hmmm,
Qwapy, i'd say put everything back the way it was except for the exhaust...start with just the airmix screw and play with that until it's running as smooth as you can, then move onto the main jet and go up one step, then onto the pilot then the spacer...after each change note if it was better or worse...step by step until it seems just right...
pilot controls idle and basically getting it up and rolling
main controls midrange throttle response
needle height is for wot....

i think i got that right but maybe not...

Thanks, I'll do that and let you know how it worked out

Clearush,

Thanks, You are referring to the vacum port on the carb, correct? The Raptor does not have vacum. I did the Petcok/Raptor mod about 3 weeks ago and I plugged the port with a rubber plug. I saw somebody on the forum  using silicone on the port but, I don't know. I am not planning to use that port anymore but don't like the idea of sealing it. I may use a clamp to ensure it stays put but as it is right now, it is pretty safe. I included a picture of it.

Before the mod? It was running fine as any S40 stock. Nothing to write home about it. I had a lot of trouble with the Petcock; did the Raptor mod, Viola! That problem was fixed. Wanted to do the Dyna mod to get a little bit more out of it. The stock muffler sound sucks. Now it sounds great (even thought is not getting up to speed) and the backfire is gone. Hopefully, this is a temporary situation. I had a problem trying to get the stock spacer back like it was; one of the screw on the needle slide is stripped and that has put a temporary halt on my work. My son is a automechanic and hopefully he will help me but, I have to wait until tomorrow or the day after.

One of my stock S40's has the same Emgo stainless mesh air filter, but had and Emgo muffler from RYCA initially and now one from Apollo Cone.  Both are high flow mufflers.  I currently have the stock 52.5 pilot, 3 washers on the needle and a 152.5 main jet.  The pilot screw is at 2 3/4 turns out so I could go up to a 55 and reset the pilot screw at about 1 turn out, but runs great as is.  On a flat section of rural highway it will peg the speedo on a good weather day.  On a funky day it only hits 95 mph.  
My other stock S40 is still on the stock air box and has a dyna muffler.  The carb has the stock 52.5 pilot, white spacer shaved 1/2 by previous owner and a 150 main jet.  It runs very well, does not backfire and will pull 90-95 on any given day.  It's not as quick or fast as the other but runs good.


The tiny screws in the slide that hold the needle are made of crap metal.  Use a small impact driver (available at Harbor Freight for about $7.50) to remove the screws and replace them with tiny screws from inside an old computer.  They are an exact replacement and are made of good hard metal.

Use the 150 main jet, it should work just fine for you.

If you still have issues after that then the cause is something other than the jet choices.  You would then need to check for clogged passageways and/or air leaks in the exhaust system, fuel delivery from the tank, ignition......

justin_o_guy2 wrote on 01/01/13 at 16:32:03:



The long skinny tip works fine as is for me with that little driver.

Remember that just fingerprints on the slide is enough to cause problems..clean & dry,

Howdee fellow bikers,
Success!!!! At least a 95% success
I put the carb in the bike after I redid the jetting and it was still running awful, worse than before. I read that one of you suggested to use a carburetor cleaner and I took the carb a parts again and this time I used one set of latex gloves to take it a parts and clean it and another set of gloves to put it back together, making sure all the jets and little holes were clean (not like they were clogged or dirty before but just to make sure “everything” was clean as I could possible make it).
Put the carb back in the bike (left the jets just like Lancer suggested; 150 Main, 52.5 Pilot) and I left the stock spacer on the needle. Remember, I also took the air cone filter and reconnected the air box.
Adjusted the pilot screw the best I could and took it for a ride on the open road.
WOAW!!!!! It’s alive! It’s alive!! The monster is alive!!!
It goes! It runs real smooth, it goes when you put down the throttle, it really goes. I can get to 70 mph in no time. I even tried (for the heck of it) to go faster and pulled the throttle down and it went like nothing; I reached 92 mph like nothing. I was really surprise, pleasantly surprise. It is not like I will be driving like mad out of hell constantly but, it is real nice to know that if you need speed to pass or just to go fast sometimes, you can do it. Before with the stock settings I could never make it more than 70 or 75 and it sounded like the bike was going to have an asthma attack. Now, it goes and you can feel the engine a lot smoother than before. I went from Orlando to Merritt Island and back (about 45 miles one way) and it did wonderfully, very, very responsive. Never new I had a beast under me, no more sluggish bike, those time are gone.
Now, you saw I said 95% success. OK, the other 5% is that it still backfires. Although it is more like a “pop” sound than a backfire and it does it every time I shift (either up or down), not that bad but it is kind of bothersome. Any suggestion? The bike runs great, just those popping sounds when shifting.  
Also, I have a minor question: I mentioned that the screws inside the slide where stripped and I replaced them with a stainless steel screws (I could not find a zinc coated screws). Are the Stainless steel screws ok for use inside the slide? My concerns is about the gas eaten them out (corrosion) I include a picture of the screws below (the original one (stripped), a first option that I replaced with a second option with a smaller diameter head).
Well, if anybody can help me or have suggestions about the popping sound I will appreciate your suggestions.
Thanks,
Qwapy