Big Bore Kits

[Newrider08]

OK you big bore guys I have a question lol

After reading post after post where you guys have done 415, 426, and 440 kits I have a couple questions

Why did you do it? was it for more power or because you had to do a re-bore and just went larger?

What parts would I need to do a big bore kit and is something that someone with general mechanical knowledge like myself can do?

I know about having to bore for a 416 and 426 and a new 440 sleeve for a 440 but what other machining has to be done for the kits?

and do you HAVE to replace your cam and your timing/cam chain?


I wont ask what the best bore size is as everyone has a preference but what is the easiest kit to do with good gains from stock?

also are the heavy duty studs worth the money and what is the best place to get them?

[honda400ex2003]

mine was burning a bit of oil from the vavle seals, I took it in under warranty and they slopped some new rings in it. after that it steadily lost power so I figured I would do it right myself. If you can change oil on a car you can do this rebuild. It is quite easy. Just boring is needed unless you go 440 then they press out the old sleeve bore the cylinder itself and press in the 440 sleeve. I would say the parts are in my sig but go with at least a stage 2 if going 426 or 440. You don't have to change the cam chain but they can stretch over time. 416 is probably the best bang for the buck across the board from what I have read. If not going over 11:1 on the mid bores hd arent really needed. If I was doing a 440 I would with 11:1. Anything over 11:1 on any needs to have HD studs added to the mix. I think I got all of the questions, good luck, steve

[Newrider08]

I mainly just ride trails and woods with some mild hill climbing, I am basically into riding wheelies and fast acceleration and some occasional fast runs in a bean field.

I guess what im trying to say is, I would like more bottom and mid and im not really needing any more top end, obviously I want faster than stock but and not too concerned with top end

[honda400ex2003]

do the stage 1 then and gear it down. that will definitely make it a wheelie monster. Mine lifts up in any gear i want and it is 15. 38 gearing. It is controlable though not just wheelie while taking off every time. I control when. steve

[Newrider08]

what all is involved in putting in a stage 1 cam?

[honda400ex2003]

making sure the motor at TDC top dead center, taking the valve cover off, unbolting the stock cam and putting the new cam in. check the vavle clearance and adjust if neccessary. then install it all and ride it to break it in. Not too bad. steve

[honda400ex2003]

oh you have to make sure the parts for the stock decompressor mechanism are out too. the hotcam comes with valve specs. I think that is about it. steve

[m36indiana]

if your cylinder is good, no need to go big bore just put in a higher compression piston to get more power out of it and save the bore and hone cash for a cam

[honda400-4-ever]

Originally posted by honda400ex2003
do the stage 1 then and gear it down. that will definitely make it a wheelie monster. Mine lifts up in any gear i want and it is 15. 38 gearing. It is controlable though not just wheelie while taking off every time. I control when. steve

im probaly going to bore to a 416 11:1 with stage 1 what is the best gearing for now and should i change the gearing if bore it(i like to ride trails and open fields)

[RoadRage77]

Don't forget if you're gonna go big bore, you're gonna need more fuel. So you're gonna need a big carb (39mm FCR). And exhaust.
I did the TC 926 grind cams in my bikes. They hit a lot better then the Hotcam stage 2 that I originally had in it.
ALso, I perfer more compression, but with more compression you're gonna need to run race fuel. Which can start to get costly. Like they say, if you wanna play you gotta pay ! Last time I got race fuel 116 oct I think it was almost 9-10 a gallon... but don't quote me on that price. I just know the price was up high.
It just all depends on what you wanna do with the bike and how much you can afford to spend. Of course you will need some tools. And get the book so you can look back for reference.
Good luck on the decision!

[jcs003]

i got a JE 89mm hi-comp piston (12:1) and one of their sleeves. i had four stroke tech do the sleeve and do the port work. it wasn't too expensive and the power is better than any kit out there and is extremely reliable. the motor ends up being 435cc.

[honda400-4-ever]

so what would be the best gearing

[jcs003]

i recommend +1 in the front with stock height tires. also depends on your riding style, type of riding and etc.

[honda400-4-ever]

WHAT WOULD BE THE BEST FOR TRAILS/OPEN FIELD WHEELIES

[jcs003]

a EX wheelies easy with any gearing im sure. i can get mine up in 4th sometimes.

[honda400-4-ever]

come up dude ur not helping me!! not to be mean..i just want answers can anybody help me :confused: