Honda ATV Forum banner

1 - 8 of 8 Posts

·
Registered
Joined
·
40 Posts
Discussion Starter · #1 ·
Just recently had my 87 250x bored 80 over and while looking for pistons the only weisco 80 over are 12:1 but you can get a 300ex same bore with 11:1...my questions are-

1> These are the same pistons right?..not the rods i know the strokes are different. If so why dont they market other compression options for each?

2> With the 12:1 you have to run race gas right? and if so is the extra power made over the 11:1 worth the trouble of race gas
 

·
Super Moderator
Joined
·
18,228 Posts
The main reason the 300EX piston is lower in CR is due to the fact that it has electric start and it is more difficult for the starter to crank it over. the 250X is a Kicker so the CR isn't that important. But the pistons are the same
 

·
Registered
Joined
·
1,285 Posts
you might be able to run 12.1 on pump. you will hear it knocking (kinda sounds like pop corn cernals poping) if it is knocking and you might need race gas.

maybe 93 octane with torco in the gas.
 

·
Registered
Joined
·
2,392 Posts
thats wat my friend does with his 480
 

·
Super Moderator
Joined
·
18,228 Posts
That is true it would be very hard to use the kick start with such compression.
Not really the 300EX dosent have the decompression system most sights that sell high compression pistons state somewhere that it's not good to run a high Comp. piston in the 300ex due to starter Issues.. However people still do it and some work and some are wondering why their starter is burnt up.
My 250X has 12:1 C/R but it as the decompression system and it kicks fairly easy. I generally slow kick it first and then one a hard kick and it starts. I have had it kick back on me a few times and it's pretty tough.
 

·
Registered
Joined
·
40 Posts
Discussion Starter · #7 ·
is the power made from the 12:1 worth the higher cr
 

·
Super Moderator
Joined
·
18,228 Posts
I think so but I suppose its a matter of what type of fuel your willing to buy.. lol pump gas at 3.00 or Cam2 and 8.75
 
1 - 8 of 8 Posts
Top