flat top piston question

ianmanning26

ianmanning26

New Member
#1
#1
i was wondering if anyone could tell me which honda engines come stock with a flat top piston. i have several honda gx160s for parts but have not cracked them open yet.
also i have read here that lots of people like to run a +.20 arc rod with the flat top piston in the blue hf clones, my question is can you still run a longer rod on a blue hf if you install a gx160 cylinder head on it. i plan on switching heads to increase compression and running a flat top piston in a blue hf and i dont want the longer rod to be too long with the smaller cylinder head.

yes i did a search and could not find a very good answer to this specific question. thanks.
 
cheezy1

cheezy1

#2
#2
You can get a new Honda flat top and rings through OldMiniBikes Warehouse. It is better to start fresh and hone the cylinder while your replacing it. The piston is only 16.50 and rings are another 13.00. But knowing everything is new is priceless. As far as the rod..you need to know how far the piston is in the hole and then you can get the rod to compensate the distance.
 
saychz316

saychz316

New Member
#6
#6
if you are installing a flat top piston, purchase a new one. don't take a used one out of an old engine. if you must, well, here is some info.

to the best of my knowledge:

older gx160's (not sure of the cutoff date or number to look for) came with dished pistons and 14cc heads.
newer gx160's come with flat top pistons and 18cc heads. (this is what my wifes motor had in it)
i forget how the newest model gx160's come.

the piston is in the hole approximately .035" on a harbor freight blue clone, just depends on how good foo lihng yoo was with the mill the day the block was built in china. with a .020" longer rod, it would move to ~ .015" in the hole. with a .010" head gasket, that puts you at ~ .025" piston to head clearance, no matter what head you put on there. what will change depending on the head with the longer rod and flat top piston will be your static compression ratio. got to www. nr-racing.com they have a compression chart on their website. look at bottom left on their home page for tech documents and data. you will find it there.
 
ianmanning26

ianmanning26

New Member
#8
#8
any idea how I can tell if my gx 160 has a 40 north 18 cc head? I would like to at least use that part because those are very expensive as I'm sure you know. the piston rings I can spring for but they are asking a ridiculous amount for the 14 cc head . if anyone could tell me how I can tell the difference with some basic hand tools that would be great .
 
graygoose420

graygoose420

New Member
#10
#10
Are your trying to get the piston for the predator ? predator piston is bigger . Stock gx160/200 Honda pistons are flat top but too small for the predator . Bigger gx's pistons will need modification. Don't know about gc series.
 
ianmanning26

ianmanning26

New Member
#11
#11
no sorry i should have clarified. it will be going on a blue greyhound 6.5 im building up. any clearance problems or fitting issues i should be aware of, oversized rings needed or stock size?
 
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