Reoccurring intake leak. Help please gentlemen

[Ohio HD]

To me as long as you have a slight gap between the heads and manifold, when everything is aligned, it should be sealing. As long as you know it can be aligned without binding, as was described above to check, you should be fine. You mentioned it was hard to start the last bolt, are you threading three in most of the way then trying the fourth bolt? You could be binding against the seal at that point and that's why the bolt has resistance against the flange. Assuming the bolt threads freely with nothing around it. I use silicone spray this last time on my intake seals. Spray it all over them, then shake the seal to fling off excess. This allows movement of the intake all the way up to the final tightening of the four fasteners. Also, if you are not already doing this, tighten the four fasteners about 1/2 turn each after they make contact with the flange. Finger tight to the flange, then 1/2 turn each till they are tight.

[kd]

   and would add .... keep a watch on the flanges to see that they are level with the head surface before you start to cinch them down (using the system Ohio explained that moves each fastener a little at a time until home).

[FXDBI]

  and would add .... keep a watch on the flanges to see that they are level with the head surface before you start to cinch them down (using the system Ohio explained that moves each fastener a little at a time until home).

Also check that you not bottomed out on the last threads.  Bob

[misfitJason]

  and would add .... keep a watch on the flanges to see that they are level with the head surface before you start to cinch them down (using the system Ohio explained that moves each fastener a little at a time until home).

Also check that you not bottomed out on the last threads.  Bob

What do you mean by not bottomed out?  Are you talking thread depth into the head?

[FXDBI]

  and would add .... keep a watch on the flanges to see that they are level with the head surface before you start to cinch them down (using the system Ohio explained that moves each fastener a little at a time until home).

Also check that you not bottomed out on the last threads.  Bob

What do you mean by not bottomed out?  Are you talking thread depth into the head?

Yes .  Bob

[misfitJason]

they definitely aren't bottoming out. 


Does anybody make a thinner (than stock) intake flange for 06-up heads?

[Herko]

Does anybody make a thinner (than stock) intake flange for 06-up heads?

Easy enough to mill the flanges. I kept a set or two of milled flanges (.015-.020) on the shelf for such cases for applications/mods that required thinner flanges.
When needed, relieves the crowding/binding of the flange to the step-shoulder on the manifold alleviating an intake leak due to binding and an unhappy fitment.

[Herko]

Manifold/throttle body position must dictate air cleaner position. Not the opposite.

When mounting an air cleaner, if the air cleaner components or the mounting process pushes, pulls, shoves, twists, re-centers, or binds the manifold/throttle body in any way...you are setting yourself up for an intake leak.

[Ohio HD]

Manifold/throttle body position must dictate air cleaner position. Not the opposite.

When mounting an air cleaner, if the air cleaner components or the mounting process pushes, pulls, shoves, twists, re-centers, or binds the manifold/throttle body in any way...you are setting yourself up for an intake leak.

Agree, you have to let the manifold go where it wants to go, providing you aren't too narrow or too wide. I also use a machine level to insure the mouth of the TB is at 90° to the motor being at 0° or level.

That's why air breather kits like the R&R Cycles Over Flow are adjustable at the support brackets. HPI and I disagreed there. They kept telling me to use a stock backing plate to set the TB location. I knew better.

[1FSTRK]

Manifold/throttle body position must dictate air cleaner position. Not the opposite.

When mounting an air cleaner, if the air cleaner components or the mounting process pushes, pulls, shoves, twists, re-centers, or binds the manifold/throttle body in any way...you are setting yourself up for an intake leak.

That is exactly why the procedure I posted assembles with no seals to check all clearances and centering when held only by the backing plate.

[kd]

Pulling the backing plate up to the heads will cause this misalignment. S&S sells rubber coated shims that can be stacked (if necessary) behind the mounting posts. If already to tall (as noticed when test fitting) some material can be removed and then shimmed back to a good fit.

[1FSTRK]

The backing plate is a 3D controller.
Up/Down
In/Out
Front/back

Milling the heads not only narrows the distance between the intake surfaces compound angle, it also moves the backing plate mounting bosses closer together.

The backing plate should be shimmed, milled, holes moved so that when bolted to the TB and heads the spigots are not touching the heads evenly front to rear and are centered in the flange bores in all directions with no seals installed.  Once it is determined that the proper clearence is set you can install the seals and make any final adjustments to insure the back plate does not fight the seals. I will add that when done this way I have never needed to make any corrections on final assembly

[misfitJason]

I rode her today.  I sprayed around the flanges with carb cleaner.  It's definitely leaking on the horn side of the bike if that tells you anything. 

I am going to try and get an appointment at a very reputable shop that does good work.  The problem is he does great work and is always booked.  If I can't get anything decently soon I'll try and take it apart again for the tenth time. 

[Schex3x]

Leaking on the horn side means your spraying towards the the a/c, now it may be leaking, but just to make sure,

I use brake clean to check for leaks, it's real easy to get false reading if the slightest amount enters the a/c.

I remove the filter and get someone to hold a 3' piece of pvc pipe up tight to the throttle body or carb opening, then I can spray it good with no false indication of a leak.

[Don D]

Finger over the IAC air feed port kill the motor at idle?

[rbabos]

Leaking on the horn side means your spraying towards the the a/c, now it may be leaking, but just to make sure,

I use brake clean to check for leaks, it's real easy to get false reading if the slightest amount enters the a/c.

I remove the filter and get someone to hold a 3' piece of pvc pipe up tight to the throttle body or carb opening, then I can spray it good with no false indication of a leak.

That bit me in the ass once but it was using propane. Went through a needless seal change only to discover when checking from left side the tb inlet was sucking up fumes. Checks from right side with flow away from the throat showed no issues.
Ron

[misfitJason]

Finger over the IAC air feed port kill the motor at idle?

Leaking on the horn side means your spraying towards the the a/c, now it may be leaking, but just to make sure,

I use brake clean to check for leaks, it's real easy to get false reading if the slightest amount enters the a/c.

I remove the filter and get someone to hold a 3' piece of pvc pipe up tight to the throttle body or carb opening, then I can spray it good with no false indication of a leak.

It kills the motor with the finger over the iac. 

I am checking only from the ac side.  It sputters when I spray the carb cleaner toward the tup backside of the flanges.  ALmost toward the fuel injectors

[Don D]

I am now doubtful you have a leak.

[1FSTRK]

I am now doubtful you have a leak.

Why would you think the bike would run with the IAC covered? It is the Idle Air Control, with it covered you do not have enough air to maintain idle.

[Don D]

Which is my point, block the idle air and they run on the leaking air by the flanges at the head if it is leaking there. They don't die.

[misfitJason]

I don't think I have that bad of a leak.  However I never tried covering the iac while it was hot which is when my leak seems to be present.

[rbabos]

I don't think I have that bad of a leak.  However I never tried covering the iac while it was hot which is when my leak seems to be present.

Jason: I would switch over to propane testing. It's effects on engine running are dramatic on the slightest leak and no mess.  I just converted a propane torch. Removed the nozzle and added a 2' hose with a restrictor in the .030-.040 plug in the end. Adjust valve to slightest flow needed. Check all around each sensor and seals. If the engine doesn't attempt to quit at any of these areas, you have no leaks.
Ron

[To The Max]

Hi , I had a problem with a air leak as well in the end the manifold was cracked at the radius of the machined spigot on the manifold. it was very hard to see and it took me a long time to find it. Max

[misfitJason]

^ it's definitely not a crack. I have been through several manifolds with the same result. I am confident it's an alignment issue with the backing plate vs placement at the ports. We have biketoberfest going on right now and as a result anyone who is any good (Indy) is busy as all get out. As am I with just life. So I have to wait for everything to quiet down

[DrSpencer]

Leaking on the horn side means your spraying towards the the a/c, now it may be leaking, but just to make sure,

I use brake clean to check for leaks, it's real easy to get false reading if the slightest amount enters the a/c.

I remove the filter and get someone to hold a 3' piece of pvc pipe up tight to the throttle body or carb opening, then I can spray it good with no false indication of a leak.

That bit me in the ass once but it was using propane. Went through a needless seal change only to discover when checking from left side the tb inlet was sucking up fumes. Checks from right side with flow away from the throat showed no issues.
Ron

2011, 103" Street Glide w/35K miles. SE intake, SE255's, pipes, TTS

I was cleaning the throttle body during a bunch of routine maintenance, and just for kicks, I thought I'd test for an intake leak (Note: air cleaner was removed for this test)

With the bike running, sprayed brake cleaner on the intake flanges/seals from the right side of the bike: No change in idle. Nothing.

Sprayed brake cleaner on the intake flanges/seals from the left side (the horn side) and the bike would stumble. If I kept spraying, it would stall.

I decided to repeat this test using a blue can of propane with a piece of fuel line attached to the brass tip.

Waved the open propane on the right side flange/seals: Nothing

Waved the open propane on the left (horn) side flange seals: Nothing.

Repeated the test again using the brake cleaner: Same results as described above

Bike runs decent. Doesn't throw any codes. Doesn't pop, backfire etc.

Do I have an intake leak? Why did the idle change with the brake cleaner, but not the propane? Any other test you'd like me to do to confirm the presence of a leak?

Thanks