high comp pistons

[gcart2]

ok so i have a race mechanic buildng my bike and i was told he was putting 13-1 comp piston.. its stock bore. what brand is this piston?

[GPracer2500]

Ask the builder.

The only 13:1 400EX shelf piston I know of is an 88mm (426cc) JE. [shrug]

[1965 honda]

yeah good luck with that:eek2:

[250x_kyle]

13 to 1 high comp stock bore piston. i think id go find a new mechanic. even if there is a 13 to 1 compression stock bore your gunna want to put hd jug studs and some vp race fule.

[gcart2]

Originally posted by 250x_kyle
13 to 1 high comp stock bore piston. i think id go find a new mechanic. even if there is a 13 to 1 compression stock bore your gunna want to put hd jug studs and some vp race fule.
yea right this guy races too. he has a stocker 450 (not stock at all) a 500r a 250r (flat track) a yfz 450 for playing with. this guy chrages nearly nothing and gurantees all. hes more of a friend to us. i no they have them i have seen them. they are just like 300 dollars and hes getting of a shop that sell parts for what they pay for them to him.

[REDRIDDER]

Can you say expensive to run 13.1=race fuel ,HD studs.13.1 is a high compression ratio for an ex,i would go with an 11.1 with little to no mods not a 13.1 WOW....

[hondaman440ex]

For a stock bore 13:1 is to much. You are going to have problems with blowing head gaskets and spend more in racing fuel. My 440ex has 12.5:1 compression and I have to run race fuel. Almost twice the cost of regular gas! I run 110VP and just paid $6.45 a gallon. Premium around my town is about $3.35. Just think is it going to be worth it or not!

[JOEX]

Why is 13:1 too much for the stock bore and how does the difference in bore size affect blowing head gaskets?