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flywheel too light??

Old 12-30-2006, 12:45 PM
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Default flywheel too light??

so while im waiting for the zen to come back from being dyno'd (fresh ZZ Racing full mod ) i went and picked up some new fuel to try and get the cat back in the water.

Went to start it up today at the house to make sure it was gonna run before driving to the lake, and it fires right up..but quickly dies. I tried several different brand new plugs with the same results... and there is only 2 things i can of that is causing this.


1. the disk is 180ΒΊ out

2. the new flywheel is too light

unfortunatly i dont have a scale to compare the flywheels, but there is a BIG weight difference. Im pretty sure that i have the disk right, although i will pull the motor out and look just to be sure.



Ive never put a lighter flywheel on any of my motors, so im not really sure of what the effects are when its too light. Does this sound like its too light and not being able to swing the crank around enough to keep it running?
Old 12-30-2006, 12:58 PM
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pedaladdictions
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Default RE: flywheel too light??

very interesting question, i've replaced flywheels n was wondering same thing on other engines trying to get them working in my boats......be nice to be educated on that point.............
Old 12-30-2006, 04:39 PM
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Default RE: flywheel too light??

Interesting thread indeed.

Why would a light flywheel cause the motor to die? I would think massive vibrations a worst.
Old 12-30-2006, 04:45 PM
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Default RE: flywheel too light??

When my flywheel came loose and was free spinning my boat would still run, but would die instantly upon touching the water. I think the flywheel helps the motor maintain its rpm when the resistance hits. I am just guessing, I hope you get everything worked out


Paul
Old 12-30-2006, 05:12 PM
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Default RE: flywheel too light??

ORIGINAL: G-1

Interesting thread indeed.

Why would a light flywheel cause the motor to die? I would think massive vibrations a worst.
could be not enough mass to keep it spinning at low rpm. I thought I read a post a while back where someone asked about the effects of a lighter flywheel. I think someone replyed that the lighter could be harder to keep running. Ill see if I can find the thread.
Old 12-30-2006, 05:22 PM
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Default RE: flywheel too light??

I thought someone said the flywheel helped the motor idle...in short it would not idle without it...not speaking from experience though.

Sean
Old 12-30-2006, 05:28 PM
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Default RE: flywheel too light??

ORIGINAL: Sean Bowf

I thought someone said the flywheel helped the motor idle...in short it would not idle without it...not speaking from experience though.

Sean
I would think it might run but my guess is that is as soon as it hit the water without a flywheel it would stall from not having enough inertia to keep it spinning under load.
Old 12-30-2006, 05:29 PM
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Default RE: flywheel too light??

if it stalls the motor, how come i see people setting up boats for racing using small or lightler flywheels...

i guess youll just have to replae the old one or have the motor at fast idle when putting it in the water
Old 12-30-2006, 05:33 PM
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Default RE: flywheel too light??

man im missing my gas boat more and more right now. Found the issue (small hole in fuel line ) but now the next issue is on the table. It starts up and idles fine... but any touch of the throttle it tries to die. I know its not a lean condition as the carb only has a HSN and i have it set decently rich. Im gonna pull the motor again and change flywheels and see if it cures that...if not, i guess it'll just go back on the shelf and ill wait til my gas motor comes back to run []
Old 12-30-2006, 05:52 PM
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Default RE: flywheel too light??

ORIGINAL: saleens7

if it stalls the motor, how come i see people setting up boats for racing using small or lightler flywheels...

i guess youll just have to replae the old one or have the motor at fast idle when putting it in the water
Well maybe there becomes a point at which lighter becomes too light. I found the thread where a guy says that a lighter flywheel give more speed but is harder to idle and a heavier will idle and run smoother but wont be as fast.
Old 12-30-2006, 05:57 PM
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Default RE: flywheel too light??

What did you do rebuild it? might be tempermental and need to be broke in again. Mine I found that I was a bit lean on both needles but it weouldnt run the first couple times when I fattened up the high side. Then after a couple runs I fattened up the high side and she ran great. I checked out the vid of your gasser a while back sweet vid.
Old 12-30-2006, 08:00 PM
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Default RE: flywheel too light??

yeah i did a rebuild on the motor. The first outting with it it broke the flexcable and the motor freespun destroying the rod and piston...so i replaced the rod/piston and sleeve (no visible damage to the original sleeve.. just did it for a non issue kind of thing). I cant really recall if the motor did the same thing trying to die with any kind of throttle when i was breaking it in... but i guess ill heat cycle it a few times and see if she will run.


Thanks for the comment. The gasser ran pretty good with the stock motor. Got 15,960rpm out of it in clean water...no idea what kind of speeds it was really running though. Hoping with the new mod to crack the 60mph zone, and run 53-55mph in heat race trim.
Old 12-30-2006, 09:39 PM
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Default RE: flywheel too light??

New piston and sleeve puts you back to breaking in the engine. It's probably tighter and you're not going to get a good idle. Get it so it's richer on the idle and you need to keep blipping the throttle to keep it going.
Old 12-30-2006, 10:09 PM
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Default RE: flywheel too light??

ORIGINAL: Believe It

yeah i did a rebuild on the motor. The first outting with it it broke the flexcable and the motor freespun destroying the rod and piston...so i replaced the rod/piston and sleeve (no visible damage to the original sleeve.. just did it for a non issue kind of thing). I cant really recall if the motor did the same thing trying to die with any kind of throttle when i was breaking it in... but i guess ill heat cycle it a few times and see if she will run.


Thanks for the comment. The gasser ran pretty good with the stock motor. Got 15,960rpm out of it in clean water...no idea what kind of speeds it was really running though. Hoping with the new mod to crack the 60mph zone, and run 53-55mph in heat race trim.
A bit of topic but I got my little Wild thing running pretty darn good after I figured it out.
Old 12-30-2006, 11:15 PM
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Default RE: flywheel too light??


ORIGINAL: piper_chuck

New piston and sleeve puts you back to breaking in the engine. It's probably tighter and you're not going to get a good idle. Get it so it's richer on the idle and you need to keep blipping the throttle to keep it going.
there is no problem with it idling. It will idle on the stand til it runs through the entire 16oz tank (not that i would let it). The problem now is that with any kind of added throttle over idle its wanting to die. Im pretty sure i have it rich enough as i have fuel on the plug..IE 3-3/4 turns out. There is NO LSN on this carb.
Old 12-30-2006, 11:31 PM
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Default RE: flywheel too light??

Try a new plug if it isnt one. Thats the first thing I check. I have had plugs that would glow and do similiar.
Old 12-31-2006, 12:43 AM
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Default RE: flywheel too light??


ORIGINAL: unclecrash

Try a new plug if it isnt one. Thats the first thing I check. I have had plugs that would glow and do similiar.

yea, that was one of the first things i did. I pulled 5 different odonnel plugs right out of the packages with the same results for all. 2 of them i stuck in my .21 truck and it ran fine...so i know its not the plugs.
Old 12-31-2006, 01:05 AM
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Default RE: flywheel too light??

I think I would do like you said go back to the other flywheel. If that dont help I would slowly try leaning it out. Man thats a drag a hate trouble shooting good luck let us know what you find out.
Old 12-31-2006, 04:43 PM
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Default RE: flywheel too light??

Are you running an IV bag or hard tank? Vent clear? Filter & all lines clear?

Sounds like fuel starvation maybe......




Old 12-31-2006, 07:56 PM
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Default RE: flywheel too light??

That was me! about lighter/smaller flywheel. My flywheel on my motor was rubbing on the boat hull bottom.So I did shaved the fly wheel down a bit,by using a drill press and a good file.It worked perfitly.Must of takend 15 to 20 thousand off of it.By doing that now my motor fits the boat and clear the floor bottom too.Plus it didnt hurt the motor running eather.I dont know about on other motor but it worked on mine.[>:]
Old 12-31-2006, 08:00 PM
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Default RE: flywheel too light??

Nope it wasnt you it was another thread I read it on.
Old 12-31-2006, 08:31 PM
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Default RE: flywheel too light??

I know there were two threads on this and mine was one of them.[>:]
Old 12-31-2006, 08:59 PM
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Default RE: flywheel too light??

Do a search on flywheel and you will see theres many more than two. Why always the evil face in post. Is this your powty face
Old 12-31-2006, 09:06 PM
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Default RE: flywheel too light??

I didnt know?that was the evil face! I'd just like the looks.I dont mean anything bad by using it.
Old 12-31-2006, 09:54 PM
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Default RE: flywheel too light??

I think it's a friendly challange type face like "Game On"!!!! [sm=devious.gif]

BTW, with gas engines as long as the magnet comes around and sends the signal to fire the spark plug I'm not sure weight of flywheel has anything to do with the engine dying.

Vibration yes. But the engine should still run.

I see they make a timing advance brace for the coil on the Zen's. Now thats interesting! Will allow different extreme timings modded to the motor. Way cool I just don't have the money to experiment with it right now.









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