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The TTR250 FAQ web pages -> TTR250 -> Repairs and maintenance -> so i messed with my mixture and now it goes like a pig.
Post Info TOPIC: so i messed with my mixture and now it goes like a pig.
davecambo


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so i messed with my mixture and now it goes like a pig.
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as the title suggests, i messed with my mixture on the carb and now it goes a bit like a pig.

I tired the whole thing of warming it up, then adjusting the idle speed to a little higher, then turning the mixture to the right until it almost conks out, then turning it to the left till it sounds better, but while riding it around it goes well down low revs each gear but shudders when reving high. i kept stopping and turning the mixer and got it pretty close to good, but can anyone tell me where it would have been set to (as in how many turns) from the factory, becuase it was running perfect before.

cheers.



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davecambo


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EDIT****

i forgot i put the snorkel back in. Took it out and BANG! hauling ass now.

ok so i ended up going for one full turn out from when it conks out or all the way right. is this too lean?

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TTRfan


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I have previously confessed to not being good at carbs but I will have a go at answering.

I think the adjustment you are playing with is for the pilot jet whose standard setting is one and a quarter turns out if I remember correctly although, as Lin pointed on another thread, the TTR is usally happier on 2 turns  out.

The pilot jet only affects slow running. The main jet comes in very quickly as I found out when riding a TTR with a completely blocked pilot jet. If I kept tweaking the throttle when at lights etc it would keep running.

I am surprised that leaving out the snorkel completely had such a big effect on the running. Presumably making it run very lean?

All good stuff wink

Brian



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davecambo


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oh ok. well at one full turn out it is hammering, well you know what i mean, for a ttr i guess. but if that is too lean it may cause engine damage so ill try two turns tomorrow and see how i go. I must admit this is fun anyways.

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davecambo


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hey wait. is that two turns out for a bike with exhaust system and filter or for a standard TTR 250?

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Lin


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Regardless of exhaust/air filter, 2 to 2.5 turns out is good. The mixture screw has most effect on the air-fuel ratio at idle rpm and slightly off idle, very soon after cracking the throttle the pilot jet comes into play. With the Teikei carb, after about 20% throttle the main jet (and emulsion tube/needle jet) has the most say.

The removal of the snorkel has the most effect at high airflows - wide throttle/high rpms. One would expect that snorkel removal would lean out the mixture, but in my experience it seems to be academic. I suspect the blue TTR may run a little rich at the high end (safety margin for piston crown temperatures) and removing the snorkel may be just enough to provide a faster burning a/f ratio at higher rpms.

Bear in mind that ambient air temp and altitude also affects a/f ratio so snorkel removal and the attendant power increase may not be as noticeable in colder temps/low altitudes. Snorkel removal may not be a good idea if you plan deep water crossings.

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davecambo


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Thanks Lin for the very detailed reply. I wont be going through any water higher than my ankles no doubt.

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truslack


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fwtian wrote:

1 amatuer question!!! This the screw that must be 2 2,5 turns out??




 

No, that is the float drain screw!!



-- Edited by truslack on Monday 30th of January 2012 04:22:27 PM

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fwtian


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1 amatuer question!!! This the screw that must be 2 2,5 turns out??











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TTRfan


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It's this one:

Air screw.jpg



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fwtian


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oops! So mixture screw must be 2 2,5 turns!!! How many turns the float drain screw must be???

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