not always immediately throttle response SV650N

It sounds like the carbs need re-jetting to me

[northwind]

Loads of conflicting advice here you'll have noticed Myself, I would say that an air filter is an upgrade, but you don't need an upgrade, you need a fix. It's rarely neccesary to have to rejet after fitting a race can alone (ie, standard filter, and a slip-on not a full system) and your symptoms aren't just slight, they're pretty drastic. It's possible a rejet would help, but I'd say it's not the most likely suspect.

Here's an idea- you can easily rule out the can causing the problem by simply going back to standard for a few days and see what happens.

Carb balancing is a part of the routine servicing of the bike- when was it last done? Basically, if you're badly out of synch the 2 carbs simply work differently, supplying different amounts of fuel to each piston. So you get one pushing harder than the other, and wasting power. It's most obvious on hard throttle openings. It'll cost you power and fuel economy too, and often vibes.

Even if it's not your problem, it's something that's worth doing regularily anyway. So I'd do it first, or get it done. When was it last serviced? If you do it (or get it done) and it doesn't help, then it might be worth looking at a rejet- best bet would be to pop it on a dyno, but that's getting a bit ahead of yourself. It might equally be a fault in the carbs.

Sounds like re-jetting to me also.

Had an R6 a few months back and put a micron on it and when you just move the throttle slightly the revs would sort of die then off it would go. In the end I bought a Dynojet kit and a filter but had to scrap the filter as I couldn't get it to run right (R6 problem)

The Dynojet kit sorted out the problem so it's worth while looking into. Can't comment on the filter though as I think all bikes behave differently.

I would say balace the throttle bodies(carbs?) first, then see what else is wrong.

Balancing the throttle bodies made a big difference to my throttle response. It's a fairly simple job too. It's in the service manual and you should be able to borrow a vacuum gauge from someone. It made my throttle response seem "closer" to the input from the wrist.

A 1-2 second delay I doubt is simply carb balancing or jetting*, that is a drastic amount and something is blatantly wrong!!!

*these make a difference, but not as drastic, or intermittent as this.

My prognosis would be that the sliders are not moving up when you whack the throttle open. This could be for a variety of reasons, from one of the butterfly valves not opening/loose, to a slider sticking, or that you are loosing vacuum above the diaphragm, be this muck in the inlet orifice, or a torn diaphragm etc etc.

I wouldn’t waste money or time jetting or balancing at this stage, but you are going to need to take the airbox off and the tops off the carbs, remove the sliders/diaphrams and take a looksee I am afraid!!!

[northwind]

Originally Posted by Blue_SV650S

My prognosis would be that the sliders are not moving up when you whack the throttle open. This could be for a variety of reasons, from one of the butterfly valves not opening/loose, to a slider sticking, or that you are loosing vacuum above the diaphragm, be this muck in the inlet orifice, or a torn diaphragm etc etc.

I wouldn’t waste money or time jetting or balancing at this stage, but you are going to need to take the airbox off and the tops off the carbs, remove the sliders/diaphrams and take a looksee I am afraid!!!

This is my suspicion too... But time and money spent on a carb balance won't be wasted, it's good diagnostically and may fix the problem if they're drastically out of whack. It's a fairly cheap and simple procedure and it's routine too, so the actual cost of doing it is minimal. So I'd start there.

i will take it to the garage and see what they say i will ask for a balancing of the carbs that was what i tought also so....

... also might be worth getting your bike on a Dyno machine, that can pick up fueling & all sorts of other issues too