Spark plugs lasting 6 hrs

Ok, new to this forum so bare with me.
I run a B1 with 701 (62t) motor, factory B pipe and 44mm carbs is the only mod.
Had carbs rebuilt a few moth ago and bought a new igntion coil but issue still there. When hitting full throttle from stand still it kinda hesitates (like its missing slightly) but then takes off. Comp test is 140psi on both pots.
Please find attached the pictures of the plugs. 1st plug is from the front of the engine which isn't really my biggest concern but the rear plug is. It's like its got hard crust on it and looks alot older than 6hrs riding in the surf. I use this ski for surf only, I mix the fuel 50/1. Any help or pointers would be great.
Thanks in advance
 

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Location
Iowa
Is it real blubbery on the take off? Or does it fall flat on its face like it wants to die? I would guess that you're rich but I'm no expert.
 

Vumad

Super Hero, with a cape!
Location
St. Pete, FL
Ok, new to this forum so bare with me.
I run a B1 with 701 (62t) motor, factory B pipe and 44mm carbs is the only mod.
Had carbs rebuilt a few moth ago and bought a new igntion coil but issue still there. When hitting full throttle from stand still it kinda hesitates (like its missing slightly) but then takes off. Comp test is 140psi on both pots.
Please find attached the pictures of the plugs. 1st plug is from the front of the engine which isn't really my biggest concern but the rear plug is. It's like its got hard crust on it and looks alot older than 6hrs riding in the surf. I use this ski for surf only, I mix the fuel 50/1. Any help or pointers would be great.
Thanks in advance

Being that black it is probably super rich. You could have a leaking pop-off causing it to get way rich while idling. It could also be a bad tune. I have stock carbs on my superjet with a stock airbox so the low popoff in itself is not bad unless you are also rich on your tuning. Like I said, different carbs so I can't comment too much on your tuning. Could also be your coil not sparking enough for a good combustion, but you said it runs good once it clears out and coils usually fail from the top down. Have you had your carbs off to check the popoff and etc to make sure they are working well? Have you done some WOT plug checks to see if you are rich enough on the top to lean out the bottom a little?
 
The carbs have been rebuilt a few month ago and everything replaced. I think I need to wind in the low screws and when I demand full throttle it takes a few seconds to pick up. WOT test?
 

88kawi5fiddy

pew pew lazers!
Location
So Utah
The carbs have been rebuilt a few month ago and everything replaced. I think I need to wind in the low screws and when I demand full throttle it takes a few seconds to pick up. WOT test?

FOR THE MILLIONTH TIME. THE LOW SPEED ADJUST IS NOT to be used for ANYTHING except idle. idle is NO: blipping, babying, touching of throttle.

Idle circuit adjustment:

Go to a lake. Strap ski down to trailer. Put on truck parking break. start ski, let said ski warm up for 3-5 minutes.
NOW, set idle SCREW on carbs to what yamaha says, i think its 1250 +/- 50 rpm. aka get a tach.
make sure both carbs are the same # of turns out to begin with.
count all turns.
dont touch it for 20 seconds, if it starts to burble and dies cla clunk, cla clunk, its going rich.
turn in screws 1/4 of a turn or less at a time. see if idle goes up. if it does, turn them in more until it sounds like it wants to die.
turn back out from highest RPM point 1/8 turn.

unstrap ski. idle for 5-10 seconds. pin throttle, should be clean and crisp MINUS the loading of the water box.

POPOFF:
get a damn gauge, theres no way around this. either make one, search the forums, like a million threads on $10 and less adjusters.
go on the jetting page, to start with rough pressures.
rule of approximate thumb, somewhere in the low mid 40's to mid 30s for a single carb with STOCK flame arrestor with no screens removed.
aftermarket f/a is USUALLY in the 30's to mid-high 20's.

POPOFF TEST:
hold 1/4 to 1/3 throttle for 10-15 seconds. PIN THROTTLE, if it dies, or power nearly cuts out, POPOFF is too high, meaning a LEAN midrange.
if it doesnt try to die, but makes a WAAAAAAAAA sound that is no loss of power, but not really a gain of power, popoff is too LOW, meaning a RICH midrange.
once it neither dies nor bogs, low speed and mid speed are taken care of.

HIGH SPEED CIRCUIT:
pin it to win it, like a scrub. let go of the throttle after you kill it and smoothly glide onto your trailer (jk you won't make it on your trailer)
if your plugs look like those black slimy things in your post, you are probably about 2 mains high.
if they are grey, you are 2-3 mains low.
IF they are the color of a Filipino, or a properly TOASTED marshmellow, its good to go.



NOW:
your issue.
turn all screws on the b pipe in all the way except 1/2 turn out on the bottom. this is a baseline.
either get a $12 USB 5mm wide camera on ebay to make sure piston wash is there or pull the head.
pistons should have black built up on them everywhere except thumbnail sized shiny spots by each of the 4 transfers and 1 by the boost port. if the piston is super shiny and clean, it is either: really friggin rich, or leaking a small amount of water in, amounting to a steam clean effect of the piston.

pull the intake manifold and check the reeds for chips or other shiz that doesnt look right like lifting off the cage, cracked reeds, chipped reeds, cracked/missing rubber from the cages etc.
apply a light coating of grease on gaskets when reinstalling manifold and carb base gaskets and such.
 
If you had stock 38 carbs, your pop off would be way too low.....i.e too rich above idle and into 1/3 rd throttle...but you running 44s. So an expert needs to comment on whether the bigger air volume can imply a lower pop off to get the fuel running in the right ratios....i also want to learn a bit here tks
 
A Jetski guy in the UK rebuilt them put never set them up on my ski as it was too far to travel to him. I did ask why it had such a large pilot jet in (115) compared to the 38's (70) and he said it was the volume of air coming in. I'm kinda struggling to get my head round the pop offs and how they work etc.
 
Ok so pop off is lowish and you have high volume pilot jets as well.......what are your mains.......sounding richy rich already but i am not an expert....help us guys
 
I think from what I've read with people having a similar spec skii that they run a 120 main. Plug gap ATM is .036
 
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