400Ex Bore?
#1
400Ex Bore?
I have an 02 400EX, I have to tear down my entire engine due to my piston being destroyed. I am going to bored it out, but not sure how big I should go. I am putting a stage 2 hotcam, stage 3 cdi box and coil on it during the rebuild. I'd like to have some room later as well if it decides to destroy itself again. So I am thinking 1 or 2 over. Tell me the upsides and down sides of each bore size.
#2
My engine machinist hates boring anything less than 0.5mm at a time. If the piston broke, you may have to go this much, or more, just to get the marks out. You do get a midge more power on max bore size, but there is no more room for further re-bores. Some aftermarket piston suppliers go bigger than Honda, but the cylinder liner is thinner, so weaker. The combination of a tuned engine and weakened cylinder is not ideal.
#4
You will really need to get the jug to your machinist to see what options you have. The thing is, being an air cooled engine, they don't like a huge over bore hence why the 440 kits can be problematic. Of you are just going up a size or two from stock should be no issues. In any case, a new jug isn't that expensive and probably less hassle if you do a kit and are doing the rest of the work yourself. At least it is easier for me to replace parts since I don't have the talent or machinery to do the cylinder bore and hone myself.