Intake leak...Help!
Thread Starter
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Road Captain
Joined: Oct 2007
Posts: 714
Likes: 64
From: El Paso, TX
Intake leak...Help!
My bike has an intake manifold leak. A small shot of starter fluid near the rear of the manifold and I get a significant change in engine RPM. The bike runs list SH*T at light throttle application. It surges noticeably under those conditions. I have tried five or six times to seat the manifold properly IAW the factory service manual. I have installed new gaskets, new flanges, all to no avail.
Does anybody have any tricks on how to get the intake manifold to seal properly?
UH60Hwkdrvr
Bike build:Fuel Moto M8 124" Piston & Cylinder Big Bore kit 11.0:1 107 engines
Screamin Eagle Milwaukee-8 Extreme CNC Ported Cylinder Heads (Part Number: 16500750) .540 lift springs, 41mm intake valve, 33mm exhaust valve
Rekluse TorqDrive manual Clutch Milwaukee-8
S&S Cycle M8 Head Bolt Kit
S&S Cam plate and oil pump
S&S 540C Camshaft
S&S Air Cleaner
S&S Adjustable Pushrods
Woods Knight Prowler Lifters
HPi Milwaukee-8 62mm Throttle Body w/6.3 fuel injectors
Khrome Works Outlaw 2 into 1 Exhaust Pipe
Thundermax ECM
Does anybody have any tricks on how to get the intake manifold to seal properly?
UH60Hwkdrvr
Bike build:Fuel Moto M8 124" Piston & Cylinder Big Bore kit 11.0:1 107 engines
Screamin Eagle Milwaukee-8 Extreme CNC Ported Cylinder Heads (Part Number: 16500750) .540 lift springs, 41mm intake valve, 33mm exhaust valve
Rekluse TorqDrive manual Clutch Milwaukee-8
S&S Cycle M8 Head Bolt Kit
S&S Cam plate and oil pump
S&S 540C Camshaft
S&S Air Cleaner
S&S Adjustable Pushrods
Woods Knight Prowler Lifters
HPi Milwaukee-8 62mm Throttle Body w/6.3 fuel injectors
Khrome Works Outlaw 2 into 1 Exhaust Pipe
Thundermax ECM
Road Warrior
Joined: Dec 2005
Posts: 1,274
Likes: 1,070
From: SE SC
Sometimes ya just gotta step back for a minute…..
Are you sure it’s the manifold? I noticed on your build you also have new heads. Could the intake portion of the head be mucked up, or slightly off on spec? Unfortunately the only option may be to try another manifold and see if the problem persists. I’m just spitballing here, but sometimes we get so focused on what we think the problem might be, that we fail to look at what might possibly (and less desirable) be the problem.
Again, just spitballing
Are you sure it’s the manifold? I noticed on your build you also have new heads. Could the intake portion of the head be mucked up, or slightly off on spec? Unfortunately the only option may be to try another manifold and see if the problem persists. I’m just spitballing here, but sometimes we get so focused on what we think the problem might be, that we fail to look at what might possibly (and less desirable) be the problem.
Again, just spitballing
Grand HDF Member
Joined: Jan 2012
Posts: 4,454
Likes: 2,840
From: Oklahoma
Did all of this stuff work properly until recently or did you get it back from servicing with this problem? Is there an evaporative emission connector on that manifold that has fallen off or sprung a leak?
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Seasoned HDF Member
Joined: Dec 2005
Posts: 19,868
Likes: 7,987
From: poway
With new heads and throttle body, the manifold may need trimming. If the fit is too tight between the heads, the manifold won't center in the head rings and the connection leaks. You will be to remove the throttle body, install without the rings and verify that the manifold had a little float.
Another thing is the if you get the throttle body to vent bolt spacing wrong, the vent bolts will place a load on the manifold and cause the head seals to leak.
Another thing is the if you get the throttle body to vent bolt spacing wrong, the vent bolts will place a load on the manifold and cause the head seals to leak.
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Thread Starter
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Road Captain
Joined: Oct 2007
Posts: 714
Likes: 64
From: El Paso, TX
I appreciate all the input. I am positive it is the rear of the manifold that is not seated correctly. A shot of starter fluid on the rear of the flange cause the engine rpm to drop sharply. When I spray anywhere else on the motor, no change. Harley has a specific torque sequence, which I have followed religiously, but to no avail. I found this video which I think may help solve my issue. I will buy a fresh set of gaskets and give this method a go. If this doesn't work, the next stop will be my local performance shop to help fix the problem.
UH60Hwkdrvr
UH60Hwkdrvr
