650 backfiring

[polako]

hey guys

ive got 91 superjet with 650 and coffmans pipe.
the pipe was installed just a month ago. In the beginning ski was running just fine and then it started to cutting off and backfiring(small ones).
I trimmed plug wires, opened electrical box(some water in it)
checked all the connectors, checked ground cables, new startstop switch.
if it sits on the trailer it revs just fine and then a small backfire.
When its on the water and I hit the throttle it feels like one cylinder doesnt work, when I hold the throttle steady half way it seems to be working ok.

I was going to buy an electrical box but figured(actually romack did :hail: )
to ask first before spending any money.

thanks for help



ps.
I know my English sucks:haha:

Polako:Banane01:

 

[SurfCrazed]

rejet the carbs to the pipe?

 

[polako]

i didnt rejet them yet.
the ski was running just fine with a pipe and stock carbs.
come on guys, I need your help

 

[Talsivar]

a backfire is usually an electrical or timing problem. i would check the stator.

 

[jeepmark4x4]

Check your compression

 

[SeaLion]

Timing, bad cdi or broken reeds.

 

[gorilla]

it's the cdi !!! for sure !!!

good luck

gorilla

 

[john zigler]

it's the cdi !!! for sure !!!

good luck

gorilla

i think gorilla is correct. especially if you had water in your box. water and electrics just don't mix.

zig

 

[polako]

ok , thanks for all the replies jetski freaks.
whats the easiest way to check if my CDI is kaputt?
can I measure it in some kind of way or should I just get a different one?
I have to make that thing running before daytona

 

[john zigler]

ok , thanks for all the replies jetski freaks.
whats the easiest way to check if my CDI is kaputt?
can I measure it in some kind of way or should I just get a different one?
I have to make that thing running before daytona

there really is no tes for a CDI, short of replacing.

i just parted out a 94 VXR 650, if that cdi will work for you, let me know.

zig

 

[extreemthrottle]

Timing, bad cdi or broken reeds.

i'd check the others first before i bought anything.. pull the carb off and with a mirror and a flashlight you can inpect the reeds. eliminate that then your one step closer to fixing it.. timing should'nt be off but if you found water in the elec. box theres a good chance there might be some under the stator cover, i'd pull that off and get a look. otherwise zig is a good guy he'll give you a fair price.. good luck

 

[john zigler]

pull your flywheel and check your flywheel key too.

zig

 

[polako]

i just took the front cover off, didnt take the flywheel off, no water at all, just a little bit of grease on the bottom of the cover.
I will check the reeds tommorrow.
guys thanks for all the help

ps what kind of tool do you use to take take flywheel off?
i know i sound really dumb now

 

[extreemthrottle]

you need a flywheel puller. might be able to use a harmonic balancer puller from an auto parts store. if you pull the flywheel, you need to be careful not to thread the three bolts in the flywheel too much as it can go through and damage the stator/pulser. also tighten the center bolt real tight, then smack the end of it with a brass hammer. it should pop off.. good luck and don't loose the key or the washer for the starter bendix..