newbie Vacuum advadce hook up w Keinhin CRS

[badbrown]

My bike is a 79 standard with the vacuum advance. I'm Currently running the VAC adv. hose to the intake boot on the number two because I have the Keihin CRS smooth bores. Any how the bike only idles high at 2000 rpm. Can't get it to drop and then idle smooth. Does this mean I have too much vacuum to the adv unit? I read a post about sticking a pilot jet in the hose. Am I on the right track? I'm usually a suzuki GS guy. But I just got back my old xs and it is sweet and havent been able to ride yet do to these minor technical issues.

[petejw]

yep ur on the right track
with restricting the vac hose.
or u can leave it disconnected altogether,
depending on ur style of riding.

[thewiz]

Well ...

Restricting the vac advance is primarily to smoothe out the vacuum pulses so the vac advance doesn't 'hammer' (move rapidly back and forth and make a loud sound). This is especially helpful when putting the vac hose on a non-ported source like a carb boot port.

Try leaning out the idle mix screws a bit at a time .... also if you use a dual cable system, as I do with my Mik smoothe bores, be sure the cables allow the throttle close all the way. Theoretically, you should be able to 'pull' the throttle valves all the way closed with one cable. A good sync is very important on these carbs as well.

[badbrown]

Cool. So I should at least restrict the vac but leave it connected to the #2 boot. Also I 've only done bench sync so far. And I'm 2 turns out on the Idle/air screws. I don't want to hook up the merc sticks until I can control the idle. Don't want it to suck into the engine. I'll try again in morning and post results.

[tarzan]

You know that if they are out of sync they will idle high or eratic and sometimes the idle start climbing.Also you dont say if you turned the big knob under the center of the bank of carbs.If not try that.It should drop if you turn it counterclockwise.But it may be the sync is too far off.
Also spray some wd40 around anything that can leak air.You probably already know that a vacuum leak will do that too.

[Bigleo]

Hi, I have the CRS carbs on my XS as well. You may be running a bit lean on the air screws at two turns out. Mine runs best at 7/8 of a turn out. I am running pod filters as well. If I turn them out any more, I get lean mixture backfires thru the carbs, even at 1 turn out. If you know of any info on how to synch the slides on these carbs, could you let me know? The Keihin site tells you nothing.
Thanks
Leo