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Engine seized up.


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Ok I was riding the old 'shee around the farm and it was running great for about 2 hours. Then I went down the road in 6th gear for about 20 minutes and all of a sudden I heard a loud exhaust noise from the right pipe so I pulled the clutch to stop. I'm lucky I didn't get thrown off! The engine died immediately. I tried to kick it over and the damn thing is seized up. :down: I seized the engine before but that was the crank which, in that situation, the engine ran really rough and then gradually died. Ok this is the first time something like this has happened to me so here go the questions. :confused:

1. Does it sound like a piston seized up or the crank?

2. It's bored .50 over so am I going to need new sleeves put in or would it be better to get the cheetah cub kit?

3. If the piston is seized up then how do I get it out?

4. How could this happen? The carb was set right with the air/fuel mixture. I run half 93 and 110 octane fuel. I put Engine Ice in the cooling system. Could it be too many rpms for too long?

 

 

List of engine mods. Pro-Circuit Platinum pipes, Pro-Circuit 304 silencers, Trinity Stage IV Head w/19cc domes (180lbs of compression), Hot Rodz Crank, Half inch reed spacers, Vforce 3 reed cages, Trinity Stage IV CV 33mm Carb, external K&N air filter with outwear, Dyna FS CDI, Megaflo Impeller, CV4 hoses, PWR radiator, Hinson 8 plate clutch system, Trinity smooth shifting cam.

 

The last time it was rebuilt was a long time ago. I hardly got a chance to ride it because I was in the military for 5 years.

I am really getting frustrated with this quad. Anyones help would be greatly appreciated.

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i would pull off the cylinders and see what it looks like. it may be froze but they will come apart. you shouldnt need new cylinders. 50 overs not bad you have a few more bores to go yet depending if the skirt is snapped off or not. i cant say what happened but pull those jugs and post pics.

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Well, to start with a 100 octane mix is a little on the scarry side for 180psi compression, I would recommend straight 110 for that much compression.

Second thing is, 20 minutes at WOT?? That is a long time for any engine to sustain peak rpm.

It is hard to say wheather it was the crank or a piston, the only way to know for sure is to pull the head and have a look. There are several things that can cause seizure or burn down: air leak, impropper jetting, leaking head gasket, impropper fuel or mixture, too hot of plug, overheating, ect, ect. The only way to know what caused it is to inspect the piston once it is out. There are tell-tale signs you can look for on the piston that will give you an idea why it blew up. I would suspect heat (too many rpms for too long) or detonation (low octane for compression), but I wouldn't rule out the other possibilities.

What kind of riding do you use the bike for? A cheetah cub wouldn't be well suited for any trail application, they are great for drags and wide open areas but have very little power in the bottom end. Also, you would likely have to upgrade your pipes and carbs to get the full potential out of the cub.

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wow 20min hahahahah I wouldnt sustain any one prolonged rpm with a 2 stroke...Id say you melted the pistons where then the piston skirt has either cracked or broke all the way off which is lodged in the side of your cylinder ...possibe rod and crank damage! It depends on how deep the groove is but you can bore .100 over although I wouldnt go further then .80 personally

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well, you made it almost 15 minutes longer than my yz 125 did lol

my connecting rod seized to the crankshaft and was blue halfway up. the jetting was good and all, just didnt like givin er for too long.

my cylinder and piston were perfect still.

 

i think you are ez=xpecting too much for it to not blow after 20 minutes at WOT, unless i misunderstood you and it wasnt full throttle...

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Have you made any modifications to the fuel delivery system? Thats a long time to run it hard. Perhaps ran the bowls dry creating a lean condition? May need a pingel valve and gutted cap to ensure good fuel flow. Really though, like has been said, you need to get it apart. I thought i blew a hole in a piston back in january based on how the bike was acting. When i got it apart, found out crank had separated and lost a rod bearing. Rod was wrapped around the crank like a pretzel. sorry man, but look on the bright side, now you can justify improvements. :biggrin:

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i was always told no longer then 40-50 seconds at WOT. talked with a guy that rebuilds motors offton and he was always telling me that his number 1 reason for a rebuild, someone just had it pinned at WOT to long...

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i was always told no longer then 40-50 seconds at WOT. talked with a guy that rebuilds motors offton and he was always telling me that his number 1 reason for a rebuild, someone just had it pinned at WOT to long...

 

 

To add to that....if you do run those 50 seconds at WOT, roll back out of the throttle, don't just let the slides drop all the way instantly or you'll be trying the feed those 9000 or so rpms through the pilot jet, which is not good. I locked 2 Cubs up like that, thinking that is was ok as long as I let back out of WOT, but it's definately not.

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Ok I figured it out. I had a detonation problem in the left cylinder and the spark plug was loose. So I figure that since some outside air was leaking in through th spark plug hole it caused the cylinder to burn too lean. The end result. My left crank rod melted. So I think I might just get a +4 stroker now.

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Im disagreeing with anyone, but werent a lot of outboard motors 2 strokes? I have always wondered how they sustained being at WOT all the time. Cause really thats the only way to drive a boat any distance is WOT until you get there. An hour isnt even unheard of on my lake.

 

Just wondering what the differences are.

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Im disagreeing with anyone, but werent a lot of outboard motors 2 strokes? I have always wondered how they sustained being at WOT all the time. Cause really thats the only way to drive a boat any distance is WOT until you get there. An hour isnt even unheard of on my lake.

 

Just wondering what the differences are.

 

 

my 2 stroke outboard boat only goes to like 5000 rpm, plus it has a constant supply of fresh mostly cold water 2 diffrent motors, being 2 stroke is the only thing they have in common.

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my 2 stroke outboard boat only goes to like 5000 rpm, plus it has a constant supply of fresh mostly cold water 2 diffrent motors, being 2 stroke is the only thing they have in common.

+1 the rpms are way lower and their being cooled by fresh water vs recycled water that at that time period and rpms does not get the chance to cool down

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