sv659 curvy idle issues

Hi, iv had problems with my girlfriends curvy. bought it around a year ago and it wasnt looked after, when warm it doesnt idle steady it 'hunts' up and down.

so far i have done:
replaced broken choke cable and lubed plungers
changed exhuast for standard
changed k&n airfilter for standard
full service
full strip of the carbs, unltrasonic clean and rebuild kit
balanced carbs
checked for vacuum and airleaks

iv run out of ideas now, is there anything that can cause this problem? it only seems to happen once warm

thanks.

[maviczap]

As you've done everything to do with the fuel, then maybe its electrical, especially when its getting warm.

Are the jets the original size?

[embee]

The description makes me suspect idle mixture.


The choke plungers are a definite candidate, even though you've been in there. Worth double checking they are moving smoothly and freely in the carb body, and the springs are in good condition. I had one stick and it would only idle on one cyl when hot (too rich).

Have you altered idle mixture while the bike is running or just turned the screws to a set position? It's very difficult to get in there without specialist tools, angled drive adjuster, but it's just possible (I wear a thin cotton clove to avoid burning my hand). If it's too rich it would run cold but start to go wooly when hot. Is the plug getting wet or sooty?


I have quite recently had a plug (admittedly quite old NGK iridium) go down. That was a bit of an odd one, it happened suddenly shortly after refuelling and I thought it was fuel related, but having been through the carbs I ended up swapping for some old plugs I had as spares and the problem was solved, so new plugs were installed. The bike would run on load but at idle it would splutter and misfire on one cyl, quite unusual as it's often the other way round.

[Bibio]

try opening the fuel cap when it happens as it could be a blocked tank breather.

[maviczap]

Does it live outside or did it with the previous owner?

Rusted drain pipe in the tank, letting water in?

after riding it to work today, it has a hard miss fire at idle and light throttle but not constant, anything over light throttle and it pulls nicely.
maviczap - im unsure of jet sizes it has and thought of a possible faulty coil when warm?
it does spend most of the time outside too but was previously stored in an underground carpark.

embee - one idle screw was seized which i sorted when stripping the carbs and set them back to just over 2.5 turns which they originally was after stripping then fitted to the bike.
when i changed the plugs the front was slightly whiter, rear was biscuit colour. i fitted NGK's

bibio - ill try that next time

thanks for your help, ill have a look at the things mentioned.

forgot to mention i had it dyno'd and was told its running leaner at idle and 60hp at the wheel.

but at the time the mixture screws were seized.

Originally Posted by Littlebaba

Hi, iv had problems with my girlfriends curvy. bought it around a year ago and it wasnt looked after, when warm it doesnt idle steady it 'hunts' up and down.

Mate I have the same problem with my girlfriend. Common problem I guess!

Sorry

[phi-dan]

Silly question, but have you checked / oiled the choke cables?
Mine wouldn't idle right for a while, and it was diagnosed as choke plungers not moving cleanly. After stripping them down it turned out that it was the cable sticking. Plenty of oil and much wiggling sorted it.

Sent from my XT1068 using Tapatalk

jagryan85 - good one!

so i took the choke cable off again and lubed it, then it broke...

new one ordered, genuine one.

hopefully it'll be sorted

[maviczap]

cool the collective wisdom of the org might have solved another problem