D17 choke

[Luke470]

I've got a d17 that will only run when fully chocked. What carb adjustment needs to be made?

Thanks

 

[DanielW]

Theoretically opening up the Main Jet/Load Adjusting Needle/Power Adjusting needle (usually called the Main Jet, but if you have one of many manuals made over the years for the D17 it might be called one of those other names). To adjust, I'd start with 1.5 turns out from stop, then with it running and warm at governed speed, turn in until the RPM just starts to drop, then back out just a smidge. Then run for a while, if it stumbles on acceleration, you may have to keep backing it out (richer) a smidge at a time.

But before you do that, however: An engine that's only running with full choke means it's really leaned out - far more than you'd typically get with a misadjusted carb (unless it's been really tampered with). Usually it's a sign of it sucking air somewhere down-stream of the carb. Check to make sure your carb-to-manifold and manifold-to-block bolts/studs are tight and the gaskets are in-place and looking good. Then look for cracks in the manifold/riser.

 

[DanielW]

I should also add. Timing issues (especially too advanced) can sometimes mimic carb issues and it will run better with some choke action. Maybe makes sure you're timing's at least close to the right ballpark before going full ham with the fuel system adjustments.

 

[Roger in Iowa]

Remove plug in bottom of carb and see if will fill a quart jar with a good stream of gas coming out of opening. If not, check plugged fuel filter or restriction in bottom of fuel tank.

 

[Skyhighballoon(MO)]

First, remove the air intake hose from the carb and inspect the choke butterfly in the carb intake to be sure the choke is on when you think it's on. On a M/S carb, it is possible to have the arm put on upside down so when you pull the choke out the choke is off instead of being on. Found that on a WD45 I bought and couldn't figure out why it wouldn't run after a couple minutes when it warmed up.