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Discussion Starter #1
Well we were having some issues keeping
the little guy running last outing, he would run for a while then die and was
dang near impossible to start, then finally no start at all. :thumbsdown:


Took him home tore it down and found
this...














I suspect a crankcase
leak.


Any other ideas what could have caused
it?
 

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Did you do a leak down test upon rebuild? I made a leak down tester for my daughters lt80 rebuild. The thread is in this subforum. I'd suggest this for the next rebuild. Are there Ny mods on this motor?
 

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Discussion Starter #3
no i didn't do a leak test :-(, I didn't have one built. do you think I could still check the crankcase after a top end??
 

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Crankcase leak is possible but usually a lean condition would lead to a hole in the piston. my observation is the exhaust side got really hot.are ousideedges(squish band) pitted? i would suggest new crank seals, rebuild the top end, compression test and leakdown test. I also run my kids aeon 110 at 28:1 fuel oil ratio, fatter on oil but on the horizontal engine I dont want to take a chance... could have been a small leak but with out a leakdown prior to teardown its just a guessing game
 

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Yes you can test the crankcase for the leak after the new top end. Make a leakdown tester and go at it. It'll test the entire motor for a leak. These motors were built so conservative from the factory that there's not much that goes wrong with them usually.

Are you still running the oil injection? Lack of oil could be a possible cause.
 

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Are you still running the oil injection? Lack of oil could be a possible cause.
Good point it was the first thing I removed and premixed... but if you notice there is a fair amount of carbon built up on the crown and what appears to be the blow by on the rings....
 

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As the others mentioned, could be most anything. Something not mentioned, how much time does the top end really have on it? The problem may have been building for a very long time. Without that leak down test, for everyone, you'd be wasting your $ cuz it could do the same thing over again. Your top end may have just been worn out. Too much time on an old top end can look just the same.
 

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Maybe a lesson learned here. If you're told that it's just had a top end job, better check the cranking compression, then you'll know for sure.
 

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Discussion Starter #11 (Edited)
Thanks for all the input guys, as far as I know it's all origianal. we got it last year he has ridin' the heck out of it. last november it had similar issues(hard starting). I removed oil injection, running 32:1 same mix I run in my 250r. I cleaned the carb real good. I recall even doing a compresion test and it seemed ok. the problems kept building, maybe it was just time for a rebuild.
I suspected a crankcase leak becuase it wouldn't idle with out the choke on, even after i cleaned the heck out of the carb, and replaced the pilot jet.
Anyone have any shop reccomendations?
 

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Discussion Starter #15
OK, so got my top end back together, went with lakesmotorsports on ebay $160 for bore and Weisco top end pretty sweet deal.:thumbsup:
Whats the proper break-in method? Also can I leave my shrouds and fan off for the break-in?
 

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Just looking at your pictures again. #2 & 3 indicate some detonation. What size piston is the new Wiesco? You may or may not have gotten a super deal on your cylinder depending on the size of the new piston. It's probably too late at this point but it would have been a good time to check the deck height & squish dimensions. It's a good time for all of you to check the top end dimensions when you're replacing things along with all of the compression checks.
It's also handy to write down recording the information for future reference.
 

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Just looking at your pictures again. #2 & 3 indicate some detonation. The new cylinder has a sleeve in it? the old one is plated. What size piston is the new Wiesco? It's probably too late at this point but it would have been a good time to check the deck height & squish dimensions. It's a good time for all of you to check the top end dimensions when you're replacing things along with all of the compression checks.
It's also handy to write down recording the information for future reference.
My lt80 jug wasn't plated....
 
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