Going back to original air filter assembly

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Saber

Saber

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Hello,
I have a '74 MkII. When I acquired the bike it had a K&N filter installed (K&N pic attached). It is running well after much restoration, fixing, replacing, etc with the K&N still in use. The ham can was in the spares box i got with the bike. After cleaning it up, paint, and purchase of new paper filter and rubber boots I am interested in converting back from K&N to the original air filter assembly. I have read the threads regarding the difficult assembly and techniques. No need to re-hash that here. I would like to know if there are other items i need to watch as i make the switch. Will the engine performance be affected? Carb adjustments? The original has the baffles / snorkel attached to the front cover. I understand older versions had no baffles. Was this an attempt at a performance enhancement or noise abatement? If it were your bike, would you remove the baffles? Amal 932's are on the bike. I assume they are the originals. The clip is on the center position of the needle. Thanks for any input you can offer.
Going back to original air filter assembly
 
I went the other way, from ham can to K&N due to installing an e-starter that wouldn't clear the stock filter. I've found that the paper filter flows a bit better than the K&N but not enough to warrant any changes to the carbs. Maybe a tweak of the idle air but not much else. The baffle was for noise reduction, and my MKII didn't have that. If you've read all the past threads, you know what a PITA it is to install. I actually found it quicker to remove the manifolds from the head than squeezing the filter in place.
 
Here is the Amal Concentric jetting through the ages:

Going back to original air filter assembly

It is worth checking the jetting - mainjet is 260.
And according to this the needle clip should be in groove 3 (so needle at it‘s highest)

On the grounds you’ve been pumping grit and dirt through a K&N I would be inclined to replace the needles and jets anyway, as they‘ve probably been well sandblasted by now.

These are of course assuming that you are running the original silencers and pipes with the balance pipe.
Although I doubt that with a mainjet of 260, the common upgrade of 750 pipes and peashooter would require different jetting as what’s listed here.


The baffled plate was supposed to reduce the induction roar.
I would be inclined to not use it, which will make getting the filter element in and out infinitely easier for you!!!
 
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maylar said:
I went the other way, from ham can to K&N due to installing an e-starter that wouldn't clear the stock filter. I've found that the paper filter flows a bit better than the K&N but not enough to warrant any changes to the carbs. Maybe a tweak of the idle air but not much else. The baffle was for noise reduction, and my MKII didn't have that. If you've read all the past threads, you know what a PITA it is to install. I actually found it quicker to remove the manifolds from the head than squeezing the filter in place.
Click to expand...

Thanks Dave,
Our bikes were built at the same time (319416). Do you think they were made with the baffles or no baffles?
 
Honestly I don't remember if I ever removed them, my front plate is chromed and I got it from a buddy who had an older bike. But I'm pretty sure I've seen my old cover in my bone yard and there's no baffles.
 
I have a 74 MkII with the standard issue airfilter. Im not a big fan of KN despite having them on other bikes because I cannot see how they filter the small stuff. It is a bother putting the ham can on and off but go slowly and it is doable.
 
(74 Mk2) -- have the current AN (replacement) stock air cleaner, w/ paper element - no internal baffles. amal 932 original carbs w/ all new internals - main jetting 260, 106 needle jet, and throttle needle, 928/104 (clip on second groove). seems to run and perform OK, but I have nothing to compare it to, thus, no complaints. stock exhaust with balance pipe and I believe the original pea shooters. I still have my original air cleaner, which has baffles. the only reason I replaced the original was the previous owner destroyed the rear air filter plate removing the ignition switch bracket. installing the air cleaner element with baffles seems like it would be somewhat of a challenge, vs. one with no baffles.
 
If I was running a road bike on petrol with mufflers, I would just fit the biggest recommended main jets and forget it. The needles and needle jets are much more important. It is very rare to ride any bike on full throttle for long distances. Even race bikes are not on full throttle for long. Accelerating fast out of corners makes your speed towards the ends of the straights faster. If your bike is tuned lean enough to be fast, you are usually forced to feed the throttle on slowly. An air cleaner makes the motor run richer, so if you change it, you must re-jet. Those small K&N cleaners are probably more restrictive than the standard air cleaner. Even a wire gauze over the end of the bell-mouths changes the mixture.
 
Those using K&N filters have you considered an NO-0100? It is the same size as Commando OEM paper filter and fits inside the ham can. I’ve used these for the last 40 years on my 750s. They are much easier to assemble as it doesn’t break up when forcing it into place.
 
illf8ed said:
Those using K&N filters have you considered an NO-0100? It is the same size as Commando OEM paper filter and fits inside the ham can. I’ve used these for the last 40 years on my 750s. They are much easier to assemble as it doesn’t break up when forcing it into place.
Click to expand...
The pleated paper filter is more effective than a K&N. (edit: not sure about that particular one) The only reason I'm using something else is that the ham can won't clear the starter motor on my cNw e-start.
And it's not the filter element that's a PITA to install, it's the perforated "can" and those damn rubber bellows. You WILL scratch the frame unless you protect it.
 
maylar said:
The pleated paper filter is more effective than a K&N. (edit: not sure about that particular one) The only reason I'm using something else is that the ham can won't clear the starter motor on my cNw e-start.
And it's not the filter element that's a PITA to install, it's the perforated "can" and those damn rubber bellows. You WILL scratch the frame unless you protect it.
Click to expand...
Yes I understand about the electric start. Several comments on this site, this string and others, about K&N not working as well as the stock paper filter. Usually the pictures of the inferior K&N is one of the small pod type filters. It doesn’t make sense to me that an equal size K&N would not be superior to a paper filter. The only equal size K&N is NO-0100.
 
illf8ed said:
Yes I understand about the electric start. Several comments on this site, this string and others, about K&N not working as well as the stock paper filter. Usually the pictures of the inferior K&N is one of the small pod type filters. It doesn’t make sense to me that an equal size K&N would not be superior to a paper filter. The only equal size K&N is NO-0100.
Click to expand...
It doesn’t make sense because marketing has convinced people a window screen & gauze will filter out fine dust. It doesn’t.
Some light reading:

I saw it first hand 40 years ago, and immediately shitcanned the K&N’s.

The Commando ham can uses a filter that is sized way larger than most, a great engineering choice. Air filter restriction is NOT AN ISSUE, and the free flowing window screen element will add nothing in the way of performance.
 
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Saber said:
Thanks Dave,
Our bikes were built at the same time (319416). Do you think they were made with the baffles or no baffles?
Click to expand...
I have 319265 in New Zealand. Mine does not have baffles now but pretty sure the original when I bought it had them.

42 years ago so memory confusion is possible. I have the original some where around here and just moved house so if I find it in my unpacking I will update.
 
Both my 71 750 and 74 850 have the original air filters. No baffles [I'm baffled there ].
Really easy to change the filter. I usually get my wife to hold the front plate and squeeze it forward against the carbs a wee bit and the air filter slides in really easy. I do place a piece of cardboard on the top of the primary to prevent scratching.
My 850 originally came with the K&N equivalent of the original paper filter. I threw that out because I could see right through it.
Dereck
 
uh what about how to make spam can work with single 34mm mikuni? is that possible? curious but yellow
 
concours said:
It doesn’t make sense because marketing has convinced people a window screen & gauze will filter out fine dust. It doesn’t.
Some light reading:

I saw it first hand 40 years ago, and immediately shitcanned the K&N’s.

The Commando ham can uses a filter that is sized way larger than most, a great engineering choice. Air filter restriction is NOT AN ISSUE, and the free flowing window screen element will add nothing in the way of performance.
Click to expand...
I looked at the report. Interesting that the AC Delco filter has 349.758 Cu Inches of area while the quoted K&N has 200.586 Cu Inches, this is not filtered surface area.
AC Delco dimensions 12.7x10.2x2.7
K&N 12.5x9.875x1.625
 
alan hodge said:
uh what about how to make spam can work with single 34mm mikuni? is that possible? curious but yellow
Click to expand...
Norvil (horror of horrors!) list a single carb front filter plate.... And whilst I know it's fashionable to knock Les and Co (his bedside manner can be a little 'annoying' at times) they have been keeping Nortons on the road and providing useful 'upgrades' (My Mk3 battery cover bracket wasn't available from anyone else) for a long time now. I've bought from all of the big three here in the UK over the past thirty years, had cause to praise them all, AND cause to be p*ssed off with service and/or dubious advice too. BUT, we all have 'off days', and it's good we are spoilt for choice. My last three orders have been: Norvil/RGM/AN, all on my doorstep within four days of ordering.....
 
We got one of the ‘slim’ ham can assemblies from RGM - it makes it a lot easier to get the filter element and perforated mesh piece in and out.

Going back to original air filter assembly Going back to original air filter assembly

They also do a single plate for the single carb conversions.

www.rgmnorton.co.uk

COMPLETE SINGLE CARB NARROW AIR FILTER ASSEMBLY, STAINLESS STEEL

COMPLETE SINGLE CARB NARROW AIR FILTER, STAINLESS STEEL 050901 RGM NORTON
www.rgmnorton.co.uk

Only the trained eye would notice there’s something different going on.
 
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