PHBG Issues

[McScooterson]

Hey all,
I've been having a difficult time tuning in my PHBG 21mm dellorto black carb. My plug was coming out black on one side and brand new looking on the opposite side.
I've had two suggestions now that it is because I have a lean spot in one area, and a rich spot in another.

I've now narrowed it down to being lean in the pilot circuit, and rich in the needle and main jet.

My setup;
MHR 70 A/c hor. Minarelli
yasuni c16
21mm carb

Now I have to order a "leaner" needle because I already have the clip on the top notch.

Does anyone have experience with this?

The stock needle in my carb is a W7. How much of a leaner needle should I buy? Should I purchase a different atomiser to go with the new needle or will the stock atomiser work?

And one last question, will a PHBG 18mm needle work in a PHBG 21mm carb?

Thanks for you help
Mike

 

[EGT]

I don't have much experience with the PHBG21 black edition, but do have experience with the PHBG19 carb.
I think the are comparible carbs in tuning and adjustment.

First check the atomiser, it should be of the type: 262 AU
If it's not (262 AN), you should insert an 262 AU atomiser, maybe you must also change the shroud to insert it. (jut use the normal PHBG 19BS shroud)
The W7 needle is already kinda lean.

Insert a W16 needle in the leanest position, and it should run fine.

Also check the idle jet and mixture screw.

 

[McScooterson]

Is the 262 AN a 4 stroke atomiser?

Idle jet is little lean, its a size 50.

Main jet is rich, its a size 92.

 

[McScooterson]

Thanks, I just ordered a W16 needle along with my main jets from CIH.

Hopefully this will cure my ill.