new carb, intake leak questions

[bump]

I decided to replace my old carb with a new one.
Bike is a late 78 FXS stock motor with staggered duel exhaust. Rebuilt top end over winter.
Ran a S&S B for the last 35 years and wanted to go to something with accelator pump.
Got a S&S E for a good price new. when started and idling it won't stay running like an intake leak. This has the rubber band intake seals Have removed intake and installed.

My question is which intake seal is better bandtype or oring.

[JW113]

I personally prefer the O-ring type in conjunction with the two piece solid brass clamps. I've used the band type in the past, but these don't work so well on heads/intake manifolds designed for the O-rings. I don't recall the exact year, perhaps 1980 (?), when they eliminated the stepped flange on both heads and manifolds that the O-rings set in. With the O-rings and solid brass clamps, the intake manifold is pretty much locked solid to the engine, and does not wiggle around as with the band type clamps. I actually had the carb & manifold fall out of the intake seals once when I was using the band type.

Another thing about the band type, it's critical you use the correct clamps, meaning the type that has a split through the center. I ultimately was using two very narrow metric clamps, on on the head spigot and one on the intake spigot, on both F & R. But then swapped the whole mess over to the O-ring type a few years ago.

-JW

[Fugawee]

I have had better "luck" with the O-ring style.  I have owned a 76' FXE, an 80' FLH, and an 80' FXWG.  Still have the FXWG.  Replaced a few of those seals.  Like I said...the O-ring seemed to work for Me.  I have also used different types of Intake Manifold Clamps.  Some better than others.  I have used the 2-piece style, and the ones that have the threaded portion that kind of swivels into the nut.  Depending on the Clamp style I have run out of thread and had to add some by means of a die to ensure that the Clamp tightened up accordingly.  After doing some Top-End work on one of them, I had to loosen the head(s) up a little to "tweak" and properly line up the Intake Manifold.  I prefer the 2-piece version of the Clamps.

Way back when in Easyriders Magazine...when they had some decent "Tech-tips", it was said by someone on their Staff to wrap a little Electrical Tape around the O-ring style, and Manifold before putting on the Clamp to hopefully eliminate any leaks.  I never did that, but some say it works.  I have also been told that some have used both the O-ring, with the Band Style over that.  I've never done that, and don't recall knowing anybody personally that did.

A Buddy of Mine has a 77' FXE and put an S+S Super "E" on it years ago.  He was always saying that it didn't run right.  Ran OK...but not great.  He had an Intake Manifold leak which He found really fast while riding one day.  He spaced out and never used the Carb Support Arm.  The Intake Manifold and Carb almost fell completely off the Bike.  Not using the Arm put too much tension on the O-rings and Clamps.  Lesson learned there.  Good Luck!

[JW113]

Indeed, when using the O-rings and clamps, you need to take some care as to how the head are installed. With both heads loose, you "dry fit" the intake manifold with no O-rings so all of the spigots line up properly, and then tighten the head bolts. Then remove the intake manifold and install the O-rings. I'm guessing this is why HD moved away from the O-rings, less labor to assemble the engine as the band type seals are more forgiving of intake/head misalignment. So they probably skipped the dry fit aligning steps.

-JW

[bump]

This bike has the band type since new (one owner). The intake has the step for the oring style. I will get a set of oring style clamps. I have replaced the bands but not sure of the stock clamps.

[JW113]

If you are going to go with the band type seals, you can find these plastic rings that can be glued into that step in the spigots to eliminate it. If you dig around a bit on ebay, can probably find a later style manifold without the step (I did). May not be absolutely necessary, but anything to prevent intake leaks is a good thing.

-JW

[JW113]

Here is a pic of the two styles of intake manifolds, O-ring and band style, along with the correct band style clamp, and a narrow clamp that you can tight down correctly on both spigots.

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-JW

[76shuvlinoff]

I haven't touched it in 16 years but I have the O ring seals with a wrap of electrical tape over them and band type clamps.

[david lee]

Here is a pic of the two styles of intake manifolds, O-ring and band style, along with the correct band style clamp, and a narrow clamp that you can tight down correctly on both spigots.

You cannot see attachments on this board.


-JW

ive run the band type for 35 yrs with no problems

[Excalibur]

I used a set square with a 60° angle to get intake spigots at exactly correct degrees. Happy with result and will use method again.

Give me O-ring style any day...

[72fl]

O-ring's here also had the ol girl 23 years now sure it can be a bit of a tussle but they work

[bump]

I got a set of oring style clamps, the brass ones. It fired right up and idled. Let it warm up then adjusted idle speed. Rode it about 10 miles and adjusted idle speed and idle jet. Set accellarater pump. Will try it for a while but think it needs next bigger pilot jet.