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GX390 build question

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fiat124

Member
Hello...looking for some advice
On my 2002 Honda GX390 the block seems to have stress cracks so I got a used block. The cylinder sleeve ID of the replacment block is 3.467 in all areas. The spec I think is 3.4646 to 3.4652 and the service limit is 3.4710. Is this block a lost cause as its outside the spec? Any help would be great. Thanks in advance
 
If you do not plan on keeping it stock they can easily be bored. Oversized pistons are common and available.
fiat124 said:
Hello...looking for some advice
On my 2002 Honda GX390 the block seems to have stress cracks so I got a used block. The cylinder sleeve ID of the replacment block is 3.467 in all areas. The spec I think is 3.4646 to 3.4652 and the service limit is 3.4710. Is this block a lost cause as its outside the spec? Any help would be great. Thanks in advanc
Click to expand...
 
fiat124 said:
Hello...looking for some advice
On my 2002 Honda GX390 the block seems to have stress cracks so I got a used block. The cylinder sleeve ID of the replacment block is 3.467 in all areas. The spec I think is 3.4646 to 3.4652 and the service limit is 3.4710. Is this block a lost cause as its outside the spec? Any help would be great. Thanks in advance
Click to expand...
89mm piston is stock (standard bore.) 90mm pistons are available, as are other over-sizes.
If you just want to remain stock, have the cylinder honed to clean it up and a stock piston with new rings should still work fine with your current bore size.

We have new take-out genuine Honda pistons and rings available if you want to go that route, or aftermarket bigger bore flat top pistons as well.
Give us a call if we can be of any help.


-----
🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
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32 years of service to the karting industry ~ 1Cor 9:24
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
 
fiat124 said:
Hello...looking for some advice
On my 2002 Honda GX390 the block seems to have stress cracks so I got a used block. The cylinder sleeve ID of the replacment block is 3.467 in all areas. The spec I think is 3.4646 to 3.4652 and the service limit is 3.4710. Is this block a lost cause as its outside the spec? Any help would be great. Thanks in advance
Click to expand...
not stress cracks...they were casting marks :) back up an running
 
thanks...though I was kinda looking forward to rebuilding it :) ...I watched several youtube video of guys in flip flops and chickens clucking in the background rebuilding these motors...I have all the tools but was searching craigslist for a good chicken assistant to be in my video LOL :)
 
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