le mans 3 jetting

[mglm850]

hi all

i am looking for information on jetting the carbs on a 1984 lemans 3.so far i have found alot of confusion and info about removing shrouds or dont remove shrouds and dont follow this or that jetting

the bike is stock except k&n filters and a bub exhaust.
the jetting has not yet been changed for the pipes and air cleaners ( back story.. the previous owner put the k&n filters on and did not jet it and i just
found a set of bub pipes that i plan on putting on )

i would think it should be .. hopefully someone can suggest the correct jetting .

any help will be greatly appreciated
thanks
mglm

[pete mcgee]

I have a 1984 mk3 lemans.
1 get rid of the k&n filters, they stop large rocks and occassional small child they do not stop any small abrasive particles that trash your rings and valves, ask me how I worked that out. Oiled foam is the go, over 100,000 miles since last rebuild compression still around 200psi.
2 Im running a compllete Staintune exhaust
3 Shrouds fitted, leave them in
4 European jetting vs what to try.
Throttle slide 60/3, fit that
Atomiser 265 ab, fit that
Main jet 115, Try anything between 123 and 128 and see how that works for your setup
Idle jet 50, try 53 or 55 with your setup
Starter jet 70 never played with it
Needle K18 3rd notch, play around 1 notch up or down and see how it goes
Set the float height 17.5 to 18.5 mm
Idle screw 1.5 turns out should be close with the above jetting. Play around + or- a 1/4 turn until you get thebest idle.
5 Set your tappet clearences to 9 thou, inlet and exhaust BEFORE you play around with jetting and get the carb balance set.

I hope this helps.

[moto-uno]

 ^ +1 , and make sure your ignition components and timing are fine :) . Peter

[GeorgiaGuzzi]

I’m just going to +1 what Pete said about foam filters vs K&N.

[SED]

Is there a problem you are trying to solve? 

For mine it was a hesitation off idle and generally anemic malaise.  The solution was to replace the valve guides.  The intake guides were absolutely blown out by 40,000.  It still had good compression, but you could wiggle the valve spring side to side - the left side was worse. Both plugs had shiny black patches from oil but the left side was larger.

Pete's set up looks good to me, but some references show a 268 atomizer.
This is mine, but it still hasn't got many miles since the guides so could maybe go to smaller atomizer.
Stock airbox (ditched the pods a couple years ago)
slide 60/3
needle K18  3rd notch
atomizer 268 (266 is also available)
main 120
idle 55
stock float height

[mglm850]

Thanks for tips.
To answer the question why..
I just picked it up not quite to months ago.  All stock  except the k& n. The bike has 16k on the clock but does run as though in need of a good time including timing and carb set up.. I am gathering needed tools and such. I also picked an exhaust and the dyna tech
I tend to think leaner is meaner but I don't want to burn it up either.
I just received my new carb balancer so that the timing and a valve adjustment will be done first .. I still have the 6mm adapter from 20 years ago when I had my first lm3 but my mercury sticks didn't make it.. I will update once I get it sorted

[SED]

Look forward to the report!