pilot mixture screws?

I have noticed on my 83 750 maxim that it appears that where the screws are located they are plugged. Is this the way some are? How do you adjust them or do you never have to? The bike runs great, I am just curious.

 

They all come with those little plugs covering them to make them "tamper proof" for emisisons considerations, etc. If you ever do any carb tweaking you will need to pull them out. That's done by drilling a small hole (be careful, the screws are soft and they are right beneath these plugs), inserting a sheet metal screw and pulling those plugs out.

 

They are Plugged at the Factory after being set to conform to the highest Emissions Standards on-the-books ... California.

Generally, the Factory "Preset" is a skootch on the Lean side. The Bike will perform quite nicely but you sacrifice smoothness in transition. The out-of-the-hole performance is crisp, but you probably have an unsteady Idle.

The Plugs are easily removed to allow for a more precise Tuning. Some Dealerships moved the California set-up a few degrees Richer and replaced the Plugs.

If your Plugs have a very tiny hole at their center ... they are Factory and you can ... if you like ... remove those Plugs and Tweak the Pilot Mixtures for a slightly more Rich Mixture that will allow the bike to Idle on its own without wristing-in some revs ... and, produce a Mixture that will give you a more smooth acceleration and engine coasting.

Since you attest that the Bike is running fine ... leave them be. But, do understand that those Screws beneath the Plugs are the Key feature to fine-tuning and can be moved in and out to make the performance of the Bike better than the Factory preset.

 

Rick, your right on as far as the idle goes. I do notice that sometimes when I come to a quick stop(clutch in and in 1st) the bike will die. If I come to normal to slow stops no problem. Also starting in 70 degree weather it takes two pushes with the starter. It seams like even when idling at 1100 rpm the engine is barly staying running(not real smooth). But the throttle response is great. The only thing that annoys me about this bike is the fast stops and killing on me. Thanks for the help, I was not positive there were screws under those plugs.

 

If you remove the Plugs and give the Pilot Mixtures a bit more Richness, you can adjust them so that the bike will Idle like an Atomic Clock.

You aren't far from that at the present setting.
You just need to TWEAK the Screw a few degrees.

When you DO have the Anti-tamper Plugs removed ... you can do a Full-House Tweaking of all four Carbs ... Individually.
Doing Spark Plug Reads and adjusting one or more of the Carbs for added Richness or Leaning-out one or two as needed.

Its fun to do the Plug Chops.
You get immediate feed-back and can make the adjustment accordingly.

Or, you can di it over time.
Every few days ... peed at the Plugs. Tweak.

Pretty soon you have the optimum setting and great performance from Idle right to the end of the Tach!

 

This is great news... I just went through a carb rebuild and rejet with a kit from DynoJet (pod air filters). The bike ('82 XJ750J Maxim) seems to be running great, but idles a bit rough. I was thinking that I may not have cleaned the enrichment circuit properly... but then again was pretty diligent. I initially had the pilot screw turned out 3 complete turns, per the Dynojet instructions, but thought that might have been a bit extreme, and turned them back to just 1.5 turns. I don't think it's running too lean... maybe it just needs a couple degrees more to smooth out idle....

Also, I've noticed that if I turn the choke up any more than a little, the bike revs *real* high. Not sure how high, as my tach is gummed up, but it seems higher than normal. Is this typical behavior?

 

I don't know what to tell you on that Pilot Mixture Screw being OK at 1.5 Out.

It would seem to me that that would be pretty darn lean.
You have to really be diligent looking at the Plugs.
If you have the right coloration on the Plugs ... I guess the Pilot Jet you get with the KIT is a size or two up from stock.

 

I'm going to throw this one out there because I remeber hearing it on thegsresources.com (Suzuki GS series bikes). The idle air adjustment screws are just that, air adjustment screws. Screwing them in restricts the amount of air that is allowed into the idle circuit resulting in a rich idle circuit. The opposite is that backing them out results in a lean idle circuit.

I have not tried it myself and just left mine at 2.5 turns for the time being, but that is what I was tought when I owned a Suzuki GS with Mikunie Carbs (same design as the Hitachis).

 

Technically, they do meter AIR. Pilot Air which passes over an open Pilot Fuel Passage and pick-up a quantity of Fuel to bring along with it.

In reduces the Air Flow and consequently reduces the amount of Fuel brought along. Out increases the Air and brings more Fuel into the Idle system.

The idea is to regulate the Flow to provide enough Air~Fuel to provide for a steady Idle while adding just enough extra to supplement the Mixture with Fuel when the Throttles are opened and the rush of fresh air enters the Cylinder.

There is a momentary delay before the Main Fuel Jet supply is enough for good ignition and power. But, the added supply from the Pilot system supplements the Main Jet Fuel making the Power Stroke smooth and seamless from the time the Throttles are opened until the Main Fuel takes over.