VM22 GS550 mysterious jet identification

[Mad Ratter]

Hi all, yes, yawn yawn another guy who shouldn't be messing with such things as carbs I know but we all have to learn and I am!

But, I have a GS550E 1978 with VM22's shes a rebuilt special with K&Ns and a Supertrapp exhaust, nearly have it running well but was going change out the pilot jets.
Where they are located there was another jet "on top" of it that looks like a smaller main jet (with 50 stamped on it I think...very small to see), what is this jet for??? and should it be size changed along with the pilot jet?

I have 15 pilots and 90 mains on all 4, should 2 & 3 be bigger as I have read about the VM's on the 750?
I know most will say put the stock airbox back on but I dont have it.
Anyone got experience with K&N pods and supertrapp? I cant seem to find info about the 550 VM's, only the 750, so apologies if this has been previously posted.

Thank you in advance.

[tom203]

Strange- I read this yesterday and figured somone knowledgeable would chime in. Anyways, I know nothing about this setup but stock airbox carb likely came with 80 mains, so you are headed in right direction! Drop down a few posts in this forum and see what the 750's with VMs might require- info should loosely apply to you too. Better yet, you tell us!

[hampshirehog]

The VM22s have that 'in-line' pilot jet arrangement and you have the standard jets in there - 15 and 50. You won't have to change these with pods and a pipe. I would try turning out the fuel screws to 1.5 turns out.

The 90 mains are a bit small I would have thought. 100 to 105, maybe a bit bigger, should bring you somewhere close. Plus lower the needle clip to the lowest position.

Keep all the carbs the same.

If you haven't already bought the K&Ns make sure you get the right ones. K&N listed the wrong ones for years (I doubt they have corrected it as it was listed incorrectly for so long). You need the short ones - the longer type hit the frame on the 2 outside carbs.

[Mad Ratter]

Thank you guys, thats good that at least I can leave pilots alone. Will try bigger mains and have moved clip on the needle. Yes, you are correct that those filters listed on K&N are the WRONG ones!! I bought them ages ago, but have managed to squeeze the outside ones right in, tho it doesn't look pretty.

I emailed K&N about it, got a reply asking for photos etc, which I supplied and have never heard back since!! thank you K&N!!

I will post results when I get some new mains on it.

Thanks.

[Mad Ratter]

The only main jets I could find in NZ were 107.5, seemed to work great on full throttle, but I raised the needle to the last but one position, Hampshirehog, did you mean to say lower as I would have thought raising would be appropriate. However.... she is running as rich as hell now, not done a plug chop at FT but after getting in from a ride the plugs and exhaust are black as and sooty.

She runs good at FT with the 107.5's, so I guess lowering the needle may cure this, also, the idle will just not settle at all and I'm constantly messing with it, it idles at around 1500 then drops, then dies!

[hampshirehog]

I meant lower the clip to raise the needle. Usually the bottom position works but you have to experiment. Plug chops is the way to go.

Dropping the needle to cure richness at full throttle won't change a thing. The needle controls up to 3/4 max throttle - do a plug chop on 1/2 to 3/4 to set your needles,

[Big T]

MR

The needle thing is always confusing because you lower the clip to raise the needle

For your set up, try

Fuel screw - 1 to 1 1/4
Air screw - 2 1/2 to start
Needle - up one level from standard
Main Jet - maybe one size lower (it's all trial and error)
Pilot jet -15

Remember all of the above have an effect, mostly at idle and off idle