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Discussion Starter #1
So I got a new set of Vance and Hines today. I put them on, and if I slam the throttle, it hesitates at 3k. If I go smoothly, there’s no problem. I put 140 jets with one shim in during the ear shave. How do I know how far I need to go up with the jets, without buying unnecessary jets? There’s no exhaust leak that I could tell, and it worked great with the stock exhaust and even no exhaust


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Looks like you need to increase the pilot jet size to get a better transition from the pilot to the main.
 

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Discussion Starter #3
Looks like you need to increase the pilot jet size to get a better transition from the pilot to the main.


I may have 40/142. I can’t remember. I do remember I have one shim though. I heard that the shim helps smooth the transfer between pilots and mains. Is that an option? It is still super rich, and when it does start, it fires up immediately with no choke.
So you’re thinking 42/142?

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Rich? That's some new info.

40 pilot? New info.

I can't imagine making it richer will help at all. But that all depends on the actual situation currently in place.
 

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Discussion Starter #5
Rich? That's some new info.



40 pilot? New info.



I can't imagine making it richer will help at all. But that all depends on the actual situation currently in place.


I dug out the receipt.



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Almost everyone jumping to 42/142 has been too rich.
 

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Discussion Starter #7
Which is consistent to the write up done. So should I try adding a second shim under the needles? Or no shims? I am surprised it didn’t do this with no exhaust


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There's apparently enough restriction in the new pipes to make a difference.

Adding shims to the needles will make it richer. You can try to remove the shims and work from there, but you'll probably end up around 40/138-140. At any rate, you'll have to start over with the shims anyway.
 

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Discussion Starter #9
Okay. I will get those jets and let you know how it goes.


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Discussion Starter #10
So playing around with the hesitation when slamming on the throttle, I have found that using choke stops this, and it has a smooth transition. However, it pops on deceleration with the choke pulled. The exhaust is turning a nice blue as well. Doesn't the choke add more fuel, and restrict the airflow? That means it is making it even more rich than the 42/142...
 

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So playing around with the hesitation when slamming on the throttle, I have found that using choke stops this, and it has a smooth transition. However, it pops on deceleration with the choke pulled. The exhaust is turning a nice blue as well. Doesn't the choke add more fuel, and restrict the airflow? That means it is making it even more rich than the 42/142...
It's not a conventional choke with a butterfly that restricts airflow, but an enriching circuit. It still adds fuel to the mix.

Your description sounds like it's lean (choke helps .. bluing pipes and pop on decel). What color are the plugs?

Could be just a bad transition from the pilots to the mains, playing with the shims might cure that. Like maybe it's a bit too lean, so add a shim? Not sure where you're at with shims now. Or, it's just too lean on the pilot altogether.

Any chance the jets have just gotten dirty? 42/142 should be plenty rich.
 

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Discussion Starter #12
It's not a conventional choke with a butterfly that restricts airflow, but an enriching circuit. It still adds fuel to the mix.

Your description sounds like it's lean (choke helps .. bluing pipes and pop on decel). What color are the plugs?

Could be just a bad transition from the pilots to the mains, playing with the shims might cure that. Like maybe it's a bit too lean, so add a shim? Not sure where you're at with shims now. Or, it's just too lean on the pilot altogether.

Any chance the jets have just gotten dirty? 42/142 should be plenty rich.


Well... I’ve been running a full bottle of either sea foam, chevron concentrated, or Lucas fuel cleaner every other tank... so something could’ve gotten shaken loose! I can try adding another shim on the needle. I have one now. I have to fix that damn pawl spring again... for the third time... so I can pull the tank again during that time. Again, I have the advanced timing, ear shave and Vance and Hines. Sometimes the bike is mean and peppy, sounding better than most sportsters. Other times, it’s sluggish. It could be debris that is clogging the jets. I was running 91 octane all summer, until I saw here that it should be 89. Never ethanol though.


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