May be on a Harley #2

[MasterGuns]

Good evening all. Just came in from the garage where I was beating myself up with this problem, i.e, #2 air valve not responding to throttle whatsoever. I ensured the vacuum port was clean and clear by squirting B12 through the port and it exiting from the top of the carb; then used moderately high pressure air with the same results. The diaphragm is good, no holes, no tears and attached with no separation. The small oring was/is in place. Carbs sync perfectly creating 24 mb of hg at idle (1050 rpm). Plug is firing. Good vacuum at the boost sensor vacuum port on the carb manifold. Everything checks out except for a dead air valve. What the h....! I have two more nights to figure this out or I am left with taking my Ultra to the rally. I really won't mind doing that but I would much rather ride the Venture because it is a much better bike. Any more ideas. H______E_______L________P!!!!

[Squeeze]

First off, I'd try to isolate the Problem by exchanging the Sliders with the Carb next to it.

 

If the Culprit is the Slider, the Problem will be at the other Carb and the #2 Carb should be back in Business as normal. While doing so, I'd check the Lifter Holes in the bottom of the Sliders.

 

If the Problem stays at #2 Carb, there's an Air Passage clogged. Air Passages come from the upper Carb Throat(the big oval Hole), a Passage is inside the Diaphragm Bowl Cover sealed with the small O-Ring(check both Direction where the O-Ring is) and one Passage is going through the Brass Jet(PAJ#2-Size 170) behind the Diaphragm on the right Side.

 

Be careful while blowing compressed Air through that Passage because there's another small Diaphragm sitting on the Side of the Carb which might be damaged if your get to much Air into the Passage.

 

Basically, if blow Air with the Air Gun carefully into the oval Hole in the Carb Throat the Slider should move.

Edited July 28, 2009 by Squeeze

[MasterGuns]

Hey Squeeze, Thanks for the input. But with Randya's advise last night, I finally think I have found the problem. I sprayed starting fluid in and around the intake manifolds of #2 and low and behold the rpms went up quite a bit.....VACUUM LEAK. I also checked all the others joining points between the bottom of the carbs and the manifolds and the heads with "positive" results as well. Only number 3 seemed to be tight with no vacuum leaks. Since this is a fairly "new to me" 86, I think the PO had the carbs and manifolds off and either didn't install the o-rings or used defective o-rings. Who knows, until I pull the off and inspect the manifolds, what else may be wrong. My only problems is getting the parts quickly in order to use this VR for the rally. Otherwise.......

[CrazyHorse]

Hey Squeeze, Thanks for the input. But with Randya's advise last night, I finally think I have found the problem. I sprayed starting fluid in and around the intake manifolds of #2 and low and behold the rpms went up quite a bit.....VACUUM LEAK. I also checked all the others joining points between the bottom of the carbs and the manifolds and the heads with "positive" results as well. Only number 3 seemed to be tight with no vacuum leaks. Since this is a fairly "new to me" 86, I think the PO had the carbs and manifolds off and either didn't install the o-rings or used defective o-rings. Who knows, until I pull the off and inspect the manifolds, what else may be wrong. My only problems is getting the parts quickly in order to use this VR for the rally. Otherwise.......

 

Remember you have to get the carbs correctly seated all the way into the boots both top and bottom. I always found it hard to seat them with the all the carbs tightend together before putting on the bike. I always left them a little loose so they could individually move a little bit and slide in thier respective boots. I could get some to seat correctly while others would pop out slightly if I had the carb block all tightend down before putting on the bike.

 

After I get them seated properly even though its hard sometimes I tightend up the carb brackets while on the bike. Now it easier on mine since I used allen head screws instead of the regular phillips head on the carbs and thier brackets. If you use the regular phillips youll need one of those 90 degree angled screw drivers.

[Squeeze]

Remember you have to get the carbs correctly seated all the way into the boots both top and bottom. I always found it hard to seat them with the all the carbs tightend together before putting on the bike. I always left them a little loose so they could individually move a little bit and slide in thier respective boots. I could get some to seat correctly while others would pop out slightly if I had the carb block all tightend down before putting on the bike.

 

After I get them seated properly even though its hard sometimes I tightend up the carb brackets while on the bike. Now it easier on mine since I used allen head screws instead of the regular phillips head on the carbs and thier brackets. If you use the regular phillips youll need one of those 90 degree angled screw drivers.

 

Or you could use standard Hex Bolts ....

[CrazyHorse]

Or you could use standard Hex Bolts ....

 

Yes you could another option in the toolbox.

[Dano]

Would a good RTV or Yamabond type sealer work on sealing up the manifold-to-head connection? Make SURE the long screws go in the upper holes! They will leak if you don't!

 

Good luck, and we don't need an HD at the rally! Unless you have to, of course.

 

Dan

[MasterGuns]

Pulled the carbs off last evening expecting to find obvious evidence of a vacuum leak with the #2 intake manifold but as far as I can tell, it, as well as the other three rubber intake manifolds appear to be fairly new; no cracks at all, shiny, smooth and in really great condition. I question the reliability of the seal between the head intake port and each of the manifolds because the o-ring seemed to me to be a whimpsy excuse for an o-ring. I suspect the PO "improvised" on the o-rings by replacing the OEMs with something he picked up at a local hardward store. I will know more once I can compare the o-rings I removed to the new OEMs I will be picking up from mother Yamaha early this after noon.

 

To ensure a good seal, has anyone used some sort of sealer on these 0-rings? I would think whatever is used would have to be able to withstand higher than normal heat. Does anyone think Yamabond could work? What else might someone recommend? This is a lot of work and I just don't want to tear these doggone carbs off again. What really gives me fits is reconnecting the throttle cables; choke is too easy.

 

Hope all this effort pays off and I don't have anymore vacuum leaks when fully reassembled.

 

Thanks for reading and any advise thrown this way concerning sealer would be highly appreciated.

 

Thanks

 

Herb

[Squidley]

Herb,

Yamabond or a good quality high temp RTV will work, no worries about it getting too hot for those products.

[Venturous Randy]

Normally, on an o-ring application, what works best is being real clean. But, since this is more of a gasket application, a sealer may be ok.

RandyA

[MasterGuns]

#2 (front left) carb air valve (diaphragm) wasn't working. Randya thought it was a vacumm leak and he was right. While tearing this thing apart and inspecting parts as I removed them, I couldn't find anything that looked faulty so all I could do was reassemble everything being very particular as I went. To make a long story short, the inside bolt hole on the #2 intake was striped which made tightening that manifold impossible. Just another thing the PO failed to mention as I am sure he knew about it. Fortunately those holes are much deeper than the OEM allen head so the fix was to use a longer allen head, about 3/8 inches longer. All I know it that it worked for me and all is well. The once dead air valve is now as active as all the others. Carbs synced just fine. All I have to do is take it for a ride tomorrow after work and find out how she runs now. I think it will run like never before since the dead valve hasn't operated since I've had her. I did do a test spray of ether around all the manifolds with no reaction; a very good thing. A great big "Thank You" to all you guys who provided input and advise. This is great organization.

[Yammer Dan]

Good News. And you provided some great info for us to remember here. Glad you got it fixed. Be carefull in those lower gears in that test ride. You might find it on its back wheel!!

[CrazyHorse]

Pulled the carbs off last evening expecting to find obvious evidence of a vacuum leak with the #2 intake manifold but as far as I can tell, it, as well as the other three rubber intake manifolds appear to be fairly new; no cracks at all, shiny, smooth and in really great condition. I question the reliability of the seal between the head intake port and each of the manifolds because the o-ring seemed to me to be a whimpsy excuse for an o-ring. I suspect the PO "improvised" on the o-rings by replacing the OEMs with something he picked up at a local hardward store. I will know more once I can compare the o-rings I removed to the new OEMs I will be picking up from mother Yamaha early this after noon.

 

To ensure a good seal, has anyone used some sort of sealer on these 0-rings? I would think whatever is used would have to be able to withstand higher than normal heat. Does anyone think Yamabond could work? What else might someone recommend? This is a lot of work and I just don't want to tear these doggone carbs off again. What really gives me fits is reconnecting the throttle cables; choke is too easy.

 

Hope all this effort pays off and I don't have anymore vacuum leaks when fully reassembled.

 

Thanks for reading and any advise thrown this way concerning sealer would be highly appreciated.

 

 

Thanks

 

Herb

 

Its easier to attach the cables while the carbs are not seated in thier boots.

[Venturous Randy]

Looks like you done good Herb. It was a good lesson for all of us and we appreciate you posting the details.

You should get a lot better sync now and I bet it does run stronger and smoother. That should also help with the vibrations on the grips.

Oh, and you do a good job representing us 1st genners at the rally on that thing.

RandyA