Vacuum leak on new Keihins

[Micah]

Hey all, need a little help from the community of twin straddling gurus. I've been working on a chop project for about 2 years now. It's almost all together now and I'm just chasing this damn tuning rabbit all over the garage trying to get it nailed down. It's a '75 motor with headpipes lengthened about a foot with 1.5" pipe, keihin PWK's with pod filters. I've been trying to get these carbs dialed in for my mods and altitude(4500ft), but have been having a hell of a time getting them right. First it had a hanging idle problem, and seemed a little rich so I rejetted it with a leaner(30) pilot. Then it was revving to high hell at idle, so I put the original pilots back in it, but still had a really high idle problem. Well after adjusting the mix screw a half dozen times(which is a real pain in the ass with the right side mix screw in the middle, btw) and couldn't get the idle to come down. SO, for shitzngiggles I pulled the starter fluid out to check for leaks again and sure enough the RPM's dropped when I hit it with the starting fluid...
So my Keihins have an air leak, not sure where yet exactly, I had to pack it up to head to class, but when I get home and pinpoint how do I fix it? I can't imagine it being a cracked boot since they're brand new with new gaskets and all, so is there a silicone spray I can use or what? Any help would be totally appreciated. Suggestions on jetting specs would be nice too!

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[Micah]

Well I did some snooping around today and the leak is definitely coming from around the right choke plunger? I can't tell if the boot that fits around the base of the plunger isn't sealing well or if the whole choke unit has a leak? I tightened it down but it's still leaking, any ideas on how to resolve? Any sealing sprays or sealants you guys recommend?

 

[retiredgentleman]

Have you read through this link;

http://www.xs650.com/forum/showthread.php?t=3446

 

[Micah]

I have, I posted in that thread a couple times... I'm going to try swapping the plunger assemblies across today to see if that will clear it up. If it doesn't I don't know what I'm going to do though...

 

[rwingsfan]

You might want to try a set of bs 38

I have, I posted in that thread a couple times... I'm going to try swapping the plunger assemblies across today to see if that will clear it up. If it doesn't I don't know what I'm going to do though...

 

[Micah]

Well I still have my originals 38's but they're off of my 75, so I was battling a sync issue since they are independent of each other... that's why I bought these pwk's in the first place...

Update: Switched choke plungers across and now they both leak... This is retarded, to put it bluntly. Guess I should have known the price was a little too reasonable...

I can't tell if it's the boots on the plungers, but I think so as the plunger assembly is tightened snugly down on the base. Any ideas or suggestions?

 

[grizld1]

Micah, synch issues may well be aggravated by poorly made junction tube and slides on the PWK replicas. Synch on the pre-76 OEM carbs is indeed touchy. You not only need to set the throttle plates to the same idle opening, you have set the throttle cable slack adjusters so that the throttle plates open at the same time. And since slack adjustment will vary somewhat between the two sides when the front wheel is turned (that's why we need slack in the cables to begin with, to keep the throttle from opening when we don't want it to), it's a good to set slack with the front wheel pointed straight ahead. Conversion of the OEM dual cable system to a split cable system with a quality junction tube and in-line adjusters in the secondary cables might improve things, but it's possible that the wide spacing of the throttle shaft perches could cause the secondaries to bind. Has anybody tried it?