Idle issue. Curvy

[Aligowers]

Hi guys im having a little of bit of trouble keeping my sv650s 02 curvy at idle. I have new spark plugs and a new air filter. The bikes runs fine apart from when i come to a stop. The idle drops to 1k and then dies. The bike starts fine and will tick over fine when its on the side stand with no issues at all. When i adjust the idle screw up to around 1.5k and it will run fine but when i come to a stop its up at 3-4k. So i have to adjust it back down.
The bike only has 15k miles on the clock. There is no loss in power and it dosent feel rough at all. Any ideas whats going on.
Didnt want to pull the carbs out to clean or add a fuel additive without asking first.
Any advice would be greatly appreciated.
Cheers guys.

[davepreston]

just a quick question when you adjust the screw to 1500 do you turn it off the start it again


iirc idle on a curvy should be 1300 roughly then up or down dependant on climate


anyway I used to set5 mine to roughly 1300 then leave it for 5 mins then start her up again I found that it was either running higher or lower than that so the made small incremental changes clock wise or anti clockwise stopping and shutting her off inbetwen every change till she was right, sounds long winded but only takes 5 or ten mins

[Aligowers]

When i adjust it i have the engine running and blip the throttle same as i have with most bikes ive owned. I have checked where the cable meets the screw nothing is catching its a little stiff. I have sprayed it with a little bit of WD40. I live in Scotland and although wet the weathers not very cold just now. I have not needed to use the choke as i said the bikes runs fine when its on its side stand.
Thanks for the reply.

[Bibio]

adjust when bike is hot. even in the hight of summer the bike should need choke when cold.

how often do you use the bike?

[Aligowers]

The bike has been used daily since i picked it up at the end of last month. Its my main mode of transport and I do around 200-400 miles a week on it. Not sure how much the previous owner used it. I have only tried to adjust the idle when the engine is hot. After letting it run for 10 mins or after a run. Never experienced this with any other bikes ive owned. The bike runs great other than the idle dropping and stalling when i stop. It dosnt feel lumpy like other bikes ive had with dirty carbs.

[Bibio]

could be a notched cam on the carbs where the idle screw end fits (the nib on the opposite end of the cable from the screw wheel). or gummed up choke plungers.

so you adjust the idle when hot to 1300rpm while out on a run, then if you let it sit idling for a while the revs will drop?

[Aligowers]

The bike idles fine at 1300rpm on the side stand and when i did my oil chain the bike sat at idle for over 5 mins with no issues at all but as soon as its on the road and I come to a stop it drops to 1000rpm then dies.

[Bibio]

have you adjusted the idle while the bike is upright rather than it sitting on the side stand?

[Aligowers]

Yes i have and it sits fine till i move off. When i come to a stop again the revs are either up at 3000rpm-4000rpm or have dropped to 1000rpm. Im not sure if its something to do with choke as i have not needed to use it i just push the start button and the bike fires up fine at 1300rpm. I leave it 3-5 mins while i get my gear ready then head off.

[Bibio]

sounds like sticky choke plungers. as said even in the hight of summer a cold engine will need choke. have a play with the choke to start the bike when cold. if the choke only makes a small difference then its the plungers.

also check your battery terminal connections to make sure they are tight.

[Aligowers]

Ill have a play around with it in the morning before work. I have checked the choke and it does make a difference. The choke is pretty stiff so i think it might be that. The previous owner had over filled the oil and it ended up blowing some into the air box so i cleaned that and replaced the air filter and sorted out the oil. Could that have effected it. I have run a few tanks of fuel through it since then. My neighbor suggested using shell expensive petrol cant remember the name and run a tank of that through it.

[Sir Trev]

The Curvy choke is I'm afraid notorious - you'll find several threads about it on here.

If your cable is stiff there is a good chance it is sticking, often it's where the thing splits into two lines by the lower headstock. Usual advice is to replace the cable, take out and clean/replace the choke plungers (caution - they are held on by very soft screws), balance the carbs once you know the choke is sorted, and THEN set the idle.


The bike will run great for not a lot of cash and you'll have a big smile on your face. Enjoy!

[Aligowers]

Thanks ill replace the cable and balance the carbs. Hopefully that will sort it.

[Sir Trev]

Thanks ill replace the cable and balance the carbs. Hopefully that will sort it.

Don't forget to check the plungers while you're at it as they can stick too. No point having a nice free-moving cable if the things they connect to are not :). Let us know how you get on.

[Aligowers]

Pulled the cable out and checked everything. The chokes working 100% Plungers are moving and it was the lever on the grip that was stiff. Sorted that out. The bikes still wont sit at idle very well when i come of the gas it slowly drops back down to 1300rmp and then sometimes stalls. Looks like its the carbs. Going to have to rip them off and clean then thoroughly by the looks of them. May have to get a garage to do it. I dont have the time and cant afford to bugger anything up. Theres a garage next to my work hopefully i can stick it in and get it sorted for me finishing work. If i had the time id do it my self but its my only mode of transport at the moment.
Cheers for all the help

[Sir Trev]

Balancing the carbs on a curvy is quite straight forward with a set of Morgan Carbtune gauges. May just be way out of whack as opposed to gummed up, especially as the balance screw is not locked down. You will also learn a new skill and know it is done right which is always nice too.


Where are you by the way, someone who's done this before could always pop round to help if you supply the coffee.

[Aligowers]

Im about 10 mins from Glasgow airport. Ive never balanced a V twin before. My local garage is fully booked as well due to the weather getting better just my luck. I am on the new A2 liscence and have fitted the restriction kit my self. But the bike was running like this before the kit was fitted.

[Aligowers]

Does the haynes manual show you how to do it. If so ill pick one up and give a go. Ive had mixed results using hyanes manuals in the past for other bikes.

[Sir Trev]

From memory (I gave my Haynes to the guy that bought my Curvy when I fancied a change) the manual is quite useful in this area. Getting to the front vacuum takeoff on a Curvy is a faff first time but most of us left the tail of the Carbtune pipe in place (blocked off of course) by the radiator filler neck so it was easier next time. The rear cylinder takeoff is easy to get to but you need to clamp off the vacuum pipe to the tank once the bike is running before disconnecting it to plug in the gauge so the bike keeps running - you can get a vacuum pump to overcome this but I never had a bother with the simple method. Getting to the balance adjuster screw is a bit tight but not that bad.


Get yourself and a set of gauges to the AR. As long as you get them before too much beer is consumed several of the lovely people there will happily show you how to do it right :).