a pig to start.

Full choke, no throttle, short prod on the starter usually gets it firing but as often as not it will stall after a second or 2. This is because the fuel in the float bowls tends to evaporate when parked up hot. The idle circuit and choke will have enough fuel to run it for a second or 2, but the fuel pump takes a touch longer to refill the carbs fully. This is perfectly normal.

Once started leave the throttle alone, and ease off the choke gradually as much as you can while keeping the engine running smoothly. Don't leave it idling to warm up, just ride off as soon as you can reasonably gently and get the choke off fully as soon as possible. Make sure your hot idle is adjusted to around 1300rpm, some people prefer it slightly higher, 1400 say.
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Old 15-10-12, 06:36 AM   #3
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Default Re: Curvy cold starting trouble.

Thanks a lot embee, very useful.

I'm assuming it's not 'properly cold' yet, as I said in my first post full choke on and the bike refuses to start at all. Or is that something to be concerned about, should it start with choke on regardless of the weather temp?

Sorry, I don't really have any experience with non FI bikes.

Last edited by Goodfella; 15-10-12 at 06:37 AM.
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Old 15-10-12, 10:12 AM   #4
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Default Re: Curvy cold starting trouble.

As embee says I think you may want to take a look at your choke plungers, springs and cables. From cold even in summer you should need full choke to get it started, mine will not fire up without it.
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Old 15-10-12, 10:25 AM   #5
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Default Re: Curvy cold starting trouble.

"choke is purely for cold startng" is with regard to engine temperature, not weather. it helps starting even in summer, so bike refusing to start at all actually is something to be concerned about.
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Old 15-10-12, 11:30 AM   #6
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Default Re: Curvy cold starting trouble.

Well for example, I got up at 8am this morning started her up (without choke) just fine but then cuts out after a little while. Like I said 3 or 4 attempts and it's good to go. With choke on it wouldn't start.

Now, the bike has been resting since 9am. I have just tried it with the choke on full (midday - so it's been resting for 3 hours) and it started just fine. How odd. So it won't start with the choke on when it's left overnight but it will start with the choke on a few hours later after riding it.
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Old 15-10-12, 12:40 PM   #7
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Default Re: Curvy cold starting trouble.

When cold use super unleaded. Sorted (usually)
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Old 25-11-12, 12:51 AM   #8
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Default Re: Curvy cold starting trouble.

i know this is a late reply. i'm new :P
i had the exact same problem with my curvy, sorted out the chokes (one was corroded) that fixed it for a couple months.
applying the choke just made the engine cut, checked the mixture and plugs all was well, whatever, i continue to ride it as its my only form of transport so i had no time to take it off the road.
Now i've come off on some mud i have the opportuity to do a complete overhall, plus it refuses to run under load and wont rev past 4000 in gear. strange.

i've stripped and cleaned the carbs (again), and have discovered my engine is running cold and i've never heard the fan running on my radiator so i did a quick check with that it works fine, so last option is of course the thermostat, i'm going to replace that and hopefully all will be well and curvy will be back up and running. i shall let you know the outcome!

also i find that 99 octane makes the curvy run sluggish because it's not tuned for it, the only way to really make the most out of it is to take it for a dyno jet.
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Old 27-11-12, 05:03 PM   #9
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Default Re: Curvy cold starting trouble.

Quote:
Originally Posted by Goodfella View Post
Thanks a lot embee, very useful.

I'm assuming it's not 'properly cold' yet, as I said in my first post full choke on and the bike refuses to start at all. Or is that something to be concerned about, should it start with choke on regardless of the weather temp?

Sorry, I don't really have any experience with non FI bikes.

I often have the very same problem in the cold, but i tend to find if i only pull the choke halfway it starts and runs fine
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Old 27-11-12, 08:18 PM   #10
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Default Re: Curvy cold starting trouble.

Quote:
Originally Posted by LMThompson View Post

also i find that 99 octane makes the curvy run sluggish because it's not tuned for it, .
Really? had to use tesco super unleaded on my old curvy this time of year until about feb/march time due to carb icing. ran a treat with that in the tank.
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