Racing idle carb fix.

So I Have an xj650 Maxim with 4 to 1 exhaust and a cut airbox with a single pod filter.

This is the process i used to fix my hitachi cards and get the bike to run and idle, with great throttle response.
Issues:
-crazy uncontrollable idle.
-hard start.
- raw fuel from the throttle shaft seals.
-raw fuel in the engine side carb boots.
- idle race to 5000 rpm after throttle blip, and not able to bring back down.

Solutions:
.
Cleaned and rebuild the cards X3 because i thought i was missing something.
sanded flush the copper washer and reseated the main and pilot jet.
Used welding wire to bench sync the cards.
Look through the carbs at a light to make sure that the butterfly valves are seated properly and that they have roughly the same sliver of light.
IMPORTANT: make sure that they close fully when backing off the idle screw!!!!
- these carbs are designed to run off the pilot jet. Not the butterfly valve.
- the raw fuel was because the butterfly was open allowing too much fuel in the carb passageway.
- There should not be raw fuel in the carb. It is atomized due to the Massive Vacuum.

Next: Do not touch mixture screw, but if you have, set at 2.5 from a soft seat.

put carbs back on the bike and get it running. any way possible(starter fluid and throttle, any means- get it started)

Now adjust the idle screw until it is at some what steady idle. 1500 rpm is okay as long as it does not race to 5000 rpm like before.
If possible get a manometer to fully sync carbs.

Finally blip throttle and see what happens. if lucky it should rev up and then com back down.
Adjust idle when bike is at operating temp.

This may not work for every bike but it worked for me on 2 different bikes. Its worth a shot. Dont Give up!

- Chinn-

 

That is why your method works. You aren't messing with the intake very much in terms of volume or velocity.
What do the plugs look like? I'm asking since you appear to have retained the stock jetting.

The thing that fixed the racing idle was the carb rebuild and setup, which should be done even when running the stock airbox.

 

Plugs have looked okay. nothing out of the ordinary. There has not been many miles put on the bike after getting it running better, but ill be checking them shortly to see how they look.

The racing idle was the weirdest thing. it has never happened on any carbureted bike i have owned.

 

when you adjusted the idle screw was the choke on or off? I think you are saying, you turned off the choke, and while the bike was idling on its own, you turned the idle screw to get it 1100-1500. Then you did a vac sync.
Let me know. I had same problem.