Rich AND lean????

Hey all,

I was unable to richen the plugs on my 85 maxim 700 so I bought larger pilot jets (36.5 to 41) and a colortune and found some success. Now, I have one cylinder on which the mixture screw is all the way in and still produces a black plug. The other three are either black or white depending on how long I have run the bike at high speeds. No nice brown in between even after weeks of tweaking. Not only that, but the bike will sputter and bog out if I don't ease the throttle in first gear. Once well off idle the bike runs fine. Do I need to upjet the main fuel jets as well to eliminate the pearly white plugs? Am I running lean or rich if the bike hesitates getting out of the hole? The bike was running great before I messed with the mixture settings and now I'm wondering if I shouldn't have left well enough alone if it's going to produce white plugs even after upjetting. Carbs are clean by the way and it idles well.

Thanks
marshall

 

if oyu have an improper float height (too high) the fuel will overfill and flow too much through the main circuit causing a rich mixture regardless of the pilot screw settings.....just something to look at for that one rich side.

as for the hesitation i would say go up on the pilot jet. there is no accelerator pump on these carbs, if its running lean the initial rush of air causes the mixture to lean out for a split second...if you are already lean on the pilot + temporary leanness from the slide lifting = BOG.

 

Mixture Screw all the way in and Mixture STILL TOO Rich.
AIR Jets incorrectly placed or of the wrong size.



Make some Tools to check the Float Heights of your Carbs while the Bike is running.

You need some vinyl hose, four 90-degree hose unions, plastic wire ties.
Make four Float Level sight glasses.
Keep the section coming off the Fuel Bowl short
Add the 90 and run the hose up the sides.

See what the situation looks like when you are at various throttle ranges.
You might have uneven distribution of Gas.
Levels too high. (or low)

Ii don't understand the situation with being Rich with the PMScrew closed.

 

Thanks for the input,


I do plan on doing the float level check as soon as I have some time. As far as running lean, the bogging issue is new and, to my knowledge, I was running far leaner when I had the stock pilot jets installed. Could the one rich cylinder be causing the bogging... too much fuel instead of too little?

Thanks.

 

I don't think that only one Hole being too Rich is going to cause a major performance issue.
Some bikes almost don't display anything unusual. An untrained ear would fail to detect the miss.
But, bringing-in the Hole that is misfiring will be a challenge if there is anything wrong with the Cylinder ... going-in!

The Mixture adjustment can be hard to nail down.
Finding the Optimum Mixture can take time; even with a Colortune.

You can be too Lean at 3 Turns Out ... and then be too Rich well before 3 and-a-quarter.

 

"bringing-in the Hole that is misfiring will be a challenge if there is anything wrong with the Cylinder ... going-in"


can you elaborate on what you mean by this Rick?

Thanks

 

If the Cylinder that's misfiring is doing so because the Compression in that Hole is ... let's say "Borderline Low" ... you'll have to find a Ratio that "Works" for that Hole ... alone.
(Until corrective measures ... Yada, yada, yada)

The Hole might have Low Compression and a tendency to leave a little Oil behind.
In this case, (if it is the case at all) you'd have to Find a workable Lean Mixture and run a hotter Plug. Give and take. Compensating.

Let's hope we don't have to go there and all your Compression Numbers are right up there where they belong!

 

In the picture it says cover the hole, what do you use a screw?

 

It is the threaded hole the screw that holds the cover goes into . Some carb sets do not have the cover...

 

mine dosen't have the cover, That's my question do you use a screw to plug the hole?

 

no. the hole should be blind.

 

What he said

 

I checked compression and all four cylinders are the same, around 45 psi I think. I'm pretty sure my air jets are in the correct holes because I removed and cleaned them individually, one at a time last time I was in the top of the carbs. Next I'll check fuel levels in the float bowls to see if that is the cause of my rich cylinder. I'm still confused as to why installing larger pilot jets would cause the bike to exhibit the symptoms of being lean, i.e. bogging.


p.s., do hitachi hs 33's have that third hole that needs to be plugged? I don't remember seeing it.

Thanks all.

 

Explain how you did the Compression Test.

45- Pounds per Square Inch is so far below the Bare Minimum Compression needed to make the Bike run ... I hope YOU did something to contribute to the LOW (Critically too Low) Compression Readings.

Re-Test with:
ALL Plugs Out
Battery Fully Charged
Throttles held Wide Open

Get Compression Values.
If they are still LOW.
Re-Test doing a WET Compression Test.

Add a Tablespoon of Oil to the Cylinders reading below 120 psi.
Record Wet Compression Numbers.

 

Well...only had one plug out at a time and did not hold throttle open. Maybe I'm not out of the woods yet. I'll keep you posted.

Thanks Rick.

 

I always prefer a leak down test...maybe you could bum or borrow one. Pretty simple to use. As stated before, float levels are a must.

 

Theoretically, ...

A Compression Test IS a Leak Down Test.
If there's a Leak; you see how bad.
Followed by a wet compression test ... tells you Rings or Valves.

But, since you bring-up the Idea of doing a Leak Down Test ...
What do you need and how do you perform the test?