What kind of power upgrades would a high performance piston do to an XR400. Are they worse for the engine? Do they cut down on reliability? Is it worth the money and time to put in? Or are there other, cheeper, and less time consuming upgrades out there? Im just wondering so I can start looking for mods to do to my bike when I get it. Thanks!
1976 Honda XL250 with J&R Exhaust System - For Sale
There are all kinds of aftermarket pistons for the 400. You can get different compression ratios. Stock is 9.3:1 I have seen them up at about 12:1 which would require race gas to run properly. I have a 416 piston kit in my bike. This is an increase of 19cc's over stock. The compression ratio of the piston I have is 10.8:1 which is also an increase over stock. By increasing the compression ratio the piston is compressing the air/fuel mixture even more before the spark ignites it off to send the piston back down. By compressing it more it is going to make the ignition of the air/fuel mix more forceful, basically sending the piston down even harder than before. This will add more power, but over time could cause some parts to wear out faster than they would normally. To answer your question about it being worth it, I would say it is worth every penny. My XR400 felt like a rocket after I bored it out, and I have heard the same thing from others who have done the same thing.
I unlike Thump have a 426 kit with 11:1 comp and it is awsome.. It runs OK with 91 octane but it really comes alive with 40% race gas mixed in. The giggle factor is worth it coming up next in maybe 5 years the big one the 440 with the 12:1 comp