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beer_studd_76

hot start problem

9 posts in this topic

i finally got the old girl running somewhat reliably, but now i've got a starting problem: she starts fine cold as long as the choke is off, and hot starting is next to impossible. i guessing this is to symptoms of the same problem.

what i need is for someone to tell me that this is a problem i can fix with the air screw. if i gotta take those carbs off one more time my head will friggin' explode! i'm guessing she's running a bit rich and maybe a turn or two on the air screw will lean things up a bit. am i on the right track here any other thoughts?

jeremiah

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Do you have the stock jetting?

Try backing the air screw out some and see what happens. You sound like you have the opposite problem I do. My pilot is too lean and its a total bastard to start cold (and I have to use the choke), but it starts pretty easily once warm.

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i finally got the old girl running somewhat reliably, but now i've got a starting problem: she starts fine cold as long as the choke is off, and hot starting is next to impossible. i guessing this is to symptoms of the same problem.

what i need is for someone to tell me that this is a problem i can fix with the air screw. if i gotta take those carbs off one more time my head will friggin' explode! i'm guessing she's running a bit rich and maybe a turn or two on the air screw will lean things up a bit. am i on the right track here any other thoughts?

jeremiah

Hi Jeremiah

Sounds like you are too rich. What pilot do you have in there? I gather the litle screw at the front is an airscrew right (still waiting on my manual)? How many turns out is it at?

I'll bow to the knowledge of others on here, as I am only just getting into these carbs, but if its an airscrew, I assume the goal is the same, I'd aim for about 2 turns out max. If that doesn't cure it, I'd drop down to the next size pilot jet.

cheers

Dave

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What pilot jet do you have installed?

The screw your talking about is actually a fuel screw and you can adjust it as follows. Make sure your engine is fully warmed up. Turn the pilot screw clockwise until the idle slows. Then turn the pilot screw counterclockwise until the idle slows again. Make a mental note of how many turns you made in between the low idle points. Then turn the pilot screw half way between the low idle points to finish the adjustment. If you turn the adjuster counterclockwise and the idle doesn't drop down, then you need a larger pilot jet. If you turn the pilot screw clockwise and the idle doesn't drop down, then you need a smaller pilot jet. After adjusting your pilot circuit, re-adjust your idle speed if necessary. Don't crank down on the pilot screw when it closes or you'll damage the seat, so be gentle when it stops or becomes harder to turn.

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The 85 XR600 has the dual carbs which have an air screw.

Funky aint it? :)

Tuning would be the same procedure, except if you turn the air screw in and the idle doesnt drop, the pilot is too small. If you turn the air screw out and idle doesnt drop, then the pilot is too big.

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You would have been right for most 600's too. I dont know why the duals are so much different. :)

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