Depends on where you are. I'll be putting down about $400 for a tune. Call around and ask if they do dyno tuning. You don't want a sniffer put in the pipe either. That IMO is a waste of time and money. You want to see exactly where the A/F ratio is from idle all the way to the limiter. A sniffer just tells you the A/F ratio.

 

so if i go with the 450r carb will i have to tune the carb down to keep it from blowing up? and would you stick with the stage 2 cam or should i change?

 

You'll have to tune the carb for the new combo. I would do the stage 2 cam.

 

thanks for all the info...ill let ya know how it turns out.

 

just bore it to a 416cc then after that needs to be rebuilt get the 426cc because after you bore it to a 426cc the next size up is 440cc

 

If you plan to own it along time, save your bores. The stock 85mm sleve can go to 88mm (426). You can go up one or 2 mm and be at 406 or 416 and still have the last rebore, incase you need it.

I doubt you could find any power differences between 87mm and 88, if the same brand and compression of piston was used. Another point is the machine shop charges for each pass they make. If they cut .5mm each pass a 406 would be 4 passes less than a 426, saving money for other things.

 

you have a good point there....so is there a major differences with the 416 and the 426...and also i was goin to put a 450r carb on with the 426, should i not do this if i go with a 416?

 

I don't know the actual HP difference, but I know it would take a good dyno to see it.

I have an fcr 39 carb on my 440 stroker. The stroker doesn't need that much fuel, but the stock carb is gone. The stock stroke engine with a rev cam, would probably benefit from a bigger carb. The 450 stocker is 40mm I believe, but would be cheaper than an FCR. The yfz 450's came with 39mm carbs and the can be put on the 400ex, also. You have to take the Yamaha cable to do that swap, though. Keep in mind the 99-04 carb is 35mm and the 05 and up is 38.

 

so it would be safe to switch to a 450r or a yfz carb?