Best way to find an air/vacume leak

[garyS-NJ]

Over the years, I have tried propane, carb cleaner, brake cleaner, and water. I think the propane worked best.

I have these bst34's on my '90 kat11 and as purchased not running, and after cleaning carbs, the idle is sticking high but sometimes drops down and then it's real low and misfiring. Really seems like an air or vacume leak.

I've posted in the katriders forum without too much love yet.. after the initial carb clean, I cleaned all the plugs (they looked new) and trimmed 2 of the plug wires to get it firing on all four. It pulls hard with the throttle open but I will check compression. It's jetted for a k&n air filter and 4:1 pipe and I moved the fuel mix from 1&7/8 to 2.5. And I tried the stock air filter without changing anything else..

Oh the air leak, I couldntg locate anything with sprays but I changed the intake manifold o-rings and made sure my intake and airbox boots are sealing well. I'm really thinking it's the choke plungers.. but they are actuating nicely and go all the way home.

Oh, locating air/vacume leaks?

[fbody_mike]

I have found using a really long piece of fuel hose as a stethoscope works great. Stick one end in your ear and probe around with the other end, I found you can hear some vacuum leaks, this also works for exhaust leaks too.

[Burque73]

Do you use a vape, e-cig, or whatever the kids call them now? I have always wondered if since they produce a dense cloud of vapor, maybe slowly blowing it around the engine some would reveal an intake leak.

[garyS-NJ]

Surprised I didn't get more responses here. Maybe if I asked about oil or tires.. anyway, thanks fellas.. I got a few pops spraying carb cleaner near #2 even tho I just changed the intake boots and the clamps seemed tight. But I'm yanking them and found a spare set of intake manifolds gonna Give that a try. This shouldnt be that hard... thanks fellas.

[Guest]

Maybe not much love since you covered all the bases already in your initial post. I use carb spray and it was already on your list. Have you checked the screws that plug the holes for syncing the carbs and any vacuum lines for leaks?

[pdqford]

I use my Home Made smoke machine.

[pdqford]

And here is how I attach it to the intake.

[garyS-NJ]

what did I check?

thanks. there is only one vacume line coming off the carbs for the fuel petock. I have it plugged while tank is off and didn't detect a leak at the other side although its hard to shoot card cleaner down there. for t sync ports they are threaded holes in the carbs and Ive had this problem before and after installing the motion pro tubes

Maybe not much love since you covered all the bases already in your initial post. I use carb spray and it was already on your list. Have you checked the screws that plug the holes for syncing the carbs and any vacuum lines for leaks?