Super Jet Holy crap backfire??

JT_Freeride

JT_Freeride

John Tetenes @Jtetenes
Location
Long Island
So I just finished putting my ski back together and I wanted to just test start it. It started no prob after all the fuel lines and carbs got primed I idled it for about a minute then I started to rev it up (At this point in time all seemed fine and normal) so I let off and when if came back to idle it just died. So I tried to restart it took a little bit then it idle and died again so I tried again and it was about to fire up and BOOOOOOOM!!!!! One of the loudest back fires I have ever heard. What could have caused it to do that? I haven't tried to restart yet.



Mods

Riva red pipe
Ada girdled head 35cc domes
Carbs are 38s with pro k fa with 135 main 70 low.
Screws set to 1.5 high 1 low


Also Engine was winterized and brand new 93 octane I just bought before starting
 
TheBuzzard

TheBuzzard

Location
the jetski grave yard
backfire is caused by the unburned gasses in the exhaust system igniting. sometimes when the cdi is going out, it fires when the ports are open, causing backfire. usually grenades waterboxes or rubber hoses/couplers.
 
Byeai

Byeai

"Cheetos-Man"
Location
Melbourne FL
I had a blaster 1100 backfire it was scary I jumped so bad but I had one of the plug wires wrong

Sent from my SAMSUNG-SGH-I727 using Tapatalk 2
 
swapmeet

swapmeet

Brotastic
Location
Arlington TX
Lol yeah I checked the thread for some waterbox carnage... Happened to me on a FX1. But your symptoms are a little strange.

When you say you tried it again and booom... How long we're you 'trying'?
 
JT_Freeride

JT_Freeride

John Tetenes @Jtetenes
Location
Long Island
This didn't really sound like a back fire the motor didn't make any unusual noise and ski didn't vibrate or anything. Just like a gun shot out of the tail pipe
 
F

Forever2stroke

Location
Mullica Hill NJ
scary huh? I had a blaster waterbox blow the whole lid off due to a backfire. my stator was going bad and not firing all the time so I think my exhaust had a little fuel in it, then BANG! pretty sure I left more than skid marks
 
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lawmaster891

lawmaster891

Location
Fort Worth, TX
I had almost the same thing happen right after I assembled mine. Only happened once and no trouble so far. I have since put about 5 gal of fuel through it ( Only had 1 ride so far)
 
JT_Freeride

JT_Freeride

John Tetenes @Jtetenes
Location
Long Island
Update I just went to try and start it up again and now it won't even crank over. This ski ran great before I put it away wth is going on. I also want to add that when I was putting on the battery my wrench hit either the carb adaptor or the girdled stud and it sparked like hell. Shouldn't that not happen if the engine is grounded.


Also I checked the fuse its fine
 
S

SJ 701X

Location
In a hole
Happened to me on my 550. Thing was flooded and gasses had built up in the waterbox and pipe. I had a 3 foot flame shoot out the exhaust and singe my leg.
 
Proformance1

Proformance1

Liquid Insanity
Site Supporter
Vendor Account
Location
New York Crew
Id go with carb leaks over storage time, built up in fuel line, causing backfire. Also mentioned above about ignition. Listen closely while hitting starter, if u hear a humm, it could be bendix sheared starter nose off from kick back, not backfire.
 
JT_Freeride

JT_Freeride

John Tetenes @Jtetenes
Location
Long Island
4SeasonsPower said:
Check crank phase. A twisted crank can cause what your describing.
Click to expand...

I'm not sure if I understand what your saying can you describe it a little more.

Ok so I got it fixed its running now but I have a slight lean problem. It start to run away but only at like 3/4 throttle and just holds there but if I hit the stop it kills it. So it's not like a run away where you have to WOT while holding stop. But only after it hangs the rpm is where I get the back fire on the next start up

I do have 115g springs and my pop off is at 53-55ish should i put 95g springs in?
 
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