Air Cleaner Question

wjrich

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Oct 7, 2012
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Recently replaced the monoblocs on my '67 Atlas with Amal concentrics. I was surprised at how easy it was to set the new carbs up given that I'm a low skill mechanic.
Here's the issue i need help with- i only had velocity stacks on the monoblocs and never had an air cleaner. Since the motor has been rebuilt, I feel that an air cleaner is necessary. I bought a K&N filter that was dual flanges, with a filter width (K&N site calls this dimension Height) of 2 inches. At that height, the filter does not have enough clearance (with no velocity stacks obviously) to the battery box and oil tank.
Any thoughts?
Thanks.
 
How slim is the clearance behind the carbs ?

I seem to recall pics of the aircleaners fitted back then looked quite slim.
Like about an inch ?
You'd wonder they'd breath enough...
 
Here's a pick of the filter- about 2" wide

Air Cleaner Question


Here's a pic of the available space- less than 2". Oil tank is hard to see...

Air Cleaner Question
 
K&N makes a specially moulded air filter with canted spigots, so that is sits at the proper angle to clear obstructions. The filter in the photo has straight spigots.

Oops, may not be the same for the Atlas, sorry...
 
Britcycle Supply in Nova Scotia has the correct k&n for the Atlas or 650SS (same filter). I recently got one from them, it was about $45 and fits well. It takes a little fiddling to get it in place, but it does go on with a tiny bit of clearance from the surroundings.

Glen
 
Did an internet search and came across an article on the Old Britts site in the techincial section where Fred Eaton was describing a fix for a problem he had fitting air filters to his Commando after installing Mikuni carbs on it. basically, he cut down the filters and refitted the cap and was good to go. As iI thought about my issue, i thought why not? Again, being an amateur mechanic, I walked by my compound miter saw and wondered if if it could cut through the filter material without jerking my fingers into the saw. I lined up the filter and it cut through like butter.

I then used wire cutters to clip the filter material as close as i could on the cap of the filter (mine was a rubber compound v. Fred's chrome filter cap) then ran the surface on my grinder to get it as flat as possible. I will use silicone sealant to reattach both pieces.
Air Cleaner Question


What I ended up with was a filter with a width of approx 1.5" v the original 2" (again, K&N site calls what i call width "height")
Air Cleaner Question
 
Sorry, forgot!

To Grandpaul- the filter flanges do have a can't, although that didn't show up in my pictures. It seemed that the angle of the cant was correct, but the bulk of the filter element was too much at 2". I still have to seal both haves together and see if my reduction to 1.5" works.
 
Glued the filter to the rubber backplate with Locktite Power Grab all- purpose construction adhesive. Let it set for 2 days, and it didn't work.
Anybody have any ideas on what to use to fix the back to the filter?
 
wjrich said:
Glued the filter to the rubber backplate with Locktite Power Grab all- purpose construction adhesive. Let it set for 2 days, and it didn't work.
Anybody have any ideas on what to use to fix the back to the filter?
Click to expand...

Something like a black gasket joining compound that is petrol & oil resistance might work, but that is asking a lot, you really need to have the back wired in place.
 
As a longshot, I contacted K&N to see if thy might have a solution. Within a day, i received a response to me email asking for more details, which i provided. by return email in a couple of hours, K&N basically offered to build me a filter with the 1.5" height v. the 2" height. Robert Knudsen- the K&N person responding- said it would take about 3 weeks to produce, and he would send me cost details.
K&N gets my vote for outstanding customer service- especially given that this is a 1-off request!
 
wjrich said:
Glued the filter to the rubber backplate with Locktite Power Grab all- purpose construction adhesive. Let it set for 2 days, and it didn't work.
Anybody have any ideas on what to use to fix the back to the filter?
Click to expand...


Buy a new filter, perform the same mod BEFORE you oil it.
 
Good idea. I soaked the thing in water and dawn dish washing soap which did a pretty good job of getting the oil off. Once dry, I'm going to re glue it back together. If nothing else, I'll have a back up for the custom K&N fix.
 
Perhaps try cutting some (1/2" maybe) off of each intake tube ... instead of off the filter itself. I converted my 1971 single Amal carb Triumph 650, to a single JRC/PWK carb. But then because of the OIF type frame, the carb with filter wouldn't fit :shock: (I wondered how the heck everyone else does this change and yet I've never heard of any problems) I even used a "MAP" type intake manifold, and noticed that if I had used the single "Mikuni" 34mm carb that came with it, there was even LESS clearance. (how do they sell all these conversions, and yet they won't fit ??? :shock: :shock: :shock: )

Anyway, I cut 1/8" off the intake rubber ,,, and then the filter fit :D ( Although just barely, it does work and looks good IMO) I ALSO had to fit an EXTRA narrow hose clamp I found too, as the one that came with the "kit" was too wide since I cut the intake tube; but I HAD to cut it to make it fit :evil:

Air Cleaner Question


Air Cleaner Question
 
wjrich said:
Recently replaced the monoblocs on my '67 Atlas with Amal concentrics. I was surprised at how easy it was to set the new carbs up given that I'm a low skill mechanic.
Here's the issue i need help with- i only had velocity stacks on the monoblocs and never had an air cleaner. Since the motor has been rebuilt, I feel that an air cleaner is necessary. I bought a K&N filter that was dual flanges, with a filter width (K&N site calls this dimension Height) of 2 inches. At that height, the filter does not have enough clearance (with no velocity stacks obviously) to the battery box and oil tank.
Any thoughts?
Thanks.
Click to expand...

Just curious, how did this turn out ???
 
Pretty good , i think. after the first attempt at gluing the filter back piece onto the filter failed, I soaked the whole thing in Dawn diswashing liquid to completely remove the old oil. After completely drying, I re-glued the back and it worked. I installed the filter on the concentrics, and while still a bit of a snug fit, it looks great.
In the meantime, I contacted K&N and dealt with a customer service rep who took the appropriate dimensions and they are custom building me a couple of filters. Cost for the custom build is about $75, which is more than half again what the standard R-990 costs, but still worth it in my opinion. Custom build takes about 3 weeks, and they keey the specs on file so i can go back anytime and get another.
Will throw a pic on here once i receive it.
 
Well now, I"m impressed with K&N's customer service. Good to know, and thanks for posting. Cheers.
 
10-4 to that... I do think the prices are a bit to high but that kind of customer service is great, noteworthy & I almost want to contact them myself to tell them so, then I remember all places should be like that... Do please let us know how it turns out. Thanks.
 
Finally got the custom build K&N air filters for my Atlas- pictures below. Basically, they took the standard R-0990 model and reduced the height (width) from 2" to 1 3/8". Filter is otherwise the same as the R-0990.

Cost was $78- expensive I know- but this was a build to custom specs by K&N.

For whatever reason I ordered 2, so I'm going to list the other one- still in the wrapper w/hose clamps over on the "For Sale" section for a while then ebay if nothing happens.... Since it's basically the R-0990, it would probably work as a low profile filter for any concentric Norton.

Again, awesome curtomer service from Robert Knudsen at K&N.
Air Cleaner Question

Air Cleaner Question

Air Cleaner Question
 
Forgot to post a pic of the filter on bike. Lousy pi- i Phone in dark garage- looks much cooler in real life...

Air Cleaner Question
 
Be careful. I a K&N drop a piece of stainless wire which then dug a small trench in a cylinder wall . . . . .
 
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