Another "won't idle" thread ... (xj650j)

This is my first bike and I've been putting a lot of effort (and money) into it before getting on the road. So far I've done the following:

- got the valves in spec
- new fusebox
- cleaned carbs (including choke plungers and mixture screws)
- bench sync
- set mixture screws to 2.5 turns out

and a couple other things that wouldn't really affect how the bike runs (rear brake check is done).

I haven't checked the float levels yet because I'm waiting to get new drain plug screws as mine are seized in.


And here's a bit about the bike's behaviour:

- starts easily enough with choke, but dies after 2 seconds
- if I give it throttle during those 2 seconds, I can keep it going for a while, then turn off the choke after a minute or so
- while giving it throttle, I've tried to adjust the idle thinking it was just set too low, but I can go all the way clockwise on the adjustment knob and it makes no difference
- my intake boots are pretty cracked when I bend them a bit. The PO coated them with liquid electrical tape. while I was keeping the engine going with throttle, I sprayed some quick start on the boots, but it didn't rev higher at all.



Is that enough to go on? I really appreciate the help.

 

Pilot Mixture Screws
2-1/2 Turns Out
Preset.
Could be having a Negative effect on your Fine Tuning effort.

Take a Tuning Shortcut.
Non-EPA inspired Preset.
Try this on for size.

Take one Brand New -- Never-been-used -- No. 2 Pencil.
Remove the Rubber Eraser without damaging the Rubber.

Measure from BOTTOM -- 5/32nds of 1-Inch. (0.156in ~ 3.968mm)
Fine line MARK that distance around the Eraser.

Use this as a PRESET Tool.
INSERT Bottom of Eraser into Pilot Mixture Screw Orifice.
Observe LINE marked on Eraser.

Place LINE on Eraser --> Even with TOP of Mix Screw Orifice
Raise or Lower Mixture Screw as needed to Line-up MARK with Top of
Orifice.

Begin Fine Tuning with Pilot Mixture Screws PRESET to this depth.

::: Be the 1st to calculate how many turns-out from the bottom this value is! :::

 

Ha! that has to be the cheapest DIY tool I've heard of yet!

still, I'll have to steal a pencil from work tomorrow.

 

Ok, so 5/32" depth on the mixture screw looks like 4 - 4.5 turns out.
I could calculate the actual number if I knew the thread pitch of the screws. I just eyeballed it.

That seems really far out, but it did fix my problem. Now I'm idling at 1K!
BUT I'm getting a lot of hesitation in throttle response and it doesn't like to die back down after getting over 3K. It will just sit there at 3500 until I let the clutch out a bit to slow the engine down. At least I'm kind of at a point where I can vacuum sync, right?. After float levels of course.

I got my new drain plug screws from chacal and found out that my fuel levels are way too low (like 10mm under that ridge on the carb body). I'm gonna work on that tomorrow. off come the carbs AGAIN ...

 

Are you "Bogging-out"

-Or- ... "Hesitating"

If the Mixture is too RICH, ... you'll Bog-out.

I doubt its to Lean.
But, there exists the possibility of TOO MUCH AIR if:


IF...
The AIR Jets are misplaced.
The Pilot Mixture O-rings are flattened-out dead.
The Passages connecting the Pilot FUEL Jet to the Pilot MIXTURE Screw are clogged.

With where your Pilot Screws are NOW, ...
Begin some TWEAKING.
Save your Gauge to be able to return to HOME.

TWEAK <----- the Mixture Screws IN.

Not very much!
Think about it like a STOPWATCH
One 360 Degree Sweep of the Hand is 1-Minute = 1 Full Turn.

You move the Pilot Screws IN -----> 3 -to- 5 SECONDS !!!

::: It's nice to have a Tool with a Scribe Mark filled with White China Marker or White Nail Polish, ... so you can VISUALLY move the Screw just a skootch. :::

 

I would fix this and then work with Rick's suggestions.

 

This Illustration shows the Specs on Fuel Level Height.

You want the Upper GREEN if you can get it.

The YELLOW is the acceptable ( +/- ) range.