DIY- jet drilling

[GS-of-SIN]

G'day fellow gs riders. I'm new to the forum world and this is my
First post.
Few months ago I bought an 08 gs500f pretty standard
Apart from a yoshi slip on and new head light and gauge
Looking to start rebuilding the whole bike from scratch next year
But in the mean time I want to get some more go out of it so iv advanced
The ignition and now want to jet the carby and remove the
restriction problem. Does anyone know the size of the stage two dyno jets
As I have a set of jet drills at work and if anyone has any tips on drilling jets

Cheers, James.

[twinrat]

jets need to be reamed as drills can leave  marks in the jet causing them to be different from each other even when drilled with the same drill .jets are cheap and if you get genuine mikuni jets they are very consistant . buy the jets that have a taper reamed at both sides of the jet  (  that is inlet side and outlet side )

[Joolstacho]

Just be a little wary of this dopey, simplistic idea that a more advanced ignition will aid performance. -It's crap!!!
Many racing engines use LESS ignition advance than their roadster versions.

[GS-of-SIN]

Thanks for the feedback guys much appretiated. 

[Suzuki Stevo]

As long as this place is around, there is no need to drill jets.. http://jetsrus.com/a_jet_kit_street/suzuki_500_GS500F.htm

[Soloratov]

Also just want to offer up too, my local shop seems to always have the right jets for the GS, so if anyone in the states needs some, I might be able to get them as well.

[The Buddha]

Yea cant drill the suckers accurately, pilots you can, but you dont get numbered drills in 40 size. You get a 39.4 or something.
I sometimes drill em in other bikes, like the stupid MZ. But GS jets, better to swap em, you get the right number on them too.
Cool.
Buddha.

[Blueknyt]

Many racing engines use LESS ignition advance than their roadster versions.

would this not also depend on what RPM peak Useable power. Compression ratio,valve overlap,fuel burned, NA or forced induction? and if its just WOT or POT.  timeing advance is dictated by alot.  the advancer on the stock GS engine does give abit smoother and slightly stronger pull alittle higher up the rev range, but takes away alittle on the bottom. 

[Joolstacho]

+ Absolutely mate.
This is precisely my point, it's all about efficient combustion, and there are lots of other factors contributing. I just wanted to mention it because a lot of less experienced lads seem to have been sold this idea that more ignition advance will improve performance. All else being equal, more ignition advance is a not very useful way of compensating for an inefficient combustion system, whether it be caused by cams, ports, combustion chamber etc, etc. And more ign advance can have detrimental effects on the motor.
All this stuff is about compromise isn't it? We need tractable power that works over a fairly wide rev range, -we need good power and torque so cam grinds, overlap and all the other factors are 'balanced' to achieve the desired performance envelope.

[Big Rich]

Yea cant drill the suckers accurately, pilots you can, but you dont get numbered drills in 40 size. You get a 39.4 or something.
I sometimes drill em in other bikes, like the stupid MZ. But GS jets, better to swap em, you get the right number on them too.
Cool.
Buddha.

+1 to this. If you ever "forget" what size they are drilled out to, and you change air filters / exhaust / whatever, you're better off starting over from scratch. Jets are cheap, and fit in a toolbox for future swaps.

[Blueknyt]

+ Absolutely mate.
This is precisely my point, it's all about efficient combustion, and there are lots of other factors contributing. I just wanted to mention it because a lot of less experienced lads seem to have been sold this idea that more ignition advance will improve performance. All else being equal, more ignition advance is a not very useful way of compensating for an inefficient combustion system, whether it be caused by cams, ports, combustion chamber etc, etc. And more ign advance can have detrimental effects on the motor.
All this stuff is about compromise isn't it? We need tractable power that works over a fairly wide rev range, -we need good power and torque so cam grinds, overlap and all the other factors are 'balanced' to achieve the desired performance envelope.

yes, but you seem to be looking at it as a mid to upper level engine builder. kinda like being a victim of your own experience.   This engine was never designed or built to be a power house.  its a general purpose engine for light to mid size bikes (at time back in the 70's) to give long long life with moderate performance, to get alittle more performace, with bolt on's a timing advancer is right up there with jetting and exhaust.  an advancer doesnt  have to be drastic to be useful

[frylockjim]

You really want to be careful with ignition advancing also. If you advance it too much then you could cause your engine to start pinging/detonating, which means that you would need to change out the pistons cause theyll be blown apart, the valves would be trashed, and the cylinders would get out of round. 

[Blueknyt]

You really want to be careful with ignition advancing also. If you advance it too much then you could cause your engine to start pinging/detonating, which means that you would need to change out the pistons cause theyll be blown apart, the valves would be trashed, and the cylinders would get out of round. 

again true, however an advancer is made with the engine specs in mind. an aftermarket advancer for these engines doesnt have a lot of advance to them, now im not overly learned on the latest Gen of the 500F and how its igniter/trigger wheel is setup, i understand it uses a single trigger pickup so im willing to bet the older E modle advancer wont work. being as the F also has a TPS im sure the igniter is programed more like an ECU when it comes to spark curve adjustments.

[Joolstacho]

"kinda like being a victim of your own experience".
?
More like a victim of others' ignorance.

[Zookmang]

Hey OP, You wouldn't happen to be in Australia would you? I've heard a couple times that rejetting an Aussie GS500 is not wise as you could end up with a bike that runs like a busted arsehole. Don't know why exactly that is though.

[Blueknyt]

not ment as an insult Jool, far from it infact.  reading your words you seem to be on the ball, very knowlegable on engines, even in racing applications.  so please dont take it as such. 

The GS engine up to when they installled the Throttle position sensor all benifited in power and response from the V&H ignition advancer, be it stock jetting or stage 4 with pipe and cleaners.  if your custom making an advancer then yes, BE CAREFUL.  Bob B, a member here was converting stock rotors to the V&H advancer specs for awhile but, he has also built more gs engines for raceing then i could hope to see. 

[Big Rich]

Hey OP, You wouldn't happen to be in Australia would you? I've heard a couple times that rejetting an Aussie GS500 is not wise as you could end up with a bike that runs like a busted arsehole. Don't know why exactly that is though.

It's from the Coriolis effect - just like how water swirls backwards in the southern hemisphere, the air swirling in the carbs backwards messes up any jetting changes!

[Joolstacho]

All cool Blueknyt.