I've been posting questions about my build up on my 400EX. Here's what I've done. A JE 416cc piston (11:1), port and polished head with stock valves, Hotcams stage 1 cam, White Bros e-series slip-on, K&N filter, Dynojet jet kit, white bros clutch kit. What would you guys say on how much power this will have. Do you think maybe 10hp's over stock is possible? I hope to have it running this weekend. Thanks!!!

 

You will notice a nice difference but I doubt it will be 10 more ponies.


It takes a NICELY biult 440 with a 39mm FCR to get around 38-40 h.p.







BIgger.

 

how much would that carb cost?

 

Nicely built? How much more can be done to one? Haven't I hit every area on the engine, except a new carb?

 

I didnt mean to make you biuld sound less than "nice".

the fact is you have a very mild biuld, and thats just fine for a nice gain in power. But if you want 40 h.p power out of a 400ex then you should have went with a 13:5 piston(atleast),and a Bigger cam. then top it off with the 39mm FCR.



It all depends on what you use your quad for. If you are in and out of trals then you will have plenty of power. but if you want to take on Rptors, DS's,and etc.. in a drag race, then you will be wanting more.



Bigger.

 

Ok, Guys yes it is a mild hop up. Here whats next for our hop up, Lighten the flywheel, lighten the crank, is there a reason why you had the ports Polished??? BAD MOVE, here is why, your head will not ditribute the fuel correctly if you would just flow the heads it would work much better and gain more ponies, now I know their is ones out there that will disagree but I have had years of experience with building race quads when I raced in the late 80's, also my shop that did all the work would build 1100hp motors for cars do you ever see them polish their heads...No their is a reason ask your local machine shop they will explain your wasting money and horse power when you polish the ports. OK NEXT if you want a few more ponies have you ever thought about NOS on your bike??? Bigger oil cooler???Synthic oil as well. I would say you may be pushing a extra 8 9 hp out of your hop up. I was racing 250 Mojave's and was pushing 52 hp with my hop ups man I miss that bike. I used to hole shot 250r's with that bike in races man it was fast, them were the days. I hope that answered some questions, jim[img]i/expressions/face-icon-small-wink.gif[/img]

 

Ok, first of all, I know how to port heads. I didn't polish the intake port, just the exhaust. I finished the intake port with 80 grit cartridge rolls. This will let the air and fuel mixture bounce around some so it can mix better. This is exactly how I did my 69 Nova with a 406sbc and man does it scream (450-500hp's, 550-600hps with nitrous 100-shot). This may seem like I'm trying to be a smart@#&, but I'm not. I just wanted to explain what I meant by porting and polishing [img]i/expressions/face-icon-small-smile.gif[/img]

 

Fastone, smarter than I thought...that is exactly what a true builder does, you have idiots that think it needs to be polished on the intake side as well no no these aren't 2 strokes, nice comment, [img]i/expressions/face-icon-small-cool.gif[/img]