Vacuum vent?

[rangerguy302]

Anyone out there ever hooked up the crankcase vent to the vacuum ports on the boots? Can't see it hurting anything but asking the goo-roo's. Happy turkey day

[Schming]

Not ever less you want to fill the intake tracts with blow by gasses.

It'd be best not to even hook it up to the air box.

[skids]

Anyone out there ever hooked up the crankcase vent to the vacuum ports on the boots? Can't see it hurting anything but asking the goo-roo's. Happy turkey day

You are better off to attach a filter and allow it to free vent. Just don't plug it off or it will cause oil gaskets to leak and can blow the cam chain tensioner cap off (if stock).

[DiverRay]

Also, you will NEVER get it to tune! the caps are on for a reason!

[rangerguy302]

That might be why I can't get this stutter out of it......well now I feel like an idiot 😂 I've heard the drawing a vacuum on the crank case would help power from some circle track guys. Thanks for the info guys

[TopCatGr58]

Hey Schming,

The OEM airbox has both the small hose ports for the early model carb vent tubes, but also a larger port for the crankcase vent hose to do just that, recirculate the blow by gases to help increase the chance of them getting burned, to reduce the overall pollutant type gases emissions from the crank case(EPA thing). It's just that when folks replace the OEM airbox with Pod filters is that they will just put a filter on the end of the crankcase vent tube and let it just sit behind the carbs/engine.

But we wouldn't recommend hooking it up to the actual boot intake ports, too much vac there, and could throw off the vac. signals to the carbs themselves. Connected to the Airbox allows the fumes to get swirled/mixed with fresh air and then get drawn into the carbs spread out across all cylinders.

T.C.

[Schming]

Hey Schming,

The OEM airbox has both the small hose ports for the early model carb vent tubes, but also a larger port for the crankcase vent hose to do just that, recirculate the blow by gases to help increase the chance of them getting burned, to reduce the overall pollutant type gases emissions from the crank case(EPA thing). It's just that when folks replace the OEM airbox with Pod filters is that they will just put a filter on the end of the crankcase vent tube and let it just sit behind the carbs/engine.

But we wouldn't recommend hooking it up to the actual boot intake ports, too much vac there, and could throw off the vac. signals to the carbs themselves. Connected to the Airbox allows the fumes to get swirled/mixed with fresh air and then get drawn into the carbs spread out across all cylinders.

T.C.

Yes T.C. I'm aware of all functions of the tubes, vents and breather just didn't have enough time to get into detail had to leave to go eat some Turkey

I installed a Moroso air-oil separator in the hose from the PCV to the intake manifold on my '96 F150 and I drain 'bout an oz. of crap that resembles baby sh!t every week.

Gonna put one inline on my bike and see how much gunk I can keep out of the engine.

I know, for environmental reasons, as you stated those blow by gasses are reburnt but if you've ever had the thrill of cleaning the upper intake on any vehicle those gasses really muck it up. I choose not to recycle waste through my engines.

And I do hold the drainings in a 3lb. coffee can to be taken to Advance Auto for recycling.

[MPittma100]

Vent

Don't see anything wrong with adding "positive" crankcase venting. Gases are already vented into factory air box. Would still use the air box vent along with positive vent.

Just have to insure that you don't draw oil out of crankcase. Keep in mind that the vacuum is only present at idle. Once throttle is open, vacuum is gone.

The potential of increased power that you mentioned is likely not there with the vacuum vent. The racing guys do gain horsepower from crankcase vacuum using pumps, but you have to have 10"-20" hg to gain performance.

[rangerguy302]

I just synced the carbs and didn't get anything close to that, mabe 7.5. what's a good number for the vacuum anyway? Or is even more important?

[skids]

As you can imagine, adjusting vacuum synch can not adjust compression. Vacuum synch can only compensate for differences in compression from cylinder 3 to the other cylinders (and other losses due to leaks, etc). I don't know what is "normal at 8800 ft elevation" is, which is where I live, but if you want to get a handle on compression, use a compression gage.

[motoman]

I just synced the carbs and didn't get anything close to that, mabe 7.5. what's a good number for the vacuum anyway? Or is even more important?

At your location, each of those four vacuum ports ought to have 18in. of vacuum at idle. That poor vacuum draw you show says the sync and especially the idle mixtures are way outa' where they are supposed to be. Thirdly, that low a vacuum draw says the spark from those coils IS way low. Need to check the voltage TO the coil plug-ins. Should be the same in both locations. In other words, battery voltage with key on should be the same voltage at coil plug-ins with key on also. 10 or 11 volts at coil plug-ins is not gonna work...period. This causes to low a voltage from coils to plugs, which will result in black plugs, mis-firing, poor mileage, poor power/accelleration etc., etc.

[rangerguy302]

That could be why the plugs are always black....du..... The idle mix is 2.5 turns out. In Billings MT don't know what the elevation is here. The sync is low but they are all the same, does that matter at this point? How would you recommend I get that up? The bike seems to have plenty of power but ive never rode one that was right. Has no issue pulling 2 passengers and a rack of luggage. Stop light to stop light it either eats or keeps up with most slant bikes.

[motoman]

That could be why the plugs are always black....du..... The idle mix is 2.5 turns out. In Billings MT don't know what the elevation is here. The sync is low but they are all the same, does that matter at this point? How would you recommend I get that up? The bike seems to have plenty of power but ive never rode one that was right. Has no issue pulling 2 passengers and a rack of luggage. Stop light to stop light it either eats or keeps up with most slant bikes.

Your at 3,100ft.elev.......still needs to be 18-19in. vacuum. 2.5 turns out on idle mixtures is to far out. Your location, they should end up bout 2 1/4 turns out at most. With that issue and possible low voltage TO coils definitely will give black plugs......and your missin' out on a whole lotta' potential power. In other words, you gotta' whole lot of work ahead to get ignition firing properly, afer which a whole lotta' carb settings corrected...THEN you might get to see how these ole' scoots should REALLY run.

[TopCatGr58]

According to Google, Billings is at 3,123 feet, or about 3/5's a mile up.
Therefore, atmospheric pressure it down about 3 inches of mercury vs. Sea level, and about 1.5lbs per sq inch as well. So there's a chance that jetting for sea level could cause you to be a little rich at your altitude.

T.C.

[ViperRon]

I did the 1198 over bore kit on my xs11 and I have had instances where oil was sucked into the airbox maybe as much as a table spoon in a short period of time. In my opinion it would be a good thing to put a valve in-between to prevent oil from going into the airbox. I have not spent a lot of time with this but I did on my last trip put a PCV valve in the hose where it connected to airbox and cap off the port on the airbox. I am unsure as to whether the oil in the airbox was due to an increase of pressure in the crankcase or increase of vacuum in the airbox after the overbore kit. I know I did not get oil in the PCV valve in the end of the hose. I was mainly looking for where my oil was being lost.