dear all,
Just got my 1000 Le Mans MOt’d & taxed (its a 1986 Mk4) on the road today for first time after much effing about bleeding the bleeding linked braking… I’ve had it since 2012 in my ma’s garage for 3 yrs and with previuos owner it had been off road since 2008. The motor’s standard 28k miles still on points, & it starts well & ticksover much faster since i adjusted tappets as per Guzziology method using the timing marks.
I’ve got rid of a lot of the flaky red paint on wheels and forks and replaced clip-ons with adjustable risers to give my neck a chance.
Anyway, It came to me with louder Lanfranconi’s silencers and the K&N filters which pretty well every older le mans seems to have. But I am thinking that from the way it spits back when cold, and the time it takes to warm up, might mean its better if i refit the standard airbox?
No substitute for experience so what have my learned friends found to be most effective - K&Ns or standard airbox?
K&N’s typically need a change to next size up of main jets, but also check ALL the jets and orifices in the carbs are not half blocked with hard green/brown deposits. Guess how I know. 
ta but the main jet would only affect running when throttle past 2/3 or mainly from 3/4 open wouldn’t it?
I’d be interested to hear from someone who has changed over from standard airbox to K&N’s, was there actually any improvement in general running and throttle response? or is it mainly about accessibility for the air filter etc?
accessibility for the air filter,have changed from standard to K&N filters on my G5 & 1000s you would only notice a change on a track day
Yes of course and which is where a less restrictive filter will have the most effect also, compared to the stock one. At smaller throttle settings there’d be too little difference to bother about.
I’d be interested to hear from someone who has changed over from standard airbox to K&N’s, was there actually .any improvement in general running and throttle response? or is it mainly about accessibility for the air filter etc?
Yes I did, for the second reason, also, the stock tapered paper element was piddling small IMHO also I noticed only the front half was getting dirty, at the end where the air comes into the box. Rightly or wrongly this suggested to me that the total available surface area of the pleated paper was not being used.
I did the conversion on both my bikes so far the Spada 1 and the Le Mans 1.
The conversion kit from Motomecca for the Spada included a pair of one size up main jets.
PS (edit): K&N’s were put onto the LM1 because of course by default it has no air filters at all.
I changed the small cone-shaped K+N look-a-likes which had been fitted to my 1000S for real K+N’s, big oval ones as recommended in Guzziology and the old girl really appreciated it, although one day when I get around to it I’ll try using the original air box, with a K+N filter inside, again the word according to D.R. is that it’s a good air box to use, though some people remove the spout apparently.
I have K&N cone filters fitted simply for accessibility.
An increase in main jet size was all that was required for the reason stated above.
The increased airflow really only pays dividends at wider throttle openings. On part throttle the OEM paper filter is capable of flowing everything that the engine needs.