Rejet needed with slip-on Laser exhaust?

[Bioflap]

Hi guys,

I'm riding a '89 GS500 since january. I had lots of problems with it, but the bike is running good now, but it has a dead spot around 4-5k.
I bought the bike with standard ehaust pipes and a Laser slip-on. Because this is my second engine im afraid to ruine it again..


I already brought it to a dealer, and asked if they could make it run a bit richer for me. The only thing they did was f%$k up the pilot screw, and said that was enough. The spark plugs are a bit white.

What jet would you guys recommend? Everything is stock except the slip-on.


Thanks!

[radodrill]

Apparently the GS500 from the factory is jetted to run a bit lean.  Whenever you put on a less restrictive exhaust and/or air filter, the carbs will not adjust to the increased airflow making the bike run leaner.  Even stock you can benefit from a rejet and with a preformance air filter/exhaust a rejet is necessary.

The GStwin rejetting wiki page is a great starting point with recommended jet sizing.

Based on your post, I gather the dealer only adjusted the idle adjust screw, which simply changes how far the butterfly valves stay open when the throttle is closed and only affects idle performance.

[Bioflap]

Apparently the GS500 from the factory is jetted to run a bit lean.  Whenever you put on a less restrictive exhaust and/or air filter, the carbs will not adjust to the increased airflow making the bike run leaner.  Even stock you can benefit from a rejet and with a preformance air filter/exhaust a rejet is necessary.

The GStwin rejetting wiki page is a great starting point with recommended jet sizing.

Based on your post, I gather the dealer only adjusted the idle adjust screw, which simply changes how far the butterfly valves stay open when the throttle is closed and only affects idle performance.

I already saw that wiki, but i cant find someone with a slip-on and stock airfilter.. That's why im not sure what size to choose.

[The Buddha]

Europe bike ? it came with 40/125. You could run it and see if it acts up when super cold.
Cool.
Buddha

[Bioflap]

Europe bike ? it came with 40/125. You could run it and see if it acts up when super cold.
Cool.
Buddha

Not sure if its a European bike. How can i check it?
And can i rev it that high when its cold?

btw. When i place a stock exhaust i dont have the dead spot and it runs perfect. But i love the sound with the Laser Riding without DB-killer.

[radodrill]

Not sure if its a European bike. How can i check it?

Bikes manufactured for sale in the US market have smaller jets than those sold in Europe.  This is done for reduced emissions, but makes the bike run leaner.

[Bioflap]

Not sure if its a European bike. How can i check it?

Bikes manufactured for sale in the US market have smaller jets than those sold in Europe.  This is done for reduced emissions, but makes the bike run leaner.

The engine that was in the GS when i bought it was a US model. The pilot screw had a thing in front of it. The engine that is in now does not have them, so i think its a European model.

[The Buddha]

The carbs are what counts for euro jetting - or you can open it and look.
Cool.
Buddha.

[Bioflap]

The carbs are what counts for euro jetting - or you can open it and look.
Cool.
Buddha.

Ok, i can open them tomorrow. And then buy bigger jets? Something like +5?

[The Buddha]

The carbs are what counts for euro jetting - or you can open it and look.
Cool.
Buddha.

Ok, i can open them tomorrow. And then buy bigger jets? Something like +5?

No ... you should have 40/125 for slip on and stock airbox filter. +1 ... if you're not running euro ... OK you needle is it has clips I think second from top, or 3rd, and 3 turns on mix screws. Floats to the top of the bowl and no higher.
Cool.
Buddha.

[Bioflap]

The carbs are what counts for euro jetting - or you can open it and look.
Cool.
Buddha.

Ok, i can open them tomorrow. And then buy bigger jets? Something like +5?

No ... you should have 40/125 for slip on and stock airbox filter. +1 ... if you're not running euro ... OK you needle is it has clips I think second from top, or 3rd, and 3 turns on mix screws. Floats to the top of the bowl and no higher.
Cool.
Buddha.

I have no experiences with jetting or anything. Just to be sure.
If it's a euro and has 40/125 i don't need to buy any jets. The only thing i need to do is put the needle on the second or third place? This goes with washers or something?
And just place the float bowls at the highest points.

btw. A dealer synced my carbs for 3 weeks ago. Do i have to do it again after i change this?

Thanks for all the info!!

[DrtRydr23]

Europe bike ? it came with 40/125. You could run it and see if it acts up when super cold.
Cool.
Buddha

I find this interesting.  In my Clymer manual it lists the main jet size for US and a few foreign countries as 122.5, then it lists the main for the rest of Europe and Australia as 120.  It's always been preached on here that the bike is supposed to be 125 main because that's what they get in other places, but my Clymer says otherwise.  Weird.

[Bioflap]

Europe bike ? it came with 40/125. You could run it and see if it acts up when super cold.
Cool.
Buddha

I find this interesting.  In my Clymer manual it lists the main jet size for US and a few foreign countries as 122.5, then it lists the main for the rest of Europe and Australia as 120.  It's always been preached on here that the bike is supposed to be 125 main because that's what they get in other places, but my Clymer says otherwise.  Weird.

So its also possible that mine has another size? I assume i can get these jets at almost every bike dealer right?

[radodrill]

So its also possible that mine has another size? I assume i can get these jets at almost every bike dealer right?

It's always best to look what's actually on the bike; sometimes they are speced (or in this case jetted) differently base on where it's originally sold.

Most dealers should have jets available or else they can order them.  Alternatively, The Buddha has a FS thread in the marketplace section where he sells jet kits based on your needs/setup.

[Bioflap]

So its also possible that mine has another size? I assume i can get these jets at almost every bike dealer right?

It's always best to look what's actually on the bike; sometimes they are speced (or in this case jetted) differently base on where it's originally sold.

Most dealers should have jets available or else they can order them.  Alternatively, The Buddha has a FS thread in the marketplace section where he sells jet kits based on your needs/setup.

Thanks for all your help!
i just opened my 2nd pair of carbs. I still have some questions im not sure about how to do it.
Buddha said i have to put the floats at the highest point. Is it necessary to do? I think im going to destroy it.
Also, when i watched the slide needle, it had one position clip. Where am i supposed to place the 3 washers?

And Buddha also said i needed 125/40 jets.. +1? So i need to buy 126?
Sorry for being a noob with this. Just dont want to destroy the carb setup 

[radodrill]

The washers go between the clip and the slide so as to raise the needle with respect to the jet.

Buddha was referring to pilot size 40 and main size 125 the jet sizes increment by 2.5 so +1 step is 127.5

[Bioflap]

The washers go between the clip and the slide so as to raise the needle with respect to the jet.

Buddha was referring to pilot size 40 and main size 125 the jet sizes increment by 2.5 so +1 step is 127.5

Great. So i can buy a set of 127.5 jets? Then i'll put them in, put the pilot screw at 3 turns out at both sides. Then place 3 #4 or M3 washers under the clip and above the needle seat?

[radodrill]

That should work.  Though you may have to fine tune the idle/mixture screws and the idle adjuster to optimize the idle speed and smoothness from closed to slightly open throttle.

[Bioflap]

That should work.  Though you may have to fine tune the idle/mixture screws and the idle adjuster to optimize the idle speed and smoothness from closed to slightly open throttle.

Ok great!
Just to improve my knowledge about the GS.
I place the washers at the needle to make more fuel run through the carbs right? And it should make my dead spot around 4-5k at a higher point?

[The Buddha]

The washers go between the clip and the slide so as to raise the needle with respect to the jet.

Buddha was referring to pilot size 40 and main size 125 the jet sizes increment by 2.5 so +1 step is 127.5

Great. So i can buy a set of 127.5 jets? Then i'll put them in, put the pilot screw at 3 turns out at both sides. Then place 3 #4 or M3 washers under the clip and above the needle seat?

125 and 40 is what you should have, no need to get 127.5. if you have 125/40, let it be.
Clymers may be wrong, the suzuki manual says 125/40 in europe/canada.

Floats @ top of bowl is not all the way up, leave that be, you may screw it up ...
Cool.
Buddha