question

[patthesoundguy]

The idle air screw shouldn't have that much effect on 3/4 throttle. The idle pilot is for idle and and transitioning from idle into the throttle.

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[devenex]

Yeah, 3/4 throttle should be affected by a combination of main jet and needle settings.

[dv/dt]

Where is that handy picture Bear posted showing which jets affect which throttle ranges?

As said above, 3/4 throttle and up is all main jet size.

[swimmingfree]

swimmingfree

[devenex]

Thx for posting that pic sf. Guess I mis-remembered needle taper as clip position (aka 'needle setting' in my amazing brain).

Your CHT's seem a bit warm to simply be one step below rich and backfiring. Have you done any plug chops?

[patthesoundguy]

That stuttering is probably what we refer to as 4 stroking, which usually indicates a rich condition, which is why it got worse when you went richer. Me personally I would put the needle in the middle, get the idle pilot jet figured and get it to idle at the right mixture then I would get the main jet close as I could and get the WOT figured out then I'd fine tune with the needle to get the mid range to be smooth. What carb is it, is it a 4 stroke carb or 2 stroke carb. Sometimes 4 stroke carbs just won't work right because the atomizer is all wrong. I'm only putting that out there because you said it was a random carb.

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[patthesoundguy]

Maybe I was just lucky, I have a 19mm phbg delorto on my express, it wasn't that complicated to set up. I got the idle pilot right so it would idle right and i could properly set the idle mixture. Got the right main jet so it ran right at wot and the rest fell into place with the set up it came with from treat land. It can be a pain to get a carb dialed in sometimes.

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[bushpigwillie]

Have you done a plug chop at 3/4 throttle? That's how you're going to see if you are lean or rich. Do you know how to do a plug chop? After the chop, you pull the spark plug and look at the color down in the ceramic. Wet, black is rich. Dry tannish brown is safe. Dry light tan or white is lean, unsafe.

[ringLord4]

I just did a plug chop and I'm getting a white color. It's white on one side and darker tan on the other. Question is, how do I make it richer?

I'm premixing oil and gas at about 32 to 1 right now. I have the screw on the carb (one w/out the spring) turned 1 7/8th's out and my air mixture screw (one w/ spring) turned out almost to the point where my tire is not spinning at all when on the stand and idling.

I am running Taz's big bore kit 48mm and I am carefully breaking it in, which is why I am being super cautious about the plug chop.

I also did a compression check tonight to make sure all is A-OK and it was holding at about 124 (did the test after a short ride. WOT during compression test too). I know it's good there.

I have a larger jet, the one provided with Taz's kit (from ebay) and along with it I have taller gears, and 3, 1" holes in the air box with uni filter plugs in it to open up the air flow. (Otherwise it goes slow) What do I do?

[bakaracer]

check for air leak or exhaust leak. the white on one side is the tell tale sign. try tighten the exhaust flange nut and see if its loose. check head bolts too.

[ringLord4]

That would definitely be a factor. I don't have exhaust studs right now. I have one bolt holding in half of the exhaust where it connects to the head. Studs in mail!

[paulpauly7]

i wouldnt be running it if the exhaust isnt properly secured

[ringLord4]

Ok, thx for the tip!! I won't run it till I get those parts. Snail mail in process for em