leaning out in 4th

[allanr5gtt]

hi all just spent the day trying to set the fueling up and it still leaning out at 13.1 ish in the top end of 4th about 6/6.5 22 psi carb top

the spec of the carb is main jet 1.50, ac 0.9, e1 std, e2 1.35,

i not sure if it's emptying the carb bowel or i need to up the e2 to a 1.40/1.45

just looking for other peoples veiw's on fueling.

thanks allan

[Markey Mark (BD)]

What size is the needle valve mate?

[allanr5gtt]

good point i thinks 1.7 but not 100% on that.

[Markey Mark (BD)]

If it is worth trying a 2mm one in there, also main seems quite big whats the venturi size of the carb and whats fueling like off boost?

[BluntyR5GTT]

i thought that main seemed rather big tbh, defo try a 2mm needle :agree:

[allanr5gtt]

venturi size 27mm i think, it was built by mike 48 for me a few years ago all i have done is put a smaller ac and yes it's on the rich side off boost. is it worth try 140 main? and i will check the size of the needle valve?

[Markey Mark (BD)]

venturi size 27mm i think, it was built by mike 48 for me a few years ago all i have done is put a smaller ac and yes it's on the rich side off boost. is it worth try 140 main? and i will check the size of the needle valve?

Yes might be worth trying a smaller main in there to lean it out abit off boost, increase second stage alittle more if it then leans on boost abit. Trouble with large venturi is you have to compensate the larger venturi with a larger main, sometimes best going back to standard venturi but its not impossible to make it work better than it is now.
For that boost pressure i'd prob say it'll be the needle valve that needs enlarging, 2mm seems to work well enough.

[allanr5gtt]

Yes might be worth trying a smaller main in there to lean it out abit off boost, increase second stage alittle more if it then leans on boost abit. Trouble with large venturi is you have to compensate the larger venturi with a larger main, sometimes best going back to standard venturi but its not impossible to make it work better than it is now.
For that boost pressure i'd prob say it'll be the needle valve that needs enlarging, 2mm seems to work well enough.

thanks for your info i will let you know how i get on.

[allanr5gtt]

it's not looking good
just took it out again turned the boost down 18psi creeping to 19psi afr around 12.5/12.7 so i thought i was getting there.
sitting in traffic a hear a light niose sounds like a lose tappet so i get home give it a few light rev's i still think it a tappet after taking the rocker cover and checking the tappets i have put it down to slight piston slap only very light but there is definitely some there.

question is now
is it worth just replacing one piston?
does any where sell just pistons, pins and the rings? (liner's are not needed as i'm useing steel's)
i forgot which piston are strong perfect circle, ktr (meant to be made by p/c) or Tarabusi?

any other info i would be very great full.
thanks allan

[jonnyshaw49]

cgb sells pistons and liners seperate mate, make sure everything is equal weights though, con rods, pistons etc, so its nice and balanced, you might have different compression in the new cylinder but dont know how that will go on

[allanr5gtt]

do you know the make of cgb's pistons?

[jonnyshaw49]

no mate but i remember looking into it there as strong as the tarabusi ones, what power u running?they should be fine

[allanr5gtt]

no mate but i remember looking into it there as strong as the tarabusi ones, what power u running?they should be fine

don't have a clue on power it's gotta be 200bhp+.

just remember as i'm steel liners am i going to need different rings? total seal rings ring a bell for steel liners but i maybe wrong?

i had think best to replace all piston as it's not worth mixing make's. so the next thing is which piston are stronger than others? and which are better with steel's?

allan

[allanr5gtt]

do you think the over fueling off boost would of cause the piston slap?