78 gs 550 jet question

[turbo31grandprix]

hey I'm new here. I just need some help. I have a 78 gs550 I just got a 4 to 1 exhaust for it and pode filters. I wanted to know what size jets I should use with these changes? I already have a jet kit for it with all 4 sets of jets I just need to know which size is best for this. thank you!

[GS750]

Sorry Im not familiar with the 550 carby's but Im certain that the Carby Guru BassCliff will be along shortly with the answer and his BIG GS welcome

[turbo31grandprix]

|I'm surprized on here that no one has an answer.... oh well i'll go with what i've estimated..and sum trial and error! thanks anyways.....

[rwc1313]

pfl, id like to know the answer to this as well, im running pods and am slashing my pipes

[tkent02]

Start with the biggest jets, work your way down. When the engine burns up, go back up one size and call it good.

[rwc1313]

what were the stock main and pilot jet sizes in your carbs?

[Suzuki_Don]

This would be the jet sizes for the '78 GS550:

GS550L (77-79) the specs are for the VM's

idle r/min 1100-1200
carb mik vm22ss
id no 47110
bore size 22 (0.87)
float height 24.+/-1.0 (0.95 +/-0.04)
fuel level 4.0+/-1.0 (0.16 +/-0.04)
air screw 2.0 turns back
cut away 1.5
jet needle 5dl35-3 (the -3 3rd notch??)
pilot screw 1.0
pilot jet #15
pilot outlet 0.6
needle jet 0-6
by pass 1.0
main jet #80

[Big T]

I'd go 100 on the main and maybe up one -17.5- on the pilot

What brand of jet kit did you buy and why?

VM carbs don't really need a kit

[BassCliff]

|I'm surprized on here that no one has an answer.... oh well i'll go with what i've estimated..and sum trial and error! thanks anyways.....

Hi Mr. turbo31grandprix,

Sorry I'm late with this. I am no carb guru, but this question has been answered literally thousands of times. A simple search of the forum would reveal your answers. But let me save you the time and just give you the general guidelines, knowing that you will have to read your plugs (plug chops) to fine tune your carbs for all slide openings/throttle positions. You are correct in that it takes some trial and error to get everything dialed in properly. Good luck.

With pods and a pipe, on your VM carbs the recommendation is to start out with mains about 4 or 5 sizes up from stock. You might have to go up one size on the pilot jets, but not necessarily. You will probably have to raise the jet needles one or two clips. All this depends on how your plug chops look. Test at each throttle position. Install larger jets/raise needles if the plugs look lean. Install smaller jets/lower needles if the plugs look dark with unburned fuel. You'll find more information about jetting on my little website along with information on how to read your spark plugs.

Anyway, let me dump a TON if information on you and share some GS lovin'.

I just stopped by to welcome you to the forum in my own, special way.

If there's anything you'd like to know about the Suzuki GS model bikes, and most others actually, you've come to the right place. There's a lot of knowledge and experience here in the community. Come on in and let me say "HOoooowwwDY!"....

Here is your very own magical, mystical, mythical, mind-expanding "mega-welcome". Please take notice of the "Top 10 Common Issues", "Top 15 Tips For GS Happiness", the Carb Rebuild Series, and the Stator Papers. All of these tasks must be addressed in order to have a safe, reliable machine. Now let me roll out the welcome mat for you...



Please click here for your mega-welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike!

Thanks for joining us. Keep us informed.

Thank you for your indulgence,

BassCliff