TM 40 pilot settings

Hi

Need some advise  as I am not sure ...

Needle 9DJY4
pilot jet 22,5
main jet 145
air jet 1.2

Needle on the 3rd clip (washer on top of the needle)
Unifiler airfilter no snorkel and no holes in the side cover
Standard headers with a Leo Vince X3 silencer
2 & 1/2 turns on the pilot/mixture screw
pump is set to "spray" as soon as the throttle is opened and stops at 3/4 as per the manual and does hit the needle once the slide is high enough.

The bike starts easily and idles fine and does lift the front wheel off throttle in first, easier than when I ran the standard card (my gearing is quiet high @15/43).

The manual states that we should turn the pilot screw in until the bike is about to die the out again until it starts to idle irregularly. I can pretty much get to the point where the screw is just about all the way out. Currently it starts to die at 1.5 out. So I backed it out another 1 turn.

Coincidentally I always remember my old man saying "air screws" should be done like that and usually end up at 2.5 out but that was when two stroke were cool (and secretly still are ) so it just seemed right to have it at 2.5 turns out.

So the question is should I go to a smaller Pilot Air Jet (maybe 1.1), I did try a 25 pilot jet but I recall the same "issue" with the screw being just about all the way out with out idling becoming rough.

I looked at the spark plug but the insulator seemed to be a grey'ish color, the plug has only been in the bike as long as the TM 40 has been on the bike (a few hours running). The metal outer bit was black so I dont know if it is rich as the last time i though about reading plugs was 15 years ago  

My old plug with the original carb was reddish brown which I recall is right but cant remember if the metal bit was any color...

also sorry about the long and possibly pointless post ...

Make forking sure the valves are set to spotoncorrect before tuning a carb, just sayin'
IJ must be 25, AJ is correct at 1.2, and accept the screwsetting that comes with it - ~2.5 full turns out is fine, 3 is "ideal" but will only work in Utopia.
Pumper should not start from bottom but a bit up from that, and 3/4 open and still spraying? Too much, stop it between 1/2 & 2/3.
2stokes still rule, are coolest and bestest, just screw Soichiro Honda for, even after his death, forcing down the misbelief that 4stokes are better.... they're not! Did you know that a modern 2stroke is cleaner even? True too, but off topic.

shot dot, i was going to check valves this weekend and will set the pomp accordingly

Pomp?
P O m p ?
You're either pining for the fjords (which can be cured by eating some pap & braaivleis) or your hormones are influencing your typing (which can be cured by ....... no, nono, Focker is going to ban me!)
Mind, both can be addressed by the infamous 'Boer maak n Plan'

OK, enough of my/our local lingo - if I remember correct the pumper rod activates after just over a millimeter off 'shut' ie bottom-position of the slide - which is of course the position determined by the slide screw.
The slide screw & and airscrew settings you find by fiddling, you knew? True!
Turn the slide screw (SS) up a bit, and start the bugger.
Run it warm on a stand (not sidestand) so the bike is vertical, then run a hosepipe over one radiator to keep it cool whilst you fiddle.
Turn the air screw (AS) in until it starts to run awfullish, then out until it does same-ish. Note that this is by no means an exact science but more a fingertip-feeling thing, experience here rules. Set the screw smack-bang in the middle of this span (which will cause the revs to go highest)!
Now turn the revs down by turning the SS out until it is a more reasonable idle speed, however still a notch or so too high.
Turn the AS a bit to & fro until the engine runs better, if at all - but it often will.
Now reduce the AS to your ideal idle revs.... and again finetune the AS until it runs best. Mind, this latter will take very little turning either to or fro, so don't go berserk by turning the thing great heaps.
This now is the perfect setting for 'idle' - assuming that all the jets etc (valve clearance, airfilter etc etc) is all honeky dorey!
The above goes for any engine you care to mention! (Wait, any engine with a carburetor )

On TM40's, I've found that starting the bike cold (ie unused for a night or more, not necessarily frozen) it is somewhat reluctant to do this.
My idle speed is low I'll admit, so I just turn up the slide-screw a bit, then start it - which then goes as per the normal 'easy'.
When it reaches operating temperature I turn the AS down again, and the rest of the trip/day I don't need to touch it again.
Even with the large IMS tank on I can reach the AS easily enough, and the remote choke too.
If you find your bike (with TM40) does same then I suggest you just accept this, you'll thank your more-frugal consumption later (because an AJ 1.1 may cure this somewhat however results in a touch more richer idle mixture)

cool ill try this on the weekend while i wait for the potjie to cook

OK, that pot has boiled over already I'm sure - any improvements?

ox tail pot was yummy..

Also it seems to be better of the bottom but only rode it for a few kms. may still need to fiddle with the air/mixture screw.

BuRP wrote:On TM40's, I've found that starting the bike cold (ie unused for a night or more, not necessarily frozen) it is somewhat reluctant to do this.
My idle speed is low I'll admit, so I just turn up the slide-screw a bit, then start it - which then goes as per the normal 'easy'.
When it reaches operating temperature I turn the AS down again, and the rest of the trip/day I don't need to touch it again.
Even with the large IMS tank on I can reach the AS easily enough, and the remote choke too.
If you find your bike (with TM40) does same then I suggest you just accept this, you'll thank your more-frugal consumption later (because an AJ 1.1 may cure this somewhat however results in a touch more richer idle mixture)

Hi BuRP - Do you know what jets you have in your TM40? It is time to install mine and we are at the same altitude - I bought the TM40 kit from XR's Only and I see it has a few spare jets with it - Did you buy the same kit?
These are the jets I have
Mains are 147.5, 150 & 152.5
Pilots are 15, 17.5 and 20

Erm lol, you can throw them all away.
XRsO is great but for their jets supplied, and I bet the cables are too short too, for your SM setup?
You need the 1.2AJ, 25IJ and I think a 145MJ if you want same as me, however I've got to dyno the thing for the main still, the rest I am happy with - actually also the main but would like to make sure. A full dyno will show me how good my seat of pants is, or how shite it is

BuRP wrote:Erm lol, you can throw them all away.
XRsO is great but for their jets supplied, and I bet the cables are too short too, for your SM setup?
You need the 1.2AJ, 25IJ and I think a 145MJ if you want same as me, however I've got to dyno the thing for the main still, the rest I am happy with - actually also the main but would like to make sure. A full dyno will show me how good my seat of pants is, or how shite it is

I have the 11:1 piston, supposed HRC cam and a different exhaust. Should I maybe start off a bit bigger on the main?

Try by all means, better too rich than too lean..... unless you want to flog the exploded lot for a song to me afterwards?

Hmm, now there's an idea: why don't you start with a MJ of say 112 and go berserk for a loooong ride WO?

BuRP wrote:Erm lol, you can throw them all away.
XRsO is great but for their jets supplied, and I bet the cables are too short too, for your SM setup?
You need the 1.2AJ, 25IJ and I think a 145MJ if you want same as me, however I've got to dyno the thing for the main still, the rest I am happy with - actually also the main but would like to make sure. A full dyno will show me how good my seat of pants is, or how shite it is

Is the AJ the accelerator pump jet? I can't read the first number on mine but the second number is a 5

Nothing from XRsO jetwise is standard, however their standard is to supply the wrong jets - let me know if you don't get that
Also, never seen a roof on a carb... but the AJ sits in the intake-side if I remember well enough. Easy to spot though, one end of the jet (ie hole visible) sits in air, the other in a bore which goes to the idle system.
What's also in the intake side is the pumper jet, and this thing you should turn to aim so that it squirts onto the needle. As an aside, I think that one is rated 50 on mine, can't remember - but it has a size!

BuRP wrote:Nothing from XRsO jetwise is standard, however their standard is to supply the wrong jets - let me know if you don't get that
Also, never seen a roof on a carb... but the AJ sits in the intake-side if I remember well enough. Easy to spot though, one end of the jet (ie hole visible) sits in air, the other in a bore which goes to the idle system.
What's also in the intake side is the pumper jet, and this thing you should turn to aim so that it squirts onto the needle. As an aside, I think that one is rated 50 on mine, can't remember - but it has a size!

Where did you get a 1.2AJ from? Which one is it in the below photo?

This is handy - Mikuni maual

It is an HS40 but seems to be the same thing.

My Air jet is a 1.1, hard to read those tiny numbers

BuRP wrote:Erm lol, you can throw them all away.
XRsO is great but for their jets supplied, and I bet the cables are too short too, for your SM setup?
You need the 1.2AJ, 25IJ and I think a 145MJ if you want same as me, however I've got to dyno the thing for the main still, the rest I am happy with - actually also the main but would like to make sure. A full dyno will show me how good my seat of pants is, or how shite it is

What needle jet and needle are you running