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New build high vacuum


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Just put together a 392 and while syncing the carbs we’re getting close to 20 psi with idle gauge and having a hard time getting it down. Sounds good, but This doesn’t sound right to me and I’m not super familiar with pwk carbs. I kept My stockers around 5 psi idle and 10 under load, I cant Get anything that low here....

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What are u measuring thats 20 psi? Are you using a vacuum gauge or a flow meter?
I usually set idle to around 1500rpm and use a flow meter to sync the idle screws.
Verify that there is slack on the throttle cable. Turn the idle screws out and if the slides don't bottom out, then the cable doesn't have enough play. You may have to adjust the low speed jet to get acceptable idle.

What carbs and jets?

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7 hours ago, Keno said:

What are u measuring thats 20 psi? Are you using a vacuum gauge or a flow meter?
I usually set idle to around 1500rpm and use a flow meter to sync the idle screws.
Verify that there is slack on the throttle cable. Turn the idle screws out and if the slides don't bottom out, then the cable doesn't have enough play. You may have to adjust the low speed jet to get acceptable idle.

What carbs and jets?

Just using a carb sync tool trying to tune them in. PWK 35. Jetting is good, but throttle cable may be short 🤔. Using stock throttle cable...

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I think I did slack in throttle housing first, then bottomed the top screws all the way out, then made adjusted the slack on the tops to make sure that both carbs open ALL the way, then start bike and adjust idle syn.  part throttle syn you can do that by eye, you know if the slides are opening at the same time just by looking, thats just my opinion though other will disagree.  

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