garrett's tuning/dyno thread

[maleko89]

177.5 PAJ2 will lean out the pilot circuit. But, there has been some debate if the extra pilot air pulls in more fuel from the PFJ? Are your air box boots on tight and no leaks? Maybe do the peashooter to ensure pilot circuit is clean. You can try to turn your choke on a tad to see if the cruising improves any.

 

[4gasem]

The popping on decel can happen when you pipes aspire air into them burning the unspent fuel. This is one of the reasons why Dale likes to see all the pipes sealed with high temp RTV.

 

[gamorg02]

177.5 PAJ2 will lean out the pilot circuit. But, there has been some debate if the extra pilot air pulls in more fuel from the PFJ? Are your air box boots on tight and no leaks? Maybe do the peashooter to ensure pilot circuit is clean. You can try to turn your choke on a tad to see if the cruising improves any.

i'll check the boots n such with some carb cleaner later today. the guy had the carbs completely apart and used a UV Ultrasonic cleaner, so i assume the circuit is clean, but i could try the peashooter. Before i tear in, would it be easy to tell if i pop the choke on a tiny bit and it helps?

The popping on decel can happen when you pipes aspire air into them burning the unspent fuel. This is one of the reasons why Dale likes to see all the pipes sealed with high temp RTV.

i see. but it wasn't there for the hundred miels or so i did on dale's pipes with stock intake..

 

[gamorg02]

and also just wanted to give some info on the tests i was able to run:

1) Cruise at 4K in 5th gear .. hold RPM steady (count to 5) and then whack it WOT as quickly as you can. You shouldn't feel the slightest delay or hesitation. If you do, too rich. This does not work at 3.5K or 4.5K, only at 4K because the slides will start to retract at 4.5K even at the lightest throttle angle. 4K sets us up on the threshold and gives us a big jump when we whack it. there is no other RPM to do this where you will get as big a slide jump when rapidly moving to WOT.
I was only able to do this in 4th gear so far but it seems to flatline from about 4800 - 5500/6k. not stumble tho.

2) Verify that starting cold .. that the engine is weak .. and will complain if you try to hold the RPM at 1800 rpms. Within 1-2 min or no later than when the temp needle touches the first mark you should be able to hold the engine between 1500 and 2K w/o complaint or popping back through the carbs. At the least you should be able to do this by the time the engine is fully warmed up but if you are more than 1/2 way between the dot and cold on the temp gauge your pilots are plugged or too lean... (clean or reduce the PAJ2). If you can hold 1.5-2K as soon as you start cold then your pilots are set too rich and you will suffer rich symptoms when it comes to operating temp (clean or enlarge the PAJ2). Only change PAJ2 bigger/smaller if you mixture screws are out or in too far already.
this seems pretty spot on for me. haven't started it up enough yet to notice any big differences from before. only started it twice.

3) Do a hard WOT pull in 2nd or 3rd gear from below 3K. Look for a smooth pull all the way up. If it seems to lag in the 4-5K range then too much needle. If we sputter going past 4.5K you don't have enough needle.
Have done this, and don't notice any real stumble, i would say if anything there maybe still isn't the full kick at like 4 - 6krpms, but by the time vboost is fully open there is no hesitation. Don't feel the vboost kick as much as before, but the accel feels smoother, not as huge of rush for vboost.

4) Verify you can cruise "nice and deliberate" at 5K .. if you stumble around and are OK everywhere else you don't have enough pilot.
I would say 4800 - 5500 cruising is definitely flat. this is a problem area.

So looking at this, do i possibly need less needle and more pilot?

 

[[email protected]]

I had some slight decel popping when I put my pipes on. I did a bunch of little changes to get everything else feeling good and along the way the popping stopped. If I remeber right, it was when I changed the A/F screws from 2.5 turns out to 2.75 turn out that it disappeared. Could have been a combination of other things tho. On another note I thought you only needed to change the PAJ if you were too many turns out on the A/F screws. Like 4.5 turns or more?

So the jet kit comes with 177.5 for PAJ2's?:ummm: I don't recall seeing those in my kit. If I remeber right mine had from 150 to 167.5 minus the stock 152.5's...

 

[one2dmax]

There may have been one or two kits that got away without the 177.5's but they should be there. If you didn't get them let me know.

Sean

 

[gamorg02]

I had some slight decel popping when I put my pipes on. I did a bunch of little changes to get everything else feeling good and along the way the popping stopped. If I remeber right, it was when I changed the A/F screws from 2.5 turns out to 2.75 turn out that it disappeared. Could have been a combination of other things tho. On another note I thought you only needed to change the PAJ if you were too many turns out on the A/F screws. Like 4.5 turns or more?

well some carbs were over 5 turns out i know, i think the front 2 were 5ish, the rear two were 3.5 ish? i can't remember exactly.

i'll start by removing the shim and putting oem springs back in to resolve the rich WOT issue.

Sounds like then more tests may be needed for the cruise issue.

Sean, does it sound lean to you @ cruise, and do u still recommend the 177.5?

 

[one2dmax]

I usually like as lean as you can go and still have good driveability.

Sean

 

[gamorg02]

will do sean. i'll remove the shim/add the springs. see where we are. from what it sounds tho i may have to do some adjusting on the PAJ's to get my cruise richer. lets take one at a time. thnx everyone for their help. will update sooner hopefully rather than later.

 

[gamorg02]

finished up the unshimming and the oem spring swap. doesn't seem to help all that much.

i will say tho that running with the choke slightly on seems to help. it seems to almost be boggy all over the range until i really open up the throttle.

does that point to lean?

prior to doing that work, the 5k range was really boggy. seemed like it needed quite a bit of throttle to hold steady.

i'm off to go do a few actual miles not just around the block a few times. plus put on my full face helmet, i heard a lot more popping out of the exhaust but i have no idea if its worse or better but the half helmet makes me hear everything.

 

[gamorg02]

ok just got back and did a few tests. did about 20 miles...

4th or 5th gear@ 4k rpms, then WOT. no hesitation, just slower than i would expect the whole way up

under 3k rpms, then WOT. i would say the power is there but maybe not as much as i'd expect. there might be a stumble right before vboost, but hard to tell.

still having problems cruising @ 5k - 6krpms. choke helps slightly.

exhaust popping has increased considerably from just engine decel to now engine decel and cruising/slight engine accel.

i feel like all these point to lean? not sure tho.

please let me know what yall think.

 

[[email protected]]

Did you read any of this stuff?:
http://www.vmaxforum.net/showthread.php?t=7754

this one has a few good links in it too:
http://www.vmaxforum.net/showthread.php?t=7511


If your popping and surging in the midrange that sounds lean to me. I'd try it with 2 shims just to see what happens. It only takes 10 minutes to throw em in.

 

[MikeTD3]

Did you have the carbs off and are they re-seated all the way down?

 

[gamorg02]

Did you read any of this stuff?:
http://www.vmaxforum.net/showthread.php?t=7754

this one has a few good links in it too:
http://www.vmaxforum.net/showthread.php?t=7511


If your popping and surging in the midrange that sounds lean to me. I'd try it with 2 shims just to see what happens. It only takes 10 minutes to throw em in.

thanks mike. everything i've read is pointing me towards a lean condition except the dyno sees a rich spot there. read thru a lot of those posts and information.

my morley kit only came with 4 shims so i assumed i shouldn't put anymore than 1 per needle in the carbs. where are u guys getting more, radioshack? may have to stop there on the way home it seems!

Did you have the carbs off and are they re-seated all the way down?

i believe so. i haven't had a chance to check with carb cleaner or wd40 yet, but can easily enough. i visually inspected the carbs they all seem to be seated properly




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So i guess here is my thinking.

at WOT (main jet) i am seeing a rich surge at 5 - 6k rpms where i think if i could keep that somewhat increasing instead of flat lining i' definitely see some performance increases. does this mean my 162.5 might be too big?

at my 5 - 7.5k range non-WOT range, it definitely seems lean. i am going to try 2x shims in each needle tomorrow. Sean, hoping youd pop online to give me your input. I know you guys had said to remove the shim, but it really sounds lean, maybe i'm missing something? i'm new, so i very well could be.

the 2-4k pulls seem strong as ever, don't think its nec an issue there, however the 4.5 - 5.5k cruising still is suffering.


so i know a lot of the tuning is based on throttle position, not engine speed, but how does there seem to be so many problems right around the same rpm? and rich AND lean conditions depending on the throttle? hmm maybe more research. maybe someone can give me a push?

thanks in advance guys.

Edit:. i just looked at maleko's thread on needle differences. could this be indicative of needing stage 7's? i'd hope to exhaust my possibilities with stock first. just to ballpark, if i needed 'em, Sean do you sell them? if so what do u typically charge? hopefully i get get this nailed down and not go that route.

 

[maleko89]

Nice thing about stage 7 needles is being able to tune. I find it hard to believe you are that rich in the middle with stock needles.

 

[gamorg02]

Nice thing about stage 7 needles is being able to tune. I find it hard to believe you are that rich in the middle with stock needles.

yea the dyno guy had said he wished he had had them as well...

the dyno sheet also shows only a full WOT run tho eh? so i mean it could be rich there from the main jet? is that the only thing acting on the a/f mixture (for the most part) there, or is that still needle a bit at the 5-6k range?

it just seems too much coincidence to see a stumble (slight) on the dyno curve there AND feel it when crusing in that general 4500 - 6600 range (when it dips below 13)...

 

[Birdoprey]

everything i've read is pointing me towards a lean condition except the dyno sees a rich spot there. read thru a lot of those posts and information.

The dyno just shows your A/F AT WOT, not at partial throttle where you are feeling the surging. You can indeed be rich at WOT at 6K AND be lean at partial throttle at 6K

 

[one2dmax]

I do have a few needles left (stage seven and one). $60 plus shipping. Also, we have had to double washer a few times too even though the meter showed rich. You do tuning both by the meter and by riding. It for sure does not hurt to add them in there and or try the jet change and see what effect that has on it.

Sean

 

[maleko89]

This is where EFI would come in handy. You can tune based on throttle position.

 

[gamorg02]

I do have a few needles left (stage seven and one). $60 plus shipping. Also, we have had to double washer a few times too even though the meter showed rich. You do tuning both by the meter and by riding. It for sure does not hurt to add them in there and or try the jet change and see what effect that has on it.

Sean

Sean,

Do you recommend using the radioshack washers since your kit only came with 4 all in all?

Also you said 'try the jet change' did u mean the PAJ2 to a 177.5 or the main?

Do you think adjusting the PAJ2 at this point would only lean it out more?

If the main, would i go bigger (b/c i'm lean at cruise) or smaller (b/c i'm rich at WOT)?

thanks man.