Air cleaner mounting flange question
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Tourer
Joined: Sep 2011
Posts: 288
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From: Sweet Home Alabama!
Air cleaner mounting flange question
I was coming back from a ride last night and the air cleaner fell off my bike. I was able to "catch" it with my leg until I could pull, luckily. I expected to see either the screw that holds the cover on or the 3 screws on the inside had fallen out, but it was the whole flange. The 3 mounting screws were still tight, as was the cover screw. The flange had an o ring on the inside that fitted on the carb body, but I can't see any missing set screws or anything missing. What holds the flange to the carb body? Surely there;s something besides the o ring, but I see no marks or obvious signs of anything missing. I've looked at several exploded views of the carb, but the ones I've seem to show the flange as part of the carb body. What the hell am I missing? Thanks in advance!
Seasoned HDF Member
Joined: Jun 2010
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From: Upstate New York
'93 and up Evos with head breathers usually have some sort of bracket to tie the air cleaner back plate to the cylinder heads at the breathers. The carb flange is only meant to seal the air cleaner to the carb, not hold the air cleaner on. You're lucky you didn't lose the carb, too, since it's just a push fit on the maniifold if it's a CV or a Mikuni!
Road Master
Joined: Jun 2009
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From: Beautiful SW Missouri Ozark Mountain Country
'93 and up Evos with head breathers usually have some sort of bracket to tie the air cleaner back plate to the cylinder heads at the breathers. The carb flange is only meant to seal the air cleaner to the carb, not hold the air cleaner on. You're lucky you didn't lose the carb, too, since it's just a push fit on the maniifold if it's a CV or a Mikuni!
Cruiser
Joined: Mar 2010
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We need pictures.
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Tourer
Joined: Sep 2011
Posts: 288
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From: Sweet Home Alabama!
'93 and up Evos with head breathers usually have some sort of bracket to tie the air cleaner back plate to the cylinder heads at the breathers. The carb flange is only meant to seal the air cleaner to the carb, not hold the air cleaner on. You're lucky you didn't lose the carb, too, since it's just a push fit on the maniifold if it's a CV or a Mikuni!
It is a stock HD air cleaner base with HD Nostalgic 8" round chrome cover) and CV carb. I have always thought the mounting flange was made on to the body of the carb, but it is a separate piece sealed by an o ring.
I think my problem is the head breather bolts. Mine does not have them. The bike had a Hypercharger on it when I got it, and I put the stock air cleaner base back on it. It has bolts with no heads on them with a "X" shape in the end of them. They fit snugly into the holes of the factory A/C base, so I thought they were factory. I did not realize that the head breather bolts actually held the carb and mounting flange together. I've put around 7,000 miles on the bike the since I changed it, so yeah, I'm lucky the carb hasn't worked loose. I guess the o ring on the flange had been there long enough to kinda stick. I'm shocked that o ring is the only thing holding the carb on for this long.
Last edited by 97HeritageSpringer; Jul 14, 2012 at 11:23 PM.
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Seasoned HDF Member
Joined: Dec 2010
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From: Coromandel Peninsula New Zealand
Usually, where the head breather bolts go into the head, they bite down on crappy knurled metal spacers....these spacers are only moulded into the plastic back plate and as the plastic ages and hardens the whole assy comes off the spacers and your carby etc falls off.
Best cure is the SE Hi-Flow are cleaner assy or a decent second hand one....this may be what is wrong with yours and its hard to spot unless you know how it should all hang toegether.
Best cure is the SE Hi-Flow are cleaner assy or a decent second hand one....this may be what is wrong with yours and its hard to spot unless you know how it should all hang toegether.
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Joe Kucinski
Seasoned HDF Member
Joined: Jun 2010
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From: Upstate New York
I see that you're running a Mikuni. That separate mounitng flange with the 0-ring is part of the Mikuni mounting hardware. The stock CV carb has a screw flange with 3 tapped holes. If the air cleaner is not bolted to the heads it won't matter, as both carbs are just a push fit onto the intake manifold, and can fall off without being retained by the air cleaner assembly.
I'll admit, I'm not that familiar with the construction of the stock air cleaner. I haven't seen mine since 1994.
If the SE air cleaner for the EVO can't be located, try the Arlen Ness "big sucker". I run one and like it very much.
I'll admit, I'm not that familiar with the construction of the stock air cleaner. I haven't seen mine since 1994.
If the SE air cleaner for the EVO can't be located, try the Arlen Ness "big sucker". I run one and like it very much.
Last edited by Uncle G.; Jul 15, 2012 at 06:24 AM.
Seasoned HDF Member
Joined: Dec 2010
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From: Coromandel Peninsula New Zealand
It matters very much if the air cleaner isn't bolted to the heads......its the only thing that stops the carby falling off!!