Idle speed adjustment (carbed models)

[Surly]

Hi all. I've wanted to post this info for some time now, and since we've had a request by a new member, I dug out a spare carb and snapped a few pics to illustrate the cold idle speed adjustment procedure. This adjustment will correct a high-idle condition at engine startup. (Hot idle speed adjustment is performed afterward.) You do not need to remove the carb (or any part of the carb) to make this adjustment.

Pic 1 shows the back side of a typical Samurai carb. The yellow circle shows a mark on the cam lobe which should be aligned with the center of the post beneath it. The red circle shows the two holes which must be "pinned" together with a nail or an allen wrench to make the adjustment.



Pic 2 shows where to position a large flat-blade screwdriver. Simply lift the lower lobe until the two holes align...



...and insert a pin to hold it there.



 Now move your screwdriver to this position...



...and bend the tab slightly upward. Move it a little bit at a time, repeating the procedure as necessary until the mark aligns with the post beneath it when the pin is removed.



Now remove all your tools and start your engine. Surprise!  

[tippyzuk]

awesome, those instructions on the suzuki john thing confused me a little without looking at a carb...but yours is great...good work!

[Surly]

You're welcome! Now here's a picture of the hot idle speed adjustment screw, with a screwdriver in position. This screw is on the side of the carb facing the passenger's side fender:



I like to set my hot idle speed around 1200-1300 rpm. If I set it much lower, my engine will occasionally die in traffic when I come to a sudden stop. But it's really just a matter of personal preference. HTH

[Surly]

One more carb fact: if your idle speed mysteriously goes up and down without any apparent cause, try disconnecting the idle-up solenoid wire.  It's the green plug at the front of the engine, just above the water pump:



The idle-up solenoid is supposed to make the engine rev when there's an electrical load on the alternator. On some vehicles, the system becomes intermittent and the idle speed will go up and down (cycling) by itself. Disconnecting this plug will disable the solenoid and solve the problem. Just be sure to set your hot idle speed a bit high, and everything should work fine.

[got_zuk]

O.K. i had a problem at the spring zuwharrie, well maybe a week before. I could start it and it would run fine but if I put it in gear and tried to drive it would die. and it also started burning real rich. I put davids carb on it and it ran fine so I took it to zuwharrie and all I got out of it was 3 hours!!  
any help would be great!!

[Surly]

What happened to it after three hours... did David take it back?

[got_zuk]

it started doin the same thing as my original carb.

[Surly]

Oh no... you broke David's carb! (j/k) My guess would be either a bad O2 sensor or a plugged exhaust. HTH

[got_zuk]

thanks, I will see what happens!

[eruby]

WOW, Great information. I just found this board yesterday and read this post. Surly, your pics are great and I made the fix last nite. I have the Haynes book and a copy of the shop manual and neither clearly indicated how to adjust the cold idle. Thank you thank you thank you.

[steve_fisher]

Just joined the board.Heck I just joined the Sammi thing all together today.I hate to be a copy cat but thankyou thank you thank you.Great write up.

[brotherjack]

The carb on my Zuke looks similar to the one in the pictures (the two inlets sticking out, and a few other similarities), but I have a fast idle screw pointing out toward the drivers side located on the linkage around back of the carb.  I don't know if it's the stock carb or not, but I got my zuke from a fellow who didn't do a whole lot of upgrades that cost more than 1$, so I really doubt he changed the carb out.  Mine's a Canadian 87 LWB for reference.

[dschwab9]

Mine has a screw for the fast idle adjustment also

[Surly]

The carb on my Zuke looks similar to the one in the pictures (the two inlets sticking out, and a few other similarities), but I have a fast idle screw pointing out toward the drivers side located on the linkage around back of the carb... Mine's a Canadian 87 LWB for reference.

Does it look like this?


That's an Aisin carb, which were used on Canadian Zuks. American Zuks have Hitachi carbs. All of the photos and instructions I posted are for Hitachi carbs only. Sorry!

[Surly]

Here is some text I "borrowed" from a related post on another BBS. I'll re-post it here if it isn't against the rules:

"That's an Aisin 2A carb. I couldn't find any info on rebuilding them. The FSM is a good source, but it must be the Canadian model FSM, all US models came with Hitachi DFB306 carbs. Suzuki or any other parts places I tried for that matter, can't get a rebuild kit for the (Aisin) carb. Suzuki can special order all of the little parts separately for a full rebuild, but it will cost, and some of the stuff (I was told) has to come from Japan."

Hope this helps!