K&N + Race can = Rejet?

[Blue_SV650S]

Ok, my new bike (well new to me, it is a 01 curvy) has a race can and K&N fitted, I have no idea if the bike has been rejetted.

Is it necessary to re-jet if you have made BOTH these mods, or are the SVs overjetted anyway?

This is a trackbike, so I don’t really want to risk it being a bit lean, I don’t really want to have the carbs off to check either … and dyno is hassle and expense.

I am going to presume it has stock jets, if the consensus it that it is ‘safe’ to run the pair with stock jets then I will, if it isn’t then I’ll stick a stock filter in.

[TSM]

Ok, my new bike (well new to me, it is a 01 curvy) has a race can and K&N fitted, I have no idea if the bike has been rejetted.

Is it necessary to re-jet if you have made BOTH these mods, or are the SVs overjetted anyway?

This is a trackbike, so I don’t really want to risk it being a bit lean, I don’t really want to have the carbs off to check either … and dyno is hassle and expense.

I am going to presume it has stock jets, if the consensus it that it is ‘safe’ to run the pair with stock jets then I will, if it isn’t then I’ll stick a stock filter in.

I would get some bigger jets if you are realy woried. Get it dynoed to see if its ok. I put some DJ150s in my bike, its running rich but i will hopefully have a full system on by next week.

[Razor]

I'm running the K&N and a race can, altho my race can is a baffled road legal-ish thing. I still had to fit bigger jets to get it right. I got my bike on a dyno at one of those free days they do and from the curve it was pretty obvious it was lean. I drilled the slides with the bit from the DJ kit and fitted DJ140 jets. The throttle response is much improved and the last time I had it on the machine it was a nice dip free curve.

[northwind]

If you don't want to rejet, don't fit an aftermarket filter. If you do want to tune for power, don't get a K&N :)

[bobit69]

What are the best filters to buy and a 'worthwile' mod for the SV (pointy). BMC... or is it actually worth the trouble, and just leave the original in there?

[northwind]

For pointy, don't know. K&N pods, I suppose.

[Blue_SV650S]

So that’s a ‘yes you need to rejet if you have them both???’ are the SVs renowned to be a bit sensitive to jetting???

I have plenty of jets at home, but I wanted to avoid taking carbs off if I could. I’d rather put a stock filter in than take the carbs off, that extra ¼ hp it might give if properly jetted is not worth the hassle!!! But I didn’t want to pop a standard filter in if it was jetted for a K&N …

I can see I am going to have to have a look in there ….

Any tips in taking the carbs off??? Done loads of IL4s,but I was presuming being a v-twin it would be a sod?

[SV650Racer]

id get it run on the dyno before messing with the carbs otherwise how do you know which way to go with the jetting?. With the right jetting and filter you can see more than 1/4 of a BHP dependant on how far out your bike was to start with which you wont know till you get the fueling checked :wink:

So far the pipercross filters seem to be producing some very good results.

[northwind]

Yep, I'm with SV650Racer. I'm pretty good now at setting the things up by ear, feel, guess and **** but there's no substitute for a sniffer run on a dyno.

It's not so much that they're sensitive to jetting... It's that you're actually making a fairly big change with the swaps. You'd probably be absolutely fine with just the end can, but the filter's specifically designed to effect a big change. A free-flowing filter that doesn't need a rejet isn't very free flowing :) THe K&N's marginal.

[Blue_SV650S]

I was being a bit a little facetious with the 1/4hp … but lets face it if it isn’t jetted for it, you will probably loose HP and might even cause harm if it is a long way out!!

Dyno-smyno … that is grief … I’d rather put standard jets in it and run a standard filter and race can (just the can is fine with stock jets isn't it?). I really am not bothered about HP, I just don’t want to run it lean!!

I’d be happy to fit ‘ballpark’ jets. i.e. if someone said I have race can, standard downpipes, a k&n, at have ### jets, then I’d throw a set of them in as that should be ‘safe’.

But I’d even more rather just run a stock filter!

[northwind]

Do that then :) Makes more sense really. The benefits of the K&N, or even the BMC, don't justify the cost and the hassle IMO unless you're either needing to milk every bit of power, or you're doing other tuning and you need the induction work to make them work efficiently.

[Blue_SV650S]

Do that then :) Makes more sense really. The benefits of the K&N, or even the BMC, don't justify the cost and the hassle IMO unless you're either needing to milk every bit of power, or you're doing other tuning and you need the induction work to make them work efficiently.

Ok I guess my point is, if the bike has a K&N, does that mean the bike HAS to have been rejetted (else it would run like a bag) or is it possible they have fitted it and it is ok on the stock jets … but is actually going to be dangerously lean??

What I don’t want to do is stick a stock filter in if it has been jetted for the K&N … or run the K&N if it is going to be lean ... yet as stated I really wanted to avoid taking the carbs off to have a look …

I can see top take the uncertainly out, I am going to have to pay them a visit … is it possible to get the floatbowls off without taking the carbs off?

[northwind]

Ok I guess my point is, if the bike has a K&N, does that mean the bike HAS to have been rejetted (else it would run like a bag) or is it possible they have fitted it and it is ok on the stock jets … but is actually going to be dangerously lean??


No, not definately. But maybe. can't say for sure, every exhaust combo flows a little differently. A good acid test is the 6000rpm stutter. That's where the main jet/needle interface is most obvious on an SV. Cruise at 6000rpm or thereabouts in third, then jam the throttle open as hard as you can. If it stutters, it's well lean and needs bigger jets. Way bigger, probably. If it picks up slowly, it's a bit lean. If it jsut goes, it's OK. Doesn't tell you when it's right, but it does tell you when it's horribly wrong. Lots of people in the past have just adjusted the needle when fitting an exhaust and filter, but leave the top end alone, this picks that up.

[Blue_SV650S]

This is my track bike, so I can’t really test it before I want to use it.

As there doesn’t seem to be a definitive answer and having just read what you put I realised I don’t need to faff at all … I will soon know if the jetting is dangerously off as I will be able to ‘feel’ it!!! So have decided what I am going to do!!! I will take the bike and run it with the K&N, I will take the Stock filter too. I’ll soon know if it is running horribly lean by the way it feels and can come back in and swap over. Unlike a 2-stroke it is unlikely to go pop quickly if running lean, its probably going to be lean enough to make it erratic on the throttle before it is going to be lean enough to damage it. .

BTW you have just reminded me, a good way to tell you are lean is if when you roll the throttle off slightly on accelleration the bike picks up.