Intermittent MID and TOP end loss?? VIDEO ADDED

shawn_NJ

shawn_NJ

Chasing waves.
Location
Daytona Beach
Took the ski out today for a pre daytona checkup. It rode F'ing amazing...for about 15mins. Then the top end just went away, and it sounds like its missing up top? Do you think its fouling a plug? It seems that after I swap plugs it rides better, for awhile. I think the high jet is too fat. The temps were also very extreme. Water was in the 40's and air was 35F.

To help visualize what the issue, here is a video clip of the motor revving. I am giving it WOT in this clip.

http://www.surf-mb.com/video/780.wmv
 
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surferdude345

surferdude345

X-H
Location
Blacksburg for school
If it was running perfect b4 to me it sounds like electrical. But check ur compression any way. I would trim the plug wires back and check ur spark.

When you pull the plugs are the Completely white or real dirty?
 
ANT

ANT

Just ride
Location
Sea Isle City, NJ
sounds like your lean at and idle, and could be fat up top, check what your plugs look like. sounds like u need a new set of plugs. be careful how fat you go with jetting because its gonna be about 30 degrees when you leave NJ and about 70-80(maybe) when you get to florida your ski is gonna be super rich with the temperatre change going to daytona.

post up what your plugs look like.
 
shawn_NJ

shawn_NJ

Chasing waves.
Location
Daytona Beach
Surferdude,

I have been battling this "ON and OFF" problem since late OCT. Its a brand new CDI with NEW JSS wires and NEW MSD boots. The pulse coil resistance is right on the money. I replaced the entire length of wire from the pulse coil to the CDI to make sure there was no problems there. I have swapped out EVERY electric componant with known good ones. THE ENTIRE SYTEM! I have been attacking this as a electric/spark problem but I am leaning alot more towards the carb causing plug/spark problems. Compression is right on the money 174/173. The past 4 times I have been out it runs fine for awhile. As soon as I give it a few 15+ second open punches, it starts sounding like its hitting a rev limiter (at around 60-70%) even though I have it pinned WOT. After everytime I have the ski out I swap the plugs with new BR8ES. The problem seems to come on alot quicker now then it did in OCT. I am guessing that this is because of the progressively colder temps?

ANT,
I am with you, I think its way too fat on top and its fouling plugs up. If I swap plugs it goes away for awhile.

I think I have a 195H or 200main jet (3/4out) in a single 46 (only size I could get some decent color on the plugs). Now that is balls cold out I am guessing its fouling the plugs up faster cuz it was too fat to begin with. I pulled the front plug and I will post a pic later tonight, its pretty dark. I am going to drop down to a 180H an see if the problem goes away. I really hope so, cuz tuning in 30F air f#$king SUCKS!
 
S

sflsurfrider

sounds electrical to me. do a continuity check across both sparkplug leads. by the sound of your ski, i dont think youre going to see any continuity on the meter.
 
D Slicker

D Slicker

Durham, dont forget it
Location
Pottstown, PA
Check your JSS coil since you are running in salt water. They work great in fresh. Also I agree with the lean.
 
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shawn_NJ

shawn_NJ

Chasing waves.
Location
Daytona Beach
D Slicker said:
check your connections and and make sure no water is getting in them jetting my friend jetting.
Click to expand...

I'm going to go over all the connections again next weekend when I get a chance to work on it. Getting too close to daytona for this thing not to run right, and I am definetly starting to get nervous. I have the worst luck with skis you can imagine.
 
keefer

keefer

T1
Location
Tennessee
Check the charge coil on the stator. Even though they call it the charge coil its only job is to power the CDI. The brown/white wire to ground is the one you want to check. A failing charge coil can make the CDI act like this. Values differ between the old style 61x and the 62t stators. Here are the values for a 62t stator.

charge_coil.JPG
 
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keefer

keefer

T1
Location
Tennessee
Oops, I guess I should look at the pictures more carefully! Nevermind:bad3:

Does'nt the Kawi CDI also derive power from a coil on the stator like the yami??
 
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ANT

ANT

Just ride
Location
Sea Isle City, NJ
im still thinking fat on top cause it has a 195 main, thats 17 sizes bigger than what a 46 comes with from mikuni. if i had to guess i would say that you have a basic limited setup on that 780 with head, pipe, prop, ignition and prop. you dont have to go up that many sizes for that. turn out you low speed a 1/4 turn too its sounds like its gonna run away. i dont think your dealing with an electrical issue here if your plugs are dark.
 
shawn_NJ

shawn_NJ

Chasing waves.
Location
Daytona Beach
Just an update. I had someone with alot more electrical know-how, look over my ski this weekend. Apparently my wiring skills are below par (to be nice), so we pulled out the entire electrical system and he is going over everything and replacing alot of the crappy connections/wiring. Good news is the ground wire from the EBOX to the CDI was in bad shape, along with the EBOX to stator ground. Both of these are getting replaced.

Hopefully by next weekend I can test it again and see if the miss goes away. Also going to drop the HIGH speed jet down to a 180.
 
shawn_NJ

shawn_NJ

Chasing waves.
Location
Daytona Beach
Really.... Right now its has a 112L 195H 2.5n/s and 65g spring. What PSI do you think I should go to? I have access to a popoff gauge now (didnt when I sent this up).
 
SUPERTUNE

SUPERTUNE

Race Gas Rules
Location
Clearwater Fl.
Shawn, Why in the h*ll do you need a 195 main jet with 2.5/65 gram spring? Are you sure the return bleed is not drilled out in the carb body?
I'd say you have it WAY to rich, if you need to jet it like that, you have other set-up problems. I haven't done very much OLD SCHOOL X-2's in a while, but that doesn't make any sense to me try to run that low of pop-off and so big main jet.
Try using a 80 gram spring and about 120 L, and 165 main.
P.S. It does sound like ignition to me, have you tried closing up the sparkplug gap to .020?
Sorry I can't re-live 1986! I'm way past this stage now and can't remember a lot of engine set-ups I did then... stupid me with not writing them down. Have some porting and cutting head spec's with some old limited jetting stuff somewhere in my back shop.
 
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