question - dimensions of factory air filter.

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joe czech

joe czech

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fought with the factory air filter on the 74 - talk about getting 5 pounds of crap in a 4 pound bag. a half inch off the height would be a godsend. I found the following -- Air Filter, Round, 2-7/16" Height and 8-1/2" Outside Dia. the 2-7/16" would greatly help installation. in fact, i'm thinking it might be perfect, but the diameter may be a bit too large. it's a Hastings standard automotive paper element, and best part looks to be about $7. so, anyone know the factory filter dimensions? TIA - ;)
 
kommando said:
For info on narrow airfilter and maybe by inference the full depth filter dimensions, read this to the end.

https://www.accessnorton.com/NortonCommando/narrow-air-cleaner.28992/
Click to expand...
got that - the holy grail would be to find an off the shelf, replacement filter about 1/2" narrower and the correct diameter. the best i'm finding is the factory filter is around 8.25" diameter. half way tempted to drop $7 and give the hastings a try. there just might be enough give to fit inside the mesh housing.
 
That filter has considerably less surface area than the OEM Ham Can. Does it not make sense that Norton would have installed a thinner "ham can," like that one for ease of use IF it had provided sufficient air flow? ;)
 
MexicoMike said:
That filter has considerably less surface area than the OEM Ham Can. Does it not make sense that Norton would have installed a thinner "ham can," like that one for ease of use IF it had provided sufficient air flow? ;)
Click to expand...
can't argue the point. what you are saying is true, but i'd wager that the stock filter flows much more than maximum engine requirements. engineers always add in a plus factor - I would think at a minimum, it's at least 25%. it should be easy to calculate air requirements for a stock 850, and find the max airflow for the subject filter. the surface area of the perforated mesh housing probably restricts most of the airflow. cutting down the perforated housing to accommodate a slightly shorter filter would probably negate any airflow shortcomings of the filter. just my 2-cents.... :)
 
While I acknowledge how frustrating it is to install the connecting rubbers from the filter body face to the carburetors, there is a knack to it and after a few teeth gnashing installations it becomes much easier. Lots of silicone lube helps.
 
lazyeye6 said:
While I acknowledge how frustrating it is to install the connecting rubbers from the filter body face to the carburetors, there is a knack to it and after a few teeth gnashing installations it becomes much easier. Lots of silicone lube helps.
Click to expand...
kind of a novice at this, so let me see if I got this right - the connecting rubbers are the last thing to install. I installed the rubbers and mounting plate to the carbs, and only then squeezed the perforated housing/filter assembly in from the left side. anyone that has a knack for this, it sure would be nice if someone posted a video. :D
 
Oh! Well I install the carbs and the mounting plate first, then mount the rubbers to the carbs pushing them as far onto the carbs as possible. Then , using lube, chopsticks and long skinny screw drivers manipulate the rubbers into the mounting plate. Then push the rubbers into
their proper position on the carb mounting rings. I can do both in about 10 minutes. The first one is easy! Silicone lube!
 
I've read several different methods and the fact that different people do it differently has always made me wonder if there was some factory frame/mounting variation that provided more or less clearance between the carb mouths and the front plate of the filter on individual bikes. Mine mounts without much drama - I do it as described in the owners manual (if I remember right) - attach the plate and rubbers to the carbs and working the filter/mesh between them. Never had any big problem doing it that way. Since some folks do, it's why I wonder about frame/mounting variation.
 
MexicoMike said:
I've read several different methods and the fact that different people do it differently has always made me wonder if there was some factory frame/mounting variation that provided more or less clearance between the carb mouths and the front plate of the filter on individual bikes. Mine mounts without much drama - I do it as described in the owners manual (if I remember right) - attach the plate and rubbers to the carbs and working the filter/mesh between them. Never had any big problem doing it that way. Since some folks do, it's why I wonder about frame/mounting variation.
Click to expand...
I kind of understand - about a month ago, I did a trial fit of the air filter housing - it took me a while to sort thru things - tried several different methods, but ended up pretty much following the owners manual. first time was a pain, but I pulled it and did a second install to verify the procedure. seemed to be a piece of cake. fast forward now - that booger fought me tooth and nail. no way in hell did it want to go. can't figure it out, everything was configured the same. pretty much followed the same procedure as before, but this time, it was a no go. spent a couple hours, a few four letter words, but finally got things in there. the little I've read up on it here, i'm seeing that most folks either have a tough time with it or everything falls into place. there can't be that much difference in the bikes dimensional layout. probably has something to do with the alignment of the friggin planets - :mad:
 
well, I guessing we'll find out if the hastings filter will work as a, commercial off the shelf, narrow replacement for the stock commando filter. I had $26 in bonus dollars on my amazon account, and the price was $10.70 for the filter (free shipping), so i was a $0 purchase. as they say, nothing ventured, nothing gained. will post results and findings -- ;)
 
I actually found it easier to remove the manifolds from the head, fit the filter, then reattach the carbs.
 
maylar said:
I actually found it easier to remove the manifolds from the head, fit the filter, then reattach the carbs.
Click to expand...
don't think that's an option. I have the madass140 carb gantry system. there is no way i'm taking that thing apart.... :D
 
1. Install carbs (with boot adaptors correctly.... flange toward carb). Still nice open access

2. Install(and remove) air cleaner always/only from timing side. 2 screws. Accommodating ALL Commandos ... "S", 71-74 air cleaner(74 with snorkle) , ignition with switch mounted on backing plate and 75 MKIII. Easy peasy

3. Boots: silicone lubed generously
While standing on timing side, always mount drive side boot on carb first , then... into air cleaner plate with "flat" facing center. far side first with 10" long very thin blades screwdriver. then working toward center...rotate if required to center the flat.

Next install timing side boot on carb first, then repeat boot installation, far side with flat first and working it into the air cleaner plate keeping flat toward center of bike.

Step 3 should not take 5 minutes and on a good day has been under 2 minutes. Will take for ever without the right tool/ ie thin screwdriver

I always...only... do it this way since the late 80's
 
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lazyeye6 said:
Oh! Well I install the carbs and the mounting plate first, then mount the rubbers to the carbs pushing them as far onto the carbs as possible. Then , using lube, chopsticks and long skinny screw drivers manipulate the rubbers into the mounting plate. Then push the rubbers into their proper position on the carb mounting rings. I can do both in about 10 minutes. The first one is easy! Silicone lube!
Click to expand...

Very similar and I'd agree boots are last...long skinny/thin screwdriver is essential.
I also use dow corning silicone clear electrical grease on the inside heavily the boots and my 1988 restored combat is on its second set of boots. Carbs do spit gas/E10 back out the intake, so by protecting the boots they are longer lasting and nice to be able to reuse them if needed. If you don't lube them they will crack much quicker.
 
NAPA sells a silicone grease called Sil-Glyde that's great for this. Protects and lubes rubber. Also good for auto weatherstripping (sticky windows) and doubles as an electrical dielectric grease for connections, bullets, spark plug boots, etc. Good stuff.
 
Again, I don't understand WHY there are differences in difficulty. I've not needed grease or any tools of any kind to install the filter in a couple of minutes using the owners manual procedure. There has to be some kind of variation in the parts/alignment to account for this. If it's not in the location of the backplate mounting position in relation to the carb air horn position, the filters themselves are an obvious suspect. There are a variety of manufacturers that could have slightly different specs and the width (or thickness, however you view it) of the filter (since it sits proud of the mesh) determines the clearance between the front plate and the carb horns... ;)
 
MM just curious...what year configurations is your bike? Which owners manual are you using, I have only seen one for a 71. So I don't know what the manual procedure looks like.
I have to admit I like my general procedure because it works for all years and all models. (standard and not butchered)
When is the last time you did a "S" or "SS" or 74 with a snorkel cover plate?:eek: Is you bike still with a air cleaner mounted key switch?
 
dynodave said:
MM just curious...what year configurations is your bike? Which owners manual are you using, I have only seen one for a 71. So I don't know what the manual procedure looks like.
I have to admit I like my general procedure because it works for all years and all models. (standard and not butchered)
When is the last time you did a "S" or "SS" or 74 with a snorkel cover plate?:eek: Is you bike still with a air cleaner mounted key switch?
Click to expand...
good point on the snorkel cover plate. that pretty much dictates that the filter, perforated cover and cover plate have to go in as an assembly, and only then the carb connecting rubbers. I bought a new AN filter assembly and the cover plate is not configurated with a snorkel - just a flat plate. in my shop manual (carburetor section) , it shows sliding the filter and perforated cover in, but no illustration showing the snorkel cover. if you have a snorkel cover plate, there's no way you can remove it or install it per the service manual.

question - dimensions of factory air filter.
 
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