Is it ok to do this?

[trx99400ex]

Is it ok to just put a 440 big bore in your engine and leave everything else stock inside the engine?

[04'400ex'er]

Thats not a good idea. It would be wise to install hardened rockers heavier valve springs and a new conecting rod. That would increase your reliability ALOT!

[UglyMotha™]

he said he was only installing a bore, didn't say anything about an aftermarket cam he said he was keeping everything else stock, so if he installed hardened rockers it will eat the cam alive and also what exactly would stiffer springs do for a stock cam, these are all unecessary

the only thing i would put with the 440 would be larger head studs and a stronger rod

however a 440 will not perform to its peak performance unless you go with an aftermarket cam (depending on which one you still will not need hardened rockers) also flow the head larger carb and a full exhaust system

[04'400ex'er]

It woulden't be reasonable to me to put a 440 big bore in and not put a cam in it.

[UglyMotha™]

you didn't mention anything about a cam and if you read his question you would have noticed that he said everything was remaining stock so to me it is not reasonable to give someone information that is goin to destroy thier motor ;)

[logan]

you better put a cam and exhaust system and jet kit and air filter

[UglyMotha™]

Originally posted by logan
you better put a cam and exhaust system and jet kit and air filter



leave everything else stock inside the engine?



i think you'll have a hard time fitting that air filter inside the engine :huh

[logan]

you know what i mean

[James Parent]

get air scoops, you'll see the most gain out of them

[trx99400ex]

I would like to put in the 440 kit but I cant affored the cam and al that extra stuff right now. So would it be a bad idea to put in a 440 kit and leave all the engine stock?

Originally posted by trx99400ex
ISo would it be a bad idea to put in a 440 kit and leave all the engine stock? yes..do everything at once...and what kind of suspension do you have? if you ride trails or MX then suspension will probably do more good for you then moor work

[skidaddyjr]

I agree I think your money will do you better in a set of works no rezzie steelers $325.00new, You're opening a can of worms you probably need to research more!A steering damper $125.00new will also greatly improve your time on the trails or track.Speed on the trails and on the track is 80% rider skill and 15% bike % luck!

[F-16Guy]

Originally posted by trx99400ex
I would like to put in the 440 kit but I cant affored the cam and al that extra stuff right now. So would it be a bad idea to put in a 440 kit and leave all the engine stock?
Your bike being a '99, it would be a good idea to save a little extra money and do it right. I wouldn't rebuild a bike that old without doing at least a good valve job and replacing the cam chain and possibly the chain guides and tensioner, depending on how they look. If you're talking about one of those IMS/Wiseco 440 kits, you'll also be looking at some machine work in addition to the boring to get it set up right. Depending on the compression ratio you want to run, you may also want to replace the connecting rod (which can be pretty spendy). If you're on a tight budget and just want more power (and know how to turn a wrench), How about this:
1) Bore cylinder for 87mm (416) piston, about $40-$50
2) New piston kit, 87mm 11:1 CR, about $95-$140 depending on brand
3) Cometic Flex-Steel (make sure it's the laminated steel head gasket) top end gasket set, about $30
4) HotCams stage 2 drop-in cam (no hardened rockers or core required), about $125
5) Valve job w/new Viton seals, $110 done by ProFab ATV
6) CRF450 cam chain and 400ex clutch cover gasket from servicehonda.com, about $45 (including their $8 minimum shipping charge)
7) 165 main jet and 42 pilot jet, about $10
Total: about $475 plus shipping for a good, reliable rebuild.

[04'400ex'er]

Originally posted by UglyMotha™
you didn't mention anything about a cam and if you read his question you would have noticed that he said everything was remaining stock so to me it is not reasonable to give someone information that is goin to destroy thier motor ;)

He would be better off to save a little money like F-16 said and do the cam and the exhaust and filter. if he just did the 440, he would be putting out minimal power compared to his potential. And i dont believe he is going to rush to the garage and install hardened rockers and stiffer springs and soon as some people reply to his thread. that, would not be reasonable.

[trx99400ex]

If I was to get just a 416 piston, and get it bored and all for the kit. Do you think it would be ok without getting a new cam and all that. I have a uni filter and white brothers r4. I also have +4 durblue axle. I might go with a 416 instead of a 440. What is the best 416 kit to buy.

[skidaddyjr]

I run a stock valvetrain on a 88mm bore with a big ported head,bored carb,full exaust . Racing XC also use this same moto to trail ride it has held up two full season with just ring adn oil cahnges.Plus a stock cam is much smoother.

[olimj]

Originally posted by trx99400ex
Is it ok to just put a 440 big bore in your engine and leave everything else stock inside the engine?

Interesting question. I've been wondering the same thing.

7 years ago I did the Powroll 352cc bore/stroke to my 250x to make a brute force dunes hillclimber. I wasn't looking to win drags, but wanted a quiet sleeper that would climb like a tractor. All I did was bigger headpipe, remove the stock core, rejet, and add an oil cooler. Yes, I left lots of potential on the table, but I got exactly what I wanted - 80% of the power increase for 50% of the cost (no substitute for CCs). I've ridden the wheels off it with zero problems, and it's turned lots of heads over the years coming out of climbs (Oregon Dunes) where a stock 250x would have no business being.

I recently picked up a 400ex for cheap, and I'm considering a similar approach. I don't care about high-HP revs, just cheap reliable mid-range torque. Keeping it looking and sounding as stock as possible adds to the fun factor for me.