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Air mixture screw adjustment


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I've been tuning carbs since rebuild and it seems the more i turn the air/fuel mixture screws the better and more responsive and cleaner the sound of the exhaust...I'm at 4 1/2 turns out so far and the plug chop still shows a rich mixture?!? i ran into another banshee today and he said his was 6 1/2 turns out and let me tell ya it was fast...it has a very similar set up only diff is he has a pro curcit pipe and i have a DMC Alien. With that being said...In y'alls opinion is going 6+ turns out ok as long as the plug says it is???

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I've been tuning carbs since rebuild and it seems the more i turn the air/fuel mixture screws the better and more responsive and cleaner the sound of the exhaust...I'm at 4 1/2 turns out so far and the plug chop still shows a rich mixture?!? i ran into another banshee today and he said his was 6 1/2 turns out and let me tell ya it was fast...it has a very similar set up only diff is he has a pro curcit pipe and i have a DMC Alien. With that being said...In y'alls opinion is going 6+ turns out ok as long as the plug says it is???

are you doing wot plug chops? if so that will only give you a reading about your main jet

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I've been tuning carbs since rebuild and it seems the more i turn the air/fuel mixture screws the better and more responsive and cleaner the sound of the exhaust...I'm at 4 1/2 turns out so far and the plug chop still shows a rich mixture?!? i ran into another banshee today and he said his was 6 1/2 turns out and let me tell ya it was fast...it has a very similar set up only diff is he has a pro curcit pipe and i have a DMC Alien. With that being said...In y'alls opinion is going 6+ turns out ok as long as the plug says it is???

 

It seems like you are leaning it out with the air screw to compensate for large jets....6 turns is way too much. If you are at 2.5 turns and the plugs are showing rich (black and oily), then you need to go with a smaller jet.

 

Can you post picstures of the plug? Also, what jet sizes are you using right now?

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@ WOT the plug is wet and washed....i tinkered with the ar screws and it def likes 1 1/2 turns out best and thats what it was set to when i just checked the plugs 5 min ago....it is a 280 main havent touched the pilots other than takin out to clean the carb. also it dosen't chug but it is def a hesitation on gaining rpms. some somke till it clears out then it sounds different a lil and is vertualy smokeless, just the right looking amount.

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@ WOT the plug is wet and washed....i tinkered with the ar screws and it def likes 1 1/2 turns out best and thats what it was set to when i just checked the plugs 5 min ago....it is a 280 main havent touched the pilots other than takin out to clean the carb. also it dosen't chug but it is def a hesitation on gaining rpms. some somke till it clears out then it sounds different a lil and is vertualy smokeless, just the right looking amount.

 

If your plug is "wet and washed" after WOT, your main jet is too rich. Running rich will cause that hesitation you are talking about. You can try a 270 main jet and see if that leans it out the right amount.

 

Are you running the stock air box? Do you have pipes? What elevation are you at?

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If your plug is "wet and washed" after WOT, your main jet is too rich. Running rich will cause that hesitation you are talking about. You can try a 270 main jet and see if that leans it out the right amount.

 

Are you running the stock air box? Do you have pipes? What elevation are you at?

 

yes stock airbox, yes they are dmc alien, i'm in ohio....also it dosen't want to idle but if you just touch the throttle it idles(less then 1/8 maybe a 1/16 if that)

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yes stock airbox, yes they are dmc alien, i'm in ohio....also it dosen't want to idle but if you just touch the throttle it idles(less then 1/8 maybe a 1/16 if that)

 

Are you at a high elevation? Like 2,000 ft plus? If so, the motor will need LESS fuel, meaning smaller jets.

 

Your plugs are wet, which means rich, put in some 270 jets and see if that helps. Keep the screw at 2.5 turns out. Then do a plug chop.

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Are you at a high elevation? Like 2,000 ft plus? If so, the motor will need LESS fuel, meaning smaller jets.

 

Your plugs are wet, which means rich, put in some 270 jets and see if that helps. Keep the screw at 2.5 turns out. Then do a plug chop.

 

elevation is 738ft above sea level here UNCORRECTED....as to the rest will try in the am and thanks.

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  • 9 years later...
30 minutes ago, Conner304 said:

What do you mean your cases didn’t seal 

The case halves have sealant between them.  They didn't seal part of the case for some reason leading to an air leak. Then went chasing their tail with jetting due to said air leak.  This post is 10 years old. If you have a problem, make a new thread. 

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