yoshi RS-3 on do i have to rejet

Hello Everyone,

Just wandering if anyone can tell me do i have to rejet if im putting on a yoshi pipe
with K&N filter & Tank Raisers

or if i have to do any mods before & after

going going gone

02' SV650, Tank Raisers, K&N Filter etc

[northwind]

Probably... Either the filter or the can should be fine by themselves, but both together is askign for trouble- plus teh spacers of course, leaner still.

what if i take the tank spacers out drop it down still have K&N Filter & Yoshi Pipe


do i still have to rejet


what signs are there to know if the bike needs rejetting







Going Going Gone[/quote]

[northwind]

Probably... What you're doing is getting more air in, you need more fuel to compensate.

If this seems patronising, excuse me... Essay time! Basically, if you're doing breathing mods (intake and exhaust) for performance, you've got to expect to rejet. Anything more than a marginal increse in air flow will require it. Anything that doesn't require it is pretty much a waste of time in terms of performance.

The K&N for the SV's not very good. Well, it flows well enough and it's cleanable, and it's a very effective filter, but it's not very free flowing. So, you can sometimes get away with not rejetting, just about, simply because it's not giving you much more airflow. It would probably make you a bit lean, and possibly lean enough to worry about.

Likewise, end cans- even the best end cans don't make a huge amount of difference, so you can usually get away without rejetting. They might make you a bit lean, and just very occasionally lean enough to be a problem.

But the 2 together have a comulative effect, which will most likely cause you to run lean enough to notice. There's no definates, every bike is different, but it's likely.

This'll do 3 things- one, it'll make the bike run less well- you'll probably lose power noticably around 5-6000rpm, and by and large your power curve will be less smooth and could be down all over (it could also be up, funny old business... But it almost certainly will be down at 5-6K.)

Second, it'll probably cause hesitancy on the throttle- again, most noticable at 5-6K.

But third... If you're lean enough, you'll possibly get higher combustion chamber temperatures, which can damage your piston crows, and burn your exhaust valve seats. Expensive to fix. This is the extreme case, but it does happen...

How to know if you'er lean's not always so easy. It's usualyl most evident, as I mentioned, at 5-6K. So, here's a nice simple test. It's not conclusive or foolproof but it's a good indicator. Basically, you cruise at 5000rpm in 3rd or 4th, then bang the throttle right open as fast as you can. If the bike picks up immediately, you're in the right box. If it hesitates then picks up, you're lean. If it stumpbles or misfires then picks up, you're leaner.

Don't live by this rule! But it's the only one that's really simple to describe. You can check plugs, but that's unreliable IMO- the SV tends to lean out in the midrange, but the idle might still be fine. Mine was rich in the midrange and lean on top for a while, the plugs would tell you to lean the mixture but that would just cause more problems. You can simply "feel" for any changes in the bike... You need good mechanical sympathy to do this, especially if you've changed the power at the same time. But that I can't tell you how to do, I just do it.

Or, best of all, you can pay £20 and stick it on a dyno. Do this if at all possible. It's great to watch, anyway, and it's the best way.

If it does run lean, it can usually be fixed with maybe £4 worth of main jets and a bit of fiddling, but that's another lecture.

Thanks Northwind thats the best advice ive been given since i started studying up on it 6 Months ago i dont know but they must be dum mechanics in Australia, Or just QLD


Thanks for that i will be rejetting now










Going Going Gone Frrrrrrrrrmmmmmm

[northwind]

No probs... i learnt a lot of it from other guys here and on SV Rider, and then jsut did it myself Best way to learn IMO.

Originally Posted by northwind

Probably... What you're doing is getting more air in, you need more fuel to compensate.

If this seems patronising, excuse me... Essay time! Basically, if you're doing breathing mods (intake and exhaust) for performance, you've got to expect to rejet. Anything more than a marginal increse in air flow will require it. Anything that doesn't require it is pretty much a waste of time in terms of performance.

The K&N for the SV's not very good. Well, it flows well enough and it's cleanable, and it's a very effective filter, but it's not very free flowing. So, you can sometimes get away with not rejetting, just about, simply because it's not giving you much more airflow. It would probably make you a bit lean, and possibly lean enough to worry about.

Likewise, end cans- even the best end cans don't make a huge amount of difference, so you can usually get away without rejetting. They might make you a bit lean, and just very occasionally lean enough to be a problem.

But the 2 together have a comulative effect, which will most likely cause you to run lean enough to notice. There's no definates, every bike is different, but it's likely.

This'll do 3 things- one, it'll make the bike run less well- you'll probably lose power noticably around 5-6000rpm, and by and large your power curve will be less smooth and could be down all over (it could also be up, funny old business... But it almost certainly will be down at 5-6K.)

Second, it'll probably cause hesitancy on the throttle- again, most noticable at 5-6K.

But third... If you're lean enough, you'll possibly get higher combustion chamber temperatures, which can damage your piston crows, and burn your exhaust valve seats. Expensive to fix. This is the extreme case, but it does happen...

How to know if you'er lean's not always so easy. It's usualyl most evident, as I mentioned, at 5-6K. So, here's a nice simple test. It's not conclusive or foolproof but it's a good indicator. Basically, you cruise at 5000rpm in 3rd or 4th, then bang the throttle right open as fast as you can. If the bike picks up immediately, you're in the right box. If it hesitates then picks up, you're lean. If it stumpbles or misfires then picks up, you're leaner.

Don't live by this rule! But it's the only one that's really simple to describe. You can check plugs, but that's unreliable IMO- the SV tends to lean out in the midrange, but the idle might still be fine. Mine was rich in the midrange and lean on top for a while, the plugs would tell you to lean the mixture but that would just cause more problems. You can simply "feel" for any changes in the bike... You need good mechanical sympathy to do this, especially if you've changed the power at the same time. But that I can't tell you how to do, I just do it.

Or, best of all, you can pay £20 and stick it on a dyno. Do this if at all possible. It's great to watch, anyway, and it's the best way.

If it does run lean, it can usually be fixed with maybe £4 worth of main jets and a bit of fiddling, but that's another lecture.

i think my bike is running learn, only a scopion end can and pipe connection but at 5-6K (mid range) i hasitates when i open her up. Cheers Northwind!!

This is a N00b question but where do the jets go and are they hard to get to? i guess i need to increase the jet size a size or two (isnt that bad so maybe 1?)

which are the best to buy?

[northwind]

Quite a good link here...

http://www.geocities.com/catpoopman/sv650_rejet.html

They're not hard to get to, but the screws that hold the float bowls and choke cables on are very soft, and can be extremely difficult to shift. That's probably the hardest bit of the job to be honest.