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Heads and cylinder cracked

R

Ratchit

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Dome cracked and caused combustion to enter coolant .
Took motor apart and cylinder is cracked between ports.All done by terra alps.
 
R

Ratchit

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Did you overheat the sled??

Because of dome cracking and combustion entering coolant it did get hot because of this . Crack in dome is is suspicious of 90 degree angle machining steps weakening domes on coolant passage side . Cut the dome in half to show this .

IMG_1774.JPG
 

diamonddave

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I'm in no way defending Ted here but I have seen quite a few stock bored/stock piston'd 800 CFI's both 2 and 4 injector motor's crack the cylinder at the exhaust ports with less than 1,500 miles. And a few in the 500-800 miles range.


Is this Ted's Bigbore or ????
 

dragonfire

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New dome

Because of dome cracking and combustion entering coolant it did get hot because of this . Crack in dome is is suspicious of 90 degree angle machining steps weakening domes on coolant passage side . Cut the dome in half to show this .

I would buy a new dome for a hundred dollars and put it together. Like Diamond Dave said I have seen a lot of cylinders cracked like that. I don't understand the pictures and negative advertising over a hundred dollar dome.Parts fail and there is no warranty on after market parts. Move on be happy life is too short.:)
 
R

Ratchit

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defective parts, alloys,machining processes has a lot to do with this

This along with zero support

I could go on with two more engines that went south too on the new axys model engines.One crank was 0.022" out of balance. Thinking this is one isolated incident is wrong .
 
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R

Ratchit

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Start enjoying life. A snowmobile motor isn't worth being that upset about. Have a good day.

Hahaha, not upset. Just showing what aftermarket products are out there. As I said, have more that went down that are friends . Buyer beware!!!
 

Killer Time Racing

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I was thinking about his 180 shim and pipe/y-pipe combo

I've never seen so many people want a Race Motor at a fraction of the cost and think there is no Maintenance required .. if you have a stock bore I would be even more careful , we all know these cylinders are not straight or true .

I only want a 840 because the bore will clean up the factory .040+/- tolerance to a more industry wide .008 +/- and a better forged piston .. but I'm in the new every three so my warranty will cover my stupidity when I run it over 180 Degrees and get so much deto it unleashes fury on my motor from buying cheap gas !!
 

gtwitch

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After 40+ years in engineering (Mechanical) I can still remember one thing I learned by my 2nd year in college or maybe before I got out of highschool shop class and that was square lathe cuts cause stress concentrations leading to stress failures!! If those step cuts would have been done with a larger radius cutter, I would bet there would been less stress concentration and probably not caused a crack. IMO only and worth just what you pay for it!!! NOTHING!
gtwitch in wyoming
 
R

Ratchit

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After 40+ years in engineering (Mechanical) I can still remember one thing I learned by my 2nd year in college or maybe before I got out of highschool shop class and that was square lathe cuts cause stress concentrations leading to stress failures!! If those step cuts would have been done with a larger radius cutter, I would bet there would been less stress concentration and probably not caused a crack. IMO only and worth just what you pay for it!!! NOTHING!
gtwitch in wyoming

Exactly!!
Making 90 degree lathe cuts on domes weakens domes . A rad should be used. This is the point I've been trying to make along time ago as top machinist see this and I've discussed this with them . It cracked exactly were 90 degree lathe cut was made. Domes usually crack and fail in the squish band area , not above .
Thanks for pointing that out
 
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