Need some help....

[jwood]

Now Here is my set up...

UFO Quadzillas, Stage 7 kit with K&N pods, stock PAJ1 & 2, DJ 165 Main, Stock Springs, drilled slides, Needle 4th clip from blunt end, and A/F set at 2.5 turns, V-BOOST is unplugged and full open.. sync is perfect...

The bike runs great above 3000 RPM, pulls like a freight train all through the throttle curve, below 3000 RPM the bike has a little stumble / ruff idle..(i hear this is the norm with the stage 7), getting good mileage with the fuel light illuminating at around 95 to 105 Miles..

here is the million dollar question...

From idle to throttle blip back to idle the RPM's drop below the set 1000 RPM, but it will recover... (Rich Condition?) A/F at 2.5 turns out..

Pulled the plugs tonight and they are a dirty white, not quite tan..I believe its a HOT/LEAN Condition plug reading (Photos attached) I may be reading the plugs wrong..

How are the plugs reading lean when the throttle blip is telling me it is RICH :ummm:

Any ideas where to go from here??

I might add, the bike is hard to start, almost as if it is flooding.. If i turn the vboost back to stock, the bike starts right up instantly... With the vboost in the open position, the bike needs to turn over 4 To 5 or more seconds, once it fires the idle is like 400 rpm then it climbs and finds 1000 rpm in a few seconds...

 

[Rusty McNeil]

Correct,
Idle blip, up on RPM's, then dip below set point, then recover to set point is rich. Sometimes it will even die during this test if its way too rich.

Idle blip hanging up and slowly dropping to set point is lean, think about what a chainsaw or weed eater does very briefly right before it runs out of gas.

It's headed "too lean" and makes it want to run harder right before there's not enough to support combustion.

When you open the throttle slightly and the circuit is lean it isn't rich enough to support that little bit of extra air, goes lean, and wants to overrun until it all stabilizes.

If its too rich the the blip pulls enough fuel to "dampen" combustion and slows it down, therefor the dip and recover condition.

So I agree your idle a/f is rich. Weird tho' that your at 2.5 on the screws and its doing this.

You have air correctors installed right?

Another clue for diagnosis is the presence of a lean pop or spit through the intake on slight application of throttle through the intake when cold.
Usually will see this when your trying to take off from a dead stop when very cold, when the idle a/f is too lean.

Plug condition doesn't really have much to do with idle mixture unless all you do is idle. I would completely ignore plug
condition as a tool for analyzing idle mixture, but that just my opinion.

Either way from what you have said I would not mess with anything other than the a/f screws if this "blip test" is all your concerned with.

Whatever a/f setting it takes to get to idle blip test (warmed up) to Blip, then quickly Drop to original idle speed without dipping below original idle setting is what I would go with.

Back before I reinstalled the motor and controller I did all my setup with the Vboost butterflies closed and the simply opened the Vboost and raised the idle setting slightly afterwards.


Just me but once I have that down I'll very gradually over the course off many days of cold starts continue to lean them out till I DO get the cold engine lean pop through the intake and then
richen it up from there slightly. Keeping an eye on hot engine idle blip test result as I go.
Better fuel economy that way.

You didnt say wether you were using the choke for starting but if your bike starts without the choke the idle a/f is way too rich.
Also of course of course make sure all the choke linkage is in working order.

BTW,

I have long ago given up on the individual idle screw adjustment where you expect to see the RPM's falter as each cylinder is leaned out too far.

Ill try it now and then with iffy results but it always seems to have cylinders that don't respond as expected even when I know for a fact synch is perfect, valves are perfect, all cylinders are firing and Vboost is closed. And from other posts on here I'm not the only one.

I've done Vboost open always and also normal operation, ( with Stage 7 also) and never really had any starting or running issues with the stock motor. it was great either way.

When Idid the big motor and cams it really did not like the Vboost open at idle and had all kinds of nasty habits at idle conditions. Virtually incurable intake and exhaust popping.

Ive was told it shouldn't be a problem by a few but that was by guys running flat-slides on big motors so theres no Vboost which is just like Vboost closed.

Jon Gainey at PCW told me to put the Vboost back in service (meaning closed at low rpm) if i was running Mikunis.
So
I did and it behaves well now.

But I miss that nasty idle.

For your stock motor there's no reason that it should not start fine and behave fine with full time open Vboost if its well sorted.

And I do agree that open Vboost will have less crisp off idle response....
Air velocity through the carb is less since the same volume is now flowing through two carbs instead of one.

But that's what the throttle, tranny and clutch are for, who cares what it does below 3000rpms...I'm sure the Dyno shows some loss but its at such low RPM's I've never noticed it.

gonna run someone, even if its a rolling start in 1st at slow speed, just use the clutch and get the RPM'S where they belong.

These engines are practically lugging at less than 3000 RPM's anyway. And yes it's more noticeable with stage 7 and open Vboost so that is normal.

 

[MaxMidnight]

To answer your last question first.

Fuel need to be atomised for combustion to take place. The better it is atomised (i.e. the smaller the droplets) the better it will burn.

There are various factors that affect this, one being the speed of the air through the venturi.

One of the problems with a motor is that if you tune it to run optimally at (say) low revs the setting won't be suitable for high revs. Invariably the set-up is a compromise.

Going back to our air through the venturi - a small venturi will give good atomisation ant low revs as the air speed will be high. BUT...as there is a limit to the amount of air that can flow through and it won't be able to deliver sufficient charge higher up the rev range.

So the dilemma is whether to use a small diameter carb for good low rev performance at the expense of the top end or a bigger venturi to satisfy the demand a WOT but have poorer running at low revs.

This is where V Boost comes in - a smaller than optimum venturi for good low running but as the revs rise the V Boost butterfly opens and the paired carb can supply the additional charge. Genius idea!

So to the point (at last! I hear the cry...) by keeping the V Boost open the air speed at low revs will be reduced giving poorer atomisation, the low air speed will also mean that the mixture is more likely to pool on the inlet wall which in turn will result in poorer staring.
This is what you are experiencing.

Additionally, dyno runs that compare the power produced with normal versus open V Boost has shown that the former produces more power lower down.

Now to your spark plug conundrum.

To get an accurate plug reading you would need to do a plug chop - i.e. hold the revs at a particular throttle opening for twenty seconds or so then kill the motor. The colour of the plug will indicate the mixture at that time.
Note that the motor needs to be at operating temperature and a new plug should be used or an older one thoroughly cleaned.

That said I would suggest that some dyno time would be a worthwhile investment and, perhaps, in the long term save you time.

 

[jwood]

Correct,
Idle blip, up on RPM's, then dip below set point, then recover to set point is rich. Sometimes it will even die during this test if its way too rich.

Idle blip hanging up and slowly dropping to set point is lean, think about what a chainsaw or weed eater does very briefly right before it runs out of gas.

It's headed "too lean" and makes it want to run harder right before there's not enough to support combustion.

When you open the throttle slightly and the circuit is lean it isn't rich enough to support that little bit of extra air, goes lean, and wants to overrun until it all stabilizes.

If its too rich the the blip pulls enough fuel to "dampen" combustion and slows it down, therefor the dip and recover condition.

So I agree your idle a/f is rich. Weird tho' that your at 2.5 on the screws and its doing this.

You have air correctors installed right?

Yes, Air Correctors are installed and have been checked and confirmed not to be blocked with glue.....

Another clue for diagnosis is the presence of a lean pop or spit through the intake on slight application of throttle through the intake when cold.
Usually will see this when your trying to take off from a dead stop when very cold, when the idle a/f is too lean.

I did turn the A/F screws to 2.0 Turns and I did get a pop through the carbs when starting a roll from a stop.....

Plug condition doesn't really have much to do with idle mixture unless all you do is idle. I would completely ignore plug
condition as a tool for analyzing idle mixture, but that just my opinion.

Either way from what you have said I would not mess with anything other than the a/f screws if this "blip test" is all your concerned with.

Whatever a/f setting it takes to get to idle blip test (warmed up) to Blip, then quickly Drop to original idle speed without dipping below original idle setting is what I would go with.

Back before I reinstalled the motor and controller I did all my setup with the Vboost butterflies closed and the simply opened the Vboost and raised the idle setting slightly afterwards.


Just me but once I have that down I'll very gradually over the course off many days of cold starts continue to lean them out till I DO get the cold engine lean pop through the intake and then
richen it up from there slightly. Keeping an eye on hot engine idle blip test result as I go.
Better fuel economy that way.

You didnt say wether you were using the choke for starting but if your bike starts without the choke the idle a/f is way too rich.

Yes, I do use the choke for starting, not full choke tho, only about 25% choke...

Also of course of course make sure all the choke linkage is in working order.

BTW,

I have long ago given up on the individual idle screw adjustment where you expect to see the RPM's falter as each cylinder is leaned out too far.

Ill try it now and then with iffy results but it always seems to have cylinders that don't respond as expected even when I know for a fact synch is perfect, valves are perfect, all cylinders are firing and Vboost is closed. And from other posts on here I'm not the only one.

I've done Vboost open always and also normal operation, ( with Stage 7 also) and never really had any starting or running issues with the stock motor. it was great either way.

When Idid the big motor and cams it really did not like the Vboost open at idle and had all kinds of nasty habits at idle conditions. Virtually incurable intake and exhaust popping.

Ive was told it shouldn't be a problem by a few but that was by guys running flat-slides on big motors so theres no Vboost which is just like Vboost closed.

Jon Gainey at PCW told me to put the Vboost back in service (meaning closed at low rpm) if i was running Mikunis.
So
I did and it behaves well now.

I did try the VBOOST back to normal operation, from 4000 RPM to WOT the bike stumbles and pops, no power at all, falls on it face..pulled the plugs after this set up and they were all GHOST WHITE. (very very lean condition)

But I miss that nasty idle.

For your stock motor there's no reason that it should not start fine and behave fine with full time open Vboost if its well sorted.

And I do agree that open Vboost will have less crisp off idle response....
Air velocity through the carb is less since the same volume is now flowing through two carbs instead of one.

But that's what the throttle, tranny and clutch are for, who cares what it does below 3000rpms...I'm sure the Dyno shows some loss but its at such low RPM's I've never noticed it.

gonna run someone, even if its a rolling start in 1st at slow speed, just use the clutch and get the RPM'S where they belong.

These engines are practically lugging at less than 3000 RPM's anyway. And yes it's more noticeable with stage 7 and open Vboost so that is normal.

Thanks for the info, Rusty

 

[Rollie]

Did you install the air correctors ?

 

[tugla]

Are you getting any slight intake pops just off idle either in neutral or in gear!!! Was you bike a California bike....whats the air jets in them....one nextntomair corrector, if its 100 id go 90 and if its already there and you got the popping try 2.75 on the a/f screws....see if it helps...

 

[jwood]

To answer your last question first.

Fuel need to be atomised for combustion to take place. The better it is atomised (i.e. the smaller the droplets) the better it will burn.

There are various factors that affect this, one being the speed of the air through the venturi.

One of the problems with a motor is that if you tune it to run optimally at (say) low revs the setting won't be suitable for high revs. Invariably the set-up is a compromise.

Going back to our air through the venturi - a small venturi will give good atomisation ant low revs as the air speed will be high. BUT...as there is a limit to the amount of air that can flow through and it won't be able to deliver sufficient charge higher up the rev range.

So the dilemma is whether to use a small diameter carb for good low rev performance at the expense of the top end or a bigger venturi to satisfy the demand a WOT but have poorer running at low revs.

This is where V Boost comes in - a smaller than optimum venturi for good low running but as the revs rise the V Boost butterfly opens and the paired carb can supply the additional charge. Genius idea!

So to the point (at last! I hear the cry...) by keeping the V Boost open the air speed at low revs will be reduced giving poorer atomisation, the low air speed will also mean that the mixture is more likely to pool on the inlet wall which in turn will result in poorer staring.
This is what you are experiencing.

This makes perfect sense!

Additionally, dyno runs that compare the power produced with normal versus open V Boost has shown that the former produces more power lower down.

Now to your spark plug conundrum.

To get an accurate plug reading you would need to do a plug chop - i.e. hold the revs at a particular throttle opening for twenty seconds or so then kill the motor. The color of the plug will indicate the mixture at that time.
Note that the motor needs to be at operating temperature and a new plug should be used or an older one thoroughly cleaned.

I was thinking this morning, I never cleaned the plugs from the testing of the vboost at normal operation, when I pulled the plugs they were GHOST WHITE in that setup, wondering if the white lean condition plug reading is what I am seeing is left over residue from that set up?, I will clean them all and recheck using your method...

That said I would suggest that some dyno time would be a worthwhile investment and, perhaps, in the long term save you time.

Thanks for the info MaxMidnight...

 

[tugla]

Ok hi just read your answers above......

And doing a wide open cut.....what are the plugs like..... Top 3rd or 4th will be enough

 

[jwood]

Did you install the air correctors ?

Yes, the correctors are installed and not blocked with glue....

 

[jwood]

Are you getting any slight intake pops just off idle either in neutral or in gear!!! Only with the A/F screws set at 2.0 turns, at 2.5 turns I do not get any pops, only a sever ripping of the arms train pull ie: masive torque :biglaugh:

Was your bike a California bike....

No...not the Cal Model...

whats the air jets in them...

All stock air jets...I did replace PAJ2 with the DJ jet and the bike ran like a turd...returned back to the stock PAJ2

one nextntomair corrector, if its 100 id go 90 and if its already there and you got the popping try 2.75 on the a/f screws....see if it helps...

Tugla, thanks for your input, we will get this thing straighten out...

 

[jwood]

Ok hi just read your answers above......

And doing a wide open cut.....what are the plugs like..... Top 3rd or 4th will be enough

This is going to be my next test, will have to clean the plugs and get all the lean white combustion off of them first...

 

[jwood]

Ok, after cleaning the plugs and trying the 20 sec run turning the ignition off, I pulled the plugs, they don't look to darn bad..kinda tan in color, I am happy with that...:biglaugh:

Now I did forget to mention one thing in the original post, I am running a dyna 3000 ignition with cops, the dyna is programmed for the stock setting #1, running the setup that I am, should it be moved to another setting? say #2 or 3 ?

Here is my set up again...

UFO Quadzillas, Stage 7 kit with K&N pods, stock PAJ1 & 2, DJ 165 Main, Stock Springs, drilled slides, Needle 4th clip from blunt end, and A/F set at 2.5 turns, V-BOOST is unplugged and full open..

 

[tugla]

I'd try clip three or three plus shim and a/f screw plus/mins 1/4 turn from 2.5.....

 

[jwood]

I'd try clip three or three plus shim and a/f screw plus/mins 1/4 turn from 2.5.....

I have tried clip three with no shim, and the top end over 5000 RPM is bad, the bike falls on its face at WOT....

I am thinking of doing the Shotgun and see if it helps the idle circuit....everything above idle is great....idle is very rich....the shotgun may fix this problem..