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blow up my motor twice help!


bansheeman1974

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Hello everybody i have a 2001 banshee that i run vito pistions in and never had a problem with i took it out of the garage for the first time in a year and rode it around the track and it locked up ,had to take a piece of wood and beat the left pistion out of the jug so i rebiuld put a new water pump in and made shur it was all working good took it out again and ran it easy and once again boom it started to melt the left pistion i got it in time where i dont have to rebore but i just need to know what the hell is doing this thanks everybody the plug is black so i do beleave it is running rich any help is good help.

 

here is what i have done to it.

1. vito super stock

2. v force reeds

3. dagree key (3) i think

4. shaved head 20 thou

5.

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i think maybe your there is too much compression and timing advance this would melt pistons

what fuel are you using?

just 93 octane i raced it the year befor and it ran great when i put it up and then this happend also how hard is it to replace the crank seal ??? do i have to split the case to do it??

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Clean out the carbs, as said....

Start the bike up and spray carb cleaner around the intakes and boots. If the motor wants to die out...or lowers it's idle you have an air leak.

 

If you're running the same compression and timing as before, and no problems on pump gas...leave that be.

 

It really sounds like an air leak to me. But, it's free and easy to clean out the carbs...though....

 

Yes, if it's a crank seal, you will have to split the cases.

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You say you had to beat the piston out the first time. What happened? What did the piston look like when you got it out? Where was it melted? Near the exhaust side of the piston? Or was there a hole in the middle? Did you check the squish on the engine when you got it all back together? What was the compression of the motor? Vito's pistons are custom cut and made to his specs. Checking the squish on them is necessary IMHO.

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thanks to all of you, well it has to be a air leak becouse everything on the quad is the same for the past 5 years and just now i am havin problems so it got to be something that i am missing or that just went bad so it is apart right now and i am just going to replace all the seals and hopfuly that is it thanks also it is melting by the exhaust side what could that mean??

Edited by bansheeman1974
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HOLY CRAP....

 

boonman...how the hell are you?

 

 

 

Hey man, I'm doin alright. Just been busy as all hell. My landscaping business has been rediculously busy this season. No complaints though, just bustin' ass sunup till sundown.

 

 

Anyways, Bansheeman, knowing where the piston is melted tells you a great deal on what happened. Being that the piston melted near the exhaust port tells me that you were running extremely lean on that cylinder. Because the exhaust was soooo hot that it melted the piston when it was on it's way out of the cylinder. This could either mean a cloged jet, (usually the main) or an air leak. You should ALWAYS do a leakdown test and a squish check on a freshly built motor. I remember back when I smoked the engine 3 times in my bike in one month. I learned the hard way. SOunds as though you are as well. If you blew a hole in the center of the piston, you had some detonation issues, from either a fuel octane problem, or improper squish, improper timing, and the list goes on. One can also contribute to the other as well. You could have a lean condition, couple with some low grade "mexicana fuel" and that could melt some things, and there are other factors, but having a melted exhaust side of the piston is 99% of the time a lean condition. Also make sure the pistons go in the correct way, and not backwards. And keep the carbs clean!!!!

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