78 GS100 stock jet sizes?

[Anonymous]

My otherwise rockin' 1978 GS1000 is running rich. Really rich judging by the plugs and the way it acts. I just picked it up Friday and the previous owner did say he thought the mechanic who "got it running right" had jetted it rich. I have a manual on order but in the meantime...

what are the stock jet sizes?
Are all four the same or are 1/4 different from 2/3?

I pulled the carbs out and found 125's on 1/4 and 127.5's on 2/3. Not knowing what stock is I don't know if that's wildly out of line or if I only need a couple sizes smaller. FWIW I've got K&N pods and a 4-1 Kerker megaphone exhaust.

I should also add that I'm deliriously happy to have picked a bike with such a dedicated group of users. Egads, whatever did people do before the internet anyway?

[SqDancerLynn1]

My book shows a GS1000E to have a #95 main jet stock for the VM 26
carbs. They are all jetted the same from the factory. Some believe that running the center two richer will cool them better. The jets are available in steps of 2.5 so they have gone up 10 sizes. I would try a 112.5 and recheck the float level

[KEITH KRAUSE]

Stock mains are #95. Pilots are #15. The stock needles usually have their clips in the 3rd position from the top. The floats should be set at .94-.95" (manual calls for .90-.98".) The side air screws are generally at 2 turns out and the pilot screws (underneath) are generally 1 1/2 to 1 3/4 turns out (with pods). The pilots need fine tuning for each cylinder and the side air screws should be set for the highest RPM possible and then the idle set correctly with the idle screwknob.
I would have guessed 125 Mikuni mains and 17.5 pilots would be close? Raise the needle 2 positions from stock? Do what the plugs tell you at various throttle positions. Actually, I recommend a Dynojet jet kit, p/n 3304. Try putting in their 138 mains and set the needle clips at the 4th position from the top and use the stock pilot jets. Remove the float bowl vent lines. Adjust the air and pilot screws as I said and you should be good or close to it.

[Anonymous]

95! 8O Quite a jump indeed. Thanks very much to the both of you for the info. That definitely gives me a frame of reference.

[SqDancerLynn1]

Keith has it!! Aren't mikuni and DynoJet jets sized different??????

[KEITH KRAUSE]

Keith has it!! Aren't mikuni and DynoJet jets sized different??????

Yes, they're sized differently.

[Anonymous]

As a bit of an update I'm pleased to report that The Lizard lives again! On Tuesday I bought a range of jets and started with 112.5, got everything back together only to discover it wouldn't start. Much head scratching and swearing later I decided the petcock was at fault. The new one arrived this morning, I installed it, turned the key and after a little cranking VRROOOOMMMM!!!

SqDancerLynn1 thanks for the suggestion on a starting point with the jet size. I've only taken it for a spin around the neighborhood so far but there's a noticable improvement. It starts from cold easier, idles more smoothly, and in general seems to run better. I need pilot jets still and when my manual arrives I'll take a look at the needles, then I'll put it on the butt dyno. It's not perfect yet but getting closer. Thanks again to everyone for your input!