I have a pretty much stock 400ex except for the pipe and filter. My buddies have yfz 450's. One has about 20,000 into his after being hit by a truck 2 different times and all the upgrades and stuff he has done to it. The other one is stock and will blow the doors off the tricked out one. How can i give my 400 a chance? Is there anything i can do to pick up a little speed? This winter i will probably do a 440 kit. How hard are they to put in? I have also noticed a very light ticking when idleing so i think i may need a new timing chain maybe.

 

might want to check into the valve adjustment. . .that is probably where your ticking is. . .as for the rest im a noob [img]i/expressions/face-icon-small-smile.gif[/img]

 

I agree you may wanna check your valve adjustment. It probably is what is causing the ticking.

You mentiond the pipe and filter but didnt say anything about jetting. Jetting is a must when piping. It will run much better and prevent damage to your engine.

A 440 kit is a major rebuild. I would start with 426. Its cheaper and you won't have to re-sleeve your cylinder. You will get a noticable hp boost but no matter what you do a 400 is not a 450.

 

<div class="FTQUOTE"><begin quote>Originally posted by: Koopa

I agree you may wanna check your valve adjustment. It probably is what is causing the ticking.



You mentiond the pipe and filter but didnt say anything about jetting. Jetting is a must when piping. It will run much better and prevent damage to your engine.



A 440 kit is a major rebuild. I would start with 426. Its cheaper and you won't have to re-sleeve your cylinder. You will get a noticable hp boost but no matter what you do a 400 is not a 450.</end quote></div>

could he just put a 450R motor on his 400? that would be sick.

 

<div class="FTQUOTE"><begin quote>Originally posted by: 2kredz3

could he just put a 450R motor on his 400? that would be sick.</end quote></div>


Ha, that would freak some ppl out. I don't think I'd do that. For one I dunno where you would find just a 450 at a price I'd be willing to pay. Also, dunno if it would fit or not, never tried. Even if you did get it setup. The suspension on the 400EX is nowhere near par with the 450R.

If he must keep the 400EX I'd say 426 big bore and cam it. It'll keep up with the 450's (behind but not far behind) and may even get a few stock 450's in a drag.

 

lol, if i didnt have a 4 year warranty i would try it as soon as my 420 blew [img]i/expressions/face-icon-small-smile.gif[/img] but your right my 420 trails behind a stock 450 but not by much and on the dig with the gear ratios the rancher has i shoot out in front [img]i/expressions/face-icon-small-smile.gif[/img]

 

also, he said his friends yfz's have a few mods to them so, no matter what you do there gonna kick your butt pretty good. But the bore kit and cam and maybe a little porting would help. but after all of that your spending lots of $$ and you should just save that money for a few years and get a new 450 and smoke them all. IMO

 

also, he said his friends yfz's have a few mods to them so, no matter what you do there gonna kick your butt pretty good. But the bore kit and cam and maybe a little porting would help. but after all of that your spending lots of $$ and you should just save that money for a few years and get a new 450 and smoke them all. IMO

 

How do you check your valve adjustment? As far as the pipe and filter goes they were on the machine when i bought it so i have no clue if it has been jetted.

With a 426 Big Bore kit there is no sleeving required? What does this kit consist of? Anyone know how much they cost?

Only one of the yfz's are moded and he is the slower of the 2. Its the stock yfz that kicks us both. That thing just hauls. I guess the other moded one must of went wrong some where.

 

Yea he problably didn't rejet and he problably needs some tweaking done to his mods, but he should be winning the races unless he is bad at riding.