I heard of some people doing this. What exactly is done? Is it worth it? How about reliability?

 

This is something that a do it yourselfer can't do. It must be left to a highly compitent machine shop with experience due to needing to be kept properly ballance and or counter weighted. It reduces the rotating mass and weight so the engine can rev quicker, no real hp gaines, maybe a ponie or two, if that. But talk a bout spinning up quick, whoo.

 

I hvae a local shop that will cut me a good deal. But does anyone know about how much this would run? If done proper, is reliability no question?

 

It's a big waste of money, you might get 1 or 2 more HP but you will lose alot of torque and reliability. I did it to an 200x years ago and after spending about $350 the only difference was that it would stall easier if I didn't rev the engine high before letting out the clutch. Biggest waste of money ever. Don't do it.

 

Its been done on every kind of engine for years now. You will loose your low speed idle because there usually isnt enough weight left to maintain a smooth idle. You will gain some power but it probably isnt worth the money it costs to have it done, spend it on something else that will yield more power and drivability.

 

Reliability is not a really a question if done right. Ridability is.

Seriously question your motives for doing this. Honda spent a lot of R&D setting up the proper flywheel weight for the 400EX's engine, gearing, & weight.

You risk making your 400 stall easier and produce less low end torque for grunting over techincal terrain.

If you look to the dirtbike world, most people are ADDING weight to their flywheels, not removing it.

Unless you are strictly into drag racing, it's a bad idea.

 

I beleive i will stay away from doing this after hearing you all's opinion's. Appreciate the advice guys.