Yamaha FI Diagnostic tool - WR450 specific



150 replies to this topic
  • Bass Mechanic

Posted December 31, 2015 - 05:56 AM


Now if you'd like to be able to fire her up w/o having to pull that hot start, just give CO= 0 or (daredevil) CO= -5 a try. :thumbsup:

Hint:
That way you could leave both hands on the bars, clutch in, throttle shut, button press and off you go again. :jawdrop:

If you don't like it go back to your current settiing, trying is free.


Like I've said so many times before this problem has nothing to do with the co level it has everything to do with the decompressor
The reason the bike starts with the enrichment pulled is because it allows just a tiny bit more air into the cylinder.
I'll go ahead and spell it out even though it said I wouldn't..
The reason the bike is harder to start when hot is because the decompressor is adjusted just a tiny bit too aggressive, it holds the exhaust valve open just a little too far. This causes the compression to be too low and the bike won't light off.
Cracking the throttle open just enough allows a little more air in so the additional air in the cylinder during the compression stroke (despite the valve being held open slightly) builds just enough compression to light off.
When the engine is hot, the air getting in is also heated up and become less dense making the issue worse.
There are 2 fixes for this issue. Either take the cam out and grind about half a millimeter off the decompressor pin. Or learn to wrist the throttle just enough following my instructions mentioned earlier. The lines on the throttle grip are a good reference but I can get it every time just by feel.

And just to clarify once again it is not the mixture that causes this problem. Adjusting the co only changes the mixture. You might be able to find a setting that helps a little but it won't change the compression.

If you don't believe me try this experiment you can either turn your idle up to 2400 - 2500 rpm or open the enrichment which makes the bike idle at about that same speed or learn to crack the throttle by hand to match that speed and I guarantee you the bike will start every time. If you grind the decompressor pin it will start even easier but I caution you to try grinding it just a little at a time because you can't put the material back!
Read the threads in this post and others it has already been discussed at length.
I'm already sick of reading these threads! Throw the stupid tool away! The co level IS NOT THE PROBLEM!!!

  • ricknaz

Posted December 31, 2015 - 07:09 AM


My bike usually takes two or three tries to start when it is cold. Once it's warm it starts first go every time as far as I can remember. I tried the throttle cracked method and it wouldn't start at all cold until I closed the throttle. It works when it is hot but it starts ok anyway so I don't really need to do it.



  • WRF-Rowdy

Posted December 31, 2015 - 08:09 AM


Like I've said so many times before this problem has nothing to do with the co level it has everything to do with the decompressor
The reason the bike starts with the enrichment pulled is because it allows just a tiny bit more air into the cylinder.
I'll go ahead and spell it out even though it said I wouldn't..

Repeating your stance doesn't change the behaviour of my bike I am posting about.

 

Simply not true over here:

I had massive hot start issues with a stock '12 WRF.

I solved them with adjusting CO down to "best idle" setting.

 

I afterwards(!) swapped in YZ cams(in+ex), of course only after grinding(!) the YZ decomp

to exactly the stock WR decomp's behaviour and bike was firing up identically well,

no need to change CO.

 

 

 

The reason the bike is harder to start when hot is because the decompressor is adjusted just a tiny bit too aggressive, it holds the exhaust valve open just a little too far. This causes the compression

I'm not sure which bike you're talking about but WR/YZ exhaust cam decomps are NOT adjustible,

hence that sentence is rubbish. :thumbsdn:

 

Hey, I'm just saying instead of making the ECU deviate from CO-setting defined idle mixture

by training you to meticulously hold open the throttle a tiny bit one can simply get the CO setting right.

 

I've proven by shaky one handed video what that engine (actually the ECU) is capable of,

IF it is setup right.

 

There may be "tricks" one can lessen the hardships of messed up CO setting, that actually work,

they are simply masking the underlying issue.


Edited by WRF-Rowdy, December 31, 2015 - 08:18 AM.


  • WRF-Rowdy

Posted December 31, 2015 - 08:12 AM


My bike usually takes two or three tries to start when it is cold. Once it's warm it starts first go every time as far as I can remember. I tried the throttle cracked method and it wouldn't start at all cold until I closed the throttle. It works when it is hot but it starts ok anyway so I don't really need to do it.

Exactly! 

 

Cracking open the throttle makes the ECU mix in the lowest throttle section of the PowerTuner mapping with the CO-setting "map".

 

If your engine won't start with the throttle closed but does start with throttle cracked

that is proof, that your CO setting is set to a  start-unfriendly value.


Edited by WRF-Rowdy, December 31, 2015 - 09:10 AM.


  • Bass Mechanic

Posted January 01, 2016 - 06:01 AM


Exactly!

Cracking open the throttle makes the ECU mix in the lowest throttle section of the PowerTuner mapping with the CO-setting "map".

If your engine won't start with the throttle closed but does start with throttle cracked
that is proof, that your CO setting is set to a start-unfriendly value.

Cracking the throttle open has nothing to do with the co (fuel mixture) it does affect the cylinder pressure in a BIG way when the decompressor is active.
This is why the bike is not starting!

If the co setting was off the bike would not idle because the co setting only changes the fuel mixture at idle. It is exactly the same thing as turning the pilot mixture screw on a carb bike.
Cracking the throttle just allows more air into the cylinder to restore some compression which would otherwise be really low with the throttle closed.
The MAP sensor in the intake manifold along with the air intake sensor determines the air density and adds fuel according to the map that was programmed into the ecu.
Yes the co level at idle can be changed with the tool. But without an o2 sensor all your doing is screwing up an otherwise correct fuel setting.
The reason changing this value to a richer setting has helped some but not eliminated the problem is because your adding fuel which makes the mixture a little cooler and a little more dense and may help a hot engine light off easier by the root cause of the issue is the decompressor.
Ask anyone who has had a Honda with premature valve wear. This condition causes the bike to be hard to start when hot because the valve faces are worn and when the valves are hot, the stems get longer as a result the valve lash is at 0 because the faces are worn and all the valve lash is lost so they essentially end up zeroed out. which causes them to open just a little too far to maintain enough compression when hot.

The same issue exists here but for a different reason. The decompressor pin is too tall from the factory. They needed to lower the compression enough so the starter could turn the engine over. Any more compression and you risk damaging the starter if the engine can't turn over. Too little and it won't start.
The problem gets worse at high altitude like where I live at 6500 feet we have less dense air up here so a bike with already marginal compression up here has even less cylinder pressure than at sea level.
My mechanic finds that grinding a small amount off the decompressor pin resolves the starting issue. It causes the exhaust valve to close slightly more with the decompressor active. This increases compression on start up. It totally eliminates the starting issue.

Now you guys know the truth! Believe what you like with your hocus pocus adjusting of the co setting! It's your bike and if it makes you feel all warm and fuzzy thinking you've somehow solved the mystery here. But every time your bike doesn't start I want you to remember that bass mechanic said your decompressor is over decompressing the cylinder.
You'll find that if you crack the throttle slightly, restore some of the compression that's already to low, or if your ballsy enough to modify the decompressor pin and actually fix the root cause of the problem. Then you can continue to struggle with starting your bike.
It's your bike, not mine! mine starts easily every time. If you would like I am sure for a fee my mechanic would be happy to modify your cam for a fee if you would like to ship it to him.
If my bike starts as easy at high altitude as it does those of you who live at lower elevations should have even easier time starting at your elevation.

For ANY OF YOU WHO DOUBT THIS INFORMATION do this experiment..
Start your bike, hold the throttle at between 2300-2500 rpm and hold it there. With your left hand kill the engine without moving your hand on the throttle.
Now while holding the throttle in the exact same position hit the starter. I bet you 100 bucks it starts every time on the first try!

Now after you've started the bike a couple times and convinced yourself that I'm not full of crap, release the throttle keeping note of how much throttle you were using to start the bike. When I say "crack the throttle" this is exactly how small cracked I'm talking about. The bike is supposed to idle at 2100 rpm stock (I run mine at 1700-1800) now keep in mind how tiny of amount it takes to raise it 300-500 rpm from idle!
You'll discover just what I mean while doing this experiment.

Now after you complete this experiment and see for yourself that I am right about the hard to start nature of the bike I want you to report back to this thread with your findings so everyone else will start to see that this is a simple fix.
On a side note, I suspect that if you know how to do a valve adjustment with the shims I an confident that if you shim it on the "loose" side of in spec it will solve most of your starting issues. So for those of you who still have issues I recommend you do a valve adjustment and in particular set the exhaust valve with the decompressor pin a little on the loose side while still being in spec.
I believe this is where the variance between bikes is and how hard or easy they are to start resides.

So there you have it. If your totally bored on New Year's Day and are looking for something to tinker with on your bike give this test a try!

Ive already seen at least a dozen people who have tried this on their totally stock bike either pm me or post in threads where I've shared this info that they no longer have starting problems.

Sorry for the long post but this is really getting ridiculous and all these posts about hard to start makes this bike look bad.

Edited by Bass Mechanic, January 01, 2016 - 06:13 AM.


  • WRF-Rowdy

Posted January 01, 2016 - 09:00 AM


finally, after me teasing at bit, here they secret trickery is exposed:

 

My mechanic finds that grinding a small amount off the decompressor pin resolves the starting issue. It causes the exhaust valve to close slightly more with the decompressor active. This increases compression on start up. It totally eliminates the starting issue.

 

So you advocate an irreversible messing with the stock WR cam as solution to your starting problems,

without having tried the cost free readjustment of idle mixture. :banghead:

 

Grinding down the WR decomp pin will increase starting compression, that's true.

That increased compression will

- slow down the starter speed,

- drain the battery more everytime it hits compression stroke,

- put more load onto the start freewheel clutch

- produce situations, where the engine won't fire up in gear any more  (after too many e-starts w/o charging cruise sections in between)

- and in the end will prematurely end starter's life from more load than what it was designed for

 

 

Next thread will be about "beefing up" the allegedly week stock starter, so that it can handle Bass Mechanic's increased compression mod.

 

Are you going to pay for overloaded starters dying from Bass Mechanic's increased compression?

 

Btw.  selling a bike with messed up stock cam as "100% geniune,unmodified" would be fraud.

And who would purchase a bike whose stock cam was "tuned like I read on the Internet" ?

 

 

 

Lets sum up the options to create perfect in-gear starting w/o need for fancy throttle tricks:

 

a ) Bass Mechanics irreversively ground down WR decomp pin.

 

b ) Trying out setting CO to values of  +8, 0, -8, -16, trying each for one day with charged battery.


Edited by WRF-Rowdy, January 01, 2016 - 10:24 AM.


  • Bass Mechanic

Posted January 01, 2016 - 09:18 AM


finally, after me teasing at bit, here they secret trickery is exposed:


So you advocate an irreversible messing with the stock WR cam as solution to your starting problems,
without having tried the cost free readjustment of idle mixture. :banghead:

Grinding down the WR decomp pin will increase starting compression, that's true.
That increased compression will
- slow down the starter speed,
- drain the battery more,
- put more load onto the start freewheel clutch
- produce cases where the engine won't fire up in gear (after too many e-starts w/o charging cruise sections in between)
- and in the end will prematurely end starter's life from more load than what it was designed for


Next thread will be about "beefing up" the allegedly week stock starter, so that it can handle Bass Mechanic's increased compression mod.

Are you going to pay for overloaded starters dying from Bass Mechanic's increased compression?

Btw. selling a bike with messed up stock cam as "100% geniune,unmodified" would be fraud.
And who would purchase a bike whose stock cam was "tuned like I read on the Internet" ?



Lets sum up the options to create perfect in-gear starting w/o need for fancy throttle tricks:

a) Bass Mechanics irreversively ground down WR decomp pin.

B) Trying out setting CO to values of +8, 0, -8, -16, trying each for one day with charged battery.


Your making the assumption that I'm suggesting grinding the pin down to the point that the compression will stop the starter my bike starts fine in or out of gear, it has nothing to do with additional load on the starter, the flywheel and crank inertia will overcome the additional compression with ease. I never said to eliminate the compression that would be stupid.
A simple compression test will verify my findings.
Your making changes that you have no way to verify and several people who have changed the co setting reported it made no noticeable improvement, where as every bike my dealer has modified fires up without issue.
Someone posted that before he messed with his the AFR was right at 14:1 from the factory. Exactly where it should be.
So how do you explain that?
You obviously don't know anything about engines and clearly are just a back yard mechanic.

you just want to be right and that's all there is to it.
Frankly I don't really care what you think. If you want to mess with your fuel mixture you go ahead. It matters to me not.

As for selling my used WR I never hid the fact it was modified in my craigslist ad or in person. In fact the buyer asked if I had any issues starting the bike when hot. And I showed him how not using the throttle will get mixed results while cracking it gets it to start every time. He was quite pleased and paid me $6,200 in cash due to the fact he could see it was a well cared for bike.

I only paid $7,400 for it new so I think I did pretty well.

  • WRF-Rowdy

Posted January 01, 2016 - 10:50 AM


Your making the assumption that I'm suggesting grinding the pin down to the point that the compression will

stop the starter my bike starts fine in or out of gear, it has nothing to do with additional load on the starter, the flywheel and crank inertia will overcome the additional compression with ease. I never said to eliminate the compression that would be stupid.
A simple compression test will verify my findings.

You admitted to increasing decomp compression as being your solution.

So let's see what side effects will come with that:

 

Increasing decomp compression means more load/work for the starter than stock

If you increase it step wise you'll end up at zero decomp, e.g. disabled decompressor.

I think we all know that w/o decomp-support the starter never would be able to turn over the crank.

 

So we are looking at a continuum of options:

one end being stock yamaha WRF 2012ff decompression,

next comes the little less "Bass Mechanic's decompression" and

at the far end is zero decompression = won't start.

 

Looking forward the hearing from you on some future "how to beef up my starter" thread.

 

 

The more one decreases decomp effect (by grinding down the decomp pin)

- the more mechnical work is needed to turn the crank

- the slower the starter will turn

- the more electrical energy the starter will draw per compression

- the less cranks per battery charge.

 

If you only commute to work, or race MX you might not care. 

If you'd like to do technical woods work, or do 5MOH in Utah the less stress your many e-starts will put on the energy source do matter.

Oh, I forgot, you are the batter sales man, wasn't it you who recommended swapping in an aftermarkt battery?

In the light of your "mod" that begins to make sense.

 

 

 

Your making changes that you have no way to verify and several people who have changed the co setting reported it made no noticeable improvement, where as every bike my dealer has modified fires up without issue.

My suggestion is reversible in seconds, cost nothing, don't need any engine tearing apart, and are described at length.

 

Your suggestion is irreversible, when overdone wil - teminally - kill e-startability of the bike, especially in gear,

and you are not able to specify any instructions on how much to grind off that decomp pin,

you just promote your magic workshop.   You've got to do better than that.

 

 

 

As for selling my used WR I never hid the fact it was modified in my craigslist ad or in person. In fact the buyer asked if I had any issues starting the bike when hot. And I showed him how not using the throttle will get mixed results while cracking it gets it to start every time. He was quite pleased and paid me $6,200 in cash due to the fact he could see it was a well cared for bike.

I'm just saying that I wanted my prospective WR to be stock.  No wannabe tuner grinding things off my bike.

Hence, my suggestion should be seen as warning to those that fall for your story, try that "mod" and don't get it right.

Not telling their customers about that DIY "increasend compression mod" but claiming to sell a stock bike would be fraud.

But, hey maybe there exists people that will want to buy used bikes whose starting compression was increased.


Edited by WRF-Rowdy, January 01, 2016 - 11:33 AM.


  • Bass Mechanic

Posted January 01, 2016 - 11:03 AM


I don't sell batteries of any kind and I'm done with you in this thread so keep talking to yourself

  • WRF-Rowdy

Posted January 01, 2016 - 11:27 AM


I don't sell batteries of any kind and I'm done with you in this thread so keep talking to yourself

 

No surprise here. When questioned about the side effects of your "grind down then decomp" mod a certain lack of argument surfaces, fine with me.



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  • 270winchester

Posted January 01, 2016 - 11:41 AM


I went thru the process Rowdy posted. It took a while messing with it but I finally got the thing to stall once I set the idle down to ~1300. It stalled at +10 and -29 so the final setting I used is -10. Set rpms for 2000. It seems to start ok with this setting. I was just in my shop though and not out riding. Too freaking cold for me. I will try this setting out for a while and see what happens. Previously I was at +10 based on what others had suggested on this board. I never could really tell the difference. Btw, I never had a problem starting it so long as I cracked the throttle as bass suggests. I have been doing that for the last 2 years, it's not that big of deal...

  • WRF-Rowdy

Posted January 01, 2016 - 11:43 AM


I don't sell batteries of any kind

 

Hmm, let me help your memory a bit, you said:

 

I also just put my lithium battery in and it starts even better and saved some weight
I highly recommend earth x batteries look them up online.

They are the only ones with a built in battery management system which is crucial for lithium battery life

see http://www.thumperta...4#entry12811616



  • WRF-Rowdy

Posted January 01, 2016 - 11:47 AM


I went thru the process Rowdy posted. It took a while messing with it but I finally got the thing to stall once I set the idle down to ~1300. It stalled at +10 and -29 so the final setting I used is -10. Set rpms for 2000. It seems to start ok with this setting. I was just in my shop though and not out riding. Too freaking cold for me. I will try this setting out for a while and see what happens. Previously I was at +10 based on what others had suggested on this board. I never could really tell the difference. Btw, I never had a problem starting it so long as I cracked the throttle as bass suggests. I have been doing that for the last 2 years, it's not that big of deal...

-10 sounds prefectly in the ball park. :thumbsup:

 

Well, I hereby declare you as #1 test case for my claim,

that once one sets CO right, one can forget about throttle cracking.

Please do test and report back!  :thumbsup:  And please do evaluate in-gear e-starting, too.

 

My private experience is limited to just my single, preowned, WRF 2012. I've no idea how generally applicable my results are. :(


Edited by WRF-Rowdy, January 01, 2016 - 11:51 AM.


  • Bass Mechanic

Posted January 01, 2016 - 12:04 PM


Hmm, let me help your memory a bit, you said:

see http://www.thumperta...4#entry12811616


Well when you type on an iPhone your bound to have spelling errors! I sell insurance for the past 12 years and I make a hell of a lot of money doing it. Got no time for me to sell batteries!
But I do recommend the earth x because I've been into electronics since I was 8 years old and if you read on liFe battery technology you'll soon see that without a BMS your lithium battery won't last long. If you want your Chinese battery to last at the very least you need to buy their charger that will equalize the cells externally.

I prefer the earth x it already has it built in

  • WRF-Rowdy

Posted January 01, 2016 - 12:50 PM


re Earth-X:

after reading https://en.wikipedia...osphate_battery

they seem to be a near perfect lead-acid replacement when using four cells:

Max Voltage would be 3.65 * 4 = 14.6V, but even more importantly

"LiFePO4 batteries have a very constant discharge voltage. 
Voltage stays close to 3.2V during discharge until the cell is exhausted."

Sounds like starter rpms won't decline as much as they do with draining lead-acid batterys.

I wonder if they really feature true 12Ah, that would be twice the energy of a WRF's stock YTZ7S (claims a measly 6Ah).

 

edit:

the label http://earthxmotorsp...com/shop/ETX12Asays 12EqAh but the fine print the the bottom speaks of 4Ah :lame: 

but it stills weighs less then half a YTZ7S.


Edited by WRF-Rowdy, January 01, 2016 - 12:59 PM.


  • Ride-n-Hard

Posted January 01, 2016 - 01:06 PM


So how is being at 6500ft elevation playing into all this for bass?

Does the co setting get effect by a lack of air? I'm not sure what elevation wrf-rowdys at but maybe that's part of why he is sitting at a neg co value.

Cuz if bass is lean for his starts and wrf is leaning his co then maybe there is a relationship there. If bass is bypassing his co all together by cracking hi throttle then maybe the lower left settings that he we on his fuel / timing for his ecm has something to do with this as well.

  • WRF-Rowdy

Posted January 01, 2016 - 01:29 PM


So how is being at 6500ft elevation playing into all this for bass?

Does the co setting get effect by a lack of air? I'm not sure what elevation wrf-rowdys at but maybe that's part of why he is sitting at a neg co value.

Cuz if bass is lean for his starts and wrf is leaning his co then maybe there is a relationship there. If bass is bypassing his co all together by cracking hi throttle then maybe the lower left settings that he we on his fuel / timing for his ecm has something to do with this as well.

 

Hmm. A carburated bike will run richer at altitude. 

As the ECU "knows" about hot-start button position (presumably via the MAP sensor)

we'd need to know if they use an absolute MAP pressure sensor like the MPX4250A http://www.nxp.com/f...et/MPX4250A.pdf

 

If so, the ECU would be perfectly aware of altitude (and low/high pressure weather!) and together with ambient air temp it would "know" air density.

In that case altitude changes would be compensated for automatically, noone would have to do/setup anything differently up in the mountains compared to the buddys at the sea shore.

 

If we assume that excessive altitude (in the likes of 10.000ft and above) does result in not enough "trapped" charge after the stock decomp has closed the valve

then the engine would fire up once (the charge trapped) but the generated momentum would not be sufficient to overcome the next (full, as decomp pin would have retracted) compression cycle.

 

But of course a sufficent counter measure would be to slightly increase idle speed

(actually increase the idle air bypass by turning idle speed knob).

 

 

My personal experience of XT600, TT600, KLX650R, WR400F (buddy WR426F, 450EXC)

up in Italian mountains (7300ft, Passo di Giau) would dictate that altitude change

will not create any compression issues, just richer idle.

 

The times when we'd ride on our bikes from Austria to Italy are long gone, today we drag them along in our vans.

My 2012 WRF definitely hasn't seen more than 3000ft.

 

So we need a 6000ft or higher guinea pig with in-gear e-start issues

that has a CO adjustment tool and time to follow 270winchester's path and check if CO at -10 (or -20) solves the problem.


Edited by WRF-Rowdy, January 01, 2016 - 01:42 PM.


  • AtomicGeo

Posted January 01, 2016 - 03:56 PM


I am at 7500 ft. A negative CO number did not solve my problem.  It makes starting worse.  My bike starts better at +12, and I have to use Bass's suggestion of very very slight crack to throttle to have it start on first try.   But, this is not in gear.


Edited by AtomicGeo, January 01, 2016 - 04:00 PM.


  • Bass Mechanic

Posted January 01, 2016 - 07:12 PM


So how is being at 6500ft elevation playing into all this for bass?

Does the co setting get effect by a lack of air? I'm not sure what elevation wrf-rowdys at but maybe that's part of why he is sitting at a neg co value.

Cuz if bass is lean for his starts and wrf is leaning his co then maybe there is a relationship there. If bass is bypassing his co all together by cracking hi throttle then maybe the lower left settings that he we on his fuel / timing for his ecm has something to do with this as well.

 

higher altitude has nothing to do with the mixture on a FI bike because the MAP sensor, and air intake sensor calculates air density. the ECU then adjusts the fuel based on the air it already knows with a high degree of accuracy how much fuel is needed by changing the pulse width of the injector.

 

the only thing that happens with higher elevations is the idle will drop slightly which is easily adjusted.

 

but the main thing that makes them harder to start at altitude is simply due to the fact that with 3psi or about 20% less air pressure, you'll get 20% less pressure in the cylinder making the decompression even less necessary or a better way to say it is. if your already on the borderline of having enough compression to get the engine to light off, your going to have even less compression at this altitude.

similarly, youll never find anything higher than 91 octane gas here because it simply is not needed. if your engine has 13.5:1 compression you'll see a 20% reduction in actual cylinder pressure therefore 91 octane is plenty.

 

as i have already stated several times here the CO setting only helps because some your adding fuel and therefore making the mixture a little more dense. (the denser air in the cylinder cannot be compressed as easily) the added fuel to the already lacking amount of air compensates slightly. but only to a point. too much fuel and you'll have problems starting it because it will flood out easier.

 

the factory sets it at 14:7 or pretty close as was confirmed by another poster who tested it with an o2 sensor. you'll get the best starting, idling and emissions with a stoic setting. enriching or leaning the fuel will cause plugs to foul out faster, excess carbon build up in the muffler and packing material, more soot deposits and it can also wash the cylinder walls of oil which will cause premature wear of the piston, rings and cylinder walls and exhaust valve guides.

 

So if you would like to follow the advice of wrf-rowdy you go right ahead! my 2013 WR450 had 113 hours on it and needed nothing..

 

my suggestion of cracking the throttle works every time hot or cold. and as i stated my dealer likes to modify the decompressor pin to make it start that much easier. it does not put any wear on the starter, it just increases the cylinder pressure another 30-40 psi to help it light off easier without having to crack the throttle.

since the root cause is exactly as i have been saying over and over. it is compression, not mixture that causes the problem.

 

so for those of you who have messed with fuel setting and without an O2 sensor to verify your setting you could be too lean, or too rich and neither is good.

with the fine control and added performance you get with fuel injection it blows my mind with stupidity why anyone would want to mess with it! gone are the days of jetting gone are the days of chasing the proper fuel mixture and inconsistencies at different elevations and lack of throttle response. why mess with it? and as was again stated a couple posts back as Atomic stated he still uses the throttle because changing the Co did little to resolve the starting problem.



  • tomerb

Posted January 01, 2016 - 07:27 PM


 "it just increases the cylinder pressure another 30-40 psi to help it light off easier"

 

What's the cranking compression before and after grinding on the pin?? A gain of 30-40 psi is a lot........






 
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