Two pilot jets - rejetting

[Guest]

I'm in need of a little bit of advice and help here.

I'm in the middle of rebuilding my GS550D. The exhaust fitted on it when I bought it was completely rusty and therefore I had to change it. I ended up buying a 4-1 MAC (with silencer). So I'm in for a re-jetting and a lot of fun pulling plugs and so on. So currently I'm looking to buy new jets. I'm looking to go up a couple of sizes on the main jet and perhaps (might not be needed) up a notch on the pilot jet. And this is where I ran into problems. My 550 comes with VM22ss carbs which are equipped with two pilot jets inline (#15 and #50). Question is, say I need to go up a size on the pilot jet. Would I just go up one size on both of my pilot jets? Or what is the correct way to approach this? I haven't been able to find any information considering this matter.

Hope that some of you clever folks on here got an answer for this

[Nessism]

Pilot jet #1 (#15) is the one you should be concerned with. I'm not even sure what pilot jet #2 even is.

[11csive]

Pilot jet #1 (#15) is the one you should be concerned with. I'm not even sure what pilot jet #2 even is.

They look like this:




They are placed on top/underneath each other and in the same place as the normal pilot jet is placed on all the guides and diagrams I've seen of VM carbs

[tkent02]

You shouldn't need to do anything with the pilot jet just to change pipes. Just get the main right, and the needle clip.

[11csive]

You shouldn't need to do anything with the pilot jet just to change pipes. Just get the main right, and the needle clip.

I'm aware that it's probably not gonna be needed, but now I'm curious as to which one I'd have to swap if it some day was needed So it would only be the "long" one that should be changed out?

edit: seems like jetsrus call it a "mid jet"

[Nessism]

I rebuilt a set of those VM22's but completely forgot about that second pilot jet. Most other VM carbs don't even have them. Again, I'm pretty sure you don't need to worry about the second jet, just bump the 15 to 17.5 if you want to see if that makes a positive improvement in the way the bike runs. Dennis Kirk sells original Mikuni jets for good prices. Be sure to order the VM type with the bleeder. I think I've got some of those 17.5's is the spares box somewhere even.

[11csive]

I rebuilt a set of those VM22's but completely forgot about that second pilot jet. Most other VM carbs don't even have them. Again, I'm pretty sure you don't need to worry about the second jet, just bump the 15 to 17.5 if you want to see if that makes a positive improvement in the way the bike runs. Dennis Kirk sells original Mikuni jets for good prices. Be sure to order the VM type with the bleeder. I think I've got some of those 17.5's is the spares box somewhere even.

Thanks a lot for you answer. For now I'm probably just sticking with the 15, but it's good to know what to do, if I find it necessary to change into 17.5

[Steve]

Really, you shouldn't ever have to enlarge the 15 jets.

The only time you need to add more fuel is when you have more air. Mains are enlarged when you remove the restrictions imposed by exhaust systems and intake filters. At idle and low-throttle situations when you are using the pilot system, your "restriction" is only the throttle slides. Nothing has changed there, so no need to change the pilot jets.

.