I run a 16t font sprocket on my 400ex and would like to have more torque in 4t and 5t gear.
I dont now if I should put a hi compression piston and cam ore go with a 440 big bore kit,rev limiter, etc...
Thanks for the reply.

 

Why not bore out your cylinder (416cc, 426cc, or 440cc) and put in a higher compression piston as well?

ogre

 

You're on top of it, ogre! Re-bore requires a new piston anyway!

Tree Farmer

 

damn 16 tooth whats stock?

 

15 tooth is the orignal equipment

 

It would be a lot safer to run a 15 tooth sproket with a 41 tooth rear there for you can run the case saver...case saver saved my engine on more then one account...friggen rear bearings

 

I Have modify my case saver and run with 16t front sprocket because I need more top speed to run on long gravel road.
Now, is there anyone that can tell me if there is a big difference in the mid to high rev when you put a high compression piston(stock bore) or is it best to put a 440 big bore.Thanks for the reply.

 

How did you modify your case saver to run the 16 tooth. I found that you would have to grind it down to being only no exsitence.

 

You are going to have a problem finding a 440 piston that does not increase your compression to at least 11:1. The compression increase will definitely benefit your low and midrange. If that is the main place you are looking to gain power (low and midrange), I would not spend the extra money to go to a 440 (requires a new cylinder sleeve).

 

To griff, yes I have grind my case saver to fit my 16t front sprocket and buy a new one when I go with the original 15t.