Tuning Question..99 Vmax SX

427cobra

427cobra

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Mar 23, 2011
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Waterloo IA
Well I went though the carbs again and adjusted the floats to 13mm.

I also turned in the pilot screws 1.5 (they were 1)

NOW I have a really nice BOG....(worse than before) I hit the gas it dies out and slowy goes up to about 5K and thats where it stays....????

Of course I have the airbox installed. (what a pain that was...haha)

It has stock jetting.

SO my questions is....

Do I just go back and turn the pilots screws back to 1 turn. (seemed to run better and rev better).
 
sounds like you went the wrong way on the fuel screws, assuming all other jets are standard.

just for clarity, on most 99 600's, standard jetting and settings would be as follows:

mains: #1- 136.3
#2 and #3-133.8
pilots: 42.5
fuel screw- 2 turns out
needles set at 2.5

compare these settings to yours.

remember that turning those fuel screws in leans the mixture and turning out richens. your bog may be a lean bog, essentially your starving for fuel at a given point in fuel flow or throttle pull.

your idle setting will/can upset low end response, as will clutching, but i am guessing that your not running that under load. (air or ground)?

also consider the fact that yamaha normally jets to the rich side to error in safety favor and if your pinning the throttle when its 90* out, your running pig rich. you wont find the stock settings to be crisp in high temps.

see where you compare to the baseline i listed above and go from there.
 
Yes this is the 600 Triple....RED Head

It was running better with the pilots 1.0 turned out. I may try that again tomorrow (but that was with the air box off)

With them turned 1.5 out seems to run worse. Idles fine...just has that nice bog and wont rev past 5K.

I do have the track off the ground.

It does have the stock jetting as listed above...

Thanks for the replies!
 
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I 3x that. Turn those screws out.Too lean of a setting. Im guessing these carbs have the small screens under the inlet needles? Make sure those are clean. Any backfiring, popping? when you shut it down? Make sure those pilots are cleeeean. Sometimes they look clean but the slightest obstruction can reek havoc. Running on all three right? Idle is good and solid? Keep us posted.
 
THAT JETTING IS STOCK SPEC SNODAD POSTED.YES SIR SNODAD. INSTANT CURE HERE WOULD BE TO CHANGE NEEDLE/ CLIP POSITION. 3:16 (yammie tony)
 
well....

Turned the pilots out 2 turns....not much of a difference.

Hit the throttle and it dies out. Seems to idle rough...?? Wont rev past 5K when I feather it up to that point.

Ill take the carbs apart again but they have been cleaned twice and they were never really dirty...??

Thanks!

Where should I have the needles set
 
Ok...

Found out that is only running on 1 cylinder.

The coils are good. If I switch the two wires coming off the harness to the coil...whatever coil the wires are connected to will have spark.

The other two coils will not spark...??

Attached are the pics of how I have the wires connected. I may have had one of the wires plugged into the black wire for the carb switch. Would that have burned something out...???

I had spark on all three cylinders before... :dunno:

**UPDATE**

I didnt have the coils wired up right....after a look at the wiring diagram, I discoverd my mistake.

Running on all THREE again. haha

Have the pilots turned out 2 turns...

Looks like I am in business....until it cools off and can do some fine tuning!!

Thanks for the helpful advice. ANY fine tune adjustments would be appreciated!
 

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glad you got it figured out. after seeing the coil packs i remember that daisy chain wiring on those. easily messed up if you werent paying attention. had to refer to the diagrams or look at another sled a few times.

as for your needle settings, if your still having a bog issue come snow season, i would say to raise the needles to the #3 position. this will allow more available fuel in that given circuit.

this change can be done with the carbs installed just pay particular attention to the tiny white shim washers.
 
Thanks!

I know the secondary will have to be adjusted. So looking forward to testing it out in the snow!!

I took some pictures today so Ill have to post them up..!!
 
same sled, same problem. I ended up putting in 45.0 pilots and turning the screws out 1.5 - 1.75 turns. Part of the bog is also your primary clutch. Go to the tech pages and get Turk's (RIP buddy!) aggressive trail set up and put it in. The sled comes alive with these two mods.
 
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