Idle Speed and Petcock Vacuum hose

[RobertC]

So, here's a dumb question.... If you had the idle set to around 900 - 1000 RPM.... And then you added Berrymans, Techron, or some other cleaner to help clean out the slow jets... Would the idle start to increase as the jets start working better??

Also, in all the posts I've read the reference to the vacuum hose has always bee to connect it to carb 6. Mine is running from carb 3. Does it matter where it is running from as long as there is a vacuum line going to the petcock?? Mine was like that when I got the bike...

Robert C.

[big poppa pump]

I had mine connected to carb 4 when I bought the bike and had it that way till about a month back before I switched it over to carb 6. Did not make any difference.

[Patrick]

You probably won't a difference in the idle speed unless things are really varnished. The idle speed changes more with engine temp than anything else.

Vacuum is vacuum is vacuum [well, almost. In case it is.]. It won't make [ or shouldn't make] any difference which intake the petcock line is hooked to, in fact, it just may help to ' T ' it to a couple intakes.

[97Valk_CT_Euless]

I did my desmog without instructions so it's alittle odd.  One of the things I did was to manifold all the intake ports together through the 6 connector manifold that came out of the bike.  Tool alittle adapting but the petcock vacuum came from there.  THought it would help balance everything and keep the pulsations off the petcock diaphragm.  Works, though I can't tell it's balanced any better, probably too small of lines to really effect that.

Anyway, point is it's just vacuum.  As long as it isn't switched through a carb circuit or something.

[RobertC]

Thanks for the replies.... I may need to take a look at other components to see if I can figure out why it idles so high after the engine has warmed up pretty good....

Robert C.

[Daniel Meyer]

Thanks for the replies.... I may need to take a look at other components to see if I can figure out why it idles so high after the engine has warmed up pretty good....

Robert C.

That is typically a sign of a vacuum leak.

I'd do vacuum leakdown test on the petcock, inspect (carefully) all the caps and vacuum lines. They tend to split quite near the manifold port...and possibly need to change the intake o-rings or tighten the clamps that hold the intakes to the carbs.

It *can* also be a sign of badly out of sync carbs...but the vacuum leak is more typical and the carbs shouldn't be *badly* out of sync unless work has been done to them...and out of sync will also often cause "surging" at idle.

[Patrick]

Set the idle speed to 900 rpm when the engine is at full operating temp.  It will then be quite a bit lower during a cold start [ 500-600] depending on OAT.

[BradValk48237]

The only thing I would say its that #3 is the one you use to set all the other vacuums against.. and I think that is also the one that the idle screw directly affects( I know is has something to do with ##)

So because tis hooked to the petcock is hooked to it it might cause balance issues...

I would hook it back stock to #6......

B

[RobertC]

Ok. Got home from work. The engine was idling at about 2k. Grabbed a couple of tools and adjusted it down to about 900 to 1000. I remember a week or so back I had to gently straighten out the idle screw. I had never messed with it until then. Appears the PO or someone else had bent it. Still finding little gotchas that had been done to the bike even a year later.


Robert C.

[John Schmidt]

I did my desmog without instructions so it's alittle odd.  One of the things I did was to manifold all the intake ports together through the 6 connector manifold that came out of the bike.  Tool alittle adapting but the petcock vacuum came from there.  THought it would help balance everything and keep the pulsations off the petcock diaphragm.  Works, though I can't tell it's balanced any better, probably too small of lines to really effect that.

Anyway, point is it's just vacuum.  As long as it isn't switched through a carb circuit or something.

Keep in mind....the main purpose of the desmog is to get rid of all those vacuum lines on top of the engine. Thereby decreasing substantially the chances of a vacuum leak. By doing what you described, you really accomplished nothing. Get rid of all the extra lines and hook just one directly to #6 and be done with it. Then if you have a vacuum leak you'll have one line to check. As for why it's hooked to #6, probably because it's the easiest(possibly the closest also) vacuum port to access.

[Patrick]

Ok. Got home from work. The engine was idling at about 2k. Grabbed a couple of tools and adjusted it down to about 900 to 1000. I remember a week or so back I had to gently straighten out the idle screw. I had never messed with it until then. Appears the PO or someone else had bent it. Still finding little gotchas that had been done to the bike even a year later.


Robert C.

No tools needed to adjust the idle speed, just your little fingers.

[Jess from VA]

No tools needed to adjust the idle speed, just your little fingers.

If doing so on a hot bike, you may also require some burn medication.

[RobertC]

That's why I used the tools. :

[John Schmidt]

Only tool needed to adjust the idle knob is a screwdriver. No burns and you can move it either direction.

[whitestroke]

When my carbs were gummed up and I added Techron the idle did go up quite a bit after only a couple miles of riding.
I hope your adjusting the correct knob for idle.

[RobertC]

John.. Guess I should have been a bit clearer on tools. I used a couple of screwdrivers.. The idle screw was a bit stiff.

I REALLY need to pull the carbs and give them a good going over. I am collecting all the parts necessary to do just that.

I don't remember if I mentioned earlier, the bike only had 32000 miles on it when I picked it up. I think it sat idle more than it was ridden and I could find prof of any kind of maintenance had been done on the bike other than the air filter was replaced with a K&N and the individual I got it from said all he ever did was have the oil changed.

I have had bike a year now and am still learning a lot about these beast, mainly from searching this forum and talking with a few of the guys I have met here in Texas.

Robert C.