My carb does have a D shaped slide and a Powerjet, thank you for referring me to the correct carb type!
The carb has an adjust screw on the PJ, closing it all the will not do the trick?
It should, but because you're never going to need it, you'll be best to remove it entirely.
how do I delete & plug it correctly?
correctly is a matter of opinion. What I did was pull the brass barb from the bowl out, found a small self cutting screw to run in where the barb was, ran it all the way down before backing it out and notching it under the head so it would twist off when tightened.
as for the jet section, (like Bob said most aren't adjustable) I removed the top plug and the jet, then plugged it the same way before grinding down the carb body where the port was. I back filled the jet port with JBweld steel stick (not pulling the air horn to show), then contoured it to match the venturi.
where I live it's quite sea level (15ft), what is the right adjustments I need to do?
The default for the mixture screw is turn it in to full seat (don't crank it tight, you'll do damage) then back it off precisely two full rotations.
My pilot at 975 was #39, yours is no doubt going to be the same if not one or 2 smaller for a bone stock engine at 15ft.
Tuning the pilot is fiddley... Guess a size, put it in and use the mixture screw to confirm larger, smaller, or dead on.
1.
Set the idle screw for a slightly high idle (2k if you have a tach) preferably with the drive chain off or on jackstands... spare your back and grab a seat. Let the engine run for a good minute to get up to full operating temp.
2.
Set the needle to default wich is groove #3 for a 5 position needle, #2 for a 4 possition needle (the topmost is #1 and the leanest setting #4/5 are the richest) The needle is only in play for 1/3-almost WOT. Default is precisely 2 turns out from a soft seat (cranking it tight does damage)
3.
If the highest rpm gain turning the mixture screw out slowly (idle air control on these particular carbs) is found at more than 2¾ turns, the pilot is too big so reset to default, jet the pilot smaller and retest.
If the pilot is less than 1¾ turns out at the highest rpm the pilot is too small repeat above with a larger size instead.
4.
You CAN NOT tune the main properly if the pilot is not tuned because a rich pilot will flood when the main comes on giving a false positive rich condition (an overly rich pilot with a perfect main will act like the main is the problem by giving a flat/dead spot just above 1/8 to around 1/3) it can do the same if the pilot is too lean as well.
5.
ONLY after the pilot is sorted out and you can maintain a low smooth idle with the mixture screw in the 1¾-2¾ range do you move onto the main.
At 975 I only needed a #100 and again I would speculate yours will be damn close to the same if not exactly so.
For tuning the main you'll need the drive chain on (or off stands) because it cannot be static tuned. You need it under load and moving.
You will be listening for:
1.
Flat spots, this is where the engine is running but it isn't picking up speed when you give it more throttle, nor is it trying to stall, but then overcomes itself and goes... this is typically a lean main issue.
Plug will be dry, grayish to chalky white.. the more pale it is the leaner you're burning
2.
Bogging same as above but it has an indescribable wet sound almost like engaging a Jake brake...BWUAAAA typically this is rich and if pushed outright they tend to stall.
Plug will be wet, dark, or both
3.
Exhaust popping on deceleration.
While some find it a cool sound effect, if it's crackling and popping like crazy you're still just a little lean on the main and igniting in the hot exhaust header... a little rich can do it as well but the pipe has a more difficult time getting that hot.
Often this can be corrected by moving the needle one Position. There is the default, but unlike the mixture screw there is no "absolutely must be in this specific zone to be right"
Hopefully you read this well, understand it fully, and get it dialed in.
If not I'm always off/on lurking a comment away
