why is my 800sxr reving to the moon???

rizk828

rizk828

Location
Central Florida
I just rebuilt my 800sxr after a bad case of hydro lock:banghead: done it before but this time after all was said and done i removed the the return gas line, blew through it until it leaked at the carb, replaced it and cranked the motor. :boggled: dude that thing revved to the moon:frown: yanked the lanyard...still revving, pulled the plug boots...still revving at like 1,000,000 rpm. crap pulled the gas lines out of the carbs and it still ran for about 15secs before sputering to a dead smokey stop.:17: :boggled: :17: what the hell just happened??? anyone? took the head off, blacker than a coal mine! I was speaking to a buddy of mine that just recently finished cleaning his carbs after winter and when he cranked his motor he had the same problem. :rocketwhore: what causes this problem??? it looks and sonds very destructive, how do you remedy this??
 
the only couch rider

the only couch rider

Location
Jersey
did you possibly blow something out when you blew threw the fuel line?

you might have a bad needle or seat. i would go through your carbs to make sure everyting is ok, that is probably the most viable option to diagnose your problem. you porbably have an air leak in your carb
 
K

kawix2

X
Location
Concord, CA
sounds like dieseling usually caused by a bad seal between the cases and cylinders. When this happens you should be able to cover the intake with your hands and it would kill the motor. The reason it didn't stop is because the plugs heat up so much that they don't actually need a spark to ignite fuel. The motor starts acting like a diesel motor with glow plugs. I would do a leak down test. Unfortunately you may have to replace the top end again and I would look at replacing the base gasket.
 
rizk828

rizk828

Location
Central Florida
kawix2 said:
sounds like dieseling usually caused by a bad seal between the cases and cylinders. When this happens you should be able to cover the intake with your hands and it would kill the motor. The reason it didn't stop is because the plugs heat up so much that they don't actually need a spark to ignite fuel. The motor starts acting like a diesel motor with glow plugs. I would do a leak down test. Unfortunately you may have to replace the top end again and I would look at replacing the base gasket.
Click to expand...

so brand new gasket kit, assuming no damage to the top end, should fix this problem?
 
Big Kahuna

Big Kahuna

Administrator
Location
Tuscaloosa, AL
hey, this will shound crazy, make sure one of your butterflys on the carbs is not open more than the other, have seen this happen after a motor was torn apart, if they are both closed, then check to see if it does it when you have the throttle cable undone from the carbs, seen this happen where the cable adjustment gets moved when hooking the cable back up.
 
Maine Coast

Maine Coast

X-
Location
Nortern Maine
it was dieseling... it can happen out of teh water when you rev the engine becuase the plug tips can get red-hot and not have time to cool down so they ignite the incoming fuel charge upon compression without any spark... not relaly "dieseling" becuase that would be ignition caused by compression, but similar... you dont need any leaks or anything for this to happen, all you need is high-enough free revs
 
djkorn1

djkorn1

kidkornfilms
Site Supporter
Location
Cleveland Ohio
Air leak in your fuel lines or in between cases and cyllinder, for sure. :cool2:

This always happens with Kawis. Fix the air leak and you are all set.
If it ever happens again:

Turn off the fuel and choke the carbs with your hand or with the choke. Then cover the exhaust with your hand and a towel. Should kill it.

ps... don't pull the plug wires. :purr:
 
rizk828

rizk828

Location
Central Florida
Guys thanx for all the input, it is greatly appreciated.:biggthumpup:

well i have honed my cylinders since the incident:sneaky: i have new pistons and rings and a complete gasket kit. i'm going to rebuild it again and see what happens. even though i thought i had done everything right the first time.

any other pointers or tips??
 
SkiDaddy

SkiDaddy

Just Havin' Fun!
Location
Orange City, FL
1. Look down the carbs after install, turn the idle speed down a bit too.

2. Make sure the engine passes a leak down test before you put it back in the hull.

3. If it happens again give it WOT to kill the engine (w/kill switch pressed/lanyard removed).
 
D-Roc

D-Roc

I forgot!
Location
Dirty River Rider
my superjet did this too, i just rebuilt it and put it all together and fired it up. it idled perfect but when i cracked the throttle a little bit it started screaming. I just hit the kill and grabbed the throttle while a buddy slapped his hands on the carbs. It reved for like 5 seconds and it flooded out. I then proceeded to lower my pop off, hylomar the carb to gasket surface and tighted the middle bolt on my intake manifold that i forgot. Between any of those things i managed to fix it.
 
M

madoyster

01/10/08
Location
The Durty South
Big Kahuna said:
hey, this will shound crazy, make sure one of your butterflys on the carbs is not open more than the other, have seen this happen after a motor was torn apart, if they are both closed, then check to see if it does it when you have the throttle cable undone from the carbs, seen this happen where the cable adjustment gets moved when hooking the cable back up.
Click to expand...

Last year at the Texas Freeride, after about 15 mins of riding my engine started to rev like crazy. A Small piece of plastic was stuck in one of the butterfly's just stopping it from closing completely, it was almost unnoticeable. In fact I would have missed it if it hadn't have been for Paul L who pointed it out, God bless LPW.
 
Scorn800

Scorn800

Ride for life
Location
North NJ
I've had this happen a few times on my dry piped sxr. 1st time a blew a hole in the intake manifold. 2nd time it was a stuck needle valve in front carb.
You don't have to replace the top end. did it seize? as long as there's no scores or marks, I'd run it.
 
djkorn1

djkorn1

kidkornfilms
Site Supporter
Location
Cleveland Ohio
Make sure the cyllinders are tightened down good... no gasket goop, just the gasket dry.

Make sure carbs are down tight too and have all the washer spacers etc...
 
You must log in or register to reply here.
Top Bottom