Reoccurring intake leak. Help please gentlemen

[misfitJason]

Bike info
2006 Dyna
95 inch 80cc heads street ported with mcrs
37h cams
Thunderheader
Hpi intake
Stock throttlebody with 25 degree injectors tts

I keep getting a intake leak between the seals and the manifold.  The manifold was really tight to get in after the heads.  I had the manifold mounting flanges shortened to stop the crowding. The manifold goes on easily now.  But I have an intake leak. I can see it on the data logs via iac steps, choppy idle, and when carb cleaner is sprayed around the flanges the idle drops and almost stalls






I do have a tiny gap between the manifold and the air cleaner bracket when in a neutral position




I even switched out manifolds to make sure it wasn't something I was missing. I am going to double check my gap at the manifold to heads for .015 on each side.  Should I take .010 off of the feet of the manifold mounting flanges to get a little or squish on the seals?  I also picked up a tube of yamabond number 4. This is driving me nuts.  What would you guys recommend?

[Templer]

verify that the flanges are FLAT!! IF the material removed from the flange is not parallel to the back side (facing outward from the head) it will also cause a problem. Place yours on a piece of glass then place another on top and the gap on both ends as measured at the glass should be the same. I found that there was/is a difference in the flange to gasket angle between the alu and OEM flanges!!!???.  Do NOT over tighten them!! I myself tightened mine from side to side a LITTLE at a time.PITA time!! Try using plain old DISH SOAP on the gaskets and TB. I went thru this myself and what I have posted WORKED!!!ALL THINGS ARE IMHO!!!

[misfitJason]

They are definitely flat and not distorted

[Templer]

I also found that both of the original OEM flanges had a (casting?)ridge on the top of a set of flanges causing the seal to hang and not slide forward when tightened.Top of beveled part of the flange.

[Ajayrk]

I had issues with an HPI.  The throttle body spigots were .010" under size compared to stock. Seals just were not tight when slipped on. Tried a variety of seals. Did so many changes that I could change seals in 45 minuets.  Even tried new flanges and a set of HPI flanges.  Had the stock throttle body bored out, installed it and stopped the leaks.

[misfitJason]

I'll post some pics of when I do setup and installation. Maybe you guys will catch an error I am doing

[misfitJason]

It was tight



I removed some material with a belt sander and wet sanded it to get about .015 on each side

It can now swing up this much


And down this much


I shortened to feet on the intake flange brackets by about .005


I used some yamalube number 4 on the new intake seals and put the intake on carefully trying to allow it to center.  I then put the air cleaner backing plate on and again tried to center it.  It had a small gap from where it wanted to sit. I shimmed the backing plate with some of those s&s rubber coated washers. Until it was happy

[aabikrman]

Make sure nothing gets tightened down until the throttlebody with the backing plate is properly centered and vertically aligned.  In your pictures it looks like the manifold is centered well side to side but no clue as to vertical alignment.  The backing plate should be used to set horizontal AND vertical alignment....  Using the backing plate to get everything properly aligned and then snugging everything before final tightening is essential. 

The HPI backing plate has a lot of room for adjust-ability and its very easy to get mis-aligned but look good and even.  If you have the original Harley backing plate, it can be modified (cut up) to be used as a template or jig and have easier access to the manifold to head fasteners for proper alignment.  Use the oem backing plate to set alignment and then only snug fasteners down enough to prevent movement for the final process.  Remove the oem backing plate and then perform final tightening of the manifold fasteners and then backing plate, etc.  Hope this makes sense, don't ask me how I know this......

Good luck and I hope that's what your issue is !

[misfitJason]

The idle seemed to have improved.  I am still getting the variance in cli's at idle but my Iac steps came up some to about 22-23.  I haven't sprayed the seals yet.  What do you guys think.  Is the variance in cli's just overlap reversion or a still present vacuum/intake leak?  Here is a new log

https://www.dropbox.com/s/t15utgusrq7hah6/intake%20fix-r01.dm3?dl=0

[misfitJason]

Make sure nothing gets tightened down until the throttlebody with the backing plate is properly centered and vertically aligned.  In your pictures it looks like the manifold is centered well side to side but no clue as to vertical alignment.  The backing plate should be used to set horizontal AND vertical alignment....  Using the backing plate to get everything properly aligned and then snugging everything before final tightening is essential. 

The HPI backing plate has a lot of room for adjust-ability and its very easy to get mis-aligned but look good and even.  If you have the original Harley backing plate, it can be modified (cut up) to be used as a template or jig and have easier access to the manifold to head fasteners for proper alignment.  Use the oem backing plate to set alignment and then only snug fasteners down enough to prevent movement for the final process.  Remove the oem backing plate and then perform final tightening of the manifold fasteners and then backing plate, etc.  Hope this makes sense, don't ask me how I know this......

Good luck and I hope that's what your issue is !

I'll try that with the oem backing plate.  It can't hurt and thanks for the advice

[misfitJason]

Yeah.... it still leaks when sprayed with carb cleaner.  I got some different seals from Dennis Kirk.  One set is a James gasket set kind of like the oems.  The other set is the black ones with the metal built into them and the have a lip. I'll try those next week.  Looks like I'll be riding the softail on Saturday.

[JTM65]

I had a hard time with my 01 MM stock intake sealing. Finally got it working when I replaced the flanges and used dish soap (as suggested by another HTT member). I also used the Genuine James gaskets. Best of luck!

[misfitJason]

Well I think I may have located the issue thanks to help. 

The Hpi plate looked like it was centering the manifold.  It was a big difference between where the oem backing plate puts it.  Now, from trimming the manifold spigots, there is waay to much of a gap.  I will have to find a new to me 06-up dyna manifold to start over.  Anyone holding

[prodrag1320]

Well I think I may have located the issue thanks to help. 

The Hpi plate looked like it was centering the manifold.  It was a big difference between where the oem backing plate puts it.  Now, from trimming the manifold spigots, there is waay to much of a gap.  I will have to find a new to me 06-up dyna manifold to start over.  Anyone holding

I was thinking it would end up with something like this,the heads were not milled enough where fitment should have ever been a problem in the first place

[misfitJason]

Got the new to me intake manifold on with the stock backing plate.  It's better but still not perfect. I didn't spray it yet but it still hunts a little bit and my iac steps are better (29-32 warm).  Do you guys think it could just be I would need to adjust the throttle stop?  When I close the butterfly on a piece of printer paper it won't even come out.  I thought about adjusting it a bit if I spray it and it doesn't leak

[misfitJason]

well, it's definitely still leaking and it gets worse when it's warm.  When it's cold just off of warmup it idles nice and the steps are better.  Then it warms and the steps drop back into the twenties and my cli's bounce all around to 107 percent.  No matter what I make the idle ve's it will still stray to lean.  Any recommendations

[rbabos]

well, it's definitely still leaking and it gets worse when it's warm.  When it's cold just off of warmup it idles nice and the steps are better.  Then it warms and the steps drop back into the twenties and my cli's bounce all around to 107 percent.  No matter what I make the idle ve's it will still stray to lean.  Any recommendations

Have you logged IAT sensor and head temp sensor for correct behaviour? IAC is still in control, so any extra air from a leak, if there is one would be countered keeping the AFR intact at idle. Having both go lean with present IAC idle control makes no sense, at least to me.  :idunno:Mid 20s steps are fine.
Ron

[Don D]

06 model year is a bitch.
A small mill of the heads and this happens. The shoulder that the flange goes up against becomes a problem and in the way so guys mill the flanges. That is wrong too as they then warp. Shorten the spigots, no help. If the bolts go in tough you have an issue. Best way to fix this is milling the head flange faces.

[1FSTRK]

Jason
How much room is between the end of each spigot and the head surface when installed and centered?

How much room is between the throttle body boss and the back of the flange when the flange bolts are tight?

Did you inspect the intake surface on the head, I have seen many that have factory cutter marks that go from the port to outside the seal surface and will cause a gap the seal will not push into causing a leak.

The procedure that Vic taught me was to install the TB mounted to the backing plate with flanges and no seals. Make all the measurements and make sure the bolts screw in freely without binding and then visually check that the spigot is centered in the hole of the flange.
If all is good remove and reinstall with new seals and a light coat of dish soap on the spigot and beveled surface of the flange. Never had a leak using this method.

[misfitJason]

The intake points on the heads are flat and smooth with no marks or scratches.  WHen the manifold is mounted with no flanges or seals I have .010 between each side of the spigot and the heads.  The manifold seems to align up well and centered.  I used the plastic stock backing plate last time with james intake seals. 

All of the times before I used oem seals (new each time).  I have numerous sets of flanges (all proper ones for the 06-up style heads).  I am using ones now that were machined on the backside to help with crowding by a machinist.  I also have a set that have the feet machined off of them.  My intake manifold has not been trimmed.  I have a crowding issue with the out of the package flanges to the backside of the intake manifold spigots.  I will try and take it down again and use the flanges with no seals and check alignment.  I will also felt tip pen the spigots and how they align with the ports.  If I don't use shortened flanges, I get a crowding and binding issue when installing the manifold.

I have logged the IAT with headtemp and warm the steps are still in the twenties.  My idle hunts and hangs up when returning to idle at speed.  The bike runs hotter than it should.  Here is a log from riding into work this morning.  You can see what the idle cli's do at idle and off idle and no matter how many times I tune it or have it tuned the off idle cli's will always go to lean pretty much no matter what the ve is.  My mid range and up to speed the tune holds well.  I thoght about trying the HPI manifold flanges but Jimmy tells me they are even thicker.

this is a tts log

https://www.dropbox.com/s/0183oxwlm7ry5jy/10-08-17%20%282%29-r03.dm3?dl=0

[1FSTRK]

Are the bolts binding in the bottom of the flange holes when you start them in the heads?
My bet is when you assemble without seals you will see the spigots are touching on the top of the flange bores, this will pinch the top of the seals and not let them slide down the spigot to seal against the head. 

[misfitJason]

I don't know about binding^ but the last bolt is a bitch to get in like the intake needs to move back further.  I will try what you say on monday or tuesday

[Don D]

The intake faces on the heads need to be milled and start out with a virgin manifold and flanges, then install the way that was suggested.  The seals are not the issue, james, cometic, harley are all virtually the same. All work.

[1FSTRK]

The intake faces on the heads need to be milled and start out with a virgin manifold and flanges, then install the way that was suggested.  The seals are not the issue, james, cometic, harley are all virtually the same. All work.

Don, I agree milling the surface will help but it needs to be done sparingly. The more you take from the head surface the more the seals will overhang the end of the spigot when in place and the spogits are a little short to begin with. I have seen where a little work in the top of the backing plate bosses where they bolt to the heads will drop the TB and spigots down enough in the flanges to center them and actually keep the spigots nice and close to the heads as long as there is room between the back of the flanges and the TB bosses.

As for the seals all being the same, there is a noticable difference in the density of the material used in some brands and it can make or break the outcome on a troublesome install.

[Don D]

In this case I would only cut ~.015 but it makes all the difference in the world. And I certainly know it is no fun to have to pull the heads and any other option is better if it works, I see your point Eric