Verify my compression numbers are right

fine tuning? far cry from that.
after two good syncs... drop in colortune. ALL 4 cylinders do the EXACT same thing. 3 turns out there is barely any visible combustion.

turn out 8 degrees- I get no response. takes over 2 turns to start reacting. then it stops being spuratic with firing, and starts firing with every spark.

at this point I am 5 to 6 turns out, just to get it to burn every spark.

all 4 cyl's like that.

ran great all afternoon, just a little noisy motor (cam chain?) which started a week or so ago.

my spark looked weak in the colortune. is it possible its so weak it needs the mixtures much heavier on the gas side of the mix to burn better?

 

just ran 1/4 can seafoam in my fresh tank... only 12 miles in the tank and I felt more/even power on the highway. got off highway - running smoother.
idle went UP 150 rpm. tweaked back down to 1050 and its idling better than ever. nice and even, no skips or hiccups.

is it seriously possible... 12 miles with seafoam and its showing signs of cleaning up? or am I just losing my mind hoping for it to get better? it felt good to hear that idle not missing a beat.

 

Ran a 1/4 bottle to a full tank through the 82 Seca today... yup, it's that good. My buddy got his R1 out of hybernation (10 months!) and fired it right up (with a new battery). I shared my can of Seafoam with him for today's ride. Lake Castaic is rather nice and the weather was perfect.

 

Vegas odds are currently bid 5-to-2 on mind loss.

Of course, if you're right, then we really didn't get our carbs zestfully clean, now did we?

 

If it runs right at 6 turns out so be it.
Don't sweat the small stuff.

 

Len's right you know, if SeaFoam is making a difference, SOMETHING in the fuel system wasn't "zestfully clean." This is good news though; give it a chance to work and you may be able to get the carbs adjusted correctly yet.

 

Me too :lol: ( told you you would hate my answer but this seems to be backing it up)

 

The Pilot Mixture Screw regulates the flow of AIR from the Pilot AIR Jet into the Combustion Chamber through a TINY Inlet in the Carb Intake inside of the Throttle Plate. The Pilot AIR Passage is married to the Pilot FUEL Jet Supply by a Passage connecting the AIR and Fuel Supply.

As the AIR Supply is INCREASED the FLOW Siphons FUEL from the Pilot FUEL Jet Supply and the COMBINED MIXTURE is Delivered to the Cylinder to allow a Pilot Mixture to support IDLE and OFF Idle performance.

The FUEL Supply is Regulated by the SIZE of the Pilot FUEL Jet.
The AIR Supply is Regulated by the SIZE of the Pilot AIR Jet.
The FLOW allowed to Enter the INTAKE Manifold is regulated by the Pilot Mixture Screw.
The FLOW. NOT the Mixture. The Mixture is dependent on the Size of the FUEL and AIR Jets.

As the Pilot Mixture Screw is Turned OUT from Bottom to INCREASE the FLOW ... there is an initial distance of the Pilot Mixture Screw being LIFTED and Opening the Passage to the Combustion Chamber where ONLY AIR is Supplied to the Cylinder ... the Vacuum force upon the OPENING Pilot Mixture Screw Opening NOT opened enough to allow FUEL to be siphoned from the Pilot Fuel Jet Supply.

As the Pilot Mixture Screw is Lifted (Turned Out) the FLOW is allowed to INCREASE and the Pilot AIR Supply Siphons (Draws-up) FUEL from the FUEL Supply regulated by the Pilot FUEL Jet.
(If the JET or the Passage is clogged ... the Process DOES NOT occur)

Eventually ... (Depending on the Condition of EACH Separate Cylinder's strength of VACUUM Created during the Intake Stroke) ... the FLOW of Pilot AIR will INCREASE causing the AIR to "Suck-up" some FUEL from the Pilot FUEL Jet Supply.

As the Pilot Mixture Screw is Turned OUT and the AIR begins to Include FUEL the PILOT Air~Fuel Ratio suddenly goes from ZERO Fuel to "Containing" Fuel.
The FLOW is not at Full Strength so the FUEL included is LEAN.

As the Pilot Mixture Screw is further Turned-Out ... the FLOW of Pilot AIR Increases and likewise Siphons an Increased Amount of Pilot JET Fuel.
The Air~Fuel Ratio changes.
More FUEL accompanies a Slightly Increased AIR Flow.

Then, the Point where the Pilot Mixture Screw is Turned-Out allowing the Maximum Amount of AIR to be drawn-in through the Pilot Air~Fuel Orifice is reached. This AIR draws FUEL from the Pilot FUEL Jet as before.
The Pilot Mixture Screw is WIDE Open.
NO further adjustment OUT has any effect.

 

Thanks guys.

And Rick- that was a great description of how the pilot screw works.

You should sticky it

So if my passages were ALL PARTIALLY clogged... this would be the case, correct?

Riddle me this, Batman...
So many people on here talk about the screw affecting idle and off idle performance.

Yet - I have heard from the grapevine, of significant person, that it affects.

Now, from what I can see most everyone here denies that, saying it shuts off flow between 2000~3000.

OK, sure.

Now, remember to get that 'tan' color on the plugs, it takes a bit of riding. OFF IDLE riding. Above 3k.

When you check the plugs, and they are rich or lean, you adjust the mixture screw. BUT WHHHHYYY oh WHYYY, batman!?

I thought off idle, they didn't affect anything???

So Batman, where do we lie?

'PILOT SCREW' only affects below 3000... yet we use that to color the plugs, ABOVE 3000. Does that make any sense, Dark Knight?

If any of you want to step in and help out the Batman... please do!

 

When the Pilot Mixture Screw is Turned OUT ... the Flow INCREASES.
To a point where you set it.
If you set it to Make the Bike Idle .... the Bike runs.

If you set it to make the Bike Idle ... and ADD a little MORE Flow ...
The Bike Idles and Transitions from Idle to Off Idle without difficulty.
Too little Flow ... No Good. Backfire; hesitation waiting for Main Jet Fuel.

Too Much Flow ... No Good. Bogging-Out because there is too much Fuel ahead of the Main Jet Supply.

The Pilot Mixture Screws Supply is ALWAYS Present.
It supplements Main Jet Supply.
Main Jet Supply + Pilot Mixture Supply = Total Mixture

Main Jet Supply + Lean Pilot Mixture = Too Lean of Total mixture = Plugs too Light from not enough Fuel
Main Jet Supply + Adjusted Well Pilot Mixture = Tuned Total Mixture = Plugs Colorized according to Supplemental Pilot Mixture.

 

Awww... Rick beat me to it.

 

So what's all the BS about pilot mixtures null and void after 2-3k?

Heard a LOTTTT more people saying that, than what you just said Rick.

Personally, I believe you 100% on that notion. That's what I would say.

I just don't get why people say it dies off... I can see it obviously being confused, as in the mixture is still present but not the main source of fuel.

Lots of folks on here need to be a bit more descriptive, like not saying your pilot circuit is 'off' after 2-3k. I was thinking if that were the case, the air volume passing through the carb might be high enough to essentially block off the pilot mixture holes. But in reality - it's causing even more 'suction' out of it, right? But it's limited to so much air/fuel via the jets... so the increased suction won't allow it any more of either.

So Rick, what do you think about 6 turns out? Does that mean my carbs aren't clean enough, but they are not clogged either? Makes sense to me.

Remember - I know about the 8 degrees of fine tuning thing - but I am not close enough for that. Like I said, colortune shows blue across the board really. Light hints of yellow. Essentially, hard to get it 'rich'. So that would help show that my plugs are indeed showing lean, also explain the rough idle... and as the carbs (hopefully) clean up more with the fuel/seafoam... they should slowly turn into rich plugs, and I will have to dial in my screws.

Sound like a plan?

 

Doug I asked the same thing a while back.The answer I got is the Pilot contribution becomes negligible once the main opens. But my argument has always been then why does it effect plug chops at higher RPM. I dropped the subject. I'm glad to see Rick confirming what I thought. The contribution while minor still has enough of an effect to get rich or lean mixes at running RPMs

Rick thanks for the clarification! I always knew there was no shut off but could not refute the negligible part except that plugs change color...

 

The Mixture is dependent upon the Pilot AIR Flow and the Amount of FUEL present in the Pilot Fuel Passage to be drawn-in.

When the Screw is Wide Open ... you need:
Sufficient AIR through the Passages
Correct Quantity of FUEL Metered by FUEL Jets.

If the AIR Jet is Wrong ... the process fails ... Check AIR Jet and Passage.
If the FUEL Jet is Wrong ... the process fails ... Know Size of FUEL Jet and that Pilot FUEL Passage is clear.
If the Pilot Mixture Screws are Incorrect ... the Process suffers.

Pilot Mixture Jets are Tapered or Shouldered.
You need the right ones.

Common Mistakes;

Wrong Pilot FUEL Jet. Tuning error.
Pilot and Main AIR Jets reversed. (Haynes misprint)
O-ring & Washer Flop. (O-ring blocks passage. No Fuel or Lean)
Wrong Mixture Screws. (From different Carbs replacing drilled out Screws)

 

Hmm. Got me thinkin' bout the oring/washer flop. I'll have to check that.

 

I agree with what has been said.
As stated the mixture screws contribute a minor amount after 3000rpm in comparison to the main jets.
And as stated there comes a point when the mixture screw is all the way out.
They can make it no richer.
This is were the rejettting comes in.

 

Alright... I'll do it. :lol:

I claim that the pilot screw shouldn't affect anything except at idle. Not even the off-idle transition. 8O There. I said it.

It's off the original topic here though and I suspect it's gonna get a little messy, so I started a thread specifically to talk about it:

http://www.xjbikes.com/Forums/viewtopic/p=153711.html

Burnarr

 

I know, I've been following it. I do believe that the screws affect your mixture across the board though. The constant velocity of air running through the carb body is going to constantly suck fuel out of that port...

I believe that 'minor' amount is what makes the plugs tan, white, or black.

Think about it, if the main supplies 98% of the fuel... then the 2% missing is the bad mixture... too much air, not enough fuel. 2% shy of fuel.

That screw allows the 2% to come into play.

With the jetting correct on the bike, ie stock... and the idle set properly, those main jets should allow for proper fuel mixture WHEN the pilot mixture is set properly.

If you rejet to tune the high RPM/throttle plug chops... and get it dead on, with your screw ALL the way in (closed) then you are going to not have enough fuel to idle properly.

Then when you OPEN that screw to let fuel in for idle, and get the idle set - your jets are letting too much gas in. That 2% + 98% that is set at factory, is now 2% plus 100%, 102% total.... and that 2% extra fuel will show up as rich on the plugs.

Make sense right?

Granted - my 'numbers' are just mere guesses, it could be closer to 0.5% and 99.5% but I don't know that much about it.

But do you see where I am coming from?

I can't see SO many people tweaking those screws, SEEING colors on plugs change at high RPM chops... and still believe that the screw 'doesn't affect anything but idle'.


On topic for my problems... I am pulling my pilot screws out today to indeed see if Rick might have something going here... if my orings/washers are flip flopped, that could be my problem.

What is the proper way for them to sit?

I have to admit - when I installed mine, I just left them the way I took them out. It could have been wrong.