Skip to main content
000000 000003 000006 000009 000012 000015 000018 000021 000024 000027 000030 000033 000036 000039 000042 000045 000048 000051 000054 000057 000060 000063 000066 000069 000072 000075 000078 000081 000084 000087 000090 000093 000096 000099 000102 000105 000108 000111 000114 000117 000120 000123 000126 000129 000132 000135 000138 000141 000144 000147 000150 000153 000156 000159 000162 000165 000168 000171 000174 000177 000180 000183 000186 000189 000192 000195 000198 000201 000204 000207 000210 000213 000216 000219 000222 000225 000228 000231 000234 000237 000240 000243 000246 000249 000252 000255 000258 000261 000264 000267 000270 000273 000276 000279 000282 000285 000288 000291 000294 000297 000300 000303 000306 000309 000312 000318 000321 000324 000327 000330 000333 000336 000339 000342 000345 000348 000351 000354 000357 000360 000363 000366 000369 000372 000375 000378 000381 000384 000387 000390 000393 000396 000399 000402 000405 000408 000411 000414 000417 000420 000423 000426 000429 000432 000435 000438 000441 000444 000447 000450 000453 000456 000459 000462 000465 000468 000471 000474 000477 000480 000483 000486 000489 000492 000495 000498 000501 000504 000507 000510 000513 000516 000519 000522 000525 000528 000531 000534 000537 000540 000543 000546 000549 000552 000555 000558 000561 000564 000567 000570 000573 000576 000579 000582 000585 000588 000591 000594 000597 000600 000603 000606 000609 000612 000615 000618 000621 000624 000627 000630 000633 000636 000639 000642 000645 000648 000651 000654 000657 000660 000663 000666 000669 000672 000675 000678 000681 000684 000687 000690 000693 000696 000699 000702 000705 000708 000711 000714 000717 000720 000723 000726 000729 000732 000735 000738 000741 000744 000747 000750 000753 000756 000759 000762 000765 000768 000771 000774 000777 000780 000783 000786 000789 000792 000795 000798 000801 000804 000807 000810 000813 000816 000819 000822 000825 000828 000831 000834 000837 000840 000843 000846 000849 000852 000855 000858 000861 000864 000867 000870 000873 000876 000879 000882
English French German Italian Spanish

Carb to Air filter plate Rubbers


Whilst "Self Isolating" I'm attempting to fit the original air filter box and rubber  (Tubes) gaiters back onto my 1973 750 commando.

I've tried soap on the rubbers, entering the air filter front plate with the rubber tubes on already, attempting to squeeze the rubber tubes in after the plate has been loosly fitted but all to no avail!

The air filter element and rubber tuber are from Andover Norton and of substantial quality that allow such rough handling, but there is a limit and I don't want to mess anything up!

I did have the K&N one piece filter installed before but it just didn't fit right and I prefer the look of the standard fitment.

Any guidance / instructions would be well received, and hopefully I will have it fitted by the time this Corona Virus comes to an end!

Many thanks in anticipation Peter


Assuming you and I have the same set-up, I have the air box fitted with the gaiters, then fit the carburettors last. They slide down from above and can wriggle into the gaiter.


Use a hair dryer on the rubbers to warm & soften them when fitting, if you get one side started you can rotate the rubbers into place.




Whenever I do this job I undo the screw bolts from the manifold to head connection and remove the inlet insulators.

With the carbs hanging loose I fit the rubber connectors to the air filter 'ham can'.

I then connect the air filter rubbers to the sleeves on the carbs and refit the manifolds with the inlet insulators inserting the screw bolts hand tight.  Check the rubbers are fitted correctly and adjust if necessary. 

Tighten the manifold screw bolts. Check the rubbers are fitted correctly. If not undo screw bolts and repeat.

Job (usually) done first time.



Thanks to all the advice, its good to know there's someone out there who cares!

I'm sure, back in the 70's when these bikes were in regular service, dealers didn't revert to hair dryers or taking off the carbs, just to change the air filter, but thanks for your input, there's always more than one way to skin a cat!

After coating the rubbers again with tyre soap and the use of a steel 6" rule to prevent the rubbers falling too deep into the filter housing,I finally managed to get both rubbers home! What a palarvour!

Now its only the rubber fork gaiters to change!

Cheers. Peter



Pleased you got it sorted.  I definitely don't have much use for a hair-dryer these days.

However, I almost wish I hadn't bothered to respond. It probably took me longer to type the response than it would have done to do the job my way.  Certainly many ways of skinning a cat!

I have looked up the routine maintenance in the Workshop Manual and I couldn't find any reference to a service interval for either cleaning or replacing the air filter.

The only reference I could find is in Section  E10,

air filter

filter cleaning

I reckon that back in the day air filters were rarely inspected or changed. So much of the Commando implemented design is a 'bit of a kludge' and I reckon the carb to air filter connection is one of those.  Maintenance has definitely not been designed for.



Glad you got them on - for future reference I have found it best to mount carbs to intake runners first, then runners to head. Adjust throttle and air slide cables as you need to feel / see that they raise in unison, then fit rubbers to carbs. Next fit rubbers to air box front plate without filter and mesh in place - this will allow you to seat rubbers in their holes by reaching behind the plate with your fingers . Then pull plate forward and compress rubbers with cable ties run through plate bolt holes and around spark plugs. Insert filter and mesh , cut cable ties and fasten front plate . Job done.


… I found myself with the same problem today.

Unexpected, because

(a) I have always found that the procedure as illustrated in Andrew's excerpt from the Workshop Manual perfectly satisfactory (with the exception that it is surely easier to remove and refit the filter and "gauze band" from the other side, i.e. over the gearbox end-cover; the quotes are because a perforated metal sheet does not fit my notion of gauze)

(b) I thought I had done this successfully only a few days ago.

However, I was investigating possible weak mixture, and found that the r/h carb rubber had not properly engaged with the air cleaner cover and all my efforts to get it do so were failures.

Further inspection revealed that the seal of the air filter element was fouling the inner lip of the carb rubber, and that the reason for this was excess width of the seal compared to the previous filter element by about 1 mm: see attached picture — old seal is green, new is black.

The solution looks to be to trim the edge of the seal where it curves around the rubber. I'll report on success or otherwise in due course.



So today I

  1. Spent some time carefully bending the "gauze" to properly follow the curves in the upper corners of the front plate of the air filter housing
  2. Used a hot air gun at 100ºC to try and induce some thermosetting in conformity with the bends in the gauze
  3. trimmed the edge of the seal inside the upper corners to provide clearance for the carb rubbers

See pictures; subsequent to taking the final picture showing the relationship between seal and rubbers, I was successful in inserting the rubbers in the front plate openings having reassembled the filter housing.

One correction: I measured the seals of the old and new filters, and the difference is bigger than stated in my previous post. The old one is 15 mm wide, while the new is 17–18 mm.

I can confirm that the (relatively) easiest way to get everything back together is to take out the insulating spacers between the intake manifolds and the head, attach the carbs to the rubbers, and then re-insert the fibre spacers.

Interestingly, I have two AN-supplied "short" Allen keys; they turn out to be from different manufacturers, and one is absolutely the minimum possible length that will engage with the manifold screws, and the other is not. Guess which is easiest to use (hot tip: temporarily remove the inlet rocker cover nut to allow more movement.)


I really struggled to use an AN supplied Allen key as it was too short and the bend had enlarged and distorted the hex end. Of course I don’t own any imperial keys, so I carefully ground down a metric size to finally get the carbs off. 

once I knew what size the key was I searched on evilbay and purchased a pack of 5 extremely cheaply and proceeded to cut down a couple to the correct size, one is now kept on the bike, the other in my tool cabinet. And I still have more spares available. 


The factory article above is very lacking and not universal

The procedure I use is the same for all commandos. I've never done a SS so I can't comment there.

Consider the S commando blocking access from the LH side pipes.

Now consider the 74 air cleaners with the internal snorkel.

Also the air cleaner metal screen scratches the #### out of the primary and is additionally blocked by the LH ignition key  and switch on many versions of commando.

This is what I do.

1. Manifolds/carbs fully installed with boot adaptors with flange forward as original.

2. Air cleaner fully assembled and installed....

3. Always install from right side of bike. Use correct tool to work boots in.

About 8" long.  very thin screwdriver with sharp edged buffed off.

4. Always work on LH boot first. Silicone lube the air cleaner rubber end only. 

Install on carb flange first dry, make sure boot flat is toward center. using screwdriver to aid working  the air cleaner boot end in capturing the thin groove in the air cleaner sheet metal. Check again the flat is toward the center.

5. Only when full completed left side boot, follow similar for right side boot. Carb end first dry.

then do the air cleaner end silicone lubed putting the flat inward.

I have become fairly good at doing this and most of the time it takes under 5 minutes. I have been doing it this was since the mid 90's. The practice and skill is in using the screwdriver as a finger to manipulate the boot with minimum aid from a finge on your hand.

If the boots are hard ...change them

In reply to by julian_wells


And a further mod is to bend the long arm back so that it clears the rocker cover nut … thus obviating the need to remove it and thus obviating the opportunity to drop and lose its washer on the ground …


Norton Owners Club Website by White-Hot Design

Privacy Policy