fl350 engine help...please!

[tutie]

Hey everybody we are in serious need of help getting the odyssey to start. there is spark on the plug but it wont fire up...we've tried pouring a little bit of gas in the spark plug hole and it still wont do anything but just crank and crank...we've tried starting fluid and that wont do it. we had it running fine after a rebuild....it died one day and hasnt started since! could someone PLEASE help us out? thanks! my email is toot_x_toot@yahoo.com

[nutz4sand]

Have you tried a NEW plug? Just cause it sparks when you look at it does not make it spark inside the cylinder.

Also what kind of compression does it have?

Did you do a leakdown test on the motors bottom end?? Bill

[tutie]

Yeah it has a ton of compression. it's a brand new spark plug. not sure what a leakdown test is. how would i know if the plug is firing after i put it in? i appreciate you replying back!

[nutz4sand]

A ton of compression? 2000 pounds? Dang.

Seriously. You need to get a compression gauage and learn how to use it to monitor the engines life.

Who rebuilt the motor?

That aside I am going to assume it has some good compression.

The old adage is. "To run you need fuel, spark, and compression." (timing of the spark is also needed)

It does not try to fire or pop at all? What color is the spark when you are looking at the plug outside the motor?

Even a new plug can be fouled if there is to much fuel in the motor and its flooded badly. Which you may have done depending on how much fuel was poured in (or it got thier some other way, keep reading). Sometimes you have to remove the plug and have someon e hodthe throttle wide open and pull it over (or crank it) and if you have a puddle of fuel in the bottom of the crank case it will try to purge it out. If this has happened you either have a carb problem (stuck float?) or maybe a bad fuel pump that may be letting fuel into the crankcase. This can cause a motors crank to fill with fuel.

You say "It died one day" Explain JUST what happened and all you can recall about how it was running and how it died.

What condition is the spark plug WIRE in. Look in the cap where the plug goes. Is it nice and shiny or all carboned up? Is the wire solid or weak and flimsy? Is the wire SOLIDLY connected to the coil? I have seen wires that when the plug was taken out the wire made the connection as it was bent to a new angle. But with the plug installed the wire had a weak spot it had burned/broken through and it would not function where the wire normally resides and shakes constantly due to vibration. To test this crank the motor while moving the spark plug wire (Use insulated pliers or a friend you "owe one" to gently move the plug wire around a bit. See if it makes any differance.) You can also move it with a stick but the friend is the funniest if it has a bad plug wire. Trust me (Just make sure you can run faster than him.)

Any two stroke has seals in the crankcase. If these go bad you usually lean out the motor and fry a piston and can ruin a good cylinder along with that.
To pressure test a two stroke should be done BEFORE you tear it apart for a rebuild. (If it fails then a top end rebuild alone will fail due to the bottom end is leaking. If the motor fails a crank pressure test and the pistons is bad the bottom end is usually what caused it.) AFTER you rebuild it to check the seals (and gaskets) you just worked with. And at regular intervals (along with piston compression checks) to monitor your engines internal life.

To do a pressure check you need to remove the pipe and carb and go to a hardware store and get some stuff from the plumbing department to seal both holes. Rubber caps and a hose clamp usually work good on most exhaust pipe snouts and PVC pipe caps can normally be found easy that will fit in the carb boot. You then either need to make or get a fitting that allows you to put an air hose to either one of the caps or into the spark plug hole.

Basically you need to have a way to feed air into or out of the motor.

If you cannot find a way to use the sparkplug hole with a fitting then drill a hole in the PVC pipe cap thats in the carb manifold (Take it out of the manifold first if its already in there! I hope I didn't need to tell you that but just in case! I have seen people drill things where crap from the drill falls into the works. Not good). (My honda Pilot has a fuel pump hose fitting on the side of the cylinder (some motors have these on the crankcase) for the pulse to make the fuel pump pump fuel. If you have that fitting you can use it (on a single cylinder. In a twin it can only be used for the cylinder its under just so you know)

Once you KNOW the pipe and carb holes are sealed tight (The spark plug too if you have you air fitting there. If the plugs in it should be fine.) make sure the piston is down in the bottom of the cylinder (You don't want it blocking the ports. The very bottom is good. Just clearing the cylinder ports will be fine.) Then you need a vacuum gauge/hand pump ($20 to 30 bucks at any auto store for the hand pump version.) Put about 6 inches of vacuum to the crankcase. If it drops to 4 inches of vacuum in under three minutes the bottom end seals are bad or at least weak. Some say less than an inch of vacuum a minute is fine but as you regularly test your motor if you see it loosing its negative pressure faster then you will know the seals are getting weaker and its a lot cheaper to fix it before it toasts everything. (This requires you to make sure the carb and pipe plugs you made are good so you are only checking motor gaskets/seals.)

Thats a negative pressure test. You can go up a little higher in vaccum pressure. The motor should be able to hold some for over five minutes or the seals are toast.

Many also do a positive pressure test. Same deal as above. Seal the motor and get a hose connected with the piston at the bottom of the cylinder. In the NEG test above the pump stays in the line and holds the vacuum. For the POS test you will want a little on/off valve in the line. Then once you put pressure to it you can close this valve to hold the pressure in. As long as you have a setup that holds the pressure in at the hose your fine.

HERES THE CATCH. If you put to much POS pressure to the crack case you can literally Blow the seals out! NEVER JUST PUT A AIRCOMPRESSOR HOSE TO THE SETUP YOU MADE TO PRESSURE TEST IT AND "THINK" YOU CAN HIT IT WITH A LITTLE AIR AND TEST IT THAT WAY. You make one little mistake and its gonna need to be taken apart and repaired. So do this instead. Get one of those small portable air tanks. Put about ten PSI in it with the compressor. Then bleed it down to 6 PSI or maybe 5. This way you cannot put more than that to the crankcase. Better safe than sorry. Put the 5 or 6 PSI to the crankcase and seal the valve. It should not leak more than a pound a minute. Less is better. More is questionable.

You can get a gauge at the auto parts store that reads both POS and NEG on the same gauge. (They are NOT high pressure they are more for car manifold tests) This gauge can do both tests for you. I have in the past used these (I still have mine and use it) AND used a HUGE syringe to provide both the vacuum and the positive pressure. It sometimes takes a few pumps to get the pressures I wished but it can be done.

If that did not make sense GOOGLE pressure testing a crankcase and you will get some more insight. Meanwhile pull the plug and crank it with the throttle open. Does it try to spit a lot of fuel? You may have flooded the crank. Then try inspecting and moving the plug wire around. Let us know. Also do not forget to tell us how it dies the last time it ran. Bill

[jumpin jellybean]

great advive especillay about the air compressor DO NOT DO IT had to rebuild motorexpensive lesson learned

[masterfabr]

Great 2 smoke info nutz!!! Took some time to type and will be of great benefit for many.

[fl250driver]

nutz gave you good advice.
to check to see if it is getting gas remove the fuel line right where it goes into the carb. then hold the throttle open and see if gas comes out.
o and you might want to take a red cup to put those fuel line in, but get rid of the gas in it quick cus it can disintegrate the cup.
if it is not getting gas try putting you lips inside the gas tank and blowing out as hard as you can. (i no its seems like a bad idea and probably isnt that great for you but it works.) gas should come out no matter what if you do that.
and also when it died what mixture where you running.
my brother on his yz85(dirtbike) mixed it 20:1 instead of 40:1 and it died just like your fl350.
if you ran the wrong mixture you need to drain the gas tank and put the correct mixtute in.
it will be hard to start because the wrong mixture is still in the engine but once you get it to start let it idle for 15 minutes to get rid of all the bad gas.

hope this helps you out.
we all no its more fun to spend a weekend in the desert or dunes instead of working on your buggy.

[tutie]

This might be a dumb question but does the fl350 have timing? it's really hard to explain what it's doing but the motor is seizing and unseazing....the motor gets tight and then eventually seizes to where it takes the pull rope and the electric start BOTH to get the motor to turn over and then it gets no spark. BUT when the motor "loosens" back up it gets really good spark and u can easily pull start or electric start to get the motor to turn over....i'm sure this is gonna confuse everybody but i dont know how else to explain it! this thing is a mystery haha

[nutz4sand]

Its got spark timing.

Siezing and unsiezing? Is this just turning it over or trying to run it? I am assuming you have not gotten it running as thats what the first post was.

Sounds like your motor needs a complete teardown and rebuild. It almost sounds like a major seal is out of the crank and its leaning out and overheating and siezing the piston. But that can only happen if its running.

You never did tell us what happened the last day it ran. How was it running and what happened when it quit.

[nutz4sand]

Also you might wanna quit trying to spin it over. Your likely to make an expensive problem into a REALLLLY expensive problem. Doing what you described above will torch the starter and battery and the wires. Not to mention possibly tear the guts up that may be saveable if your lcky.